초록
<P>We produced organic acids, including lactate and succinate, directly from soluble starch under anaerobic conditions using high cell-density cultures of <I>Corynebacterium glutamicum</I> displaying α-amylase (AmyA) from <I>Streptococcus bovis</I> 148 on the cell surface. Notably, reactions performed under anaerobic conditions at 35 and 40°C, which are higher than the optimal growth temperature of 30°C, showed 32% and 19%, respectively, higher productivity of the organic acids lactate, succinate, and acetate compared to that at 30°C. However, α-amylase was not stably anchored and released into the medium from the cell surface during reactions at these higher temperatures, as demonstrated by the 61% and 85% decreases in activity, respectively, from baseline, compared to the only 8% decrease at 30°C. The AmyA-displaying <I>C. glutamicum</I> cells retained their starch-degrading capacity during five 10 h reaction cycles at 30°C, producing 107.8 g/l of total organic acids, including 88.9 g/l lactate and 14.0 g/l succinate. The applicability of cell surface-engineering technology for the production of organic acids from biomass by high cell-density cultures of <I>C. glutamicum</I> under anaerobic conditions was demonstrated.</P>