Using alamarBlue® Cell Viability Assay to Screen for Putative Antimicrobial Products

You Bin Lee


The number of pathogens resistant to antibiotics in hospitals and communities is on the rise. The costs associated with the treatment and work loss run into billions of dollars annually. Our research is focused on discovering new compounds with antimicrobial properties. With that goal in mind we have screened 30 crude plant extracts obtained from a phytochemical company. We screened these extracts on a mini panel of BSL 1 pathogens (Candida albicans, Aspergillus niger, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli) in 96 well plates. The alamarBlue® cell viability assay was used to screen against the pathogens. Viability was determined by reaction of alamarBlue®, which changes the color from blue to pink/red. Crude extracts with minimum inhibitory concentration (MIC) at or < 256 μg/ml were prioritized for further study. Four extracts showed activity against both Candida albicans and Aspergillus niger and three extracts demonstrated activity against Aspergillus niger only. The alamarBlue® viability assay is a cost-effective, quick and easy method to test for antimicrobial activity. The method can be easily utilized by any researcher interested in drug discovery and new antimicrobial products.


alamarBlue®, Drug Discovery, Microbial Viability Assay, Natural Products

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