Inductive production of chitinolytic enzymes in soil microcosms using chitin, other carbon-sources, and chitinase-producing Streptomyces

Abstract

The inductive production of chitinolytic enzymes (chitinase and N-acetylglucosaminidase) in soil microcosms by the amendment with various carbon sources and/or inoculation of chitinase producing Streptomyces sp., was examined. Chitinase activity in soil was measured by using 4-methylumbelliferyl (4MU) derivatives of N-acetyl-n-glucosamine (GlcNAc) oligom~rs as substrates, i.e., 4MU -chitobiose and 4MU -chitotriose, and N -acetylglucosaminidase activity by using 4MU-GlcNAc. The highest chitinase activity was attained by the amendment with chitin powder. GlcNAc and yeast extract also increased the chitinase activity significantly and incubation with glucose increased the chitinase activity only for 4MU-chitobiose. In contrast, the increase of the chitinase activity by other carbon sources including cellulose, xylan, laminarin, chitosan, and xylose was negligible. The ratio of chitinase activity for 4MU -chitobiose to that for 4MU-chitotriose in the soil varied with the substrate applied, suggesting that different types of chitinases were produced depending on the carbon-source added. Inoculation of Streptomyces sp. S-84, which produces a large amount of chitinase, stimulated the synthesis of chitinolytic enzymes in soil.

Key Words:

• chitinase
• inductive production
• N-acetylglucosaminidase
• soil enzyme
• Streptomyces