Revista de Microbiología y Patología

Determination of Minimum Inhibitory Concentrations of Antimicrobial Herb and Spice Extracts against Flavobacterium columnare

Abstract

Grace Ramena, Yathish Ramena, William Duke and Nitin Challa

Bacterial diseases like columnaris caused by Flavobacterium columnare, has huge economic impact on aquaculture industry. Proven the low efficacy of vaccines and tight regulations with antibiotic usage, there is a need for alternative therapeutics. We have previously found that methanolic extracts (50 mg/ml) from eleven herbs and spices had bactericidal effects against Flavobacterium columnare (3 × 108 CFU/ml). In the present study we determined the minimum inhibitory concentrations of all the eleven extracts and found that clove had the best significant growth inhibitory effect at the lowest concentration tested. Our results suggest that clove, cinnamon, thyme and cumin could serve as potential alternative therapeutics to deal with columnaris in fish.