Effect of culture medium on fermentative and CO-dependent H 2 production activity in Citrobacter amalonaticus Y19
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International Journal of Hydrogen Energy, ISSN: 0360-3199, Vol: 41, Issue: 16, Page: 6734-6742
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- Energy; Physics and Astronomy; Citrobacter amalonaticus; Water-gas shift reaction; CODH; CO-Hyd; CooA
Citrobacter amalonaticus Y19 is a unique chemoheterotrophic microorganism capable of carbon monoxide (CO)-dependent hydrogen (H 2 ) production. To improve its biocatalytic potential, the effects of medium composition on cell growth and H 2 production were investigated. Among several carbon sources tested, maltose resulted in the best CO consumption and H 2 production. Meanwhile, l -cysteine supplementation improved cell growth and H 2 production, suggesting that this amino acid stimulates synthesis of Fe S clusters. When molybdenum and selenium, which are essential cofactors of formate-hydrogen lyase (FHL), were added, formate accumulation was reduced. Optimized medium composition improved the activities of CO-dependent H 2 production (6.3-fold), CODH (22.3-fold) and hydrogenase (2.9-fold). The optimized medium composition also enhanced H 2 production in recombinant C. amalonaticus Y19- cooA, which homologously overexpresses CooA, the transcriptional activator of the coo operons. Cells grown under this condition exhibited improved stability in the course of repeated-batch CO-dependent H 2 production under non-growing conditions.