Isolation Of Alginate Lyase Strain And Their Optimization For Culture

Alginate is a kind of brown algae polysaccharide extracted from brown algae,It is aimed to isolate and optimize the culture conditions to produce alginate lyase by echinoderms gut bacteria.Alginate lyase bacteria were well used for producing alginate oligosaccharide as the later had the potential for various bioactivities.By using sodium alginate as the sole carbon source,12 strains with alginate lyase bacteria isolated from abalone Haliotis discus hannai gut,two strains were selected,which had the highest alginate lyase activities and named M3 and M7.Based on the phylogenetic analysis of 16 S rDNA,the strain M3 and M7 grouped within the genus Pseudoalteromonas.Eight variables were tested using the Plackett–Burman design for strain M3,and four variables were shown exerted effects on alginate lyase activity,including culture temperature,initial pH,alginate concentration and peptone concentration.The findings obtained by Central-Composite Design indicated that the optimal values were temperature of 28 ?,pH of 7.5,alginate concentrations of 0.5%(w/v),and peptone concentration of 0.6%(w/v),inoculum size of 2%,the volume of media of 50 mL,agitation frequency of 200 r/min,at these optimized conditions,the alginate lyase activity was 1.063 U/mL.The orthogonal test was applied for optimizing strain M7 and the results showed that the alginate concentration of 1%,sodium chloride concentration of 1%,inoculum size of 6%,temperature of 18 ?,the volume of media 10 mL,pH of 7.5,the agitation frequency of 200 r/min,at those optimized conditions,the alginate lyase activity could raise to 1.751 U/mL.