Soluble pyridine nucleotide transhydrogenase (STH), catalyzes a reversible hydrogen transfer between NADH and NADPH, is widely utilized in cofactor engineering. In the present study, we expanded the distribution range of STH to more unreported bacteria. Meanwhile, STH was mainly found in α, γ, δ-proteobacteria, acidobacteria, actinobacteria and planctomycetes. The enzymological properties of two novel STHs from Acidobacteria bacterium KBS 146 (AbSTH) and Nocardia jiangxiensis (NjSTH) were characterized. The optimum temperature and pH of AbSTH and...