Isolation of a Psychrotrophic Bacterium Sanguibacter sp. KCTC 10714 from Antarctica and characterization of its Extracellular Endochitinase Gene

Abstract

A psychrotrophic bacterium strain KCTC 10714 was isolated from sea sand from sea water, King George Island, Antarctic. It was identified as Sanguibacter sp., based on the biochemical properties and 16S rDNA sequence. We cloned the endochitinase gene, Chi21702 from Sanguibacter sp. using inverse PCR cloning method. Chi21702, showing a characteristic of an endochitinase, produced chitinoligomer and recognized dimmer. As a results of genetic analysis of chi21702, the total length of genomic DNA was 1,888 bp. Among 1,888 bp, 5'-UTR was 388 bp, ORF was 1,449 bp (482 amino acid), and 3'-UTR was 51 bp. In the ORF region, Chi21702 gene has a ChtBD3, Chitin/cellulose binding domain and a Chitinases family 18 active site. We also confirmed that the recombinant protein of Sanguibacter sp. endochitinase made approximately 56 kDa after expression of recombinant gene construct in E. coli. It is active in a broad pH (pH 4-9) at temperature from 0 to 70℃. At 0℃, it contained 70.9% of relative activity in comparison to 100% at 40℃.