Optimal Cultivation Conditions Of A Polysaccharide Rich Botryococcus Sp. Strain And Its Effect On Bacteriostasis In Vivo And Swage Treatment In Vitro

Traditional fishing fodder has the disadvantages of mono -function, low - level of nutrition. Besides, the fodder which hadn't been eating may lead to breeding of microbe or eutrophication. At the same time, abuse of antibiotic may lead to drug resistance, residue and pollution. These problems are becoming a big threating to food safety.Micro - algae immobilized microsphere will be full of nutriments. It will play a role of bacteriostat in vivo with a strong ability of swage treatment in vitro. By lucubrating this microsphere we may promote the development of fodder resource, find a new way to disease prevention and swage treatment.In this study, Taxonomic evaluation of a microalgae from factory was performed, results shows that the algae strains is Botryococcus sp. Choricystis (Phylum), Trebouxiophyceae (Class), Chlorophyta (Order).Using it as a base, in order to obtain a biomass rich micro - algae with high yield of polysaccharide, culture conditions was optimized. Results shows that in the light intensity of 65 ?mol·m-2·s-1,28 ?, BG11 medium, in 15d Botryococcus sp. biomass can reach 0.92 g/L (DW),and it's total sugar content can reach 32.7% (DW), and it's total sugar production can reach 0.30g/L (DW).At the same time, enzyme activities of GPI and HK were assayed,and the correlation between this two kinds of enzymes and polysaccharide content was analyzed. Results shows that enzyme activities of GPI and HK had significant positive correlations with polysaccharide content. This result may offer a new measure to monitor and control the accumulation of polysaccharide.In order to test the antibacterial activity of polysaccharide which is from microalgae after it was disintegrated in fish, polysaccharide was extracted from microalgae. And its monosaccharide composition was analyzed, the results shows that it was composited by 9 kinds of monosaccharide. Its antibacterial activity was also tested by a C. elegans model. Results shows that this polysaccharide has a significant antibacterial activity against Salmonella and Staphylococcus aureus. Its IC50 was 3.75 mg/mL and 1.04 mg/mL.After that, a immobilized microalgae microsphere was prepared. The ability of swage treatment was analyzed to make sure that this microsphere can improve water quality and prevent eutrophication. Results shows that in 0.75 g/L (microalgae) The removal rate of NO2- - N and PO43- - P can reach 76.9% and 89.6% after 10 days.At last, in consideration of the time difference between production and using of microsphere, short - time storage is necessary. Activity of microsphere after short - time storage was analyzed, Results shows that the optimum conditions for preservation is 2.5 times concentration (microalgae), 1:3 (microalgae:Sodium alginate),2.2 mm (microsphere diameter); The effects of activity - maintain:Times concentration (microalgae)> microalgae:Sodium alginate> microsphere diameter.