Purification and characterization of two antifungal chitinases extracellularly produced by Bacillus amyloliquefaciens V656 in a shrimp and crab shell powder medium.

Abstract

A Gram-positive bacterium with antagonistic activity was isolated from the soil. It has been identified as Bacillus amyloliquefaciens strain V656 on the basis of 16S ribosomal DNA analysis and standard bacteriological tests. B. amyloliquefaciens V656 produced antifungal enzymes when it was grown in a medium containing shrimp and crab shell powder (SCSP) of marine waste. The antifungal enzymes displayed chitinase activities. Two extracellular antifungal chitinases (FI and FII) were purified and characterized, and their molecular weights, isoelectric points, pH and thermal stabilities, and antifungal activities were determined. The characteristics of V656 chitinases are similar to those of the known bacterial chitinases in terms of their isoelectric points, thermal instabilities, and lack of lysozyme activity. In contrast to other known bacterial chitinases, the unique characteristics of V656 chitinases include extremely low molecular weights and nearly neutral optimum pH. Furthermore, this is the first report of the isolation of chitinases from B. amyloliquefaciens that are active against fungi.