Bioprocess and Metabolic Engineering

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Microbial Metabolism, Physiology & Genetics".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 28410

Special Issue Editors


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Guest Editor
Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU, Leicestershire, UK
Interests: biochemical engineering; biotechnology; systems biology; synthetic biology; metabolic engineering; computational biology; bioinformatics; bioremediation; electro-fermentation; environmental biotechnology
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Guest Editor
Ipsen Biopharm, Unit 9 Ash Road North, Wrexham Industrial Estate, Wrexham LL13 9UF, UK
Interests: bioprocesses; scale up/down; process intensification; cell-free synthesis

Special Issue Information

Dear Colleagues,

The future of our planet has reached a crossroads due to the current climate emergency. Compounded by the unprecedented rise in greenhouse gas (GHG) emissions to the atmosphere and global warming, the climate emergency has severely exposed the vulnerability of our planet and threatened its security and very existence. However, one of the main causes of climate emergency is our ever-growing demand for commodities, i.e., fuels, chemicals, and materials; almost all of these are currently being sourced from unsustainable and GHG-emitting fossil fuel-based petrochemical and allied industries. As these commodities are the backbone of modern industry and economy, a more sustainable and ‘green’ route to these commodities is essential for our survival and prosperity. Therefore, transforming the petrochemical sector from a GHG emitter to a net GHG consumer or converter is the major challenge towards achieving a net-zero or carbon-neutral future. The versatility and ingenuity of bioprocesses can play a pivotal role in transforming the unsustainable commodity chemical sector into a sustainable one. Engineered microbial cell factories or chassis strains can be the main vectors of this transformation with the potential to produce petro-commodities at scale. In addition, cell-free synthesis systems have gained considerable attention from bioprocess engineers recently due to their relative ease of use without requiring extensive genetic manipulation of cell-based systems. With the advent of state-of-the-art metabolic engineering and synthetic biology technologies, as well as computational cheminformatics tools, it is now possible to produce virtually any commodity using engineered cell factories or cell-free synthesis systems. These systems can use GHGs and other renewable resources, including lignocellulosic biomass, industrial waste gases, and municipal solid waste as raw materials to produce high-value commodities.

This special issue aims to assemble and publish a collection of high-quality research articles and review papers on bioprocess and metabolic engineering efforts to produce bio-based commodities and healthcare products using both engineered microbial cell factories and cell-free synthesis systems. For review papers, it is advisable to contact one of the editors to discuss topic relevance before submitting the manuscript.

Dr. M. Ahsanul Islam
Dr. Williams Olughu
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fermentation is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Bioprocess engineering
  • Metabolic engineering
  • Synthetic biology
  • Microbial cell factories
  • Cell-free synthesis systems
  • Sustainable bioprocesses
  • Commodity biochemicals
  • Healthcare products

Published Papers (12 papers)

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Research

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14 pages, 2408 KiB  
Article
Metabolic Engineering of Zymomonas mobilis for Acetoin Production by Carbon Redistribution and Cofactor Balance
by Weiwei Bao, Wei Shen, Qiqun Peng, Jun Du and Shihui Yang
Fermentation 2023, 9(2), 113; https://doi.org/10.3390/fermentation9020113 - 25 Jan 2023
Cited by 5 | Viewed by 2092
Abstract
Biorefinery to produce value-added biochemicals offers a promising alternative to meet our sustainable energy and environmental goals. Acetoin is widely used in the food and cosmetic industries as taste and fragrance enhancer. The generally regarded as safe (GRAS) bacterium Zymomonas mobilis produces acetoin [...] Read more.
Biorefinery to produce value-added biochemicals offers a promising alternative to meet our sustainable energy and environmental goals. Acetoin is widely used in the food and cosmetic industries as taste and fragrance enhancer. The generally regarded as safe (GRAS) bacterium Zymomonas mobilis produces acetoin as an extracellular product under aerobic conditions. In this study, metabolic engineering strategies were applied including redistributing the carbon flux to acetoin and manipulating the NADH levels. To improve the acetoin level, a heterologous acetoin pathway was first introduced into Z. mobilis, which contained genes encoding acetolactate synthase (Als) and acetolactate decarboxylase (AldC) driven by a strong native promoter Pgap. Then a gene encoding water-forming NADH oxidase (NoxE) was introduced for NADH cofactor balance. The recombinant Z. mobilis strain containing both an artificial acetoin operon and the noxE greatly enhanced acetoin production with maximum titer reaching 8.8 g/L and the productivity of 0.34 g∙L−1∙h−1. In addition, the strategies to delete ndh gene for redox balance by native I-F CRISPR-Cas system and to redirect carbon from ethanol production to acetoin biosynthesis through a dcas12a-based CRISPRi system targeting pdc gene laid a foundation to help construct an acetoin producer in the future. This study thus provides an informative strategy and method to harness the NADH levels for biorefinery and synthetic biology studies in Z. mobilis. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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20 pages, 1716 KiB  
Article
Physiological and Molecular Characterization of Yeast Cultures Pre-Adapted for Fermentation of Lignocellulosic Hydrolysate
by João R. M. Almeida, Magnus Wiman, Dominik Heer, Daniel P. Brink, Uwe Sauer, Bärbel Hahn-Hägerdal, Gunnar Lidén and Marie F. Gorwa-Grauslund
Fermentation 2023, 9(1), 72; https://doi.org/10.3390/fermentation9010072 - 14 Jan 2023
Cited by 2 | Viewed by 1705
Abstract
Economically feasible bioethanol process from lignocellulose requires efficient fermentation by yeast of all sugars present in the hydrolysate. However, when exposed to lignocellulosic hydrolysate, Saccharomyces cerevisiae is challenged with a variety of inhibitors that reduce yeast viability, growth, and fermentation rate, and in [...] Read more.
Economically feasible bioethanol process from lignocellulose requires efficient fermentation by yeast of all sugars present in the hydrolysate. However, when exposed to lignocellulosic hydrolysate, Saccharomyces cerevisiae is challenged with a variety of inhibitors that reduce yeast viability, growth, and fermentation rate, and in addition damage cellular structures. In order to evaluate the capability of S. cerevisiae to adapt and respond to lignocellulosic hydrolysates, the physiological effect of cultivating yeast in the spruce hydrolysate was comprehensively studied by assessment of yeast performance in simultaneous saccharification and fermentation (SSF), measurement of furaldehyde reduction activity, assessment of conversion of phenolic compounds and genome-wide transcription analysis. The yeast cultivated in spruce hydrolysate developed a rapid adaptive response to lignocellulosic hydrolysate, which significantly improved its fermentation performance in subsequent SSF experiments. The adaptation was shown to involve the induction of NADPH-dependent aldehyde reductases and conversion of phenolic compounds during the fed-batch cultivation. These properties were correlated to the expression of several genes encoding oxidoreductases, notably AAD4, ADH6, OYE2/3, and YML131w. The other most significant transcriptional changes involved genes involved in transport mechanisms, such as YHK8, FLR1, or ATR1. A large set of genes were found to be associated with transcription factors (TFs) involved in stress response (Msn2p, Msn4p, Yap1p) but also cell growth and division (Gcr4p, Ste12p, Sok2p), and these TFs were most likely controlling the response at the post-transcriptional level. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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14 pages, 2327 KiB  
Article
Confirmation of Glucose Transporters through Targeted Mutagenesis and Transcriptional Analysis in Clostridium acetobutylicum
by Kundi Zhang, Dandan Jiang, Wolfgang Liebl, Maofeng Wang, Lichuan Gu, Ziyong Liu and Armin Ehrenreich
Fermentation 2023, 9(1), 64; https://doi.org/10.3390/fermentation9010064 - 12 Jan 2023
Viewed by 1536
Abstract
The solvent-producing bacterium Clostridium acetobutylicum is able to grow on a variety of carbohydrates. The main hexose transport system is the phosphoenolpyruvate-dependent phosphotransferase system (PTS). When the gene glcG that encodes the glucose transporter was inactivated, the resulting mutant glcG::int(1224) grew as [...] Read more.
The solvent-producing bacterium Clostridium acetobutylicum is able to grow on a variety of carbohydrates. The main hexose transport system is the phosphoenolpyruvate-dependent phosphotransferase system (PTS). When the gene glcG that encodes the glucose transporter was inactivated, the resulting mutant glcG::int(1224) grew as well as the wild type, yet its glucose consumption was reduced by 17% in a batch fermentation. Transcriptomics analysis of the phosphate-limited continuous cultures showed that the cellobiose transporter GlcCE was highly up-regulated in the mutant glcG::int(1224). The glcCE mutation did not affect growth and even consumed slightly more glucose during solventogenesis growth compared to wild type, indicating that GlcG is the primary glucose-specific PTS. Poor growth of the double mutant glcG::int(1224)-glcCE::int(193) further revealed that GlcCE was the secondary glucose PTS and that there must be other PTSs capable of glucose uptake. The observations obtained in this study provided a promising foundation to understand glucose transport in C. acetobutylicum. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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17 pages, 2971 KiB  
Article
A Toolkit for Effective and Successive Genome Engineering of Escherichia coli
by Bahareh Arab, Adam Westbrook, Murray Moo-Young and Chih-Hsiung Perry Chou
Fermentation 2023, 9(1), 14; https://doi.org/10.3390/fermentation9010014 - 23 Dec 2022
Cited by 2 | Viewed by 1970
Abstract
The bacterium Escherichia coli has been well-justified as an effective workhorse for industrial applications. In this study, we developed a toolkit for flexible genome engineering of this microorganism, including site-specific insertion of heterologous genes and inactivation of endogenous genes, such that bacterial hosts [...] Read more.
The bacterium Escherichia coli has been well-justified as an effective workhorse for industrial applications. In this study, we developed a toolkit for flexible genome engineering of this microorganism, including site-specific insertion of heterologous genes and inactivation of endogenous genes, such that bacterial hosts can be effectively engineered for biomanufacturing. We first constructed a base strain by genomic implementation of the cas9 and λRed recombineering genes. Then, we constructed plasmids for expressing gRNA, DNA cargo, and the Vibrio cholerae Tn6677 transposon and type I-F CRISPR-Cas machinery. Genomic insertion of a DNA cargo up to 5.5 kb was conducted using a transposon-associated CRISPR-Cas system, whereas gene inactivation was mediated by a classic CRISPR-Cas9 system coupled with λRed recombineering. With this toolkit, we can exploit the synergistic functions of CRISPR-Cas, λRed recombineering, and Tn6677 transposon for successive genomic manipulations. As a demonstration, we used the developed toolkit to derive a plasmid-free strain for heterologous production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by genomic knock-in and knockout of several key genes with high editing efficiencies. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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12 pages, 854 KiB  
Article
Hydrogen-Rich Water Can Restrict the Formation of Biogenic Amines in Red Beet Pickles
by Duried Alwazeer, Menekşe Bulut and Yasemin Çelebi
Fermentation 2022, 8(12), 741; https://doi.org/10.3390/fermentation8120741 - 14 Dec 2022
Cited by 6 | Viewed by 2059
Abstract
Fermented foods are considered the main sources of biogenic amines (BAs) in the human diet while lactic acid bacteria (LAB) are the main producers of BAs. Normal water (NW) and hydrogen-rich water (HRW) were used for preparing red beet pickles, i.e., NWP and [...] Read more.
Fermented foods are considered the main sources of biogenic amines (BAs) in the human diet while lactic acid bacteria (LAB) are the main producers of BAs. Normal water (NW) and hydrogen-rich water (HRW) were used for preparing red beet pickles, i.e., NWP and HRWP, respectively. The formation of BAs, i.e., aromatic amines (tyramine, 2-phenylethylamine), heterocyclic amines (histamine, tryptamine), and aliphatic di-amines (putrescine), was analyzed in both beet slices and brine of NWPs and HRWPs throughout the fermentation stages. Significant differences in redox value (Eh7) between NWP and HRWP brine samples were noticed during the first and last fermentation stages with lower values found for HRWPs. Total mesophilic aerobic bacteria (TMAB), yeast–mold, and LAB counts were higher for HRWPs than NWPs for all fermentation stages. Throughout fermentation stages, the levels of all BAs were lower in HRWPs than those of NWPs, and their levels in brines were higher than those of beets. At the end of fermentation, the levels (mg/kg) of BAs in NWPs and HRWPs were, respectively: tyramine, 72.76 and 61.74 (beet) and 113.49 and 92.67 (brine), 2-phenylethylamine, 48.00 and 40.00 (beet) and 58.01 and 50.19 (brine), histamine, 67.89 and 49.12 (beet) and 91.74 and 70.92 (brine), tryptamine, 93.14 and 77.23 (beet) and 119.00 and 93.11 (brine), putrescine, 81.11 and 63.56 (beet) and 106.75 and 85.93 (brine). Levels of BAs decreased by (%): 15.15 and 18.35 (tyramine), 16.67 and 13.44 (2-phenylethylamine), 27.65 and 22.7 (histamine), 17.09 and 21.76 (tryptamine), and 21.64 and 19.5 (putrescine) for beet and brine, respectively, when HRW was used in pickle preparation instead of NW. The results of this study suggest that the best method for limiting the formation of BAs in pickles is to use HRW in the fermentation phase then replace the fermentation medium with a new acidified and brined HRW followed by a pasteurization process. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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18 pages, 2196 KiB  
Article
Engineering Escherichia coli for Efficient Aerobic Conversion of Glucose to Malic Acid through the Modified Oxidative TCA Cycle
by Alexandra Yu. Skorokhodova, Anastasiya A. Stasenko, Natalya V. Krasilnikova, Andrey Yu. Gulevich and Vladimir G. Debabov
Fermentation 2022, 8(12), 738; https://doi.org/10.3390/fermentation8120738 - 14 Dec 2022
Cited by 2 | Viewed by 2106
Abstract
Malic acid is a versatile building-block chemical that can serve as a precursor of numerous valuable products, including food additives, pharmaceuticals, and biodegradable plastics. Despite the present petrochemical synthesis, malic acid, being an intermediate of the TCA cycle of a variety of living [...] Read more.
Malic acid is a versatile building-block chemical that can serve as a precursor of numerous valuable products, including food additives, pharmaceuticals, and biodegradable plastics. Despite the present petrochemical synthesis, malic acid, being an intermediate of the TCA cycle of a variety of living organisms, can also be produced from renewable carbon sources using wild-type and engineered microbial strains. In the current study, Escherichia coli was engineered for efficient aerobic conversion of glucose to malic acid through the modified oxidative TCA cycle resembling that of myco- and cyanobacteria and implying channelling of 2-ketoglutarate towards succinic acid via succinate semialdehyde formation. The formation of succinate semialdehyde was enabled in the core strain MAL 0 (∆ackA-pta, ∆poxB, ∆ldhA, ∆adhE, ∆ptsG, PL-glk, Ptac-galP, ∆aceBAK, ∆glcB) by the expression of Mycobacterium tuberculosis kgd gene. The secretion of malic acid by the strain was ensured, resulting from the deletion of the mdh, maeA, maeB, and mqo genes. The Bacillus subtilis pycA gene was expressed in the strain to allow pyruvate to oxaloacetate conversion. The corresponding recombinant was able to synthesise malic acid from glucose aerobically with a yield of 0.65 mol/mol. The yield was improved by the derepression in the strain of the electron transfer chain and succinate dehydrogenase due to the enforcement of ATP hydrolysis and reached 0.94 mol/mol, amounting to 94% of the theoretical maximum. The implemented strategy offers the potential for the development of highly efficient strains and processes of bio-based malic acid production. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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23 pages, 3666 KiB  
Article
Deep Eutectic Solvent Pretreatment of Water Hyacinth for Improved Holocellulosic Saccharification and Fermentative Co-Production of Xylitol and Lipids Using Rhodosporidium toruloides NCIM 3547
by Ramachandran Devasena Umai, Samuel Jacob and Vinod Kumar
Fermentation 2022, 8(11), 591; https://doi.org/10.3390/fermentation8110591 - 31 Oct 2022
Cited by 7 | Viewed by 2306
Abstract
In this study, delignification of water hyacinth (WH) using a mild ionic liquid-like chemical deep eutectic solvent (DES) synthesized using choline chloride and urea was conducted and the process parameters were optimized by Box–Behnken design (BBD)-based response surface methodology (RSM). From the results, [...] Read more.
In this study, delignification of water hyacinth (WH) using a mild ionic liquid-like chemical deep eutectic solvent (DES) synthesized using choline chloride and urea was conducted and the process parameters were optimized by Box–Behnken design (BBD)-based response surface methodology (RSM). From the results, a delignification of 64.32 ± 4.08% (w/w) was obtained under 1:12.5 (biomass:DES ratio), 4.63 h (time) and 87 °C (temperature). Further, a dilute sulphuric acid (2%, v/v) hydrolysis was carried out to destabilize the hemicellulose that resulted in 23.7 ± 0.50 g/L of xylose. Fermentation of the obtained xylose was carried out using a red oleaginous yeast, Rhodosporidium toruloides NCIM 3547, with free and Ca2+-alginate-immobilized cells for xylitol production under microaerophilic conditions and obtained yields of 4.73 ± 0.40 g/L (168 h) and 9.18 ± 0.10 g/L (packed bed reactor with a retention time of 18 h), respectively. Further, when the same fermentation was performed under aerobic conditions about 40.93 ± 0.73% lipid accumulation was observed with free cells. For saccharification, Aspergillus-niger-derived cellulase was used and this resulted in a yield of 27.45 ± 0.04 g/L of glucose. The glucose-enriched hydrolysate was supplemented for fermentation under nitrogen starved conditions from which 46.81 ± 2.60% (w/w) lipid content was obtained. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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12 pages, 2468 KiB  
Article
The Effect of E. coli Uridine-Cytidine Kinase Gene Deletion on Cytidine Synthesis and Transcriptome Analysis
by Fengmin Liu, Tong Ye, Xiangjun Zhang, Cong Ma, Huiyan Liu and Haitian Fang
Fermentation 2022, 8(11), 586; https://doi.org/10.3390/fermentation8110586 - 29 Oct 2022
Viewed by 1537
Abstract
Cytidine is an antiviral and anticancer drug intermediate, its primary method of manufacture being fermentation. Uridine-cytidine kinase (UCK) catalyzes the reverse process of phosphorylation of cytidine to produce cytidylic acid, which influences cytidine accumulation in the Escherichia coli cytidine biosynthesis pathway. The cytidine-producing [...] Read more.
Cytidine is an antiviral and anticancer drug intermediate, its primary method of manufacture being fermentation. Uridine-cytidine kinase (UCK) catalyzes the reverse process of phosphorylation of cytidine to produce cytidylic acid, which influences cytidine accumulation in the Escherichia coli cytidine biosynthesis pathway. The cytidine-producing strain E. coli NXBG-11 was used as the starting strain in this work; the udk gene coding UCK was knocked out of the chromosomal genome using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology. The mutant strain E. coli NXBG-12 was obtained; its transcriptomics were studied to see how udk gene deletion affected cytidine synthesis and cell-wide transcription. The mutant strain E. coli NXBG-12 generated 1.28 times more cytidine than the original strain E. coli NXBG-11 after 40 h of shake-flask fermentation at 37 °C. The udk gene was knocked out, and transcriptome analysis showed that there were 1168 differentially expressed genes between the mutant and original strains, 559 upregulated genes and 609 downregulated genes. It was primarily shown that udk gene knockout has a positive impact on the cytidine synthesis network because genes involved in cytidine synthesis were significantly upregulated (p < 0.05) and genes related to the cytidine precursor PRPP and cofactor NADPH were upregulated in the PPP and TCA pathways. These results principally demonstrate that udk gene deletion has a favorable impact on the cytidine synthesis network. The continual improvement of cytidine synthesis and metasynthesis is made possible by this information, which is also useful for further converting microorganisms that produce cytidine. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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17 pages, 1685 KiB  
Article
Enabling Ethanologenesis in Moorella thermoacetica through Construction of a Replicating Shuttle Vector
by Barbara Bourgade, James Millard, Christopher M. Humphreys, Nigel P. Minton and M. Ahsanul Islam
Fermentation 2022, 8(11), 585; https://doi.org/10.3390/fermentation8110585 - 28 Oct 2022
Cited by 3 | Viewed by 1658
Abstract
Replicating plasmid shuttle vectors are key tools for efficient genetic and metabolic engineering applications, allowing the development of sustainable bioprocesses using non-model organisms with unique metabolic capabilities. To date, very limited genetic manipulation has been achieved in the thermophilic acetogen, Moorella thermoacetica, [...] Read more.
Replicating plasmid shuttle vectors are key tools for efficient genetic and metabolic engineering applications, allowing the development of sustainable bioprocesses using non-model organisms with unique metabolic capabilities. To date, very limited genetic manipulation has been achieved in the thermophilic acetogen, Moorella thermoacetica, partly due to the lack of suitable shuttle vectors. However, M. thermoacetica has considerable potential as an industrial chassis organism, which can only be unlocked if reliable and effective genetic tools are in place. This study reports the construction of a replicating shuttle vector for M. thermoacetica through the identification and implementation of a compatible Gram-positive replicon to allow plasmid maintenance within the host. Although characterisation of plasmid behaviour proved difficult, the designed shuttle vector was subsequently applied for ethanologenesis, i.e., ethanol production in this organism. The non-native ethanologenesis in M. thermoacetica was achieved via plasmid-borne overexpression of the native aldh gene and heterologous expression of Clostridium autoethanogenum adhE1 gene. This result demonstrates the importance of the developed replicating plasmid vector for genetic and metabolic engineering efforts in industrially important M. thermoacetica. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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Review

Jump to: Research

31 pages, 2216 KiB  
Review
Petroleum Hydrocarbon Catabolic Pathways as Targets for Metabolic Engineering Strategies for Enhanced Bioremediation of Crude-Oil-Contaminated Environments
by Nandita Das, Ankita Das, Sandeep Das, Vasudha Bhatawadekar, Prisha Pandey, Kamlesh Choure, Samir Damare and Piyush Pandey
Fermentation 2023, 9(2), 196; https://doi.org/10.3390/fermentation9020196 - 20 Feb 2023
Cited by 4 | Viewed by 4532
Abstract
Anthropogenic activities and industrial effluents are the major sources of petroleum hydrocarbon contamination in different environments. Microbe-based remediation techniques are known to be effective, inexpensive, and environmentally safe. In this review, the metabolic-target-specific pathway engineering processes used for improving the bioremediation of hydrocarbon-contaminated [...] Read more.
Anthropogenic activities and industrial effluents are the major sources of petroleum hydrocarbon contamination in different environments. Microbe-based remediation techniques are known to be effective, inexpensive, and environmentally safe. In this review, the metabolic-target-specific pathway engineering processes used for improving the bioremediation of hydrocarbon-contaminated environments have been described. The microbiomes are characterised using environmental genomics approaches that can provide a means to determine the unique structural, functional, and metabolic pathways used by the microbial community for the degradation of contaminants. The bacterial metabolism of aromatic hydrocarbons has been explained via peripheral pathways by the catabolic actions of enzymes, such as dehydrogenases, hydrolases, oxygenases, and isomerases. We proposed that by using microbiome engineering techniques, specific pathways in an environment can be detected and manipulated as targets. Using the combination of metabolic engineering with synthetic biology, systemic biology, and evolutionary engineering approaches, highly efficient microbial strains may be utilised to facilitate the target-dependent bioprocessing and degradation of petroleum hydrocarbons. Moreover, the use of CRISPR-cas and genetic engineering methods for editing metabolic genes and modifying degradation pathways leads to the selection of recombinants that have improved degradation abilities. The idea of growing metabolically engineered microbial communities, which play a crucial role in breaking down a range of pollutants, has also been explained. However, the limitations of the in-situ implementation of genetically modified organisms pose a challenge that needs to be addressed in future research. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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29 pages, 3133 KiB  
Review
Engineering Microorganisms to Produce Bio-Based Monomers: Progress and Challenges
by Chenghu Chen, Xiulai Chen, Liming Liu, Jing Wu and Cong Gao
Fermentation 2023, 9(2), 137; https://doi.org/10.3390/fermentation9020137 - 31 Jan 2023
Cited by 4 | Viewed by 3196
Abstract
Bioplastics are polymers made from sustainable bio-based feedstocks. While the potential of producing bio-based monomers in microbes has been investigated for decades, their economic feasibility is still unsatisfactory compared with petroleum-derived methods. To improve the overall synthetic efficiency of microbial cell factories, three [...] Read more.
Bioplastics are polymers made from sustainable bio-based feedstocks. While the potential of producing bio-based monomers in microbes has been investigated for decades, their economic feasibility is still unsatisfactory compared with petroleum-derived methods. To improve the overall synthetic efficiency of microbial cell factories, three main strategies were summarized in this review: firstly, implementing approaches to improve the microbial utilization ability of cheap and abundant substrates; secondly, developing methods at enzymes, pathway, and cellular levels to enhance microbial production performance; thirdly, building technologies to enhance microbial pH, osmotic, and metabolites stress tolerance. Moreover, the challenges of, and some perspectives on, exploiting microorganisms as efficient cell factories for producing bio-based monomers are also discussed. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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17 pages, 553 KiB  
Review
Recent Advances on the Production of Itaconic Acid via the Fermentation and Metabolic Engineering
by Renwei Zhang, Huan Liu, Yuchen Ning, Yue Yu, Li Deng and Fang Wang
Fermentation 2023, 9(1), 71; https://doi.org/10.3390/fermentation9010071 - 14 Jan 2023
Cited by 9 | Viewed by 2582
Abstract
Itaconic acid (ITA) is one of the top 12 platform chemicals. The global ITA market is expanding due to the rising demand for bio-based unsaturated polyester resin and its non-toxic qualities. Although bioconversion using microbes is the main approach in the current industrial [...] Read more.
Itaconic acid (ITA) is one of the top 12 platform chemicals. The global ITA market is expanding due to the rising demand for bio-based unsaturated polyester resin and its non-toxic qualities. Although bioconversion using microbes is the main approach in the current industrial production of ITA, ecological production of bio-based ITA faces several issues due to: low production efficiency, the difficulty to employ inexpensive raw materials, and high manufacturing costs. As metabolic engineering advances, the engineering of microorganisms offers a novel strategy for the promotion of ITA bio-production. In this review, the most recent developments in the production of ITA through fermentation and metabolic engineering are compiled from a variety of perspectives, including the identification of the ITA synthesis pathway, the metabolic engineering of natural ITA producers, the design and construction of the ITA synthesis pathway in model chassis, and the creation, as well as application, of new metabolic engineering strategies in ITA production. The challenges encountered in the bio-production of ITA in microbial cell factories are discussed, and some suggestions for future study are also proposed, which it is hoped offers insightful views to promote the cost-efficient and sustainable industrial production of ITA. Full article
(This article belongs to the Special Issue Bioprocess and Metabolic Engineering)
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