Involved in chitin degradation. Catalyzes the oxidative cleavage of glycosidic bonds in both alpha- and beta-chitin via a copper-dependent mechanism, leading to oxidized chitooligosaccharides with a dominance of even-numbered products. Acts synergistically with the chitinase EfChi18A, and 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. [(1->4)-N-acetyl-beta-D-glucosaminyl]n+m + reduced acceptor + O2 = [(1->4)-N-acetyl-beta-D-glucosaminyl]m-1-(1->4)-2-(acetylamino)-2-deoxy-D-glucono-1,5-lactone + [(1->4)-N-acetyl-beta-D-glucosaminyl]n + acceptor + H2O. The copper metal center seems to be reduced from a Cu(II) to Cu(I) oxidation state prior to binding of dioxygen for catalysis. Glycan degradation; chitin degradation.