Chitinase and chitin oligosaccharide were purified and separated from the Pedobacter sp. PR-M6 culture medium using general and modified processes. The chitinase and chitin oligosaccharide yields were 0.274 mg and 133 mg/ 751 mg chitin with the general process and 0.403 mg and 410 mg/978.4 mg chitin with the modified process, respectively. In addition, PR-M6 chitinase activity in two purified chitinases (P-chitinase 1 and 2) at 25 o C and 37 o C was investigated. In the P-chitinase 1, chitinase activity was 43.5 unit/mg protein and 73.2 unit/mg protein under 25 o C and 37 o C enzyme reaction conditions, respectively. However, in P-chitinase 2, chitinase activity was 50.8 unit/mg protein and 84.4 unit/mg protein under 25 o C and 37 o C, respectively. The PR-M6 chitinase isozymes were expressed as Chi-A, Chi-B, and Chi-C on sodium dodecyl sulfate-polyacrylamide gels at 25 o C and 3 o C. Thin-layer chromatography revealed that the main chitin oligosaccharide products from PR-M6 were dimer, trimer, and tetramer molecules in all P-chitinase lanes and monomer, dimer, trimer and tetramer molecules in crude enzymes. Furthermore, the PR-M6 Pchitinase inhibited Alternaria brassicicola conidia germination and hyphal development.