Biological process effective in co-production of biohydrogen and α-amylase by the conversion of carbon monoxide

Abstract

In order to develop co-production of H2 and α-amylase from carbon monoxide (CO), we constructed a mutant strain, designated as 156T-AM, by integrating gene encoding mature form of α-amylase with C-terminal His6 tag into the intergenic region between TON_1126 and TON_1127 of the parental strain, 156T. The 156T-AM mutant displayed higher activity of α-amylase than that of the parental strain during the growth on CO-containing medium. Final cell yield (OD600), maximum H2 production rate and maximum specific H2 production rate of 156T-AM mutant strain was similar to those of 156T strain in a bioreactor using 100% CO or coal-gasified syngas. After the cultivation, α-amylase could be purified by one-step metal affinity chromatography from the cell extract, and the purified protein displayed specific activity of 3048.1 ± 85.5 U mg-1. Additionally, the whole cell extract was applicable to saccharify potato peel at 80 oC and approximately 0.25 g L-1reducing sugar could be generated from 5% (v/v) potato peel waste. This study successfully demonstrated co-production of H2 and a valuable protein from CO or syngas, providing envision to develop hyperthermophilic cell factory to upcycle industrial waste gas.