Exploring new marine bacterial species, Alcaligenes faecalis Alca F2018 valued for bioconversion of shrimp chitin to chitosan for concomitant biotechnological applications

The exploitation of chitinous materials seems to be an infinite treasure. To this end, using shellfish waste as the sole carbon/nitrogen source solves environmental challenges while lowering microbial chitinase production costs. Bioconversion of shellfish chitin wastes such as shrimp shells has recently been investigated for the production of enzymes and bioactive materials in order to maximize the utilization of chitin-containing seafood processing wastes. In this study, the bioconversion of chitin to chitosan by Alcaligenes faecalis Alca F2018 revealed the highest chitin deacetylase (CDA) activity of 40.6 U/μg. The resulted low Km and high Vmax values explain the high affinity of the purified CDA to the p-nitroacetanilide substrate. CDA with a molecular weight of 66 KDa was purified from F2018 strain, with a 14.5% yield. FT-IR revealed distinct chitosan peaks and XRD revealed that chitosan samples had lower crystallinity than chitin. TGA analysis revealed that the recovered chitosan samples were more thermally stable. The deacetylation degree percentages of the produced chitosan are in the same range as that of the commercial chitosan, suggesting the promising potential of A. faecalis Alca F2018 to utilize shrimp shells in their raw form in the fermentation media based on its CDA enzyme activity.