Identification and characterization of three endophytic bacteria from Neesia altissima (Malvaceae) antagonistic to diarrhea-causing bacteria
Aims: Diarrheal disease is one of serious healthcare problems in developing countries. Endophytic bacteria have been known as a promising source of new antibiotics against susceptible and resistant forms of microorganisms. In this study, we identified three endophytic bacteria isolated from Neesia altissima and screened their antagonistic activity against diarrhea-causing bacteria in order to find new potential secondary metabolites. Methodology and results: Samples of N. altissima were collected from mount Halimun-Salak national park. Endophytic
bacteria were isolated from roots, barks, and fresh leaves of N. altissima by surface sterilized method. Screening of antagonistics activity was conducted against five diarrhea-causing bacteria such as Escherichia coli, Staphylococcus
aureus, Salmonella typhimurium, Shigella flexneri, and Bacillus cereus using crude extract dilution and diffusion disc methods. Three endophytic bacteria showed antagonistic activity against the pathogenic bacteria. Identification of the
three potential endophytic bacteria using molecular analysis showed that two isolates determined as Pseudomonas aeruginosa and one isolate belongs to P. azotoformans. Conclusion, significance and impact study: Crude extract of P. aeruginosa (strain 1.4.1A and 1.2.7D) and P. azotoformans (strain 1.8.7KB) showed growth inhibition activity to the diarrhea-causing bacteria. This is the first report of P. azotoformans exhibited antagonistic activities against diarrhea-causing bacteria. This data suggested that bacterial endophytes from N. altissima provided potential sources for the discovery of new secondary metabolites to combat the diarrhea-causing bacteria. This finding highlights potential prospects of endophytic bacteria utilization from endemic medicinal plants for the discovery of novel bioactive compounds.