Isolation And Characterization Of Tetragenococcus Halophilus Strains From Moromi

Soy sauce is a traditional fermented condiment which develops rapidly in recent years. Food safety issues which reported that ethyl carbamate(a cancergenic compound) was detected in soy sauce catch scholar’s attention. There are many methods to eliminate ethyl carbamate, but few reports for soy sauce. Citrulline is the main ethyl carbamate precursor in soy sauce, which is accumulated and correlated with the metabolism of arginine by lactic acid bacteria via arginine deiminase passway(ADI) during soy sauce fermentation process. Therefore, the objective of this study is to screen strains with excellent metabolic capability of citrulline to control the accumulation of citrulline in soy sauce.In the present study, we researched the arginine deiminase passway-related genes and arginine, citrulline metabolism of Tetragenococcus halophilus from soy sauce. The arginine deiminase passway-related genes whether exist in lactic acid bacteria was tested by colony PCR method. Isolated the Tetragenococcus halophilus from soy sauce by morphological characteristics of lactic acid bacteria and gro EL gene-specific amplification. Analyze arc A, arc B, arc C gene of Tetragenococcus halophilus and arginine, citrulline metabolic capability. The effect of condition factor such as different concentration of arginine and temperature on metabolic capability of Tetragenococcus halophilus was investigated.The result showed that the amount of lactic acid bacteria which had ADI was an obvious advantage in different samples. Phylogenetic analysis of the 16 S r RNA showed that all the strains which had gro EL gene were Tetragenococcus halophilus. In comparison with other Tetragenococcus halophilus, Tetragenococcus halophilus R23 had arc A gene and maximum number of arc B, arc C gene and the metabolic capability of arginine, citrulline was strongest in high salt environment. Culture and environmental conditions(temperature, arginine concentration) had influence on the capability of Tetragenococcus halophilus R23 to consume citrulline and arginine.Finally, we have screened Tetragenococcus halophilus R23 with excellent metabolic capability of arginine and citrulline from moromi. It will be help to solve the problem of ethyl carbamate in soy sauce.