Use of chemical elicitors to stimulate the production of antimicrobial natural products from mangrove microorganisms

Abstract

Actinomycetes are widely recognized as a highly productive source of antimicrobial natural products. However, discovery of novel compounds was unfavourable due to presence of silent antibiotic-producing gene clusters. This study used chemical elicitors to stimulate cryptic clusters to produce novel antibiotics. 61 strains of actinomycetes isolated from Sungei Buloh Wetland Reserve were cultured on Minimal Media agar containing N-acetylglucosamine and sodium butyrate in separate experiments. Agar Overlay Method was used as preliminary screening of antimicrobial property. Results showed that growth of both Gram-positive and Gram-negative bacteria was inhibited by antibiotics produced by varying actinomycete strains under the addition of chemical elicitors. Among these, only antibiotics produced by SD70 and SW24 were able to hinder growth of Pseudomonas aeruginosa. We concluded that chemical elicitors can be used to awaken cryptic gene clusters, but activation is strain-dependent. Secondary antimicrobial screening will be performed to further assess bioactive property and identification of possible new antibacterial compounds will be carried out in the future.