(177p) Enhanced Hydrogen Production from Non-Sterilized Lignocellulose Hydrolysates By Nfnab-Deleted Thermoanaerobacterium Aotearoense SCUT27

As a renewable and clean energy carrier, the production of biohydrogen from low value feedstock such as lignocellulose has continuously garnered interest. The NfnAB (NADH-dependent reduced ferredoxin: NADP⁺ oxidoreductase) complex catalyzes the electron transfer between reduced ferredoxin and NAD(P)⁺, which is critical for NAD(P)H-dependent products production (such as hydrogen and ethanol). In this study, the effects of nfnAB deletion in Thermoanaerobacterium aotearoense SCUT27 on end-products formation were investigated. Compared to the parent strain, the NADH/NAD⁺ ratio in â–³nfnAB mutant was increased which changed the products distribution. Consequently, hydrogen and ethanol concentration increased by (41.1 ± 2.37) % (p<0.01) and (13.24 ± 1.12) % (p<0.01), respectively, while lactic acid concentration decreased by (11.88 ± 0.96) % (p<0.01) when glucose was the sole carbon. In addition, no obvious inhibition effect was observed for both SCUT27 and SCUT27/â–³nfnAB in six kinds of dilute-acid pretreated lignocellulose hydrolysates for hydrogen production. It is worth noting that 196.35-214.49 mmol/L hydrogen, with a yield of 1.67-1.80 mol/mol and productivity of 13.09-14.31 mmol/L•h, could be obtained by SCUT27/â–³nfnAB from non-sterilized dilute-acid pretreated rice straw and corn cob hydrolysates. Hence, we demonstrated that the deletion of nfnAB in T. aotearoense SCUT27 is an effective approach to improve hydrogen production by redirecting the electron flux, and SCUT27/â–³nfnAB is a promising candidate for efficient biohydrogen production from lignocellulosic hydrolysates.