Engineering of a Xylose Metabolic Pathway in Rhodococcus Strains

Xiong, Xiaochao; Wang, Xi; Chen, Shulin

doi:10.1128/aem.08022-11

Cited by 49 publications

(28 citation statements)

References 62 publications

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“…In this study, the former strategy, involving expression of the genes xylA and xylB , contributed to the improvement of xylose metabolism for R. opacus PD630. The findings are in accordance with the results that recently addressed engineering of a xylose metabolic pathway in Rhodococcus strains [31]. Meanwhile, we suggest that there is at least one additional molecular target in the R. opacus genome which fully enables the functionality of xylA and xylB genes to generate the xylose-fermenting strain capable of efficiently producing TAGs at high xylose concentrations (Figure 6).…”

Section: Discussionsupporting

confidence: 92%

Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacusfor lignocellulosic fuel production

Kurosawa

Wewetzer

Sinskey

2013

Biotechnol Biofuels

100

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BackgroundThere has been a great deal of interest in fuel productions from lignocellulosic biomass to minimize the conflict between food and fuel use. The bioconversion of xylose, which is the second most abundant sugar present after glucose in lignocellulosic biomass, is important for the development of cost effective bioprocesses to fuels. Rhodococcus opacus PD630, an oleaginous bacterium, accumulates large amounts of triacylglycerols (TAGs), which can be processed into advanced liquid fuels. However, R. opacus PD630 does not metabolize xylose.ResultsWe generated DNA libraries from a Streptomyces bacterium capable of utilizing xylose and introduced them into R. opacus PD630. Xsp8, one of the engineered strains, was capable of growing on up to 180 g L-1 of xylose. Xsp8 grown in batch-cultures derived from unbleached kraft hardwood pulp hydrolysate containing 70 g L-1 total sugars was able to completely and simultaneously utilize xylose and glucose present in the lignocellulosic feedstock, and yielded 11.0 g L-1 of TAGs as fatty acids, corresponding to 45.8% of the cell dry weight. The yield of total fatty acids per gram of sugars consumed was 0.178 g, which consisted primarily of palmitic acid and oleic acid. The engineered strain Xsp8 was introduced with two heterologous genes from Streptomyces: xylA, encoding xylose isomerase, and xylB, encoding xylulokinase. We further demonstrated that in addition to the introduction and the concomitant expression of heterologous xylA and xylB genes, there is another molecular target in the R. opacus genome which fully enables the functionality of xylA and xylB genes to generate the robust xylose-fermenting strain capable of efficiently producing TAGs at high xylose concentrations.ConclusionWe successfully engineered a R. opacus strain that is capable of completely utilizing high concentrations of xylose or mixed xylose/glucose simultaneously, and substantiated its suitability for TAG production. This study demonstrates that the engineered strain possesses a key trait of converters for lipid-based fuels production from lignocellulosic biomass.

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Section: Discussionsupporting

confidence: 92%

Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacusfor lignocellulosic fuel production

Kurosawa

Wewetzer

Sinskey

2013

Biotechnol Biofuels

100

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“…Considering that xylose is the second most abundant sugar in hardwood, obtaining bacteria with xylose-degrading ability is of importance for better utilization of its hydrolysate. Recently, the xylose metabolic pathway has been successfully established in engineered strain of R. opacus PD630 (Xiong et al 2012;Kurosawa et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Microbial lipid production by oleaginous Rhodococci cultured in lignocellulosic autohydrolysates

Wei

Zeng

Huang

et al. 2015

Appl Microbiol Biotechnol

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Metabolic synthesis of single cell oils (SCOs) for biodiesel application by heterotrophic oleaginous microorganisms is being hampered by the high cost of culture media. This study investigated the possibility of using loblolly pine and sweetgum autohydrolysates as economic feedstocks for microbial lipid production by oleaginous Rhodococcus opacus (R. opacus) PD630 and DSM 1069. Results revealed that when the substrates were detoxified by the removal of inhibitors (such as HMF-hydroxymethyl-furfural), the two strains exhibited viable growth patterns after a short adaptation/lag phase. R. opacus PD630 accumulated as much as 28.6 % of its cell dry weight (CDW) in lipids while growing on detoxified sweetgum autohydrolysate (DSAH) that translates to 0.25 g/l lipid yield. The accumulation of SCOs reached the level of oleagenicity in DSM 1069 cells (28.3 % of CDW) as well, while being cultured on detoxified pine autohydrolysate (DPAH), with the maximum lipid yield of 0.31 g/l. The composition of the obtained microbial oils varied depending on the substrates provided. These results indicate that lignocellulosic autohydrolysates can be used as low-cost fermentation substrates for microbial lipid production by wild-type R. opacus species. Consequently, the variety of applications for aqueous liquors from lignocellulosic pretreatment has been expanded, allowing for the further optimization of the integrated biorefinery.

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“…R. opacus can metabolize and degrade aromatic compounds found in lignocellulosic biomass [64] and accumulate intracellular single cell oils [54][55][56][57][58][59]. Rhodococcus strains have been engineered to express enzymes to degrade cellulose [65] and xylose [66]. Co-fermentations using wild-type and engineered strains have also been successfully employed [67].…”

Section: Fermentations Using Different Lignin Substrates or Pretreatmmentioning

confidence: 99%

A Review on The Bioconversion of Lignin to Microbial Lipid with Oleaginous Rhodococcus opacus

Mahan¹,

Le²,

Yuan³

et al. 2017

J Biotechnol Biomater

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Rhodococcus opacus produces intracellular lipids from the biodegradation of lignocellulosic biomass. These lipids can be used to produce biofuels that could potentially replace petroleum-derived chemicals. Current studies are focusing on deconstructing lignin through efficient and cost-effective pretreatment methods and improving microbial lipid titers. R. opacus can reach high levels of oleaginicity (>80%) when grown on glucose and other aromatic model compounds but intracellular lipid production is much lower on complex recalcitrant lignin substrates. This review will discuss recent advances in studying R. opacus lignin degradation by exploring different pretreatment methods, increasing lignin solubility, enriching for low molecular weight lignin compounds and laccase supplementation.

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Engineering of a Xylose Metabolic Pathway in Rhodococcus Strains

Cited by 49 publications

References 62 publications

Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacusfor lignocellulosic fuel production

Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacusfor lignocellulosic fuel production

Microbial lipid production by oleaginous Rhodococci cultured in lignocellulosic autohydrolysates

A Review on The Bioconversion of Lignin to Microbial Lipid with Oleaginous Rhodococcus opacus

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