Resazurin is an oxidation–reduction indicator used for the evaluation of cell growth, particularly in various cytotoxicity assays. It has been used over five decades to monitor bacterial and yeast contamination of milk, and also for assessing semen quality. This chemical reduction is mainly used in viability assays for mammalian cells. In the present study, antibacterial activity of marine yeasts is assessed by using resazurin method. For the first time, the resazurin assay is used to check whether the marine yeasts are capable of killing clinical pathogens and to identify the most efficient yeast species to arrest growth of the pathogens. Eight species of marine yeasts were screened for antibacterial activity against four clinical pathogens viz. Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Staphlyococcus aureus and providentia sp. The maximum inhibition was found with the yeast species: Saccharomyces cerevisiae, Candida albicans, Pachysolen tannophilus, Debaryomyces hansenii, Kuraishia capsulate, Geotrichum sp., Candida sp., and Candida wickerhamii., against bacterial strains of E.coli, P. aeruginosa S. typhi, and S. aureus respectively. Among the pathogens, Staphylococcus aureus was found to be highly susceptible to all the yeast extracts. Thus the present work has revealed that marine yeasts are potent source of antibacterials which can be further developed to cure bacterial diseases in humans.

Keywords: Antibacterial assay; Resazurin; Marine yeasts; Clinical pathogens