Study On Bacillus Strains Producing Extracellular Polysaccharide

With the development of carbohydrate chemistry,glycobiology and sugar engineering,polysaccharides are now recognized as having important properties,and have wide application prospect in many industries.Many polysaccharides have many effects,and some of them have not been studied in depth,which limits the application of polysaccharides to a certain extent.Polysaccharides can come from plants,animals and microorganisms,animal and plant polysaccharides more in-depth study.In recent years,due to microbial polysaccharide has a stable structure and function,low cost,short production cycle and production control and other advantages of much attention.Expanding the production of polysaccharides by microbial fermentation and its application are of great significance to promote the development of polysaccharides and its practical application.In this paper an extracellular polysaccharide producing Bacillus was studied,the main contents were as follows:strain identification,fermentation optimization,polysaccharide extraction,polysaccharide purification,polysaccharide composition analysis and partial properties.The strain was Bacillus sp.named as Bacillus sp.C-12,by morphological,physiological and biochemical characteristics and 16S rDNA sequence alignment of an exopolysaccharide-producing strain.Using single factor method to determine the influence bacillus sp.C-12 secretion of extracellular polysaccharide fermentation medium main determines the main lord is sucrose,peptone,yeast extract.On three main factors using the response surface design to determine the optimal proportion of medium(g/L)as follows:sucrose 20.4,peptone 9.8,yeast extract 8.9.At the same time,the factors such as temperature,shaking speed,loading volume,inoculation amount and initial pH were optimized by single factor method.The optimized culture conditions were as follows:temperature 30?,shaking speed 160 r/min,loading volume 10%,inoculation 6%and initial pH 6.0.The optimum fermentation conditions were shake flask culture and fermentation,and the glucuronic acid content of the exopolysaccharide was 4.08 mg/mL.The purified polysaccharides can be obtained by treating the fermentation broth with the steps of centrifugation sterilization,Vacuum concentration,ethanol washing,deproteinization,anion exchange resin and so on.The method of extraction and purification of extracellular polysaccharide was determined,and more purified pure polysaccharide products were obtained under the goal of reducing the cost of extraction and purification.The extracellular polysaccharide produced by Bacillus sp C-12 is an exopolysaccharide composed of glucose,mannose and three kinds of unknown monosaccharides.The infrared spectrum showed that the polysaccharide was a kind of polysaccharide containing functional groups such as acetylamino,carboxyl,sulfate,and sugar ring.The exopolysaccharide was obtained by scanning electron microscopy,and the polysaccharide was analyzed by elemental analysis.Based on the preliminary understanding of the exopolysaccharide,the antioxidant properties,development,moisture retention,hygroscopicity,add it to cosmetic formulations for flocculation properties and moisturizing properties were studied,which laid a solid foundation for its application.