Abstract
Genome sequencing was used to identify key genes for the generation of hydrogen gas through cotton stalk hydrolysate fermentation by Klebsiella sp. WL1316. Genome annotation indicated that the genome size was 5.2Mb with GC content 57.6%. Xylose was metabolized in the pentose phosphate pathway via the conversion of xylose to xylulose in Klebsiella sp. WL1316. This strain contained diverse formate-hydrogen lyases and hydrogenases with gene numbers higher than closely related species. A metabolic network involving glucose, xylose utilisation, and fermentative hydrogen production was reconstructed. Metabolic analysis of key node metabolites showed that glucose and xylose metabolism influenced biomass synthesis and biohydrogen production. Formic acid accumulated during fermentation at 24-48h but decreased sharply after 48h, illustrating the splitting of formic acid to hydrogen gas during early-to-mid fermentation. The Kreb's cycle was the main competitive metabolic branch of biohydrogen synthesis at 24h of fermentation. Lactic and acetic acid fermentation and late ethanol accumulation competed the carbon skeleton of biohydrogen synthesis after 72h of fermentation, indicating that these competitive pathways are regulated in middle-to-late fermentation (48-96h). This study is the first to elucidate the metabolic mechanisms of mixed sugar utilisation and biohydrogen synthesis based on genomic information.
Highlights
Under the combined pressure of decreasing fossil energy reserves and increasing environmental pollution, making full use of lignocellulose and other renewable resources to develop clean energy has attracted the attention of the scientific community worldwide (Boodhun et al 2017; Rodionova et al 2017; Tian et al 2019)
WL1316 to gain a comprehensive understanding of the functional genes of this strain, especially those response to glucose and xylose metabolism and hydrogen production
Annotation of the metabolic pathways for glucose and xylose utilisation and bioconversion In a previous study, we reported that Klebsiella sp
Summary
Under the combined pressure of decreasing fossil energy reserves and increasing environmental pollution, making full use of lignocellulose and other renewable resources to develop clean energy has attracted the attention of the scientific community worldwide (Boodhun et al 2017; Rodionova et al 2017; Tian et al 2019). Hydrogen produced by the dark fermentation of lignocellulosic materials by microorganisms is one of the most prominent strategies (Saratale and Oh 2015; Sivagurunathan et al 2017; Kamaraj et al 2020; Kumar et al 2019; Shanmugam et al 2020). In this method, the selection of the fermentation strain is of great importance. Fermentative hydrogen production by single wild strains is relatively low. Measurements, such as metabolic pathway analysis and engineering modification, are needed for strains with clear genome information (Tran et al 2014; Cha et al 2013; Lu et al 2016; Jo and Cha 2015; Lu et al 2017; Lee et al 2019; Zhang et al 2020) in order to reconstruct the hydrogen production metabolic pathways and increase the yield of hydrogen produced by hydrogenproducing strains
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Schedule a callMore From: International microbiology : the official journal of the Spanish Society for Microbiology
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