Detection and isolation of novel antimicrobial compounds in mangrove actinomycetes

Potentially novel antimicrobial compounds were detected and isolated from mangrove actinomycetes that were obtained from Sungei Buloh Wetland Reserve. Of the 52 strains tested for antimicrobial activity, nine showed strong activity against multiple test organisms. Partial 16S rDNA sequencing of selected strains with antimicrobial activity showed that the strains were from the genera Streptomyces, Micromonospora and Jishengella. Five strains were selected based on their growth rate and antimicrobial activity for small-scale culturing and compound extraction. Extracts of the strain MD100 showed broad-spectrum activity against the test organisms MRSA, E. coli and P. aeruginosa. A coupled HPLC/SPE/HLPC separation using Sepbox yielded a fraction, Fraction 10, which was present in relative abundance and exhibited activity against both MRSA and P. aeruginosa. LC-MS analyses showed that the major component of Fraction 10 had a m/z value of 266. Future work will involve the optimisation of the Sepbox procedure and further purification procedures to isolate the pure target compound, while mass and structure determination strategies will allow the identity of Fraction 10 to be elucidated. The optimised protocols can be applied to other fractions of interest in MD100 and other promising actinomycete strains, to facilitate the discovery of novel antimicrobial compounds from mangrove actinomycetes.Bachelor of Science in Biological Science