Study Of Exopolysaccharides Produced By Bifidobacterium Astroides 22-5

Bifidobacterium is a physiological bacterium in hunman and animal's intestinal tracts. It's existence directly affects the health of digestive tract. At the present time, there are few reports of Bifidobacterium exopolysaccharide (EPS) from the abroad, and no ones in our country. According to present status, in order to supply the direction to development of new EPS and to base the study of mechanics in physiological function of Bifidobacterium, we choose the subject about Bifidobacterium EPS.The study is specificly as follows:1) Bifidobacterium astroides 22-5, which can produce more EPS, was screened from a mass of crude materials. It was identified as Bifidobacterium asteroides. The method of detection of EPS was determined as phenol-sulfuric acid method by the experiment of recovery rate.2) To optimize EPS production, researching was done on the respect of incubation condition and the media components. And the optimum incubation time was 24h, the optimum temperature was 25 °C, the optimum broth initial pH was 5.5. The optimum carbon source, nitrogen source and irritant factor were defined by single element, then optimized by CCRD. Production of EPS under the optimum broth was 1.21g/L, 6 times than CMRS media.3) The route which is with highest purity and lest lost is defined by the optimization of the method of abstraction and purification of EPS. It is as following: caption of upper fluid→concentration →deposition with elthanol→decolorization→removement of protion→dialysis→gel choromatography. And the EPS was washed with 0.05M NaCl, at 30mL/h. It was proved that the EPS was purity by UV spectrum and HPLC.4) The EPS moleculor produced by 22-5 is 3.92 × 10~5 Da. EPS has strong and stable viscosity. The EPS cannot prohibit the growth of 4 kinds of popular pathogenic bacterial, but it can promote the growth of LAB. It could scavenge DPPH and stimulate the adhesion to Caco-2 of the strain 22-5.