Cloning of Serratia marcescens KFRI314 chitinase genes and its role on chitin degradation

Serratia marcescens KFRI314 chitinase 유전자의 클로닝과 키틴분해에 관한 효소의 역할

Three chitinase genes (chiA,chiB,and chiC)were cloned into E.coliby PCR amplification from Serratia marcescens KFRI314.The sizes of cloned chitinase genes were1692 bp,1500 bp, and 1443 bp which correspond to 563,499, and 480 aminoacids, respectively. Recombinantchitinaseswereoverexpressedusing pHCEIA expression vector and purified to homogenity. The molecular weights of chitinases were about 60kDa, 50kDa, 52kDa, respectively. Optimum pHs were around pH 5~6 and optimum temperatures were 45∼50℃ while 90% of enzyme activities were stable up to 50℃. The specific activities of ChiA, ChiB, and ChiC were 233.1, 278.8,111.3 μ ㏖ (min) -1 mg –1 against colloidal chitin. From experiments using TLC and fluorescent substrate analogues, it was demonstrated that ChiA was endo-chitinase while ChiB and ChiC were chitobiosidase.