Study On The Screening And Fermentation Conditions Of A Novel Cold-active Cellulase Producing Strain

Cellulase is an enzyme that degrades cellulose to glucose. It has already been applled in a lot of industries, such as food, brewing, fur and leather, collagen fiber and fodder, etc. A strain SWD-28 producing cold-active cellulase was isolated from samples of Changhai county in Yellow Sea. It was identified as Penicillium cordubense based on the morphological and ITS sequence.Penicillium sp. SWD-28 was selected as cold-adapted cellulase production strain. Its cellulase production was studied under liquid fermentation condition with single factor, Plackett-Burman and response surface method. The optimal cultivation condition of SWD-28 was corn meal powder 2.2%(W/V), ammonium sulfate 0.24%(W/V), branc 1.5%(W/V). Under the preferable conditions,the FPase was 109.8 U/mL which is 2.25 times of that before optimization.It was selected as cold-adapted cellulase production strain. Its cellulase production was studied under liquid fermentation condition with single factor, Plackett-Burman and response surface method. The optimal fermentation condition of SWD-28 was rotational speed 150r/min, seed age 33h, broth content 100mL, pH 5, inoculum 12.5%, temperature 17℃. Under the preferable conditions,the FPase was 219.9 U/mL which is 2.01 times of that before optimization.An endoglucanase was isolated and purified from it. The specific activity of endoglucanase was 26.4 U/mg increased 20.6 fold and coefficient of recovery was 13.1%, the molecular mass was 33.1kD. Analysis by circular dichroism (CD) spectrum of purified endoglucanase protein revealed that it displayed typical a-helix structure and a-helix 49.9%,β-sheet 0.0%, turn 24.3% and random coil 25.8%. Enzymatic properties showed that the optimum pH value is 5.0 and the optimum reaction temperature is 35℃, at 5℃the relative enzyme activity still reach to 60%.