Chitinase Inhibitor Allosamidin Is a Signal Molecule for Chitinase Production in Its Producing Streptomyces

Abstract

Allosamidin, a typical secondary metabolite of Streptomyces, has been known as a chitinase inhibitor. We found that allosamidin can dramatically promote chitinase production and growth of its producer, Streptomyces sp. AJ9463, in a chitin medium at a few hundred nM. Allosamidin promoted production of the main chitinase detected in the culture filtrate and the chitin-hydrolytic activity of the chitinase was not inhibited by allosamidin at the concentration. The gene encoding the chitinase showed that it is a family 18 chitinase and it was revealed that two genes encoding proteins constructing two-component regulatory system were present at 5'-upstream region of the chitinase gene. Allosamidin is located in the microbial mycelia cultured in a medium without chitin, but it was released from the mycelia by responding to chitin. These results show that allosamidin acts as a key signal molecule for chitinase production in its producing strain, which may be useful for its growth in chitin-rich environment.