ANTIMICROBIAL POTENTIAL OF THE BACTERIA ASSOCIATED WITH SARGASSUM WIGHTII AGAINST PLANT FUNGAL PATHOGENS

Abstract

This study focuses on the isolation and characterization of the antifungal bacteria associated with the marine algae Sargassum wightii from two study sites (coast of Vizhinjam, site1 and Varkala, site2,Thiruvananthapuram, Kerala).The isolates were characterized by morphology, Gram Staining and Biochemical tests. Ethyl acetate extracts of bacterial supernatant were screened for antibacterial activity. From the eleven isolates, eight strains revealed antibacterial potential against the plant pathogens Rizoctonia solani, Fusarium monoliforme and Claviceps purpurae. The two isolates showing maximum activity from each site were identified upto species level by 16S rRNA profiling. The one with maximum activity was identified as Pseudomonas stutzeri (site1) and Staphylococcus vitulinus (site2). The HPTLC assay was carried out for the most active isolate. Spot of the EPS developed on HPTLC was analyzed by GC-MS analysis. S.vitulinus can produce Pyrrolo[1,2-a pyrazine-1,4 dione hexahydro-3-(phenylmethyl)-compound,2(Acetoxymethyl)-3-(methoxycarbonyl)biphenyl compound and P.stutzeri can produce the biocompounds pyrrolo[1,2-a pyrazine-1,4 dione hexahydro-3-(phenylmethyl)-,2(Acetoxymethyl)-3-(methoxycarbonyl)biphenyl,Phenol,2,5-bis(1,1 dimethylethyl) in their medium. These marine bacteria are expected to be potential resources of natural antibiotic products. It can be concluded that isolation of associated marine bacteria can provide a number of microbial strains as a source of new marine biomolecules. Further studies are required for the purification and chemical characterization of the bioactive products.