Metabolic Engineering of Bacteria for Renewable Bioethanol Production from Cellulosic Biomass

Banerjee, Sanchita; Mishra, Gargi; Roy, Ankoor

doi:10.1007/s12257-019-0134-2

Cited by 33 publications

(14 citation statements)

References 101 publications

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“…The yeast Saccharomyces cerevisiae is an industrial microorganism with superior sugar fermentation capabilities and stress tolerance. However, this yeast cannot metabolize xylose, requiring the introduction of a heterologous xylose pathway [ 3 , 4 ] as summarized in Fig 1A . The first step is to introduce either the NAD(P)H-specific xylose reductase/NAD + -specific xylitol dehydrogenase (oxidoreductase, XR/XDH) pathway derived from Pichia stipitis or the xylose isomerase (XI) pathway derived from various anaerobic microorganisms, both of which convert xylose to xylulose.…”

Section: Introductionmentioning

confidence: 99%

Metabolic engineering considerations for the heterologous expression of xylose-catabolic pathways in Saccharomyces cerevisiae

Jeong

et al. 2020

PLoS ONE

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Xylose, the second most abundant sugar in lignocellulosic biomass hydrolysates, can be fermented by Saccharomyces cerevisiae expressing one of two heterologous xylose pathways: a xylose oxidoreductase pathway and a xylose isomerase pathway. Depending on the type of the pathway, its optimization strategies and the fermentation efficiencies vary significantly. In the present study, we constructed two isogenic strains expressing either the oxidoreductase pathway (XYL123) or the isomerase pathway (XI-XYL3), and delved into simple and reproducible ways to improve the resulting strains. First, the strains were subjected to the deletion of PHO13, overexpression of TAL1, and adaptive evolution, but those individual approaches were only effective in the XYL123 strain but not in the XI-XYL3 strain. Among other optimization strategies of the XI-XYL3 strain, we found that increasing the copy number of the xylose isomerase gene (xylA) is the most promising but yet preliminary strategy for the improvement. These results suggest that the oxidoreductase pathway might provide a simpler metabolic engineering strategy than the isomerase pathway for the development of efficient xylose-fermenting strains under the conditions tested in the present study.

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Section: Introductionmentioning

confidence: 99%

Metabolic engineering considerations for the heterologous expression of xylose-catabolic pathways in Saccharomyces cerevisiae

Jeong

et al. 2020

PLoS ONE

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“…B. subtilis can survive on a range of different substrates due to its metabolic diversity and robust systems for the production and secretion of enzymes [11][12][13][14]. The bacterium exhibits low nutrient requirements and remarkable tolerance to high concentrations of salt and solvents.…”

Section: Discussionmentioning

confidence: 99%

Consolidated Bioprocessing for Bioethanol Production by Metabolically Engineered Bacillus Subtilis Strains

Maleki

Changizian

Zolfaghari

et al. 2021

Preprint

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Background: Bioethanol produced by fermentative microorganisms is regarded as an alternative to fossil fuel. Bioethanol to be used as a viable energy source must be produced cost-effectively by removing expense-intensive steps such as the enzymatic hydrolysis of substrate. Consolidated bioprocessing (CBP) is believed to be a practical solution combining saccharification and fermentation in a single step catalyzed by a microorganism. Bacillus subtills with innate ability to grow on a diversity of carbohydrates seems promising for affordable CBP bioethanol production using renewable plant biomass and wastes. Results: In this study, the genes encoding alcohol dehydrogenase from Z. mobilis (adhZ) and S. cerevisiae (adhS) were each used with Z. mobilis pyruvate decarboxylase gene (pdcZ) to create ethanologenic operons in a lactate-deficient (Δldh) B. subtilis resulting in NZ and NZS strains, respectively. The S. cerevisiae adhS caused significantly more ethanol production by NZS and therefore was used to make two other operons including one with double copies of both pdcZ and adhS and the other with a single pdcZ but double adhS genes expressed in N(ZS)2 and NZS2 strains, respectively. In addition, two fusion genes were constructed with pdcZ and adhS in alternate orientations and used for ethanol production by the harboring strains namely NZ:S and NS:Z, respectively. While the increase of gene dosage was not associated with elevated carbon flow for ethanol production, the fusion gene adhS:pdcZ resulted in more than two times increase of productivity by strain NS:Z as compared with NZS during 48 h fermentation. The CBP ethanol production by NZS and NS:Z using potatoes resulted in 16.3 g/L and 21.5 g/L ethanol during 96 h fermentation, respectively. Conclusion: In this study for the first time, Bacillus subtilis was successfully used for CBP ethanol production with S. cerevisiae alcohol dehydrogenase. The results of the study provide insights on the potentials of B. subtilis for affordable bioethanol production from inexpensive plant biomass and wastes. However, the potentials need to be improved by metabolic and process engineering for higher yields of ethanol production and plant biomass utilization.

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“…Lignocellulosic biomass, one of the most earth‐abundant materials that can be obtained as agricultural, forest, and industrial residues, has a carbohydrate (mainly cellulose, hemicellulose, and lignin) content of ~70 wt% and contains fermentable sugar, therefore being a cost‐effective fermentation feedstock for the production of value‐added products such as biofuel, biochemicals, biomaterials, and enzymes (Banerjee et al, 2019; Lien et al, 2019; Park et al, 2018; Siripong et al, 2018). Efficient utilization of lignocellulosic biomass requires enzymatic saccharification to obtain fermentable sugars.…”

Section: Introductionmentioning

confidence: 99%

Improved production of bacterial cellulose through investigation of effects of inhibitory compounds from lignocellulosic hydrolysates

et al. 2021

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Although the unique nanostructure of bacterial cellulose (BC) imparts superior mechanochemical properties and thus allows for diverse applications, the high production cost of BC necessitates the development of more cost‐effective solutions, for example, those using lignocellulosic biomass as a substrate and relying on its pretreatment and saccharification to generate fermentable sugars. However, the various species (e.g., aliphatic acids, furans, and phenolics) produced during pretreatment may interfere with bacterial cell growth and BC production. Herein, we investigated the effects of aliphatic (acetic and formic) acids, furans (5‐hydroxymethylfurfural [5‐HMF] and furfural), and phenolics (syringaldehyde and p‐coumaric acid) on the production of BC. This production was enhanced at low aliphatic acid concentrations (1 g/L acetic acid and 0.5 g/L formic acid) but was suppressed by at least 90% in cases of 0.75 g/L formic acid, 0.4 g/L furfural, 4 g/L 5‐HMF, 2.5 g/L syringaldehyde, and 2.5 g/L p‐coumaric acid. BC production efficiencies of 97.86%, 76.66%, and 73.50% were observed for Miscanthus, barley straw, and pine tree hydrolysates, respectively, under optimal conditions. Therefore, these results provided the possibility to utilize the most abundant and sustainable lignocellulose on the planet for BC production.

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Metabolic Engineering of Bacteria for Renewable Bioethanol Production from Cellulosic Biomass

Cited by 33 publications

References 101 publications

Metabolic engineering considerations for the heterologous expression of xylose-catabolic pathways in Saccharomyces cerevisiae

Metabolic engineering considerations for the heterologous expression of xylose-catabolic pathways in Saccharomyces cerevisiae

Consolidated Bioprocessing for Bioethanol Production by Metabolically Engineered Bacillus Subtilis Strains

Improved production of bacterial cellulose through investigation of effects of inhibitory compounds from lignocellulosic hydrolysates

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