Screening and identification of novel chitin deacetylases for the sustainable valorisation of chitin

Chitin is one of the most abundant organic molecules after lignocellulose, yearly produced in nature in the range of 1010-1011 tons. However, its direct applications are mainly restricted to low value-added products (e.g., animal feed and agricultural fertilizers) because of the high crystallinity and inflexibility of its structure. On the contrary, molecules such as chitosan, N-acetylglucosamine, and chitooligosaccharides, which derive from its deacetylation and/or hydrolysis, have attracted attention because of their water solubility and various favourable bioactive properties. Consequently, there is much interest in the discovery of novel chitinases and chitin deacetylases (CDAs), which would allow to produce them in a more targeted and environmentally friendly way, as opposed to the currently prevalent chemical route. To this point, we are applying both in silico and functional screening approaches in order to identify novel CDAs from bacterial strains originating from diverse ecological niches, from European soils to the extreme Antarctic Ocean. Three putative CDAs have thus far been identified from a soil Streptomyces sp. MEL8 strain, a marine Antarctic Acinetobacter sp. C33 strain, and from a Nonomuraea sp. strain. The enzymes’ biochemical characterization revealed promising features concerning their temperature activity profile and tolerance to various salts, solvents, and detergents. This will favour the development of sustainable bioprocesses for chitin valorisation, with applications in a wide range of industrial sectors, including polymer functionalization, enzyme immobilization, and biocatalysis, as well as packaging, biomedical, pharma, cosmetics, and food ones.