Publication

Abstract : Biological control of infection in wastewater and compost is posed to be ecologically and economically very attractive but needs a detailed understanding of the complex interaction of the abiotic and biotic factors controlling infection. We intend to screen different cheap natural compounds from plant biomass waste which can effectively control infection in wastewater/ compost. Resazurin (alamarBlue®) based viability method is a sensitive and cost effective assay which can be adopted to screen antimicrobial compounds with high throughput compared to culture based methods. However, the assay needs to be standardized for each type of bacterial species as their metabolic activity varies widely. Antimicrobial assay generally requires substantial (12-24 h) time for both culture and fluorescence based assay. In the present study, resazurin assay was standardized for Salmonella typhi and Staphylococcus aureus where time required was reduced to 4 h. This method was utilized for the screening of plant extracts (Cocos nucifera, Areca catechu and Allium cepa) from plant waste material against target microorganisms. Among the extracts tested, MEK (Methyl ethyl ketene) extract of onion peel (Allium cepa) showed maximum (2-log) reduction in relative fluorescence unit (RFU) for both Salmonella typhi and Staphylococcus aureus. These results were compared with conventional culture based techniques as well. Thus our resazurin based assay method shows a good promise for rapid screening of the compounds against the two important human pathogens, S. typhi and S. aureus.