Multicomponent Cellulase Production by Cellulomonas biazotea NCIM-2550 and Its Applications for Cellulosic Biohydrogen Production

摘要

Among four cellulolytic microorganisms examined, Cellulomonas biazotea NCIM-2550 can grow on various cellulosic substrates and produce reducing sugar. The activity of cellu-lases (endoglucanase, exoglucanase, and cellobiase), xylanase, amylase, and lignin class of enzymes produced by C. biazotea was mainly present extracellularly and the enzyme production was dependent on cellulosic substrates (carboxymethyl cellulose [CMC], sugarcane bagasse [SCB], and xylan) used for growth. Effects of physicochemical conditions on cellulolytic enzyme production were systematically investigated. Using MnCl2 as a metal additive significantly induces the cellulase enzyme system, resulting in more reducing sugar production. The efficiency of fermentative Conversion of the hydrolyzed SCB and xylan into clean H2 energy was examined with seven H2-producing pure bacterial isolates. Only Clostridium-butyricum CGS5 exhibited efficient H2 production performance with the hydrolysate of SCB and xylan. The cumulative H2 production and H2 yield from using bagasse hydrolysate (initial reducing sugar concentration = 1.545 g/L) were approximately 72.61 mL/L and 2.13 mmol H2/g reducing sugar (or 1.91 mmol H2/g cellulose), respectively. Using xylan hydrolysate (initial reducing sugar concentration = 0.345 g/L) as substrate could also attain a cumulative H2 production and H2 yield of 87.02 mL/L and 5.03 mmol H2/g reducing sugar (or 4.01 mmol H2/g cellulose), respectively.