Study On Screening Of Saccharomyces Cerevisiae Strain With High Production For Polysaccharides And Antitumor Activity

Medicinal fungi is a kind of medication which has treatment, prevention or inhibition to disease and no toxicity to human and health maintenance. Fungal polysaccharide is one of the main active ingredient in medicinal fungi, and has obvious effects on strengthening the body immunity, anti-tumor, anti-oxidation and anti-virus activity. The reseach of fungal polysaccharides has become one of the development of new drugs.The Sac-charomyces cerevisiae polysaccharide has many activities such as adsorption of pathogenic bacteria, enhancing the cell immunity,elevation macrophagocyte activity, anti-virus activity and the function of anti-cancer.Sac-charomyces cerevisiae belongs to Saccharomyces, known as the fungal of beer making. It has a lot of polysaccharide in it.However, the research on Sac-charomyces cerevisiae both at home and abroad is rarely carried out. For its in-depth development and application,this paper gained mutant Sac-charomyces cerevisiae stains with high-yeilding polysaccharide and researched the polysaccharide extraction process, as well as its anti-tumor activity in vitro.Sac-charomyces cerevisiae was mutated by UV-LiCl and DES.Then, the mutants were screened with the colony diameter in the YPD medium.23 mutants were choosen and 4 mutants then choosen by the assay of polysaccharides.The polysaccharide yield of the 4 mutants were 15.82%,16.02%,16.25%,15.95%,respectively.genetic stability research was carried among the 4 mutants.The 4 mutants all had the stable yeiilding after 5 generations were cultured. The polysaccharides yeilding of the seventeenth mutant is 16.14% which was the most.One-factor tests and Response Surface Methodology (RSM) were applied to optimize the hot water extraction and ultrasound extraction conditions of Sac-charomyces cerevisiae polysaccharides. Experiment factors and levels were first selected by one-factor tests. On the basis of this, extracting temperature, extracting time the ratio of water to sample, were chosen as the factors of hot water extraction in RSM and each factor in the design was studied at three different levels. The optimum hot water extraction conditions were confirmed as follows:extracting temperature 92.6℃, extracting time 3.3 h, the ratio of water to sample 61:1 (mL:g).The extraction rate of polysaccharides under the optimum hot water extraction conditions could reach the highest value of 12.96%with two-times extraction.Ultrasound extracting time, ultrasound power and the ratio of water to sample were chosen as the factors of ultrasound extraction in RSM and each factor in the design was studied at three different levels. The optimum ultrasound extraction conditions were confirmed as follows:ultrasound extracting time 184 s, ultrasound power 410 W, the ratio of water to sample 48:1(mL:g). The extraction rate of polysaccharides under the optimum ultrasound extraction conditions could reach the highest value of 14.95% with two-timesextraction.Ultrasound extraction could greatly shorten the extraction time and reduce the ratio of water to sample,and the extraction rate of polysaccharides was slightly higher than hot water extraction.MTT assay was used to study the effect of Sac-charomyces cerevisiae polysaccharides on various human tumor cells proliferation in vitro.polysaccharides couldn't inhibit the proliferation of tumor cells in vitro on ZR-75-30,SMMC7721,SW-111C,but they had promotive effect. polysaccharides couldn't inhibit the proliferation of tumor cells in vitro or inhibitory activity on MCF-7,SGC-7901, but with the concentration of 500μg/mL the inhibitory ratio reached 0.75%,1.2% respectively.polysaccharides significantly inhibited the proliferation of NCI-H460 with low inhibitory ratio in vitro. The inhibitory ratio of Sac-charomyces cerevisiae polysaccharides on NCI-H460 reached 62.14%when the concentration was 500μg/mL,which is the most significant.