Isolation, identification and probiotic properties of a Bacillus cereus strain from Golden crucian carp
WU Zhenchao1, CHEN Yuke2*, GAO Yongsheng2, WANG Sen2, LEI Xinyu1, YU Mengnan1, ZHANG Yurou1, ZHANG Dongming2,3*
1.College of Life Sciences, Jilin Agricultural University,Changchun 130118, China; 2. College of Animal Science and Technology, The Key Laboratory of Animal Production and Product Quality and Safety of the Ministry of Education,Key Laboratory of Animal Nutrition and Feed Science of Jilin Province, Jilin Agricultural University,Changchun 130118, China;3.Tonghua Normal University,Tonghua 134000, China
Abstract: Bacteria were isolated from the intestine of Golden crucian carp Carassiusauratus and identified by morphological observation, physiological and biochemical analysis, and molecular characterization. The linear relationship between the number of viable bacteria and OD value was established by UV spectrophotometer and counting method, and the tolerance of bacteria was evaluated by measuring the tolerance of bacteria to high temperature, acid, gastric juice, intestinal fluid and bile salt. The adhesion ability of bacteria to intestinal mucus protein of golden crucian carp was detected by fixing the intestinal mucus protein model in vitro and combining with the fluorescent marker Hoechst 3325. The safety of the strain was tested by an acute toxicity test,in vitro antibacterial test, and antibiotic sensitivity test in order to screen out golden crucian carp-derived probiotics suitable for the production of aquatic microecological preparations. It was found that 5 strains with enzyme-producing ability were isolated from the intestinal tract of the golden crucian carp, in which HJJ-1 strain had good enzyme-producing characteristics, effectively inhibited the growth of Staphylococcusaureus and Escherichiacoli, with sensitive to a variety of drugs, so the strain was further identified and the probiotic effect was evaluated. Sequence analysis of 16S rRNA showed that HJJ-1 was 100% similar to Bacilluscereus, combined with morphological characteristics and physiological and biochemical indices and finally identified HJJ-1 as Bacilluscereus. The regression equation between OD600 nm value and viable count of the strain was expressed as y=5.493 3e7.823 8x (R2=0.990 2), characterized by characteristics of high temperature resistance, acid resistance, gastric juice resistance, intestinal fluid resistance, bile salt resistance, adhesion to the Golden crucian carp intestinal mucus protein, and good safety. The findings indicated that Bacilluscereus isolated from golden crucian carp intestines had good potential probiotic characteristics and an excellent and safety.
2020, Vol. 35 
