Evaluation of chitinolytic enzymes activities during microbial biotransformation of Archachatina marginata exoskeleton to chitooligosaccharide

Abstract

Natural macromolecules such as polysaccharides are bioactive substances obtained from the agricultural feed stocks and\ or crustacean shell wastes, thus chitin biomass as a rich renewable resource; is an additional abundant natural polysaccharide in the environment. Despite the recent interests in the biomedical applications of chitin, complexity of chitosan and their derivatives in terms of controlling their chemical synthesis due to the formation of secondary compounds is a major problem, thus this research aimed to focus on the microbial biosynthesis of chitinous products and their derivatives from the seafood wastes. In the current research work; chitin, chitosan and chitooligosaccharides (COS) were biosynthesized from Archachatina marginata exoskeletons; through chemical deacetylation and microbial transformation techniques. During this study, Archachatina marginata exoskeleton was analyzed according to the method adopted by the Association of Official Analytical Chemists. In addition, a synthetic route for chitooligosaccharides production was investigated using a previously characterized Saccharomyces cerevisiae KR13 strain. The crude extract obtained after the biotransformation period was subjected to derivatization, and then the chitooligosaccharides yield, enzymes activities and their molecular weights were determined using Gas chromatography (GC). Moreover, the size exclusion chromatography revealed the presence of several enzymes, including chitin deacetylase; chitooligosaccharide deacetylase, chitinase and chitosanase; in addition to chitooligosaccharides derivatives such as; chitohexose, chitopentose, chitotetrose, chitotriose, chitobiose and chitosan with varying concentrations. Based on the results obtained in this study, manipulation of S. cerevisiae KR13 strain clarified the poor solubility of chitin and chitosan, which makes a challenge in using them in the biomedical applications, despite their important functional activities.