In this study, a novel psychrotolerant chitinolytic bacterium Pedobacter sp. PR-M6 that displayed strong chitinolytic activity on 0.5% colloidal chitin was isolated from the soil of a decayed mushroom. Chitinase activity of PR-M6 at 25 °C (C25) after 6 days of incubation with colloidal chitin increased rapidly to a maximum level (31.3 U/mg proteins). Three chitinase isozymes (chiII, chiIII, and chiIV) from the crude enzyme at 25 °C (C25) incubation were expressed on SDS-PAGE gels at 25 °C. After purification by chitin-affinity chromatography, six chitinase isozymes (chiI, chiII, chiIII, chiIV, chiV, and chiVI) from C25-fractions were expressed on SDS-PAGE gels at 25 °C. Major bands of chitinase isozymes (chiI, chiII, and chiIII) from C4-fractions were strongly expressed on SDS-PAGE gels at 25 °C. Pedobacter sp. PR-M6 showed high inhibition rate of 60.9% and 57.5% against Rhizoctonia solani and Botrytis cinerea, respectively. These results indicated that psychrotolerant Pedobacter sp. PR-M6 could be applied widely as a microorganism agent for the biocontrol of agricultural phytopathogens at low temperatures.
Keywords: Chitinase isozyme; Chitinolytic activity; Pedobacter sp.; Psychrotolerance.
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