Comparison Characteristics And Function Of Tetragenococcus Halophilus From Soy Sauce Moromi

Tetragenococcus halophilus is a type of lactic acid bacteria which has tolerance for high osmotic pressure and widely exists in fermented products such as soy sauce,pickled fishes,soybean products.Studies have shown that T.halophilus can increase the content of organic acids,aldehydes,esters,amino acids and other flavor substances in fermented products.Some strains can reduce the harmful substances such as biogenic amines and ethyl carbamate.Systematic understanding of the classification and physiological characteristics of T.halophilus is of great significance for the industrial application and optimization of the production process of the strain.In this study,classification of T.halophilus strains from soy sauce moromi mash were performed and their physiological characteristics were compared.The main results are listed below.?1?Based on polyphasic taxonomy analysis,through the combination of multilocus sequence typing?MLST?and carbohydrate metabolism cluster analysis,twelve strains of T.halophilus from soy sauce mash were classified into two groups.There is a certain correlation between the taxonomic categories of the two groups of strains and the native environment of the isolated strains.?2?The physiological characteristics of the strains were analyzed and compared through protease activity test and analysis of the environmental tolerance of strains.T.halophilus from sauce mash had high tripeptidase activities in high salt environment.The tolerance to osmotic pressure was different:strain C25,C33,C3,R55 had strong tolerance to high salt and high sugar.T.halophilus is generally not resistant to acid and low temperature,but the two strains?C33 and R44?still grow normally in acid culture system?pH 5.0?,and their growth is slightly better than those of other strains at low temperature?15°C and 25°C?.T.halophilus has peroxidase and other antioxidant enzyme activities.Strain C25 has strong antioxidant activity,and strain R23 and R21 has catalase activity under the heme-induced and aerobic conditions.Catalase has successfully improved the antioxidant ability of R23 and R21.?3?T.halophilus from sauce mash were consists of six genotypes of arginine deiminase pathway?ADI?,among which R23 and strains with the same ADI type have the most number of genes and multiple copy gene number.The utilization of arginine and citrulline is greatly affected by environmental conditions.Among the multiple-copy genes of the ADI metabolism pathway,arcB gene was found to be critical to citrulline metabolism,based on corresponding genes transcriptional level analysis and comparison of the utilization of arginine and citrulline.The transcriptional level of arcB is 10.5 and 29.8 of that of arcB₁ and arcB₂.