Screening and identification of lactic acid bacteria with degrading nitrite and cholesterol from Laminaria japonica

Laminaria japonica is a kind of natural healthy food. In this paper,the lactic acid bacteria with higher degradation of nitrite and cholesterol were screened from light dried L.japonica.The method of Spectrophotometric hydrochloride naphthylethylenediamine was used to determinate nitrite degradation; and the method of Spectrophotometric Ortho- phthalaldehyde was used to determinate cholesterol degradation in MRS liquid medium.7 strains with more than 97% degradation rates of nitrite were screened from 27 strains isolated from the light dried L.Japonica. Through determining their ability of cholesterol degradation,3 strains La- 3,La- 10,La- 15 were screened out with higher cholesterol removal,which were 55.02%,61.21%,56.85%,respectively.According to their characteristics,physiology and biochemistry and 16 S r DNA gene sequence similarity analysis,the 7 strains were Lactobacillus plantarum. The result indicated that the same L. plantarum had difference in degradation of cholesterol,showing species diversity.