DIVERSITY OF CELLULOLYTIC BACTERIA ISOLATED FROM A FRESHWATER WETLAND RESERVE IN THAILAND AND THEIR CELLULOLYTIC ACTIVITY

Freshwater wetlands are unique aquatic ecosystems, which are a tremendous source of organic carbon. A bacterial community plays a significant role in the carbon cycle of organic matter through its cellulolytic enzymes; namely, cellulases. For this study, culturable bacteria were isolated from a freshwater wetland reserve situated in Thailand and screened for their cellulase production. Seventy-six cellulolytic bacteria were grouped by a PCR-RFLP of 16S rDNA technique and identified by a nucleotide sequencing analysis. A total of 17 different RFLP patterns were obtained, belonging to nine bacterial genera including Acinetobacter, Aeromonas, Bacillus, Chromobacterium, Citrobacter, Enterobacter, Herbaspirillum, Paenibacillus and Vibrio. The predominant genera of the isolated cellulolytic bacteria were Bacillus, Chromobacterium and Herbaspirillum. The cellulolytic bacterium isolated from the moist peat samples designated as B. megaterium strain S0702 could produce three types of cellulases and showed the highest CMCase activity at 4.48 +/- 0.08 U/mL. The optimum pH and temperature for the CMCase activity were determined to be 45 - 50 degrees C at a pH of 7.0 with a stability range of 25 60 degrees C and pH 5.0 - 8.0. The CMCase activity was greatly enhanced by Mn2+ and considerably inhibited by EDTA and ethyl-acetate. This enzyme could possibly be used in various biotechnological applications.