Isolation of chitinase yielding Bacillus cereus JF68 from soil employing an edible crab shell chitin

摘要

Chitin degradation is one of the major steps in nutrients' cycling, especially in marine environment. Chitinolytic bacteria play primary role in depolymerizing the complex polysaccharide in natural as well as sea food waste areas. Chitinolytic bacterium was isolated from a soil sample in medium containing edible crab shell waste as major carbon source. The strain showed clear zone of hydrolysis in colloidal chitin agar medium. Using morphological, biochemical and 16S rDNA analysis the isolate was identified as Bacillus cereus under accession No. KC849453. The G + C content of the genomic DNA were 53.58%. Maximum production of chitinase occurred after 5 days of cultivation at 30℃, pH 7.0 and with peptone as nitrogen source. Highest chitinolytic index of the B.cereus JF68 was 2831.75U/ml. The enzyme was partially purified by ammonium sulfate precipitation and dialysis. The precipitation gave a 3.72 fold increase of the specific activity with a yield increase of 72.26%. Extensive production of stable microbial chitinolytic enzymes has a promising potential for biological control of insect as well as fungal pests.