김치로부터 exopolysaccharide 생성 유산균의 분리 및 특성 규명

Abstract

Lactic acid bacteria isolated from kimchi were screened for exopolysaccharides(EPS) production. Three lactic acid bacteria were able to produced EPS from sucrose media. The selected strains were identified as Leuconostoc kimchii, Leuconostoc citreum, Leuconostoc mesenteroides strains GJ2, C3 and C11 by using Biolog test and 16S rDNA sequencing. In the viability tests in the presence of artificial gastric juice or bile, the isolated Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 showed high viability(maintain initial viable cell, 108 CFU/mL) for 2 hours in 0.05 M sodium phosphate buffer (pH 3.0), in artificial gastric juice and for 24 hours in artificial bile. In liquid media containing sucrose as carbone source, the amount of EPS produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 was 21.49 g/L, 16.46 g/L and 22.98g/L, respectively. In the EPS produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11, sugar comprised 96.48% w/w, 89.38% w/w and 91.05% w/w, respectively while the protein content was found to be 0.8% w/w, 0.9% w/w and 0.95% w/w for GJ2, C3 and C11 EPS, respectively. The sugar compositions of the EPSs were analyse by TLC and HPLC analysis from acid hydrolysis of the EPS. EPSs produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 contained only glucose. Viscosity of the 4% EPSs and purified EPSs solution were highest EPS produced by Leu. citreum C3(136.3cp and 3719cp, respectively) while lowest EPS produced by Leu. mesenteroides C11(3.57cp and 6.07cp, respectively). The viscosity results showed that the difference in viscosity of the EPS produced by Leu. kimchii GJ2, Leu. citreum C3 and Leu. mesenteroides C11 may be caused by the difference in molecular weight and structure of the EPSs.