Colonization of B.bifidum ATCC 29521 In Mice Intestinal Tract / 肠外与肠内营养

ABSTRACT

Objective:Effect of gut microbiota on human health has become a hotspot in recent years with the emergence of new microbial technology.B.bifidum is a traditional probiotics and has been widely used in food and medicine.But the metabolism and function of B.bifidum ATCC 29521 has not been well documented.To investigate colonization and growth of B.bifidum ATCC 29521 in mice intestine,fecal B.bifidum concentrations were analyzed by real-time fluorescent quantitative PCR.Methods:Female C57BL/6 mice were orally gavaged with eigher a single dose of 1 × 109 CFU B.bifidum ATCC 29521 or continuous doses of 1 × 109/day for 3 weeks.Feces were collected at 0,2,4,6,8,10,12,16,20,24 h and at 10,7,14,21,24,28 d,respectively.Total DNA was isolated from the feces using the Qiagen DNA stool extraction kit according to the manufacturer's instructions.The linear standard curve was established by each dilution degrees of B.bifidum ATCC 29521 and their corresponding CT values.The curve equation was y =0.1835x + 9.0628 and R2 was 0.9994.The concentration of B.bifidum ATCC 29521 in mice feces were calculated by substituted CT values obtained by RT-PCR into the curve equation.Results:The curves of B.bifidum ATCC 29521 concentration rose at first and then reduced gradually.In single dose group,the concentration of B.bifidum ATCC 29521 began to increase at 4h after oral gavage,reaching its peak 6.0 × 107 CFU/g at 10h and then decreased gradually.The biggest drop occurred at the period between 12 h and 16 h after B.bifidum treatment.In successive administration group,the concentration rose at the highest rate in the first week when it achieved 2.0 × 107CFU/g and kept on inceasing to 1.0 × 108CFU/g in the next week.However,the concentration did not rose up significantly in the third week.It means that the concentration of B.bifidum ATCC 29521 in mice intestine reached platform in the second week after oral gavage.The concentration of B.bifidum ATCC 29521 significantly decreased at 24h and one week after B.bifidum treatment course in two group repectively and was still higher than baseline before oral gavage.Conclusion:Once the B.bifidum ATCC 29521 supplement was discontinued,the concentration fell down in short time.B.bifidum ATCC 29521 could not sustain colonization and growth in mice intestine without external supplement.It is necessary to provide daily supplemention for at least two weeks and to keep on in order to maintain sufficient concentration.