Jaclyn Demartini, M. Foston, Xianzhi Meng et al.

Biotechnology for Biofuels • 2015

BackgroundWoody biomass is highly recalcitrant to enzymatic sugar release and often requires significant size reduction and severe pretreatments to achieve economically viable sugar yields in biological production of sustainable fuels and chemicals. However, because mechanical size reduction of woody biomass can consume significant amounts of energy, it is desirable to minimize size reduction and instead pretreat larger wood chips prior to biological conversion. To date, however, most laboratory research has been performed on materials that are significantly smaller than applicable in a commercial setting. As a result, there is a limited understanding of the effects that larger biomass particle size has on the effectiveness of steam explosion pretreatment and subsequent enzymatic hydrolysis of wood chips.ResultsTo address these concerns, novel downscaled analysis and high throughput pretreatment and hydrolysis (HTPH) were applied to examine whether differences exist in the composition and digestibility within a single pretreated wood chip due to heterogeneous pretreatment across its thickness. Heat transfer modeling, Simons’ stain testing, magnetic resonance imaging (MRI), and scanning electron microscopy (SEM) were applied to probe the effects of pretreatment within and between pretreated wood samples to shed light on potential causes of variation, pointing to enzyme accessibility (i.e., pore size) distribution being a key factor dictating enzyme digestibility in these samples. Application of these techniques demonstrated that the effectiveness of pretreatment of Populus tremuloides can vary substantially over the chip thickness at short pretreatment times, resulting in spatial digestibility effects and overall lower sugar yields in subsequent enzymatic hydrolysis.ConclusionsThese results indicate that rapid decompression pretreatments (e.g., steam explosion) that specifically alter accessibility at lower temperature conditions are well suited for larger wood chips due to the non-uniformity in temperature and digestibility profiles that can result from high temperature and short pretreatment times. Furthermore, this study also demonstrated that wood chips were hydrated primarily through the natural pore structure during pretreatment, suggesting that preserving the natural grain and transport systems in wood during storage and chipping processes could likely promote pretreatment efficacy and uniformity.

D. P. Maurya, A. Singla, S. Negi

3 Biotech • 2015

Second-generation bioethanol can be produced from various lignocellulosic biomasses such as wood, agricultural or forest residues. Lignocellulosic biomass is inexpensive, renewable and abundant source for bioethanol production. The conversion of lignocellulosic biomass to bioethanol could be a promising technology though the process has several challenges and limitations such as biomass transport and handling, and efficient pretreatment methods for total delignification of lignocellulosics. Proper pretreatment methods can increase concentrations of fermentable sugars after enzymatic saccharification, thereby improving the efficiency of the whole process. Conversion of glucose as well as xylose to bioethanol needs some new fermentation technologies to make the whole process inexpensive. The main goal of pretreatment is to increase the digestibility of maximum available sugars. Each pretreatment process has a specific effect on the cellulose, hemicellulose and lignin fraction; thus, different pretreatment methods and conditions should be chosen according to the process configuration selected for the subsequent hydrolysis and fermentation steps. The cost of ethanol production from lignocellulosic biomass in current technologies is relatively high. Additionally, low yield still remains as one of the main challenges. This paper reviews the various technologies for maximum conversion of cellulose and hemicelluloses fraction to ethanol, and it point outs several key properties that should be targeted for low cost and maximum yield.

Xiaolu Li, Yucai He, Libing Zhang et al.

Biotechnology for Biofuels • 2019

BackgroundBiological routes for utilizing both carbohydrates and lignin are important to reach the ultimate goal of bioconversion of full carbon in biomass into biofuels and biochemicals. Recent biotechnology advances have shown promises toward facilitating biological transformation of lignin into lipids. Natural and engineered Rhodococcus strains (e.g., R. opacus PD630, R. jostii RHA1, and R. jostii RHA1 VanA−) have been demonstrated to utilize lignin for lipid production, and co-culture of them can promote lipid production from lignin.ResultsIn this study, a co-fermentation module of natural and engineered Rhodococcus strains with significant improved lignin degradation and/or lipid biosynthesis capacities was established, which enabled simultaneous conversion of glucose, lignin, and its derivatives into lipids. Although Rhodococci sp. showed preference to glucose over lignin, nearly half of the lignin was quickly depolymerized to monomers by these strains for cell growth and lipid synthesis after glucose was nearly consumed up. Profiles of metabolites produced by Rhodococcus strains growing on different carbon sources (e.g., glucose, alkali lignin, and dilute acid flowthrough-pretreated poplar wood slurry) confirmed lignin conversion during co-fermentation, and indicated novel metabolic capacities and unexplored metabolic pathways in these organisms. Proteome profiles suggested that lignin depolymerization by Rhodococci sp. involved multiple peroxidases with accessory oxidases. Besides the β-ketoadipate pathway, the phenylacetic acid (PAA) pathway was another potential route for the in vivo ring cleavage activity. In addition, deficiency of reducing power and cellular oxidative stress probably led to lower lipid production using lignin as the sole carbon source than that using glucose.ConclusionsThis work demonstrated a potential strategy for efficient bioconversion of both lignin and glucose into lipids by co-culture of multiple natural and engineered Rhodococcus strains. In addition, the involvement of PAA pathway in lignin degradation can help to further improve lignin utilization, and the combinatory proteomics and bioinformatics strategies used in this study can also be applied into other systems to reveal the metabolic and regulatory pathways for balanced cellular metabolism and to select genetic targets for efficient conversion of both lignin and carbohydrates into biofuels.

Leo A Holt, Brian Milligan

Australian Journal of Biological Sciences • 1981

Experiments with the N-benzyloxycarbonyl derivatives of asparagine and glutamine as models show that, in unbuffered solutions, I,I-diacetoxyiodobenzene (1) is more effective than the corresponding trifluoroacetoxy derivative (2) for converting the amide side-chains of proteins to amines. Maximum modification of the glutamine residues of insulin and lysozyme occurs within 1-2 h of treatment with 1 in aqueous methyl cyanide at 20�C, but asparagine residues react more slowly. The amide side-chains are converted to the corresponding amines in at least 90 % yield, as shown by analysis of acid hydrolysates for aspartic acid, lX,p-diaminopropionic acid, glutamic acid and lX,y-diaminobutyric acid. Numerous side-reactions also occur, tyrosine, cystine, methionine, arginine, lysine and N-terminal residues all being modified to some extent.

Vishnu Baba Sundaresan, Stephen Andrew Sarles, Brian J Goode et al.

MRS Proceedings • 2006

ABSTRACT Ion transport across cell membranes happens through protein channels and pumps expending concentration gradients, electrical gradients and energy from chemical reactions. Ion exchange in cell membranes is responsible for nutrient transport from production sites to where they are broken down to release energy. Sucrose transport is vital for growth in higher plants and recent research has led to the discovery of a class of sugar carriers called SUT4. The SUT4 transporter is a low affinity, high capacity proton-sucrose transporter that participates in long distance sucrose transport in higher plants. We demonstrated the possibility to use purified SUT4 transporter proteins — with the genetic code from Arabidopsis thaliana expressed on yeast cells — for fluid transport driven by pH gradient and from exergonic ATP hydrolysis reaction in the presence of ATP-ase enzyme. The SUT4 proteins were reconstituted on a planar bilayer lipid membrane formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) phospholipids on a porous substrate. This article builds upon our previous work to harness energy from the ATP-ase reaction using SUT4 to produce a proton current through SUT4 and demonstrates the technical feasibility to generate electrical current in an external circuit. The results from our characterization experiments on a single cell demonstrate that the power source behaves like a constant current power source with an internal resistance of 10-22 kΩ and produces a peak power of 150 nW.

Florent Collas, Beau B. Dronsella, Armin Kubis et al.

bioRxiv (Cold Spring Harbor Laboratory) • 2023

Abstract To advance the sustainability of the biobased economy, our society needs to develop novel bioprocesses based on truly renewable resources. The C1-molecule formate is increasingly proposed as carbon and energy source for microbial fermentations, as it can be efficiently generated electrochemically from CO 2 and renewable energy. Yet, its biotechnological conversion into value-added compounds has been limited to a handful of examples. In this work, we engineered the natural formatotrophic bacterium C. necator as cell factory to enable biological conversion of formate into crotonate, a platform short-chain unsaturated carboxylic acid of biotechnological relevance. First, we developed a small-scale (150-mL working volume) cultivation setup for growing C. necator in minimal medium using formate as only carbon and energy source. By using a fed-batch strategy with automatic feeding of formic acid, we could increase final biomass concentrations 15-fold compared to batch cultivations in flasks. Then, we engineered a heterologous crotonate pathway in the bacterium via a modular approach, where each pathway section was assessed using multiple candidates. The best performing modules included a malonyl-CoA bypass for increasing the thermodynamic drive towards the intermediate acetoacetyl-CoA and subsequent conversion to crotonyl-CoA through partial reverse β-oxidation. This pathway architecture was then tested for formate-based biosynthesis in our fed-batch setup, resulting in a two-fold higher titer, three-fold higher productivity, and five-fold higher yield compared to the strain not harboring the bypass. Eventually, we reached a maximum product titer of 148.0 ± 6.8 mg/L. Altogether, this work consists in a proof-of-principle integrating bioprocess and metabolic engineering approaches for the biological upgrading of formate into a value-added platform chemical.

Liesje De Schamphelaire, Willy Verstraete

Biotechnology and Bioengineering • 2009

Abstract In the quest for renewable resources, algae are increasingly receiving attention. Their high growth rate, high CO 2 fixation and their lack of requirement for fertile soil surface represent several advantages as compared to conventional (energy) crops. Through their ability to store large amounts of oils, they qualify as a source for biodiesel. Algal biomass, however, can also be used as such, namely as a substrate for anaerobic digestion. In the present research, we investigated the use of algae for energy generation in a stand‐alone, closed‐loop system. The system encompasses an algal growth unit for biomass production, an anaerobic digestion unit to convert the biomass to biogas and a microbial fuel cell to polish the effluent of the digester. Nutrients set free during digestion can accordingly be returned to the algal growth unit for a sustained algal growth. Hence, a system is presented that continuously transforms solar energy into energy‐rich biogas and electricity. Algal productivities of 24–30 ton VS ha −1 year −1 were reached, while 0.5 N m 3 biogas could be produced kg −1 algal VS. The system described resulted in a power plant with a potential capacity of about 9 kW ha −1 of solar algal panel, with prospects of 23 kW ha −1 . Biotechnol. Bioeng. 2009;103: 296–304. © 2009 Wiley Periodicals, Inc.

Anqi Ji, Linjing Jia, Deepak Kumar et al.

Fermentation • 2021

Sustainable, economically feasible, and green resources for energy and chemical products have people’s attention due to global energy demand and environmental issues. Last several decades, diverse lignocellulosic biomass has been studied for the production of biofuels and biochemicals. Industrial hemp has great market potential with its versatile applications. With the increase of the hemp-related markets with hemp seed, hemp oil, and fiber, the importance of hemp biomass utilization has also been emphasized in recent studies. Biological conversions of industrial hemp into bioethanol and other biochemicals have been introduced to address the aforementioned energy and environmental challenges. Its high cellulose content and the increased production because of the demand for cannabidiol oil and hempseed products make it a promising future bioenergy and biochemical source. Effective valorization of the underutilized hemp biomass can also improve the cost-competitiveness of hemp products. This manuscript reviews recent biological conversion strategies for industrial hemp and its characteristics. Current understanding of the industrial hemp properties and applied conversion technologies are briefly summarized. In addition, challenges and future perspectives of the biological conversion with industrial hemp are discussed.

R. Schönberger

Water Science and Technology • 1990

At the end of 1988 a 22,000 p.e. municipal wastewater treatment plant in Northern Germany was converted to the EASC-biological phosphorus removal process. By simple modifications of the flow scheme of the plant, one of two existing primary clarifiers was converted to an anaerobic basin, into which both sewage and recycle sludge are fed. The supernatant as well as the sludge withdrawn from the bottom are discharged into the aeration basin. This operation mode achieves very good phosphorus uptake in the aeration basin. Since start up in November '88, the uptake-capacity increased continually, since April '89 phosphorus is removed down to concentrations of less than 1 mg/l PO4-P in the aeration basin. Due to an inadequate design and size of the existing final clarifier, phosphorus bleedback occurs and reduces removal efficiency. This bleedback could be minimized by either intensifying denitrification or reducing sludge detention time in the final clarifier.

Xiaoqing Cao, Kai Xia, Hongfei Zhao et al.

Frontiers in Forests and Global Change • 2024

Introduction Land-use changes significantly impact soil properties in forests, which is an area of concern. Therefore, the effects of changing forest types on soil microbial communities and their functions in northern subtropical forest regions need to be further researched. Methods We used 16S rDNA sequencing and Functional Annotation of Prokaryotic Taxa (FAPROTAX) to assess the variation of soil bacterial communities and potential functions related to carbon (C) and nitrogen (N) cycling in two soil layers (0–10 and 10–30 cm) after the conversion of the secondary masson pine ( Pinus massoniana , PM) forest to plantations of slash pine ( Pinus elliottii , PE) and Chinese fir ( Cunninghamia lanceolata , CL) located in Jingde County, Anhui Province, China. Results The study found that converting coniferous secondary forests to coniferous plantations resulted in a notable increase in soil pH and a decrease in nitrate nitrogen and organic carbon contents. Additionally, soil microbial diversity increased significantly, and microbial community structure changed, particularly in the topsoil. These changes might affect the C- and N-cycling mediated by soil bacteria. The analysis revealed a significant decrease in the abundance of functional groups associated with C-cycling and a significant increase in the abundance of functional groups associated with N-cycling, particularly those associated with denitrification. Soil organic carbon, pH, and ammonium nitrogen were the most critical variables affecting changes in the soil microbial community. Discussion These findings provide valuable information for ecological restoration and future sustainable forest management.

Ahmed K. Saleh, Emad Tolba, Ahmed Salama

Biomass Conversion and Biorefinery • 2024

Abstract Bacterial cellulose (BC) has garnered attention among biomaterial scientists for its unique physicochemical features and biocompatibility; however, the lack of bioactivity has limited its biomedical applications. Thus, this study describes the in situ preparation of BC/hydroxyapatite (HA) nanocomposite membranes using static and agitated fermentation to enhance the bioactivity of BC. The incorporation of HA increased BC production from 2.31 g/L without HA to 4.10 and 3.26 g/L under static and agitated fermentation, respectively, although the SEM observation indicates the formation of a fibrous structure in BC mesh under both fermentations. It was also observed that the content of HA nanoparticles in BC obtained from agitated fermentation was higher than that obtained from static fermentation. In addition, the average fiber diameter was increased from 56 ± 17 nm for agitated nanocomposites (BC/HA-A) to 145 ± 48 nm for static BC/HA nanocomposites (BC/HA-S) and 122 ± 26 nm for BC. In conclusion, the in situ formation of BC/HA nanocomposite under agitated fermentation appears more convenient in term of BC yield, HA content and distribution, and cytotoxicity against fibroblast cells (BJ1). This strategy will inspire new ways to prepare BC-based materials for medical applications.

Roland H. Müller, Thore Rohwerder, Hauke Harms

Applied and Environmental Microbiology • 2007

ABSTRACT The utilization of the fuel oxygenate methyl tert -butyl ether (MTBE) and related compounds by microorganisms was investigated in a mainly theoretical study based on the Y ATP concept. Experiments were conducted to derive realistic maintenance coefficients and K s values needed to calculate substrate fluxes available for biomass production. Aerobic substrate conversion and biomass synthesis were calculated for different putative pathways. The results suggest that MTBE is an effective heterotrophic substrate that can sustain growth yields of up to 0.87 g g −1 , which contradicts previous calculation results (N. Fortin et al., Environ. Microbiol. 3:407-416, 2001). Sufficient energy equivalents were generated in several of the potential assimilatory routes to incorporate carbon into biomass without the necessity to dissimilate additional substrate, efficient energy transduction provided. However, when a growth-related kinetic model was included, the limits of productive degradation became obvious. Depending on the maintenance coefficient m s and its associated biomass decay term b , growth-associated carbon conversion became strongly dependent on substrate fluxes. Due to slow degradation kinetics, the calculations predicted relatively high threshold concentrations, S min , below which growth would not further be supported. S min strongly depended on the maximum growth rate μ ma x , and b and was directly correlated with the half maximum rate-associated substrate concentration K s , meaning that any effect impacting this parameter would also change S min . The primary metabolic step, catalyzing the cleavage of the ether bond in MTBE, is likely to control the substrate flux in various strains. In addition, deficits in oxygen as an external factor and in reduction equivalents as a cellular variable in this reaction should further increase K s and S min for MTBE.

Harald Brüssow, Carlos Canchaya, Wolf-Dietrich Hardt

Microbiology and Molecular Biology Reviews • 2004

SUMMARY Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished: Vibrio cholerae , Shiga toxin-producing Escherichia coli , Corynebacterium diphtheriae , and Clostridium botulinum depend on a specific prophage-encoded toxin for causing a specific disease, whereas Staphylococcus aureus , Streptococcus pyogenes , and Salmonella enterica serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like “swarms” of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework.

Ronald Benner, Jan Lay, Elizabeth K&nees et al.

Limnology and Oceanography • 1988

Carbon conversion efficiencies were determined for the bacterial utilization of lignocellulosic detritus in waters from an estuarine and a freshwater wetland. Conversion efficiencies during bacterial growth on lignocellulose averaged ∼30% in both estuarine (salt marsh) and freshwater (Okefenokee Swamp) samples. Our estimates of bacterial growth efficiencies on refractory particulate detritus are twofold to threefold higher than previous estimates owing, in large part, to the higher biovolume‐to‐carbon conversion factor (0.22 g C cm ‒3 ) used in the present study to convert bacterial biovolumes into units of carbon. Bacterial growth on lignocellulosic detritus was N limited in salt‐marsh water and P limited in Okefenokee water; carbon conversion efficiencies increased to 45% upon addition of ammonium and phosphate to salt‐marsh and Okefenokee incubations, respectively. These results indicate that bacterial biomass produced at the expense of lignocellulosic detritus is likely to be an important nutrient source to food webs in aquatic ecosystems with an abundance of macrophyte detritus and favorable conditions for microbial decomposition.

Thomas Maskow, Dayo Olomolaiye, Uta Breuer et al.

Biotechnology and Bioengineering • 2004

Abstract The microbial conversion of toxic substrates into valuable products in continuous culture requires the equivalent of a tight rope walk between formation of the desired product and intoxication of the microbial catalyst. The condition of the latter is reflected immediately by changes in heat flow rate and β‐dispersion in an electrical RF field. Therefore, these were applied to the example of the continuous growth‐associated synthesis of polyhydroxyalcanoates (PHA) from phenol by the bacterial strain Variovorax paradoxus DSM 4065. By controlling the supply of phenol to the chemostat, the rates of degradation, biomass formation, and synthesis of target product, respectively, were increasingly elevated until the onset of poisoning the organisms. The boundary between the maximum rates and the initiation of intoxication coincided with a sudden change in the heat flux. Using this occurrence, it was possible to develop a control strategy and test it successfully for a time period of 80 h. After 40 h the process stabilized at mean values, i.e., at rates of 92% phenol degradation, 100% biomass formation, and 70 – 75% of PHA formation compared with the situation shortly before poisoning the organisms. Using a moving‐average technique to filter the raw dielectric spectroscope data, changes were followed in biomass concentration of approximately 100 mg/L. However, this technique was not sensitive or rapid enough to control the process. © 2004 Wiley Periodicals, Inc.

Michael Funaro, Venkata Krishnamurthy Nemani, Zhihang Chen et al.

Cancer Research • 2012

Abstract Introduction Enzymes of non-human origin possess tremendous potential as anticancer agents, especially in enzyme-prodrug therapy. Unfortunately, these enzymes are recognized as foreign agents by the human immune system and are targeted by an immune response. This immune reaction limits enzymes’ efficacy, particularly in treatments requiring repeated dosing. Current strategies for deimmunizing these therapeutic enzymes are labor/time intensive and yield limited success. Encapsulating enzymes in a hydrogel, such as sodium alginate, can confer immunoprotection and enhance in vivo stability. Alginate serves as a barrier between enzyme and host and its porosity can be controlled to prevent antibody infiltration while allowing the diffusion of the prodrug and the drug. The bacterial enzyme cytosine deaminase (bCD) mediates the conversion of 5-fluorocytosine (5-FC) to the anticancer drug 5-fluorouracil (5-FU). We encapsulated the bCD in sodium alginate microbeads and tested enzyme efficacy post encapsulation as determined by conversion of 5-FC to 5-FU, with concomitant cell kill assays. Methods bCD was encapsulated in sodium alginate microbeads, ∼200 microns, using a NISCO microencapsulation system (www.nisco.ch). The beads were incubated with 5-FC (25, 50, 100 and 200 microM), and conversion to 5-FU was monitored over time using spectrophotometry. Unencapsulated bCD was used as controls. Then, microbeads were incubated with 9L rat glioma cells in the presence of 5-FC. Cytotoxicity of the enzyme-prodrug system to 9L cells was evaluated using an MTT assay. 5-FC alone in the absence of bCD and 5-FU were used as controls. Experiments were repeated using beads stored for 72 h at 4°C and 37°C and temperature effects on the stability of encapsulated bCD were noted. Results summary We observed the complete conversion of 5-FC to 5-FU for all concentrations of encapsulated enzyme, albeit at a slower rate than unencapsulated controls. Cytotoxicity of the encapsulated enzyme-prodrug system toward 9L cells was similar to that of 5-FU alone, and of unencapsulated controls, indicating that encapsulation had no deleterious effect on enzyme efficacy. Though the enzyme kinetics were slower for the stored beads (at 4°C and 37°C), these beads resulted in similar cell kill. Our results suggest that sodium alginate microencapsulation of bCD maintained the enzyme's functionality and may therefore be a suitable platform for immunoisolative enzyme-prodrug therapy. We are extending our work to other cancer cell lines and to in vivo study of the anti-tumor effects of these encapsulated enzymes. This system has the advantage of localized 5-FC to 5-FU conversion, thereby potentially reducing systemic toxicity and increasing the locally available dose of the toxic drug. The strategy can be extended to the encapsulation of enzyme-producing cells that serve as de novo drug factories. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5632. doi:1538-7445.AM2012-5632

J. D. Robinson, K. H. Mann, J. A. Novitsky

Limnology and Oceanography • 1982

The efficiency with which particulate organic carbon from seaweed detritus was transformed to bacterial carbon was determined in the laboratory by comparing changes in bacterial numbers with changes in the organic carbon content of detritus in incubation experiments lasting between 2 and 36 days. In general, the efficiencies were highest (43%) in the shortest incubations and declined with increasing length of experiment to a mean of 22% at 36 days. Nitrogen enrichment of the cultures accelerated decomposition and increased bacterial abundance but did not lead to higher conversion efficiencies than those observed without enrichment. Of the initial detrital carbon, 54% was rapidly leached into the seawater and a further 23% was removed by microbial activity. The remaining material was relatively refractory and had a low C:N ratio. The results indicate that the C:N ratio of detritus is not a good indication of its nutritional value.

Wolfgang Zinth, Josef Wachtveitl

ChemPhysChem • 2005

Abstract In this Minireview, we describe the function of the bacterial reaction centre (RC) as the central photosynthetic energy‐conversion unit by ultrafast spectroscopy combined with structural analysis, site‐directed mutagenesis, pigment exchange and theoretical modelling. We show that primary energy conversion is a stepwise process in which an electron is transferred via neighbouring chromophores of the RC. A well‐defined chromophore arrangement in a rigid protein matrix, combined with optimised energetics of the different electron carriers, allows a highly efficient charge‐separation process. The individual molecular reactions at room temperature are well described by conventional electron‐transfer theory.

Huan Wang, Xiaodong Peng, Hu Li et al.

Frontiers in Chemistry • 2022

The complexity and recalcitrance of the lignin structure is a major barrier to its efficient utilization and commercial production of high-value products. In recent years, the “bio-funneling” transformation ability of microorganisms has provided a significant opportunity for lignin conversion and integrated biorefinery. Based on the chemical structure of lignin, this mini-review introduces the recent advances of lignin depolymerization by bacterial strains and the application of microbial lignin degradation in lipids production. Furthermore, the current challenges, future trends and perspectives for microbe-based lignin conversion to lipids are discussed.

A. Schug, S. M. Schoberth, H. Sahm

Acta Biotechnologica • 1987

Abstract The conversion of lactose — the main constituent of whey — to methane and carbon dioxide was studied using different defined constructed cultures, imploying strains of Methanosarcina barkeri, Methanobacterium bryantii, Escherichia coli, Acetobacterium woodii, Lactobacillus casei , and Lactobacillus plantarum . The following combinations of strains (food chains) were studied with respect to efficiency and yield of lactose conversion (methane yield in parentheses): E. coli and M. barkeri (4.5–7.6%), E. coli and M. bryantii (13.3%), E. coli, M. barkeri and M. bryantii (54%), L. casei, A. woodii and M. barkeri (93.3%). These conversions were carried out in pH controlled batch fermentations. A very efficient coculture was a combination of L. plantarum with A. woodii and M. barkeri : in chemostat cultures lactose was converted to methane and carbon dioxide with a yield of about 90%, at dilution rates of 0.27 d ‐1 to 0.37 d ‐1 .

Izabella Ślęzak-Prochazka, Kornelia M. Batko, Andrzej Ślęzak

Entropy • 2022

We evaluated the transport properties of a bacterial cellulose (BC) membrane for aqueous ethanol solutions. Using the Rr version of the Kedem–Katchalsky–Peusner formalism (KKP) for the concentration polarization (CP) conditions of solutions, the osmotic and diffusion fluxes as well as the membrane transport parameters were determined, such as the hydraulic permeability (Lp), reflection (σ), and solute permeability (ω). We used these parameters and the Peusner (Rijr) coefficients resulting from the KKP equations to assess the transport properties of the membrane based on the calculated dependence of the concentration coefficients: the resistance, coupling, and energy conversion efficiency for aqueous ethanol solutions. The transport properties of the membrane depended on the hydrodynamic conditions of the osmotic diffusion transport. The resistance coefficients R11r, R22r, and Rdetr were positive and higher, and the R12r coefficient was negative and lower under CP conditions (higher in convective than nonconvective states). The energy conversion was evaluated and fluxes were calculated for the U-, F-, and S-energy. It was found that the energy conversion was greater and the S-energy and F-energy were lower under CP conditions. The convection effect was negative, which means that convection movements were directed vertically upwards. Understanding the membrane transport properties and mechanisms could help to develop and improve the membrane technologies and techniques used in medicine and in water and wastewater treatment processes.

Yixin Zhang, Musen Wang, Samaila Usman et al.

Microbial Biotechnology • 2023

Abstract To explore the biofuel production potential of Caragana korshinskii Kom., Pediococcus acidilactici and an exogenous fibrolytic enzyme were employed to investigate the fermentation profile, structural carbohydrates degradation, enzymatic saccharification and the dynamics of bacterial community of C . korshinskii silage. After 60 d of ensiling, all additives increased the fermentation quality. The highest lactic and acetic acids and lowest non‐protein nitrogen (NPN) and ammonia nitrogen (NH 3 ‐N) were observed in P. acidilactici and Acremonium cellulase (PA + AC) treated silage. Additionally, all additives significantly increased the ferulic acid content and fibre degradability with the highest values obtained from PA + AC silage. The bacterial community in all silages was dominated by P. acidilactici throughout the entire fermentation process. The bacterial community was also modified by the silage additives exhibiting a relatively simple network of bacterial interaction characterized by a lower bacterial diversity in P. acidilactici (PA) treated silage. The highest 6‐phospho‐beta‐glucosidase abundance was observed in PA‐treated silage at the mid‐later stage of ensiling. PA treatment exhibited lower structural carbohydrates degradation but performed better in lignocellulose conversion during enzymatic saccharification. These results indicated that pretreating C. korshinskii improved its silage quality and potential use as a lignocellulosic feedstock for the production of bio‐product and biofuel.

Rajani Pydipalli

Asian Journal of Applied Science and Engineering • 2020

To improve efficiency and scalability, this study investigates the integration of artificial intelligence (AI) and IT-enabled techniques for the microbial conversion of rubber waste in metabolic engineering. The primary goals are to build synthetic biology constructs for enhanced rubber degradation, optimize bioprocess parameters through IT techniques, and use computational tools for route optimization. Methodologically, the study synthesizes insights from AI-driven techniques and IT-enabled procedures through an extensive analysis of existing literature and secondary data sources. Notable discoveries underscore the progress made in synthetic biology design, bioprocess optimization, and pathway prediction, highlighting the transformative potential of AI-driven metabolic engineering for sustainably produced rubber. The consequences of the policy include the need for more funding for research infrastructure, capacity building, and regulatory monitoring to enable the ethical use and responsible deployment of AI technologies in biotechnology and to remove any technological implementation impediments. This work advances sustainable approaches to resource recovery and waste management for rubber, tackles global environmental issues, and advances the circular economy goal.

Giannis Penloglou, Alexandros Pavlou, Costas Kiparissides

Fermentation • 2023

The intended circular economy for plastics envisages that they will be partially replaced by bio-based polymers in the future. In this work, the natural polyester polyhydroxybutyrate (PHB) was produced by Azohydromonas lata using cheese whey (CW) as a low-cost substrate. Initially, CW was evaluated as the sole carbon source for PHB production; it was found to be efficient and comparable to PHB production with pure sugars, such as saccharose or glucose, even when mild (with dilute acid) hydrolysis of cheese whey was performed instead of enzymatic hydrolysis. An additional series of experiments was statistically designed using the Taguchi method, and a dual optimization approach was applied to maximize the intracellular biopolymer content (%PHB, selected as a quantitative key performance indicator, KPI) and the weight average molecular weight of PHB (Mw, set as a qualitative KPI). Two different sets of conditions for the values of the selected bioprocess parameters were identified: (1) a carbon-to-nitrogen ratio (C/N) of 10 w/w, a carbon-to-phosphorous ratio (C/P) of 1.9 w/w, a dissolved oxygen concentration (DO) of 20%, and a residence time in the stationary phase (RT) of 1 h, resulting in the maximum %PHB (61.66% w/w), and (2) a C/N of 13.3 w/w, a C/P of 5 w/w, a DO of 20%, and a RT of 1 h, leading to the maximum Mw (900 kDa). A final sensitivity analysis confirmed that DO was the most significant parameter for %PHB, whereas C/N was the most important parameter for Mw.

John Phillips, Raymond Huhnke, Hasan Atiyeh

Fermentation • 2017

Biomass and other carbonaceous materials can be gasified to produce syngas with high concentrations of CO and H2. Feedstock materials include wood, dedicated energy crops, grain wastes, manufacturing or municipal wastes, natural gas, petroleum and chemical wastes, lignin, coal and tires. Syngas fermentation converts CO and H2 to alcohols and organic acids and uses concepts applicable in fermentation of gas phase substrates. The growth of chemoautotrophic microbes produces a wide range of chemicals from the enzyme platform of native organisms. In this review paper, the Wood–Ljungdahl biochemical pathway used by chemoautotrophs is described including balanced reactions, reaction sites physically located within the cell and cell mechanisms for energy conservation that govern production. Important concepts discussed include gas solubility, mass transfer, thermodynamics of enzyme-catalyzed reactions, electrochemistry and cellular electron carriers and fermentation kinetics. Potential applications of these concepts include acid and alcohol production, hydrogen generation and conversion of methane to liquids or hydrogen.

Andrea C Humphries, David W Penfold, Lynne E Macaskie

Journal of Chemical Technology & Biotechnology • 2007

Abstract Use of biologically‐produced hydrogen (bio‐H 2 ) as an electron donor for Cr(VI) reduction by native and palladized cells of Desulfovibrio vulgaris NCIMB 8303 was demonstrated. The bio‐H 2 was produced fermentatively by Escherichia coli HD701 (a strain upregulated with respect to formate hydrogenlyase expression) using glucose solution or two industrial confectionery wastes as fermentable substrates. Maximum Cr(VI) reduction occurred at the expense of bio‐H 2 using palladized biomass (bio‐Pd(0)), with negligible residual Cr(VI) remaining from a 0.5 mmol dm −3 solution after 2.5 h. Use of bio‐H 2 as the electron donor for Cr(VI) reduction by agar‐immobilized bio‐Pd(0) in a continuous‐flow system gave 90% reduction efficiency at a flow residence time of 0.7 h, which was maintained for the duration of bio‐H 2 evolution by E. coli HD701. This study shows the potential to remediate toxic metal waste at the expense of food processing waste, as a sustainable alternative to landfilling. Copyright © 2007 Society of Chemical Industry

Amandeep Kaur, Anju Goyal, Sapna Kumari et al.

BIO Web of Conferences • 2024

This tutorial review summarizes the basic new concepts of green chemistry in relation to education and pharmaceutical industries. The origin and history of Green analytical chemistry is described in detail. Basic twelve principles are well summarized with suitable examples of each principle such as oxidation of alcohol, enzymatic reactions, and non-covalent derivatization. This article also covers the concept of E-factor for waste minimization, detailed various solvent selection guidelines and tools for betterment of synthetic pathways at laboratory and industrial level. The efficiency of green chemistry in organic synthesis for greenness of traditional organic synthesis methods are discussed. Nowadays, there is a constant need to add catalysts for chemical synthesis to minimize or downsize the risks correspondent with chemical manufacture. Catalyst helps to enhance air quality by reducing harmful gas emissions such as NOx. It cuts down on the use of VOCs (volatile organic compounds). It developed an alternative catalytic method which substitutes the usage of chlorine-based intermediates in chemical synthesis and processes. Biocatalysts is a term used to describe compounds that aid in the stimulation of biological reactions. In the fine chemical industry, cleaner biocatalytic alternatives are replacing traditional chemical operations.

Khaled F. Alshammari

Luminescence • 2024

Abstract The efficient degradation of organic pollutants in diverse environmental matrices can be achieved through the synergistic application of piezo‐catalysis and photocatalysis. The focus of this study is on understanding the fundamental principles and mechanisms that govern the collaborative action of piezoelectric and photocatalytic materials. Piezoelectric nanomaterials, under mechanical stress, generate piezo‐potential, which, when coupled with photocatalysts, enhances the generation and separation of charge carriers. The resulting cascade of redox reactions promotes the degradation of a wide spectrum of organic pollutants. The comprehensive investigation involves a variety of experimental techniques, including advanced spectroscopy and microscopy, to elucidate the intricate interplay between mechanical and photoinduced processes. The influence of key parameters, such as material composition, morphology, and external stimuli on the catalytic performance, is systematically explored. This study contributes to the increasing knowledge of environmental remediation and lays the foundation for the development of advanced technologies using piezo and photocatalysis for sustainable pollutant removal.

Duygu Zabitler, Esra Ülker, Kübra Turan et al.

Topics in Catalysis • 2026

Abstract Electrochemical sensors and biosensors have attracted considerable interest due to their wide range of applications in pharmaceutical analysis, drug detection, cancer diagnosis, and monitoring toxic elements in drinking water. These sensors are characterized by their affordability, ease of manufacturing, fast response times, compact size, and ability to detect multiple analytes simultaneously. Electrochemical sensors are promising tools as they can be designed to detect a variety of analytes. Common materials employed in sensor fabrication include conducting polymers, nanomaterials, and bioreceptors. This review provides a comprehensive summary of electrochemical sensors developed for the determination of various analytes in biological samples, such as blood, plasma, serum, cerebrospinal fluid, saliva, tears, sweat, and urine. It also discusses future considerations regarding recent critical studies aimed at advancing research toward the development of novel functional electrochemical biosensors for electrochemical detection in biological samples.

S. C. Barton

Handbook of Fuel Cells • 2010

Abstract Biocatalysts represent a compelling alternative to precious metals as catalysts for low‐temperature fuel cell power systems. Enzymatic catalysts capable of reducing oxygen or oxidizing small organic molecules can be less expensive and manufacturable, and have favorable reaction selectivity as compared to precious metals. The key barriers to realization of practical biocatalyzed fuel cells are the insufficient current, power, and lifetime achievable with current devices. Recently, significant progress has been made in addressing these issues, from the standpoint of fundamental studies of electron transfer to enzymes, mediation of enzyme‐catalyzed reactions, and immobilization of enzymes in materials that confer stability and high surface area for heterogeneous reactions. In this article, we introduce concepts in enzyme catalysis for energy applications and describe important recent progress.

Xiqing Cheng, Shuai Zhang, Huihui Liu et al.

ACS Applied Materials & Interfaces • 2020

Encapsulating nanopartiles/biomolecules into metal-organic freamworks (MOFs) has proven highly effective in creating new functions during their applications. However, it is highly desirable yet remains challenging to achieve the synergy of specific functions between MOF host and guest species. Herein, inspired by natural multienzyme system, a novel MOF composite biomimetic structure based on co-encapsulation of glucose oxidase (GOx) and L-arginine (L-Arg) into Cu-MOFs (CuBDC) with Fenton-like catalytic activity is designed for achieving synergistic antibacterial effect. Once activated by GOx-catalyzed glucose oxidation, a large amount of oxygen radicals, toxic ONOO- and NO are rapidly produced over this well-designed L-Arg/GOx@CuBDC through a double-cascade reaction. Thanking to the synergy of highly reactive species, outstanding antibacterial effects (bacterial inactivation ≥97%) are observed at very low doses (38 μg mL-1 for E. coli and 3.8 μg mL-1 for S. aureus). In addition, the in vivo experiment in mice demonstrated that the as-prepared L-Arg/GOx@CuBDC has good biocompatibility, indicating its good potential in practical applications. Such biomimetic multienzyme system proposes a new design idea for highly efficient antibiosis as well as even therapy of tumors.

M. Saini, Amuliya Kashyap, Shruti Bindal et al.

Frontiers in Microbiology • 2021

Gamma-glutamyl transpeptidase (GGT) enzyme is ubiquitously present in all life forms and plays a variety of roles in diverse organisms. Higher eukaryotes mainly utilize GGT for glutathione degradation, and mammalian GGTs have implications in many physiological disorders also. GGTs from unicellular prokaryotes serve different physiological functions in Gram-positive and Gram-negative bacteria. In the present review, the physiological significance of bacterial GGTs has been discussed categorizing GGTs from Gram-negative bacteria like Escherichia coli as glutathione degraders and from pathogenic species like Helicobacter pylori as virulence factors. Gram-positive bacilli, however, are considered separately as poly-γ-glutamic acid (PGA) degraders. The structure–function relationship of the GGT is also discussed mainly focusing on the crystallization of bacterial GGTs along with functional characterization of conserved regions by site-directed mutagenesis that unravels molecular aspects of autoprocessing and catalysis. Only a few crystal structures have been deciphered so far. Further, different reports on heterologous expression of bacterial GGTs in E. coli and Bacillus subtilis as hosts have been presented in a table pointing toward the lack of fermentation studies for large-scale production. Physicochemical properties of bacterial GGTs have also been described, followed by a detailed discussion on various applications of bacterial GGTs in different biotechnological sectors. This review emphasizes the potential of bacterial GGTs as an industrial biocatalyst relevant to the current switch toward green chemistry.

J. Chan, Jacqueline N. Watson, April Lu et al.

Biochemistry • 2012

Mutagenesis of the conserved glutamic acid of influenza type A (E277) and Micromonospora viridifaciens (E260) sialidases was performed to probe the contribution of this strictly conserved residue to catalysis. Kinetic studies of the E260D and E260C M. viridifaciens mutant enzymes reveal that the overall mechanism of action has not changed. That is, the mutants are retaining sialidases in which glycosylation and deglycosylation are rate-limiting for k(cat)/K(m) and k(cat), respectively. The solvent kinetic isotope effect and proton inventory on k(cat) for the E260C mutant sialidase provide strong evidence that the newly installed cysteine residue provides little catalytic acceleration. The results are consistent with the conserved aspartic acid residue (D92) becoming the key general acid/base residue in the catalytic cycle. In addition, the E277D mutant influenza type A sialidase is catalytically active toward 4-nitrophenyl α-D-sialoside, although no measurable hydrolysis of natural substrates was observed. Thus, mutating the glutamate residue (E277) to an aspartate increases the activation free energy of hydrolysis for natural substrates by >22 kJ/mol.

N. J. Reiter, Amy K. Osterman, A. Mondragón

Nucleic Acids Research • 2012

RNase P is an RNA-based enzyme primarily responsible for 5′-end pre-tRNA processing. A structure of the bacterial RNase P holoenzyme in complex with tRNAPhe revealed the structural basis for substrate recognition, identified the active site location, and showed how the protein component increases functionality. The active site includes at least two metal ions, a universal uridine (U52), and P RNA backbone moieties, but it is unclear whether an adjacent, bacterially conserved protein loop (residues 52–57) participates in catalysis. Here, mutagenesis combined with single-turnover reaction kinetics demonstrate that point mutations in this loop have either no or modest effects on catalytic efficiency. Similarly, amino acid changes in the ‘RNR’ region, which represent the most conserved region of bacterial RNase P proteins, exhibit negligible changes in catalytic efficiency. However, U52 and two bacterially conserved protein residues (F17 and R89) are essential for efficient Thermotoga maritima RNase P activity. The U52 nucleotide binds a metal ion at the active site, whereas F17 and R89 are positioned >20 Å from the cleavage site, probably making contacts with N−4 and N−5 nucleotides of the pre-tRNA 5′-leader. This suggests a synergistic coupling between transition state formation and substrate positioning via interactions with the leader.

Feili Lai, Wei Zong, Guanjie He et al.

Angewandte Chemie International Edition • 2020

Vacancy engineering has been proved repeatedly as an adoptable strategy to boost electrocatalysis, while its poor selectivity restricts the usage in nitrogen reduction reaction (NRR) as overwhelming competition from hydrogen evolution reaction (HER). Revealed by density functional theory calculations, the selenium vacancy in ReSe 2 crystal can enhance its electroactivity for both NRR and HER by shifting the d -band from -2.91 to -2.33 eV. To restrict the HER, we report a novel method by burying selenium vacancy-rich ReSe 2 @carbonized bacterial cellulose (V r -ReSe 2 @CBC) nanofibers between two CBC layers, leading to boosted Faradaic efficiency of 42.5% and ammonia yield of 28.3 μg h -1 cm -2 at a potential of -0.25 V at an abrupt interface. As demonstrated by the nitrogen bubble adhesive force, superhydrophilic measurements, and COMSOL Multiphysics simulations, the hydrophobic and porous CBC layers can keep the internal V r -ReSe 2 @CBC nanofibers away from water coverage, leaving more unoccupied active sites for the N 2 reduction (especially for the potential determining step of proton-electron coupling and transferring processes as *HNNH 2 → *H 2 NNH 2 ).

Xinyu Gao, Yihong Liu, Yuqing Li et al.

ACS Applied Materials & Interfaces • 2023

Catalytic nanomedicine can in situ catalytically generate bactericidal species under external stimuli to defend against bacterial infections. However, bacterial biofilms seriously impede the catalytic efficacy of traditional nanocatalysts. In this work, MoSe2 nanoflowers (NFs) as piezoelectric nanozymes were constructed for dual-driven catalytic eradication of multi-drug-resistant bacterial biofilms. In the biofilm microenvironment, the piezoelectricity of MoSe2 NFs was cascaded with their enzyme-mimic activity, including glutathione oxidase-mimic and peroxidase-mimic activity. As a result, the oxidative stress in the biofilms was sharply elevated under ultrasound irradiation, achieving a 4.0 log10 reduction of bacterial cells. The in vivo studies reveal that the MoSe2 NFs efficiently relieve the methicillin-resistant Staphylococcus aureus bacterial burden in mice under the control of ultrasound at a low power density. Moreover, because of the surface coating of antioxidant poly(ethyleneimine), the dual-driven catalysis of MoSe2 NFs was retarded in normal tissues to minimize the off-target damage and favor the wound healing process. Therefore, the cascade of piezoelectricity and enzyme-mimic activity in MoSe2 NFs reveals a dual-driven strategy for improving the performance of catalytic nanomaterials in the eradication of bacterial biofilms.

Y. Yu, Lei Tan, Zhaoyang Li et al.

ACS Nano • 2021

Osteomyelitis, as a severe bone disease caused by bacterial infection, can result in lifelong disability or fatal sepsis. Considering that the infection is stubborn and deep-sited in bone tissue, in situ and rapid treatments for osteomyelitis remain a significant challenge. Herein, we prepare an ultrasound (US)-activated single-atom catalyst that consists of a Au nanorod (NRs)-actuated single-atom-doped porphyrin metal-organic framework (HNTM-Pt@Au) and red cell membrane (RBC), which can efficiently treat methicillin-resistant Staphylococcus aureus (MRSA)-infected osteomyelitis under US. Besides the outstanding performance in the field of photocatalysis, we find that single atoms (such as Pt, Au, Cu) also improve the sonocatalytic ability of the sonosensitizer. Due to the strong electron-trapping and oxygen adsorption capacity, the Pt single atom endows RBC-HNTM-Pt@Au with an excellent sonocatalytic activity. It shows an excellent antibacterial performance with an antibacterial efficiency of 99.9% toward MRSA under 15 min of US irradiation. Meanwhile, the RBC-HNTM-Pt@Au can be propelled directionally under US and thus dynamically neutralize the secreted toxins. The MRSA-infected osteomyelitis in rat tibia was successfully treated, which shows negligible bone loss, reduced inflammation response, and great biocompatibility. This work presents an efficient sonodynamic therapy for the treatment of deep tissue infections via a multifunctional single-atom catalyst.

Xavier Arqué, Marcelo D. T. Torres, Tania Patiño et al.

ACS Nano • 2022

The increasing resistance of bacteria to existing antibiotics constitutes a major public health threat globally. Most current antibiotic treatments are hindered by poor delivery to the infection site, leading to undesired off-target effects and drug resistance development and spread. Here, we describe micro- and nanomotors that effectively and autonomously deliver antibiotic payloads to the target area. The active motion and antimicrobial activity of the silica-based robots are driven by catalysis of the enzyme urease and antimicrobial peptides, respectively. These antimicrobial motors show micromolar bactericidal activity in vitro against different Gram-positive and Gram-negative pathogenic bacterial strains and act by rapidly depolarizing their membrane. Finally, they demonstrated autonomous anti-infective efficacy in vivo in a clinically relevant abscess infection mouse model. In summary, our motors combine navigation, catalytic conversion, and bactericidal capacity to deliver antimicrobial payloads to specific infection sites. This technology represents a much-needed tool to direct therapeutics to their target to help combat drug-resistant infections.

Sheng Dong, Tian‐Di Wei, Xiulan Chen et al.

Journal of Biological Chemistry • 2014

Background: The maturation and catalysis mechanisms of the PL18 alginate lyases have not yet been reported. Results: The N-terminal extension in the precursor of PL18, aly-SJ02, helped the catalytic domain fold correctly. Key residues for substrate recognition and catalysis were determined. Conclusion: The catalytic mechanism of aly-SJ02 is proposed. Significance: This study provides the foremost insight into maturation and catalysis of PL18 alginate lyases. Bacterial alginate lyases, which are members of several polysaccharide lyase (PL) families, have important biological roles and biotechnological applications. The mechanisms for maturation, substrate recognition, and catalysis of PL18 alginate lyases are still largely unknown. A PL18 alginate lyase, aly-SJ02, from Pseudoalteromonas sp. 0524 displays a β-jelly roll scaffold. Structural and biochemical analyses indicated that the N-terminal extension in the aly-SJ02 precursor may act as an intramolecular chaperone to mediate the correct folding of the catalytic domain. Molecular dynamics simulations and mutational assays suggested that the lid loops over the aly-SJ02 active center serve as a gate for substrate entry. Molecular docking and site-directed mutations revealed that certain conserved residues at the active center, especially those at subsites +1 and +2, are crucial for substrate recognition. Tyr353 may function as both a catalytic base and acid. Based on our results, a model for the catalysis of aly-SJ02 in alginate depolymerization is proposed. Moreover, although bacterial alginate lyases from families PL5, 7, 15, and 18 adopt distinct scaffolds, they share the same conformation of catalytic residues, reflecting their convergent evolution. Our results provide the foremost insight into the mechanisms of maturation, substrate recognition, and catalysis of a PL18 alginate lyase.

T. V. Zharova, V. G. Grivennikova, V. Borisov

International Journal of Molecular Sciences • 2023

F1·Fo-ATP synthases/ATPases (F1·Fo) are molecular machines that couple either ATP synthesis from ADP and phosphate or ATP hydrolysis to the consumption or production of a transmembrane electrochemical gradient of protons. Currently, in view of the spread of drug-resistant disease-causing strains, there is an increasing interest in F1·Fo as new targets for antimicrobial drugs, in particular, anti-tuberculosis drugs, and inhibitors of these membrane proteins are being considered in this capacity. However, the specific drug search is hampered by the complex mechanism of regulation of F1·Fo in bacteria, in particular, in mycobacteria: the enzyme efficiently synthesizes ATP, but is not capable of ATP hydrolysis. In this review, we consider the current state of the problem of “unidirectional” F1·Fo catalysis found in a wide range of bacterial F1·Fo and enzymes from other organisms, the understanding of which will be useful for developing a strategy for the search for new drugs that selectively disrupt the energy production of bacterial cells.