Hydrolyzes the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin to form chitosan and acetate (PubMed:9133736). Chitosan is a component of the spore wall (PubMed:9133736). [(1->4)-N-acetyl-beta-D-glucosaminyl](n) + n H2O = n acetate + chitosan Induced during sporulation. Belongs to the polysaccharide deacetylase family.