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Lignin, a biopolymer derived from plant biomass, is recognized as a highly promising substance for developing self-healing polymers owing to its dynamic linkages and functional groups. This paper provides a thorough review of lignin-based self-healing polymer, from the process of extracting lignin, chemical modification, synthesis techniques such as via reversible addition-fragmentation chain transfer (RAFT) polymerization, crosslinking with polymers like polyvinyl alcohol (PVA) and chitosan, and reactions with isocyanates to create lignin-based networks with reversible interactions. This work also summarizes the optimization of self-healing ability, such as including dynamic copolymers, encapsulating healing agents like dicyclopentadiene and polycaprolactone (PCL), and chain extenders with disulfide or Diels-Alder (DA) moieties. The material's characterization focuses on its capacity to recover via hydrogen bonding and dynamic re-associations, improved mechanical properties from lignin's rigid structure, and enhanced temperature resistance. Primary obstacles involve the optimization of lignin extraction, enhancement of polymer compatibility, and the establishment of efficient procedures for synthesis and characterization. Overall, lignin shows great potential as a renewable component of self-healing polymers, with plenty of opportunities for further development.
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The biological conversion of methane under ambient conditions can be performed by methanotrophs that utilize methane as both a sole source of energy and a carbon source. However, compared to the established microbial chassis used for general fermentation with sugar as a feedstock, the productivity of methanotrophs is low. The fundamental knowledge of their metabolic or cellular bottlenecks is limited. In this review, the industrial-scale potential of methane bioconversion was evaluated. In particular, the enzyme kinetics associated with the oxidation and assimilation of methane were investigated to evaluate the potential of methane fermentation. The kinetics of enzymes involved in methane metabolism were compared with those used in the metabolic processes of traditional fermentation (glycolysis). Through this analysis, the current limitations of methane metabolism were identified. Methods for increasing the efficiency of methane bioconversion and directions for the industrial application of methane-based fermentation were discussed.
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Metabolismo Energético , Fermentación , Metano , Metano/metabolismo , Cinética , Fermentación/fisiología , Metabolismo Energético/fisiología , Oxidación-ReducciónRESUMEN
Methane (CH4) and carbon dioxide (CO2) are the dominant greenhouse gases (GHGs) that are increasing at an alarming rate. Methanotrophs have emerged as potential CH4 and CO2 biorefineries. This study demonstrated the synchronous incorporation of CH4 and CO2 into polyhydroxybutyrate (PHB) for the first time using 13C-labeling experiments in methanotrophs. By supplying substantial amounts of CO2, PHB content was enhanced in all investigated type II methanotrophic strains by 140 %, 146 %, and 162 %. The highest content of PHB from CH4 and CO2 in flask-scale cultivation reached 38 % dry cell weight in Methylocystis sp. MJC1, in which carbon percentage in PHB from CO2 was 45 %. Flux balance analysis predicted the critical roles of crotonyl-CoA carboxylase/reductase and phosphoenolpyruvate carboxylase in CO2 recycling. This study provided proof of the conversion of GHGs into a valuable and practical product using methanotrophic bacteria, contributing to addressing GHG emissions.
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Dióxido de Carbono , Hidroxibutiratos , Metano , Metano/metabolismo , Dióxido de Carbono/metabolismo , Hidroxibutiratos/metabolismo , Poliésteres/metabolismo , Methylocystaceae/metabolismo , Isótopos de CarbonoRESUMEN
This study explores the ability of methanotrophs to convert biogas into biopolymers, addressing H2S as a limitation in the utilization of biogas as a carbon source for bioconversion. Transcriptomic analysis was conducted to understand the growth and changes in the expression patterns of Type I and II methanotrophs under varying H2S concentrations. Results suggested that Type II methanotrophs can possess a native H2S utilization pathway. Both Type I and II methanotrophs were evaluated for their growth and polyhydroxybutyrate (PHB) production from biogas. Methylocystis sp. MJC1 and Methylocystis sp. OK1 exhibited a maximum biomass production of 4.0 and 4.5 gDCW/L, respectively, in fed-batch culture, aligning with the transcriptome data. Furthermore, Methylocystis sp. MJC1 produced 2.9 g PHB/L from biogas through gas fermentation. These findings underscore biogas-based biotechnology as an innovative solution for environmental and industrial challenges with further optimization and productivity enhancement research expected to broaden the potential in this field.
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Biocombustibles , Hidroxibutiratos , Hidroxibutiratos/metabolismo , Fermentación , Methylocystaceae/metabolismo , Biomasa , Poliésteres/metabolismo , Metano/metabolismo , Técnicas de Cultivo Celular por LotesRESUMEN
Owing to the unmet demand, the pharmaceutical industry is investigating an alternative host to mammalian cells to produce antibodies for a variety of therapeutic and research applications. Regardless of some disadvantages, Escherichia coli and Pichia pastoris are the preferred microbial hosts for antibody production. Despite the fact that the production of full-length antibodies has been successfully demonstrated in E. coli, which has mostly been used to produce antibody fragments, such as: antigen-binding fragments (Fab), single-chain fragment variable (scFv), and nanobodies. In contrast, Pichia, a eukaryotic microbial host, is mostly used to produce glycosylated full-length antibodies, though hypermannosylated glycan is a major challenge. Advanced strategies, such as the introduction of human-like glycosylation in endotoxin-edited E. coli and cell-free system-based glycosylation, are making progress in creating human-like glycosylation profiles of antibodies in these microbes. This review begins by explaining the structural and functional requirements of antibodies and continues by describing and analyzing the potential of E. coli and P. pastoris as hosts for providing a favorable environment to create a fully functional antibody. In addition, authors compare these microbes on certain features and predict their future in antibody production. Briefly, this review analyzes, compares, and highlights E. coli and P. pastoris as potential hosts for antibody production.
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Historically, the genus Aloe has been an indispensable part of both traditional and modern medicine. Decades of intensive research have unveiled the major bioactive secondary metabolites of this plant. Recent pandemic outbreaks have revitalized curiosity in aloe metabolites, as they have proven pharmacokinetic profiles and repurposable chemical space. However, the structural complexity of these metabolites has hindered scientific advances in the chemical synthesis of these compounds. Multi-omics research interventions have transformed aloe research by providing insights into the biosynthesis of many of these compounds, for example, aloesone, aloenin, noreugenin, aloin, saponins, and carotenoids. Here, we summarize the biological activities of major aloe secondary metabolites with a focus on their mechanism of action. We also highlight the recent advances in decoding the aloe metabolite biosynthetic pathways and enzymatic machinery linked with these pathways. Proof-of-concept studies on in vitro, whole-cell, and microbial synthesis of aloe compounds have also been briefed. Research initiatives on the structural modification of various aloe metabolites to expand their chemical space and activity are detailed. Further, the technological limitations, patent status, and prospects of aloe secondary metabolites in biomedicine have been discussed.
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Aloe , Aloe/química , Aloe/metabolismo , Extractos Vegetales/farmacología , Extractos Vegetales/químicaRESUMEN
Synthetic biodegradable and bio-based polymers have emerged as sustainable alternatives to nonrenewable petroleum-derived polymers which cause serious environmental issues. In particular, polyhydroxyalkanoates (PHA) are promising biopolymers owing to their outstanding biodegradability and biocompatibility. The production of the homopolymer poly(3-hydroxybutyrate) (PHB) and copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from type II methanotrophs via microbial fermentation was presented. For the efficient extraction and recovery of intracellular PHA from methanotrophs, different extraction approaches were investigated including solvent extraction using 1,3-dioxolane as a green solvent, integrated cell lysis and solvent extraction, and cell digestion without the use of organic solvents. Among various extraction approaches, the integrated method exhibited the highest extraction performance, with PHA recovery and purity exceeding 91 % and 93 %, respectively, even when the PHA content of the cells was low. Furthermore, the molecular weight, thermal stability, and mechanical properties of the recovered PHA were comprehensively analyzed to suggest its suitable practical applications. The obtained properties were comparable to that of the commercial PHA products and PHA produced from other microbial species, indicating an efficient recovery of high-quality PHA produced from methanotrophs.
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Polihidroxialcanoatos , Biopolímeros , Ácido 3-Hidroxibutírico , Hidroxibutiratos , SolventesRESUMEN
Methane (CH4), one of the greenhouse gases, is considered a promising feedstock for the biological production of fuels and chemicals. Although recent studies have demonstrated the capability of methanotrophs to convert CH4 into various bioproducts by metabolic engineering, the productivity has not reached commercial levels. As such, there is a growing interest in synthetic methanotrophic systems as an alternative. This review summarizes the strategies for enhancing native CH4 assimilation and discusses the challenges for the construction of synthetic methanotrophy into nonmethanotrophic industrial strains. Additionally, we suggest a mixed heterotrophic approach that integrates CH4 assimilation with glucose and xylose metabolism to improve productivity. The synthetic methanotrophic system presented in this review could pave the way for sustainable and efficient biomanufacturing using CH4.
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Metano , Xilosa , Metano/metabolismo , Biocatálisis , Ingeniería MetabólicaRESUMEN
The production of polyhydroxyalkanoates (PHAs) through the biological conversion of methane is a promising solution to address both methane emissions and plastic waste. Type II methanotrophs naturally accumulate a representative PHA, poly(3-hydroxybutyrate) (PHB), using methane as the sole carbon source. In this study, we aimed to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV copolymer) with improved properties compared with PHB, using the type II methanotroph, Methylocystis sp. MJC1. We optimized the pH, valerate concentration, and valerate supply time in a one-step cultivation process using a gas bioreactor to enhance PHBV copolymer production yield and the 3-hydroxyvalerate (3HV) molar fraction. Under the optimal conditions, the biomass reached 21.3 g DCW/L, and PHBV copolymer accumulation accounted for 41.9 % of the dried cell weight, with a 3HV molar fraction of 28.4 %. The physicochemical properties of the purified PHBV copolymer were characterized using NMR, FTIR, TGA, DSC, and GPC.
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Methylocystaceae , Poliésteres , Hidroxibutiratos , Valeratos , MetanoRESUMEN
Methanotrophs are environmentally friendly microorganisms capable of converting gas to liquid using methane monooxygenases (MMOs). In addition to methane-to-methanol conversion, MMOs catalyze the conversion of alkanes to alcohols and alkenes to epoxides. Herein, the efficacy of epoxidation by type I and II methanotrophs was investigated, and type II methanotrophs were observed to be more efficient in converting alkenes to epoxides. Subsequently, three (Epoxide hydrolase) EHs of different origins were overexpressed in the type II methanotroph Methylosinus trichosporium OB3b to produce 1,2-diols from epoxide. Methylosinus trichosporium OB3b expressing Caulobacter crescentus EH produced the highest amount of (R)-1,2-propanediol (251.5 mg/L) from 1-propene. These results demonstrate the possibility of using methanotrophs as a microbial platform for diol production and the development of a continuous bioreactor for industrial applications.
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Methylosinus trichosporium , Oxigenasas , Oxigenasas/genética , Oxigenasas/química , Alcoholes , Metano , Alcanos , Metanol , Compuestos EpoxiRESUMEN
Methanol has recently gained significant attention as a potential carbon substrate for the production of fuels and chemicals, owing to its high degree of reduction, abundance, and low price. Native methylotrophic yeasts and bacteria have been investigated for the production of fuels and chemicals. Alternatively, synthetic methylotrophic strains are also being developed by reconstructing methanol utilization pathways in model microorganisms, such as Escherichia coli. Owing to the complex metabolic pathways, limited availability of genetic tools, and methanol/formaldehyde toxicity, the high-level production of target products for industrial applications are still under development to satisfy commercial feasibility. This article reviews the production of biofuels and chemicals by native and synthetic methylotrophic microorganisms. It also highlights the advantages and limitations of both types of methylotrophs and provides an overview of ways to improve their efficiency for the production of fuels and chemicals from methanol.
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The development of biorefineries for a sustainable bioeconomy has been driven by the concept of utilizing environmentally friendly and cost-effective renewable energy sources. Methanotrophic bacteria with a unique capacity to utilize methane as a carbon and energy source can serve as outstanding biocatalysts to develop C1 bioconversion technology. By establishing the utilization of diverse multi-carbon sources, integrated biorefinery platforms can be created for the concept of the circular bioeconomy. An understanding of physiology and metabolism could help to overcome challenges for biomanufacturing. This review summaries fundamental gaps for methane oxidation and the capability to utilize multi-carbon sources in methanotrophic bacteria. Subsequently, breakthroughs in harnessing methanotrophs as robust microbial chassis for industrial biotechnology were compiled and overviewed. Finally, challenges and capabilities to exploit the inherent advantages of methanotrophs to synthesize various target products in higher titers are proposed.
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Carbono , Metano , Metano/metabolismo , Oxidación-Reducción , BiotecnologíaRESUMEN
Biodegradable polyhydroxybutyrate (PHB) can be produced from methane by some type II methanotroph such as the genus Methylocystis. This study presents the comparative genomic analysis of a newly isolated methanotroph, Methylocystis sp. MJC1 as a biodegradable PHB-producing platform strain. Methylocystis sp. MJC1 accumulates up to 44.5% of PHB based on dry cell weight under nitrogen-limiting conditions. To facilitate its development as a PHB-producing platform strain, the complete genome sequence of Methylocystis sp. MJC1 was assembled, functionally annotated, and compared with genomes of other Methylocystis species. Phylogenetic analysis has shown that Methylocystis parvus to be the closest species to Methylocystis sp. MJC1. Genome functional annotation revealed that Methylocystis sp. MJC1 contains all major type II methanotroph biochemical pathways such as the serine cycle, EMC pathway, and Krebs cycle. Interestingly, Methylocystis sp. MJC1 has both particulate and soluble methane monooxygenases, which are not commonly found among Methylocystis species. In addition, this species also possesses most of the RuMP pathway reactions, a characteristic of type I methanotrophs, and all PHB biosynthetic genes. These comparative analysis would open the possibility of future practical applications such as the development of organism-specific genome-scale models and application of metabolic engineering strategies to Methylocystis sp. MJC1.
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Metano , Methylocystaceae , Filogenia , Metano/metabolismo , Genómica , Methylocystaceae/genética , Methylocystaceae/metabolismoRESUMEN
Methanotrophs are potent natural producers of several bioactive secondary metabolites (SMs) including isoprenoids, polymers, peptides, and vitamins. Cryptic biosynthetic gene clusters identified from these microbes via genome mining hinted at the vast and hidden SM biosynthetic potential of these microbes. Central carbon metabolism in methanotrophs offers rare pathway intermediate pools that could be further diversified using advanced synthetic biology tools to produce valuable SMs; for example, plant polyketides, rare carotenoids, and fatty acid-derived SMs. Recent advances in pathway reconstruction and production of isoprenoids, squalene, ectoine, polyhydroxyalkanoate copolymer, cadaverine, indigo, and shinorine serve as proof-of-concept. This review provides theoretical guidance for developing methanotrophs as microbial chassis for high-value SMs. We summarize the distinct secondary metabolic potentials of type I and type II methanotrophs, with specific attention to products relevant to biomedical applications. This review also includes native and non-native SMs from methanotrophs, their therapeutic potential, strategies to induce silent biosynthetic gene clusters, and challenges.
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Péptidos , Terpenos , Metabolismo Secundario/genética , Péptidos/genética , Familia de Multigenes , CarotenoidesRESUMEN
Since the introduction of the first transformer model with a unique self-attention mechanism, natural language processing (NLP) models have attained state-of-the-art (SOTA) performance on various tasks. As DNA is the blueprint of life, it can be viewed as an unusual language, with its characteristic lexicon and grammar. Therefore, NLP models may provide insights into the meaning of the sequential structure of DNA. In the current study, we employed and compared the performance of popular SOTA NLP models (i.e., XLNET, BERT, and a variant DNABERT trained on the human genome) to predict and analyze the promoters in freshwater cyanobacterium Synechocystis sp. PCC 6803 and the fastest growing cyanobacterium Synechococcus elongatus sp. UTEX 2973. These freshwater cyanobacteria are promising hosts for phototrophically producing value-added compounds from CO2. Through a custom pipeline, promoters and non-promoters from Synechococcus elongatus sp. UTEX 2973 were used to train the model. The trained model achieved an AUROC score of 0.97 and F1 score of 0.92. During cross-validation with promoters from Synechocystis sp. PCC 6803, the model achieved an AUROC score of 0.96 and F1 score of 0.91. To increase accessibility, we developed an integrated platform (TSSNote-CyaPromBERT) to facilitate large dataset extraction, model training, and promoter prediction from public dRNA-seq datasets. Furthermore, various visualization tools have been incorporated to address the "black box" issue of deep learning and feature analysis. The learning transfer ability of large language models may help identify and analyze promoter regions for newly isolated strains with similar lineages.
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Methanotrophic bacteria are attractive hosts for mining metabolic pathways of C1 assimilation to produce value-added products. Herein, the type I methanotroph Methylotuvimicrobium alcaliphilum 20Z was employed to explore the carbon flux from methane and methanol via the EMP pathway to produce 1,2-propanediol (1,2-PDO). The production of 1,2-PDO on methane was found to be mainly restricted by the lower carbon flux toward the EMP pathway. The co-utilization of C1 substrates and glycerol (C3) could contribute to enhance 1,2-PDO. Lactate was co-produced in much higher amounts than 1,2-PDO. This unexpected product was probably derived from lactaldehyde by inherent aldehyde dehydrogenases. The 1,2-PDO production without increased accumulation of lactate was observed via establishing the acetol-based pathway by propane utilization with the overexpression of pmoD. This is the first study to provide experimental insights into the operation of metabolic routes for 1,2-PDO and lactate co-production from C1 and C3 compounds in methanotrophs.
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Ácido Láctico , Propilenglicol , Propilenglicol/metabolismo , Glicoles de Propileno/metabolismo , Metano/metabolismo , Glicerol/metabolismoRESUMEN
Ethanol has recently been demonstrated as a suitable carbon source for acetyl-CoA-derived products with high theoretical yield. Herein, the short-chain-length polyhydroxyalkanoates production pathway was constructed in an industrial platform P. putida KT2440, allowing the engineered strain to produce 674.97 ± 22.3 mg/L of Polyhydroxybutyrate (PHB) from ethanol as sole carbon source. Furthermore, the ethanol catabolic pathway was reconstructed to enhance the acetyl-coA pool by expressing the novel Aldehyde dehydrogenases from Klebsiella pneumonia and Dickeya zeae, resulting in a titer of 1385.34 ± 16.5 mg/L and 9300 ± 0.56 mg/L of PHB in shake flask and fermenter, respectively. Furthermore, transcriptome analysis was conducted to provide insights into the central metabolic pathways and different expression patterns in response to changes in substrate. Additionally, the production of co-polymer poly(3-hydroxybutyrate-co-3-hydroxypropionate) was shown using glycerol and ethanol as co-substrates from recombinant P. putida KT2440. This work demonstrates the potential of P. putida KT2440 as a promising industrial platform for short-chain-length PHAs production from structurally unrelated carbon sources.
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Polihidroxialcanoatos , Pseudomonas putida , Pseudomonas putida/genética , Pseudomonas putida/metabolismo , Etanol/metabolismo , Acetilcoenzima A/metabolismo , Carbono/metabolismoRESUMEN
Methylotuvimicrobium alcaliphilum20Z recombinant strain co-utilizing methane and xylose from anthropogenic activities and lignocellulose biomassis a promising cell factory platform. In this study, the production of (R)-3-hydroxybutyrate and poly (3-hydroxybutyrate) inM. alcaliphilum20Z was demonstrated. The production of (R)-3-hydroxybutyrate was optimized by introducing additional thioesterase, and a tunable genetic module. The final recombinant strain produced the highest titer of 334.52 ± 2 mg/L (R)-3-hydroxybutyrate (yield of 1,853 ± 429 mg/g dry cell weight). The poly (3-hydroxybutyrate) yielded 1.29 ± 0.08% (w/w) from methane and xylose in one-stage cultivation. Moreover, the study demonstrated the importance of pathway reversibility as an effective design strategy for balancing the driving force and intermediate accumulation. This is the first demonstration of the production ofbiodegradablepoly (3-hydroxybutyrate) from methane in type I methanotrophs, which is a key step toward sustainable biomanufacturing and carbon-neutral society.
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Methylococcaceae , Xilosa , Ácido 3-Hidroxibutírico , Carbono/metabolismo , Hidroxibutiratos/metabolismo , Metano/metabolismo , Methylococcaceae/metabolismo , Poliésteres/metabolismo , Xilosa/metabolismoRESUMEN
2-Propanol is a widely used industrial solvents. Herein, we employed a unique feature of type I methanotrophic bacterium Methylotuvimicrobium alcaliphilum 20Z possessing only particulate methane monooxygenase (pMMO) for one-step direct production of pure 2-propanol from propane. By maintaining cell growth on glycerol, and after deletion of both Ca2+-dependent and La3+-dependent methanol dehydrogenases, propane was converted to 2-propanol by pMMO. Although most of the 2-propanol produced was further oxidized to acetone, deletion of active alcohol dehydrogenase, concomitant with synchronous overexpression of secondary alcohol dehydrogenase, significantly inhibited such undesirable oxidation. As a result, a remarkable enhancement (263 mg/L) of 2-propanol was achieved for 120 h by increasing cell growth with a supply of 50% (v/v) propane in headspace. This is the first demonstration to develop an engineered methanotrophic strain for the one-step direct production of pure 2-propanol from propane using one-phase cultivation without the supply of chemical inhibitors or additional reducing-power sources.
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2-Propanol , Propano , Acetona , Alcohol Deshidrogenasa , Metano , Oxidación-ReducciónRESUMEN
With the rising environmental concern, sustainable chemistry should be accomplished by considering technical, economic, and environmental factors that guarantee the successful implementation of new alternative products. Hence, we performed the integrated techno-economic and life cycle assessment for two-step solvothermal liquefaction (two-pot synthesis) and simplified solvothermal liquefaction (one-pot synthesis) based on experiment results. Based on the itemized cost estimation, the unit biopolyol production costs obtained from the two-pot synthesis and one-pot synthesis were 10.0 $ kg-1 and 2.89 $ kg-1, respectively. To provide techno-economic guidelines for biopolyol production, profitability analysis, and uncertainty analysis were used to identify the economic feasibility of the proposed processes. In addition, the life cycle assessment results indicated that biopolyol production via the two-pot synthesis leads to a slightly lower greenhouse gas emission compared with the one-pot synthesis, which further required the use of an analytic hierarchy process to determine the best process for biopolyol production depending on the different weight points in the economic and environmental aspects. From these results, we can provide the technical performance, economic feasibility, and environmental impact of lab-scale biopolyol production from silvergrass residue, a low-cost waste of biomass saccharification.