Comparison of hydrothermolysis and mild-alkaline pretreatment methods on enhancing succinic acid production from hydrolyzed corn fiber.

In the present work, mild alkaline pretreatments using either sodium hydroxide (0.05 g/g corn fiber) or calcium hydroxide (lime) (0.05 g/g corn fiber) were optimized and compared with hydrothermolysis pretreatment to enhance bioproduction of succinic acid from hydrolyzed corn fiber. The concentration, yield, and productivity of succinic acid from sodium hydroxide corn fiber hydrolysate (SH-CFH) were 14.0 g/L, 0.63 g/g sugars, and 0.47 g/L*h, respectively, while the concentration, yield, and productivity of succinic acid from hydrothermolysis-pretreated corn fiber hydrolysate (H-CFH) were 30.2 g/L, 0.71 g/g sugars, and 1.01 g/L*h, respectively. Very little succinic acid production (<1 g/L) was observed from lime pretreated corn fiber hydrolysate (L-CFH). When SH-CFH was supplemented only with yeast extract, succinic acid concentration was enhanced to 15.2 g/L with a yield of 0.64 g/g sugars, and productivity of 0.51 g/L*h. In this study, succinic acid concentration and productivity from H-CFH both increased by 8.6% and an succinic acid yield from sugars increased 1.2 times when compared to succinic acid production from H-CFH in a previous study in our lab.