Involved in chitin degradation. Catalyzes the cleavage of glycosidic linkages in chitooligosaccharides and in alpha- and beta-chitin. Its activity on chitooligosaccharides increases considerably with degrees of polymerization (the initial rate of hydrolysis for GlcNAc5 is about 130-fold higher than that for GlcNAc3). Its activity is greatly stimulated in the presence of the lytic chitin monooxygenase EfCBM33A, which attacks the crystalline structure of chitin and makes the polymer more accessible to the chitinase; combining the two enzymes leads to rapid and complete depolymerization of crystalline chitin, especially with beta-chitin as a substrate. Is likely involved in a chitin degradation pathway that allows E.faecalis V583 to grow on chitin as a carbon source. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Glycan degradation; chitin degradation. Belongs to the glycosyl hydrolase 18 family.