Anti-Methicillin Resistant Staphylococcus aureus (MRSA) Activity of Pseudoalteromonas flavipulchra Isolated from Marine Waters of Batangas, Philippines

The ocean boasts untapped novel producers of antibiotic substances in the form of unicellular organisms. One of the newest bioproducers of pharmacologically-significant substances studied for its potential against clinically-significant pathogens is the genus Pseudoalteromonas, a gammaproteobacterial group. This study is a preliminary report detailing the isolation of a Pseudoalteromonas flavipulchra species from Philippine marine waters. The isolate coded as PAM-003 was identified as 100 % similar to P. flavipulchra strain NCIMB2033 through 16s rRNA gene amplification and sequencing. PAM-003 was allowed to produce bioactives for 12 days. Afterwards, non-polar products were isolated from the base medium through membrane filtration, organic solvent extraction and rotary evaporation. The crude solution of bioactives injected in sterile discs was used for disc-diffusion assay against Methicillin Resistant Staphylococcus aureus (MRSA). Results indicate that PAM-003 demonstrated visually-appreciable zones of inhibition with a mean value of 8 mm. To further describe the antibacterial activity of the isolate, minimum inhibitory concentration (MIC) of the bacterial extract was determined through broth microdilution technique. Results indicate that PAM-003 demonstrated a MIC of 1000 µg/mL against MRSA. Additional investigation on the bioactivity of Philippine isolates from the genus Pseudoalteromonas isolated from highly diverse regions of the country is a considerable initiative for increasing the pipeline of new molecular entities for drug discovery.