He Pin-Jing, Lü Fan, Shao Li-Ming, Pan Xiu-Jiang, Lee Duu-Jong
State Key Laboratory of Pollution Control & Reclamation, Tongji University, Shanghai 200092, PR China.
Biotechnol Bioeng. 2006 Apr 20;93(6):1145-51. doi: 10.1002/bit.20834.
Hydrolysis of organic particulates in rapid fermentative processes can be inhibited. The volatile fatty acids (VFA) released during fermentation reduce pH. Whether VFA or the drop in pH inhibits hydrolysis is unclear. The effects of pH and acetate on the enzymatic hydrolysis of a potato sample that contains both carbohydrate and protein were studied at fixed pH (5-9) in the presence/absence of 20 g/L of acetate. Experimental results showed that the effects of pH and acetate on the hydrolysis of carbohydrate differed from those on the hydrolysis of protein. Numerous kinetic models fitted the hydrolysis data obtained during the first 40 h of hydrolysis when inhibitory effects were insignificant. The Chen-Hashimoto model was used herein to fit the hydrolysis data obtained during 144 h of reaction. Also, the non-competitive inhibition model of three inhibitors (H(+), OH(-), total/undissociated/dissociated acetate) successfully described the inhibition of the hydrolysis of both carbohydrate and protein.
