Screening of Highly Pectinase-Producing Strain from Tobacco Leaf and Enzymatic Properties Thereof

Seventy-four samples of aged tobacco strips and 8 samples of bundle leaf were collected to isolate bacteria and fungi with plate method,and strains with higher enzymatic activity were screened by transparent loop method and assay of pectinase activity in fermentation liquid. The screened strains were identified with morphological characteristics and molecular technique,and its enzymatic properties were preliminarily studied. The results showed that 60 strains and 21 fungi were screened from 389 isolated strains and 81 fungi,among them, strain TS63-9 possessed the highest pectinase activity of 142.43 U/mL, which was identified as Penicillium verruculosum according to its morphological characteristics and ITS rDNA sequence analysis. The optimal catalytic temperature for TS63-9 pectinase was 55℃,and 73.9% of its maximum activity still retained after incubation for 4 hours at 40℃. The preferable reaction pH was 4.0,and held good enzymatic stability in the pH range of 4.0 and 6.0.