Study On Screening And Condition Optimization Biosynthesis Of Exopolysaccharide Producing By Lactobacillus

Lactic acid bacteria exopolysaccharide is mucinous or capsular polysaccharide metabolism during fermentation produced and secreted to the extracellular by lactic acid bacteria. In this study, one strain high yield of exopolysaccharide lactic acid bacteria, named as NM18, was selected by phenol-sulfuric acid method from117strains lactic acid bacteria, and observed a rod-shaped bacterium based on its morphological characteristics. NM18was identified as Lactobacillus plantarum combined API50sugar fermentation experiment and with the result of16S rDNA genes sequence analysis, which was1478bp PCR amplified gene sequences, PCR product sequences, homology comparison with NCBI databases using the software Blast.Determine the strain NM18synthetic extopolysaccharides optimum medium and fermentation conditions by single factor and orthogonal test, soy peptone12.0g/L, beef extract11.0g/L, yeast extract5.0g/L, sucrose28.0g/L, lemon silicate hydrate6.0g/L, anhydrous sodium acetate6.0g/L, Tween-801.0mL/L, initial pH6.5, fermentation temperature37℃, fermentation time34h and optimal inculum quantity1.5%. And, soy peptone, beef extract, yeast extract, sucrose, tween-80, anhydrous sodium acetate on the exopolysaccharide has a significant effect (p<0.05), strain NM18exopolysaccharide synthesis in this condition in the extracellular reached238.1mg/L, compared with the basic fermentation medium exopolysaccharide synthesis improve25.2%.Through single factor and orthogonal test to determine the strain NM18synthesis of exopolysaccharides optimum extraction conditions for the ethanol concentration ethanol of80.0%, add multiple of4.0, trichloroacetic acid concentration of4.0%, alcohol precipitation time24h, pH5.5, centrifuged speed16000r/min and centrifugation time35min, where the concentration of ethanol, alcohol precipitation time, initial pH and centrifugation time on the exopolysaccharides has a significant effect (p<0.05). Under this conditions, exopolysaccharide amount improve295.0mg/L; before optimization and improvement of41.6%.Strain NM18produced exopolysaccharide use of cellulose DEAE-52column isolated from the4main components of the preliminary EPS-1, EPS-2, EPS-3and EPS-4; and by Sepharose CL-6B further purified by single component NM18-1, NM18-2, NM18-3and NM18-4. To lay the foundation for the study identification structures and functions of that strain NM18produced exopolysaccharide.