A comprehensive account of fungal chitin deacetylases: Aspects and prospects

Chitin deacetylases (CDA, EC 3.5.1.41), found in bacteria, insects and fungi, are the only enzymes in nature that catalyzes the conversion of chitin (polymer of N-acetyl-β-D-glucosamine) to chitosan (polymer of β-D-glucosamine). Presently, the commercial production of chitosan involves using harsh chemicals at high temperatures, causing pollution, while producing low-quality chitosan. CDAs, especially from fungal sources, produce chitosan, with high degree of deacetylation and low molecular weight, in an eco-friendly method, making it extremely valuable. The utility of fungal CDA to obtain chitosan with desired properties is highlighted in the review. With a view to improving the viability of use of CDAs in the production of better-quality chitosan, this review delves into the biochemical, molecular, and structural aspects of fungal CDAs. It also emphasizes the physiological roles of the CDA in fungi, including virulence and host immunity evasion, thus highlighting the possibility of targeting the enzyme to produce various antifungal drugs and vaccines. The recent advances in the molecular studies of fungal CDAs, including site-directed mutagenesis and genome editing using CRISPR-Cas9-induced modifications to the CDA gene, which can pave the way to make the enzyme robust and thus valuable for the biotechnology industry are also discussed.