Biotechnology for Biofuels最新文献

{"title":"Strategies and tools to construct stable and efficient artificial coculture systems as biosynthetic platforms for biomass conversion","authors":"Xinyu Song,&nbsp;Yue Ju,&nbsp;Lei Chen,&nbsp;Weiwen Zhang","doi":"10.1186/s13068-024-02594-2","DOIUrl":"10.1186/s13068-024-02594-2","url":null,"abstract":"<div><p>Inspired by the natural symbiotic relationships between diverse microbial members, researchers recently focused on modifying microbial chassis to create artificial coculture systems using synthetic biology tools. An increasing number of scientists are now exploring these systems as innovative biosynthetic platforms for biomass conversion. While significant advancements have been achieved, challenges remain in maintaining the stability and productivity of these systems. Sustaining an optimal population ratio over a long time period and balancing anabolism and catabolism during cultivation have proven difficult. Key issues, such as competitive or antagonistic relationships between microbial members, as well as metabolic imbalances and maladaptation, are critical factors affecting the stability and productivity of artificial coculture systems. In this article, we critically review current strategies and methods for improving the stability and productivity of these systems, with a focus on recent progress in biomass conversion. We also provide insights into future research directions, laying the groundwork for further development of artificial coculture biosynthetic platforms.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02594-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142859816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction of nicotine content in tobacco through microbial degradation: research progress and potential applications","authors":"Zi-Jia Li,&nbsp;Dong-Dong Yang,&nbsp;Zhi-Yun Wei,&nbsp;Jie Huang,&nbsp;Yi-Qian Chi,&nbsp;You-Xuan Lu,&nbsp;Feng-Wei Yin","doi":"10.1186/s13068-024-02593-3","DOIUrl":"10.1186/s13068-024-02593-3","url":null,"abstract":"<div><p>Originally native to South America, tobacco and is now distributed worldwide as a major cash crop. Nicotine is the main harmful component of tobacco leaves, cigarette smoke and tobacco waste, which severely affects not only the flavor of the tobacco leaf, but also causes great damage to human health. As the anti-smoking movement continued to grow since the 1950s, and consumers become more aware of their health and environmental protection, the world tobacco industry has been committed to research, develop and produce low nicotine cigarette products with relatively low risk to human health. Among various approaches, the use of microorganisms to reduce nicotine content and improve tobacco quality has become one of the most promising methods. Due to increasing interest in nicotine-degrading microorganisms (NDMs), this article reviews recent reports on NDMs, nicotine-degrading enzymes, regulation of nicotine-degrading bacterial consortia and optimization of fermentation conditions, aiming to provide updated references for the in-depth research and application of microorganisms for the degradation of nicotine.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02593-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrophosphate-free glycolysis in Clostridium thermocellum increases both thermodynamic driving force and ethanol titers","authors":"Bishal Dev Sharma,&nbsp;Shuen Hon,&nbsp;Eashant Thusoo,&nbsp;David M. Stevenson,&nbsp;Daniel Amador-Noguez,&nbsp;Adam M. Guss,&nbsp;Lee R. Lynd,&nbsp;Daniel G. Olson","doi":"10.1186/s13068-024-02591-5","DOIUrl":"10.1186/s13068-024-02591-5","url":null,"abstract":"<div><h3>Background</h3><p><i>Clostridium thermocellum</i> is a promising candidate for production of cellulosic biofuels, however, its final product titer is too low for commercial application, and this may be due to thermodynamic limitations in glycolysis. Previous studies in this organism have revealed a metabolic bottleneck at the phosphofructokinase (PFK) reaction in glycolysis. In the wild-type organism, this reaction uses pyrophosphate (PP_i) as an energy cofactor, which is thermodynamically less favorable compared to reactions that use ATP as a cofactor. Previously we showed that replacing the PP_i-linked PFK reaction with an ATP-linked reaction increased the thermodynamic driving force of glycolysis, but only had a local effect on intracellular metabolite concentrations, and did not affect final ethanol titer.</p><h3>Results</h3><p>In this study, we substituted PP_i-<i>pfk</i> with ATP-<i>pfk</i>, deleted the other PP_i-requiring glycolytic gene <i>pyruvate:phosphate dikinase</i> (<i>ppdk</i>), and expressed a soluble <i>pyrophosphatase</i> (<i>PPase</i>) and <i>pyruvate kinase</i> (<i>pyk</i>) genes to engineer PP_i-free glycolysis in <i>C. thermocellum</i>. We demonstrated a decrease in the reversibility of the PFK reaction, higher levels of lower glycolysis metabolites, and an increase in ethanol titer by an average of 38% (from 15.1 to 21.0 g/L) by using PP_i-free glycolysis.</p><h3>Conclusions</h3><p>By engineering PP_i-free glycolysis in <i>C. thermocellum</i>, we achieved an increase in ethanol production. These results demonstrate that optimizing the thermodynamic landscape through metabolic engineering can enhance product titers. While further increases in ethanol titers are necessary for commercial application, this work represents a significant step toward engineering glycolysis in <i>C. thermocellum</i> to increase ethanol titers.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02591-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antimicrobial peptide production with Corynebacterium glutamicum on lignocellulosic side streams","authors":"Daniel Waldschitz,&nbsp;Mark-Richard Neudert,&nbsp;Jakob Kitzmüller,&nbsp;Jae Hwi Bong,&nbsp;Yannick Bus,&nbsp;Eva Maria Karner,&nbsp;Peter Sinner,&nbsp;Oliver Spadiut","doi":"10.1186/s13068-024-02587-1","DOIUrl":"10.1186/s13068-024-02587-1","url":null,"abstract":"<div><h3>\u0000 <b>Background</b>\u0000 </h3><p>Biorefineries usually focus on the production of low-value commodities, such as bioethanol, platform chemicals or single cell protein. Shifting production to bioactive compounds, such as antimicrobial peptides, could provide an opportunity to increase the economic viability of biorefineries.</p><h3>\u0000 <b>Results</b>\u0000 </h3><p>Recombinant production of the antimicrobial peptide pediocin PA-1 in <i>Corynebacterium glutamicum</i> was transferred from yeast extract-based media to minimal media based on lignocellulosic spent sulfite liquor. Induced batch, fed batch, and extended batch process modes were compared for highest pediocin PA-1 production.</p><h3>\u0000 <b>Conclusion</b>\u0000 </h3><p>For pediocin PA-1 production on lignocellulosic residues, extended batch cultivation was identified as the optimal process mode, producing up to <span>(simeq)</span> 104 mg/L active pediocin PA-1. Moreover, the production of pediocin PA-1 on this sustainable second generation resource exceeded its state-of-the-art production on yeast extract-based media <span>(simeq)</span> 1.5-fold.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02587-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biofilm application for anaerobic digestion: a systematic review and an industrial scale case","authors":"Getachew Birhanu Abera,&nbsp;Erik Trømborg,&nbsp;Linn Solli,&nbsp;Juline M. Walter,&nbsp;Radziah Wahid,&nbsp;Espen Govasmark,&nbsp;Svein Jarle Horn,&nbsp;Nabin Aryal,&nbsp;Lu Feng","doi":"10.1186/s13068-024-02592-4","DOIUrl":"10.1186/s13068-024-02592-4","url":null,"abstract":"<div><p>Biofilm is a syntrophic community of microorganisms enveloped by extracellular polymeric substances and displays remarkable adaptability to dynamic environments. Implementing biofilm in anaerobic digestion has been widely investigated and applied as it promotes microbial retention time and enhances the efficiency. Previous studies on anaerobic biofilm primarily focused on application in wastewater treatment, while its role has been significantly extended to accelerate the degradation of lignocellulosic biomass, improve gas–liquid mass transfer for biogas upgrading, or enhance resistance to inhibitors or toxic pollutants. This work comprehensively reviewed the current applications of biofilm in anaerobic digestion and focused on impacting factors, optimization strategies, reactor set-up, and microbial communities. Moreover, a full-scale biofilm reactor case from Norway is also reported. This review provides a state of-the- art insight on the role of biofilm in anaerobic digestion. </p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02592-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving productivity of citramalate from CO2 by Synechocystis sp. PCC 6803 through design of experiment","authors":"Matthew Faulkner,&nbsp;Fraser Andrews,&nbsp;Nigel Scrutton","doi":"10.1186/s13068-024-02589-z","DOIUrl":"10.1186/s13068-024-02589-z","url":null,"abstract":"<div><h3>Background</h3><p>Cyanobacteria have long been suggested as an industrial chassis for the conversion of carbon dioxide to products as part of a circular bioeconomy. The slow growth, carbon fixation rates, and limits of carbon partitioning between biomass and product in cyanobacteria must be overcome to fully realise this industrial potential. Typically, flux towards heterologous pathways is limited by the availability of core metabolites. Citramalate is produced in a single enzymatic step through the condensation of the central metabolites pyruvate and acetyl-CoA; improvements in citramalate productivity can, therefore, be used as a measure of overcoming this limitation. Furthermore, citramalate is a useful biomaterial precursor and provides a route to renewable methyl methacrylate and poly(methyl methacrylate), which is often traded as Perspex or Plexiglas.</p><h3>Results</h3><p>Here, we describe a phenomenon where the concerted optimisation of process parameters significantly increased citramalate production in <i>Synechocystis</i> sp. PCC 6803. Design of experiment principles were used to determine the optima for each parameter and the interplay between multiple parameters. This approach facilitated a ~ 23-fold increase in citramalate titre from initial unoptimised experiments. The process of scale-up from batch cultures to 0.5, 2, and 5 L photobioreactors is described. At the 2-L scale, citramalate titres from carbon dioxide reached 6.35 g/L with space–time yields of 1.59 g/L/day whilst 5-L PBRs yielded 3.96 ± 0.23 g/L with a productivity of 0.99 ± 0.06 g/L/day. We believe the decrease in productivity from 2-L to 5-L scale was likely due to the increased pathlength and shading for light delivery reducing incident light per cell. However, changes in productivity and growth characteristics are not uncommon when scaling up biotechnology processes and have numerous potential causes.</p><h3>Conclusions</h3><p>This work demonstrates that the use of a process parameter control regime can ameliorate precursor limitation and enhance citramalate production. Since pyruvate and/or acetyl-CoA give rise to numerous products of biotechnological interest, the workflow presented here could be employed to optimise flux towards other heterologous pathways. Understanding the factors controlling and thus increasing carbon partitioning to product will help progress cyanobacteria as part of a carbon–neutral circular bioeconomy. This is the first study using design of experiment to optimise overall carbon fixation rate and carbon partitioning to product, with the goal of improving the performance of a cyanobacterium as a host for biological carbon capture.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02589-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142778251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative physiology and biomass composition of Cyberlindnera jadinii in ethanol-grown cultures","authors":"Marcel A. Vieira-Lara,&nbsp;Marieke Warmerdam,&nbsp;Erik A. F. de Hulster,&nbsp;Marcel van den Broek,&nbsp;Jean-Marc Daran,&nbsp;Jack T. Pronk","doi":"10.1186/s13068-024-02585-3","DOIUrl":"10.1186/s13068-024-02585-3","url":null,"abstract":"<div><h3>Background</h3><p>Elimination of greenhouse gas emissions in industrial biotechnology requires replacement of carbohydrates by alternative carbon substrates, produced from CO₂ and waste streams. Ethanol is already industrially produced from agricultural residues and waste gas and is miscible with water, self-sterilizing and energy-dense. The yeast <i>C. jadinii</i> can grow on ethanol and has a history in the production of single-cell protein (SCP) for feed and food applications. To address a knowledge gap in quantitative physiology of <i>C. jadinii</i> during growth on ethanol, this study investigates growth kinetics, growth energetics, nutritional requirements, and biomass composition of <i>C. jadinii</i> strains in batch, chemostat and fed-batch cultures.</p><h3>Results</h3><p>In aerobic, ethanol-limited chemostat cultures, <i>C. jadinii</i> CBS 621 exhibited a maximum biomass yield on ethanol (<span>(Y_{X/S}^{max})</span>) of 0.83 <i>g</i>_biomass (g_ethanol)⁻¹ and an estimated maintenance requirement for ATP (<i>m</i>_ATP) of 2.7 mmol_ATP (g_biomass)⁻¹ h⁻¹. Even at specific growth rates below 0.05 h⁻¹, a stable protein content of approximately 0.54 g_protein (g_biomass)⁻¹ was observed. At low specific growth rates, up to 17% of the proteome consisted of alcohol dehydrogenase proteins, followed by aldehyde dehydrogenases and acetyl-CoA synthetase. Of 13 <i>C. jadinii</i> strains evaluated, 11 displayed fast growth on ethanol (<i>μ</i>_max &gt; 0.4 h⁻¹) in mineral medium without vitamins, and CBS 621 was found to be a thiamine auxotroph. The prototrophic strain <i>C. jadinii</i> CBS 5947 was grown on an inorganic salts medium in fed-batch cultures (10-L scale) fed with pure ethanol. Biomass concentrations in these cultures increased up to 100 g_biomass (kg_broth)⁻¹, with a biomass yield of 0.65 g_biomass (g_ethanol)⁻¹. Model-based simulation, based on quantitative parameters determined in chemostat cultures, adequately predicted biomass production. A different protein content of chemostat- and fed-batch-grown biomass (54 and 42%, respectively) may reflect the more dynamic conditions in fed-batch cultures.</p><h3>Conclusions</h3><p>Analysis of ethanol-grown batch, chemostat and fed-batch cultures provided a quantitative physiology baseline for fundamental and applied research on <i>C. jadinii</i>. Its high maximum growth rate, high energetic efficiency of ethanol dissimilation, simple nutritional requirements and high protein content, make <i>C. jadinii</i> a highly interesting platform for production of SCP and other products from ethanol.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02585-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142778462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermobifida fusca Cel6B moves bidirectionally while processively degrading cellulose","authors":"Madeline M. Johnson,&nbsp;Antonio DeChellis,&nbsp;Bhargava Nemmaru,&nbsp;Shishir P. S. Chundawat,&nbsp;Matthew J. Lang","doi":"10.1186/s13068-024-02588-0","DOIUrl":"10.1186/s13068-024-02588-0","url":null,"abstract":"<div><h3>Background</h3><p>Cellulose, an abundant biopolymer, has great potential to be utilized as a renewable fuel feedstock through its enzymatic degradation into soluble sugars followed by sugar fermentation into liquid biofuels. However, crystalline cellulose is highly resistant to hydrolysis, thus industrial-scale production of cellulosic biofuels has been cost-prohibitive to date. Mechanistic studies of enzymes that break down cellulose, called cellulases, are necessary to improve and adapt such biocatalysts for implementation in biofuel production processes. <i>Thermobifida fusca</i> Cel6B (<i>Tf</i>Cel6B) is a promising candidate for industrial use due to its thermostability and insensitivity to pH changes. However, mechanistic studies probing <i>Tf</i>Cel6B hydrolytic activity have been limited to ensemble-scale measurements.</p><h3>Results</h3><p>We utilized optical tweezers to perform single-molecule, nanometer-scale measurements of enzyme displacement during cellulose hydrolysis by <i>Tf</i>Cel6B. Records featured forward motility on the order of 0.17 nm s⁻¹ interrupted by backward motions and long pauses. Processive run lengths were on the order of 5 nm in both forward and backward directions. Motility records also showed rapid bidirectional displacements greater than 5 nm. Single-enzyme velocity and bulk ensemble activity were assayed on multiple crystalline cellulose allomorphs revealing that the degree of crystallinity and hydrogen bonding have disparate effects on the single-molecule level compared to the bulk scale. Additionally, we isolated and monitored the catalytic domain of <i>Tf</i>Cel6B and observed a reduction in velocity compared to the full-length enzyme that includes the carbohydrate-binding module. Applied force has little impact on enzyme velocity yet it readily facilitates dissociation from cellulose. Preliminary measurements at elevated temperatures indicated enzyme velocity strongly increases with temperature.</p><h3>Conclusions</h3><p>The unexpected motility patterns of <i>Tf</i>Cel6B are likely due to previously unknown mechanisms of processive cellulase motility implicating irregularities in cellulose substrate ultrastructure. While <i>Tf</i>Cel6B is processive, it has low motility at room temperature. Factors that most dramatically impact enzyme velocity are temperature and the presence of its native carbohydrate-binding module and linker. In contrast, substrate ultrastructure and applied force did not greatly impact velocity. These findings motivate further study of <i>Tf</i>Cel6B for its engineering and potential implementation in industrial processes.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02588-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142761850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing hexanoic acid biosynthesis in Saccharomyces cerevisiae for the de novo production of olivetolic acid","authors":"Kilan J. Schäfer,&nbsp;Marco Aras,&nbsp;Eckhard Boles,&nbsp;Oliver Kayser","doi":"10.1186/s13068-024-02586-2","DOIUrl":"10.1186/s13068-024-02586-2","url":null,"abstract":"<div><p>Medium chain fatty acids (MCFAs) are valuable platform compounds for the production of biotechnologically relevant chemicals such as biofuels and biochemicals. Two distinct pathways have been implemented in the yeast <i>Saccharomyces cerevisiae</i> for the biosynthetic production of MCFAs: (i) the mutant fatty acid biosynthesis (FAB) pathway in which the fatty acid synthase (FAS) complex is mutated and (ii) a heterologous multispecies-derived reverse β-oxidation (rBOX) pathway. Hexanoic acid has become of great interest as its acyl-CoA ester, hexanoyl-CoA, is required for the biosynthesis of olivetolic acid (OA), a cannabinoid precursor. Due to insufficient endogenous synthesis of hexanoyl-CoA, recombinant microbial systems to date require exogenous supplementation of cultures with hexanoate along with the overexpression of an acyl-CoA ligase to allow cannabinoid biosynthesis. Here, we engineer a recombinant <i>S. cerevisiae</i> strain which was metabolically optimized for the production of hexanoic acid via the FAB and rBOX pathways and we combine both pathways in a single strain to achieve titers of up to 120 mg L⁻¹. Moreover, we demonstrate the biosynthesis of up to 15 mg L⁻¹ OA from glucose using hexanoyl-CoA derived from the rBOX pathway.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02586-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142778463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Valorization of milling byproducts and ergot-sclerotia-contaminated rye via clostridial ABE fermentation","authors":"Holger Edelmann,&nbsp;Nils Thieme,&nbsp;Armin Ehrenreich,&nbsp;Vladimir Zverlov,&nbsp;Wolfgang Liebl","doi":"10.1186/s13068-024-02590-6","DOIUrl":"10.1186/s13068-024-02590-6","url":null,"abstract":"<div><h3>Background</h3><p>Acetone–butanol–ethanol (ABE) fermentation by solventogenic clostridia can be harnessed to produce CO₂ emission neutral bio-based 1-butanol, a valuable compound with a broad range of applications, e.g., in industrial production, as a solvent and as a fuel additive or replacement. However, the relatively low butanol titers and high feedstock costs prevent bio-butanol production on an industrial scale. Agricultural side-stream materials, like milling byproducts, are starch-rich, low-cost and produced all year round. They could be suitable substrates for bio-butanol production by ABE fermentation.</p><h3>Results</h3><p>The milling byproducts wheat red dog (WRD), rye second flour (RSF), wheat bran (WB), rye bran (RB) and ergot sclerotia-containing rye waste stream (ER) were found to contain between ~ 30 and ~ 85% glucan, most of which was starch based. WRD, RSF and ER had the highest glucan content, while the brans contained significant xylan concentrations. Four strains selected from the collection of solventogenic clostridia available in our group produced &gt; 6 g/L butanol on the majority of these substrates, with <i>Clostridium beijerinckii</i> NCIMB 8052 showing the best ABE production performance when regarding all tested substrates. Toxic ergot sclerotia-containing waste material was found to be a suited substrate for ABE fermentation. Strain NCIMB 8052 exhibited butanol titers of up to 9 g/L on substrate mixtures of WRD plus ER and the highest butanol yield per used sugars. Finally, a semi-continuous ABE fermentation of <i>C. beijerinckii</i> NCIMB 8052 on WRD plus ER could be maintained for 96 h. The volumetric ABE productivity during the continuous phase of fermentation was ~ 0.41 g L⁻¹ h⁻¹ and a total of 37.7 g ABE was produced out of 168.2 g substrate.</p><h3>Conclusions</h3><p>Based on their carbohydrate composition, WRD, RSF and ER were the milling byproducts best suited as substrates for bio-butanol production by clostridial ABE fermentation. Importantly, also ergot sclerotia-containing waste materials can be used as substrates, which can help to reduce process costs. The semi-continuous fermentation showed that clostridial ABE fermentation on milling byproducts may represent a suitable avenue for commercial butanol production after further process and/or strain optimization.</p></div>","PeriodicalId":494,"journal":{"name":"Biotechnology for Biofuels","volume":"17 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://biotechnologyforbiofuels.biomedcentral.com/counter/pdf/10.1186/s13068-024-02590-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142753975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}