Isolation,Identification of Limosilactobacillus reuteri from Shrimp and Its Characterization
The purpose of this experiment was to screen a strain of lactic acid bacteria from shrimp with a strong ability to control aquatic pathogens and to study its properties of inhibiting aquatic pathogenic bacteria.Microflora in different intestinal segments of healthy Penaeus vannamei were used as the source of strain isola-tion.Lactic acid bacteria were isolated and purified using CaCO3-MRS solid medium.Subsequently,a safe strain was obtained through the bacteriostatic ability test of common aquatic pathogens and the hemolysis test,and identified by 16S rRNA sequencing.Their growth characteristics,tolerance,antibiotic sensitivity,and the bacteriostatic ability of the fermentation supernatant with different treatments were evaluated.The results showed that Limosilactobacillus reuteri SAMMRS-1G was identified as the safe strain with the strongest bacteri-ostatic ability against common aquatic pathogens.In terms of growth characteristics,the optimum culture pH for Limosilactobacillus reuteri SAMMRS-1G was 5.0,and the optimum culture temperature was 39 ℃,with the logarithmic growth period occurring between 4 to 14 h.From the perspective of tolerance,Limosilactobacil-lus reuteri SAMMRS-1G exhibited a certain tolerance to artificial gastrointestinal fluids and osmotic pressure.The survival rate was 90.7％under pH 3.0 incubation for 4 h,85.3％under 3.0 g/L bile salt concentration for 4 h,and 98.7％under 60％o high salinity incubation for 4 h.Regarding the influence of different treatments on the bacteriostatic ability of the Limosilactobacillus reuteri SAMMRS-1G fermentation supernatant,the bacterio-static ability of the fermentation supernatant to pathogenic bacteria followed the order of Vibrio vulnificus＞Staphylococcus aureus＞Vibrio parahaemolyticus＞Shewanella putrefaciens＞Salmonella typhimurium＞Aeromonas hydrophila＞Escherichia coli＞Pseudoalteromonas sp.＞Vibrio alginolyticus＞Vibrio cholerae＞Vibrio harveyi.The fermentation supernatant of Limosilactobacillus reuteri SAMMRS-1G exhibited good thermal stability,retaining 82％bacteriostatic activity after gastrointestinal protease treatment.It demonstrated stronger stability.In addi-tion,the safety tests in mice showed that the Limosilactobacillus reuteri SAMMRS-1G had no negative effects on the growth performance and organ indexes.In conclusion,Limosilactobacillus reuteri SAMMRS-1G from shrimp,screened in this experiment,is a safe lactic acid bacterium with good tolerance,a strong ability to con-trol aquatic pathogenic bacteria,stable activity of metabolites,and probiotic potential.It can provide reference strains for the development of anti-bacterial products in aquaculture.[Chinese Journal of Animal Nutrition,2024,36(4):2660-2673]
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维普
