Chitin is the second most abundant polysaccharide after cellulose, and the enzyme that can decompose chitin is chitinase, which has high industrial value. In this study, the characteristics of chitinase produced by three chitinolytic bacterial isolates, Jeongeupia naejangsanensis GR-1, Paenibacillus gorillae GR-2, and Paenibacillus chitinolyticus GR-3, were investigated according to three chitin substrates: crab shell colloidal chitin (CC), Korean blockish cicada colloidal chitin (KC), and mealworm colloidal chitin (MC). The determination of the protein content and chitinase activity showed low values for two chitin substrates, excluding CC. The chitinase expression patterns of the three bacteria were investigated through SDS-PAGE, native-PAGE, and gradient (5%-12%) native-PAGE. The results confirmed that the J. naejangsanensis GR-1 expressed a different pattern of chitinase in KC. Through TLC using colloidal chitin as a substrate, it was found that J. naejangsanensis GR-1 produced endo- and exo-type chitinase, whereas P. gorillae GR-2 and P. chitinolyticus GR-3 mainly produced endo-type chitinase. API analysis confirmed that the three bacteria were positive for N-acetyl-D-glucosamine, a monosaccharide of chitin. Given the current lack of research investigating the chitinase of t...