Sponge-associated Bacteria Producing Antimicrobial Compounds and their Genetic Diversity Analysis

Abstract

Bacteria associated with the marine sponge Haliclona sp. from the coastal region of Waigeo Island were screened for antimicrobial activities using the agar-overlay method. There were 125 bacterial isolates recovered and were subjected to antimicrobial screening for antibiotic production against five test bacterial strains, viz., Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Enteropathogenic Escherichia coli (EPEC), Pseudomonas aeruginosa and two fungal pathogen, viz., Candida albicans and Candida tropicalis. A total of 39 (31%) bacterial strains were found to be antimicrobial producers; however, 15 (38%) of these active strains were eliminated based on the results of Hemolytic Test. The remaining 24 isolates were further analyzed by amplified ribosomal DNA restriction analysis (ARDRA) to assess their genetic diversity and results obtained revealed eight phylotypes. There were nine isolates that were exhibiting wide spectrum of activities against the test strain. The Minimum Inhibitory Concentration of the nine strains was determined and three strains (HAL13, HAL74, and HAA01) showed bactericidal effects. Bacterial extracts were obtained using n-butanol and were subjected to bioactivity assay and TLC autobiography overlay assay. Phylogenetic analysis using 16S rRNA gene sequences revealed that the nine strains belong to the genus Bacillus. The isolation of sponge associated bacteria possessing inhibitory activity against clinical pathogenic strains suggests that they could be potential sources of novel marine natural products.