Mechanisms of enhanced bio-H2 production in Ethanoligenens harbinense by l-cysteine supplementation: Analyses at growth and gene transcription levels

• Published in: Fuel (Guildford) Vol. 252; pp. 143 - 147
• Main Authors: Zhao, Xin, Ye, Sicen, Qi, Nan, Li, Xuejie, Bao, Nisha, Xing, Defeng, Ren, Nanqi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-09-2019; Elsevier BV
• Subjects: Acetate kinase; Acetic acid; Alcohol dehydrogenase; Alcohols; Biohydrogen; Cell growth; Cysteine; Dehydrogenase; Dehydrogenases; Dry cells; Ethanoligenens harbinense; Gene expression; Genes; Hydrogen production; Hydrogenase; Kinases; l-cysteine supplementation; L-Lactate dehydrogenase; Lactate dehydrogenase; Lactic acid; Lignocellulose; Organic wastes; Oxidation; qRT-PCR; Reducing agents; Reverse transcription; Supplements; Sustainability; Wastewater; hydrogenase; Biohydrogen; Ethanoligenens harbinense; l-cysteine supplementation; qRT-PCR
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2019.04.037

•Enhanced H2 production by l-cysteine was realized through increased cell growth and functional gene expression.•H2 yield and bacteria biomass were over 1.5 folds with 800 mg/L l-cysteine compared to the negative control.•Expressions of functional genes related to H2 metabolism over 3 times influenced by l-cysteine.
Bio-H2, produced from lignocellulosic biomass or organic wastewater, is an ideal future energy candidate due to its feature of renewability and sustainability. In order to uncover the mechanisms of the reducing agent of l-cysteine in bio-H2 production process, effects of l-cysteine on oxidation–reduction potential (ORP), cell growth, H2 yield by Ethanoligenens harbinense were investigated. Meanwhile, effects of l-cysteine on the expression of genes such as [FeFe]-hydrogenase (hydA), acetate kinase (AK), alcohol dehydrogenase (ADH), and lactate dehydrogenase (LDH) were analysed by quantitative reverse transcription PCR (qRT-PCR). The maximum H2 yield of 1.88 mol-H2/mol-glucose and dry cell weight of 0.92 g/L, which were about 1.57 and 1.51 folds of that of negative control, were obtained with supplementation of 800 mg/L l-cysteine. The experimental results indicated that the supplementation of l-cysteine at a suitable dosage (<800 mg/L) can enhances the H2 production by E. harbinense. The underlying mechanisms include decreasing ORP, promoting cell growth, and stimulating expression of key functional genes (hydA, AK, and ADH) involved in H2 production, together promoted the H2 release and enhanced the H2 production rate.