Enhanced Production of Cellobiase by a Marine Bacterium, Cellulophaga lytica LBH-14, in Pilot-Scaled Bioreactor Using Rice Bran

Abstract

The aim of this work was to establish the optimal conditions for the production of cellobiase by a marine bacterium, Cellulophaga lytica LBH-14, using response-surface methodology (RSM). The optimal conditions of rice bran, ammonium chloride, and the initial pH of the medium for cell growth were 100.0 g/l, 5.00 g/l, and 7.0, respectively, whereas those for the production of cellobiase were 91.1 g/l, 9.02 g/l, and 6.6, respectively. The optimal concentrations of K2HPO4, NaCl, MgSO4•7H2O, and (NH4)2SO4 for cell growth were 6.25, 0.62, 0.28, and 0.42 g/l, respectively, whereas those for the production of cellobiase were 4.46, 0.36, 0.27, and 0.73 g/l, respectively. The optimal temperatures for cell growth and for the production of cellobiase by C. lytica LBH-14 were 35 and 25℃, respectively. The maximal production of cellobiase in a 100 L bioreactor under optimized conditions in this study was 92.3 U/ml, which was 5.4 times higher than that before optimization. In this study, rice bran and ammonium chloride were developed as carbon and nitrogen sources for the production of cellobiase by C. lytica LBH-14. The time for the production of cellobiase by the marine bacterium with submerged fermentations was reduced from 7 to 3 days, which resulted in enhanced productivity of cellobiase and a decrease in its production cost. This study found that the optimal conditions for the production of cellobiase were different from those of CMCase by C. lytica LBH-14.

Enhanced Production of Cellulase from the Agricultural By-product Rice bran by Escherichia coli JM109/LBH-10 with a Shift in Vessel Pressure of a Pilot-scale Bioreactor

“…Each year, 90% of the rice bran produced in the world is utilized cheaply as a feedstock, and the remainder is used for the extraction of rice bran oil (Kim et al 2012a;Todhanakasem et al 2014). The complete enzymatic hydrolysis of agricultural by-products into fermentable sugars requires the synergistic action of three types of cellulases: endoglucanses, exoglucanases, and cellobiases Kim et al 2011;Cao et al 2013a). The enzymatic saccharification of agricultural by-products for the production of ethanol uses commercial cellulases.…”