Antimicrobial potential of marine organisms collected from the southwest coast of India against multiresistant human and shrimp pathogens

Diverse marine flora and fauna collected from the southwest coast of India was evaluated for its antimicrobial potential against shrimp Vibrio and multiresistant human pathogens. In total, 47 species of various taxa of marine organisms (29 flora and 18 fauna) were screened for antimicrobial activity. The marine flora includes twenty species of seaweeds, two species of mangroves, four species of cyanobacteria and three species of microalgae. The marine fauna comprises three species of porifera, twelve species of molluscans, one species of sea urchin, one of sea cucumber and one of cnidarian. The organic extractives were tested against five type cultures (Microbial Type Culture Collection) of prominent shrimp Vibrio pathogens, including V. parahaemolyticus, V. vulnificus, V. harveyi, V. alcaligenes and V. alginolyticus, and five multiresistant clinical pathogens: Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Klebsiella pneumoniae and Staphylococcus epidermidis. Among the marine organisms screened, seaweeds showed a broad spectrum of antibacterial activity. The highly active seaweed Falkenbergia, a heteromorphic sporophyte of Asparagopsis taxiformis (Delile) Trevisan, was evaluated further to purify the active compounds using different chromatographic systems, including reverse phase HPLC and GC-MS. The analysis revealed that the most abundant metabolites are oleic acid (51.33%) followed by n-hexadecanoic acid (42.87%