Effect of biohydrogen by overexpressing small RNA RyhB combined with ldh impairment in novel Klebsiella sp. FSoil 024.

Biotechnological hydrogen production is considered as an environmentally sustainable alternative to petrochemical sources or electrolysis. Here, disruption of lactate dehydrogenase (LDH) and metabolic regulation via the small RNA RyhB were adopted to improve hydrogen production in the novel Klebsiella sp. strain FSoil 024. The hydrogen production of FSoil 024-L (Δ ldh) and FSoil 024-L/R (Δ ldh /RyhB) from glucose in a 5-L fermenter respectively increased by 40 and 50% compared to the wild type. When glycerol was adopted as a more favorable substrate, FSoil 024-L generated 3.3 L/L of hydrogen after 52 h of fermentation, implying its great potential for the utilization of crude glycerol to produce hydrogen. Overexpression of RyhB downregulated formate biosynthesis in FSoil 024, thereby redirecting NADH toward the hydrogen production pathway. This finding provides new insights into the role of cellular reducing power in hydrogen metabolism and establishes a rationale for improving hydrogen production. [Display omitted] • Deletion of ldh redirected NADH to hydrogen production in FSoil 024. • RyhB downregulated formate biosynthesis thus improving hydrogen yield in FSoil 024. • FSoil 024-L exhibited great potential of hydrogen production using crude glycerol. • Hydrogen yield of FSoil 024-L/R increased by 50% with glucose in 5-L fermenter. [ABSTRACT FROM AUTHOR]