Isolation and screening of cellulolytic bacteria from soil and optimization of cellulase production and activity

Abstract

Objective: The aim of the present study is to demonstrate the isolation, identification and screening of bacteria with high cellulase activity from soil samples. Materials and Methods: Cellulose degrading bacteria were isolated from soil sample using serial dilution and pour plate method. Bacteria were further identified by morphological and biochemical tests and subjected to cellulase production in 250 ml Erlenmayer flask using potato waste medium for 48h of fermentation period at 35oC with agitation speed of 140rpm. Results: Seven different bacterial strains were isolated and screened for cellulase production in submerged fermentation process. Among these seven tested bacterial strains; ASN2 showed maximum yield for cellulase production. This strain was further characterized by biochemical and morphological tests and identified as Cellulomonas sp. ASN2. Supplementation of glucose, peptone and cysteine to the fermentation medium are favored enzyme secretion. The optimum pH and temperature for the activity of crude enzyme was 7.5 and 60oC, respectively. Metal profile of the enzyme indicated that Co2+ and Mn2+ are the strong stimulators while Hg 2+ and Fe 2+ inhibited the activity of cellulase from cellulolytic bacterial strain, Cellulomonas sp.ASN2. Conclusion: Results indicated that favorable fermentation conditions and the selection of a suitable growth medium played a key role in the production of cellulase from newly isolated Cellulomonas sp. ASN2. Due to its particular characteristics this enzyme will be used in saccharification process for bioethanol production from plant biomasses.