Primary Study On Polysaccharide And Its Production Of Nostoc Flagelliforme Cells

The method of measuring polysaccharide content in culture medium of Nostoc flagelliforme cells as well as extraction, primary isolation and purification of polysaccharide was described in this paper. Two productions made of culture medium and polysaccharide from Nostoc flagelliforme cells were also developed.Phenol-sulfuric acid method and anthrone-sulfuric acid method were two usual methods to determine the content of polysaccharide. The stability, repeatability, recovery and effects of ions in medium of the methods were compared. The results showed that accuracy, stability and repeatability of the two methods were good, but determination results were significantly influenced by ions in the medium. So ions should be removed from the sample before determination. Phenol-sulfuric acid method was more suitable in determining the sample that has less polysaccharide content.Two kinds of Nostoc flagelliforme cells----type I and type II, which have significant difference in shape, were found in the culture. Growth rate of type I was slower than that of type II, but EPS production of type I was much higher than that of type II. Yield of EPS reached 60.6mg/L when cells of type I were cultured for 30 days.Primary purification and contrast among three different polysaccharides were done by means of ion exchange chromatograph and gel chromatograph. The IEC results showed one fraction in EPS (eluted at 0.2M NaCl) and two fractions in CPS (eluted at 0.25M NaCl and 0.37M NaCl, respectively).For the polysaccharide extracted from Nostoc flagelliforme, only one fraction was obtained (eluted at 0.3M NaCl).The eluted profile of gel chromatograph revealed one fraction in EPS and two fractions with different molecular mass in CPS. One peak was shown in eluted profile of polysaccharide from Nostoc flagelliforme in this experiment.The extraction process of EPS and CPS from culturing of Nostoc flagelliforme cells was determined. Polysaccharide was obtained from culture medium and extraction of Nostoc flagelliforme cells by centrifugation, concentration, removal of small molecular mass matters and protein, deposition and freeze-dry. Technics of extraction was also optimized.We developed two products----artificial Nostoc flagelliforme and Nostoc flagelliforme-balsam pear powder, which were made from liquid medium and polysaccharide of Nostoc flagelliforme cells.