Arabian Sea associated bacterial strains a source of novel antibiotics against superbugs

One of the most severe health threats to both humans and animals is Antimicrobial resistance development in microorganisms AMR is a significant and growing challenge and to combat this issue new antimicrobials are urgently needed Fifteen microbial strains isolated from Arabian Sea were screened for their capacity to produce antimicrobial metabolites of pharmaceutical interest. These strains were associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan). Bacterial strains were isolated from sea weeds attached to rocks of Baluchistan coast line using marine agar 2216 and screened for antibacterial activity by agar well diffusion method and crude extract was made and antimicrobial metabolites were purified using silica gel column and structure of pure compound was elucidated using spectroscopic techniques. Crude extract filtrates from CMG 2180 strain, grew on ZMA medium, showed the most remarkable antimicrobial activity, and thus was chosen for further examination. The identification of CMG 2180 as a probable new type strain of the Actinobacterium Kocuria marina was based on phenotypic aspects and biochemical characteristics (e.g. halotolerant Gram-positive micrococcoid) as well as on the nucleotide sequence analysis of its full-length 16S rRNA gene showing the highest similarity with the type strain KMM 3905 (GenBank accession number EU073966). Interestingly, a unique UV-bioactive compound, for which the name of kocumarin was proposed, was isolated and purified from CMG 2180 strain’s crude extracts by flash silica gel column chromatography and TLC/HPTLC. Using routine methods, kocumarin demonstrated prominent and rapid activities against all tested fungi and pathogenic bacteria including MRSA. Its chemical structure was unraveled by 1D and 2D-NMR spectroscopy as 4-[(Z)−2 phenyl ethenyl] benzoic acid.