Optimization of preparation conditions for β-chitosan derived from diatom biomanufacturing using response surface methodology

Chitosan is a polymeric polysaccharide with widely application. At present, commercialized chitosan obtained by deacetylating chitin with acid-alkali method. The homogeneity of the molecular weight of chitosan is difficult to adjust due to the low homogeneity of chitosan itself and the degradation effect of the extraction process. And the single source of raw material has limited the further development of chitosan. In this study, diatoms were used as the source of chitosan extraction through alkalization freeze-thaw method, and response surface methodology was also used to optimize the best preparation conditions of diatom chitosan. The extracted chitosan from diatom was β-type chitosan with low molecular weight, great homogeneity. Diatom chitosan was able to reduce blood loss and clotting time >30 % in vivo experiment compared to control. The hemolysis rate of diatom chitosan was lower than 1 %, and the survival rate was higher than 95 % when co-cultured with L929 cells. Diatom chitosan with 0.005 % could inhibit E. coli and S. aureus by >90 %. Considering the large-scale cultivation properties of diatom, the extraction of diatom chitosan based on alkalization freeze-thaw method will provide a viable solution for obtaining β-chitosan with homogeneity on a large scale.