Application of resazurin for estimating abundance of contaminant-degradingmicro-organisms

Aims: The aim of the current study was to tl-st whether resazurin changed c olour when incubated with a range of organic chemicals used as growth subst rates in bioremediation studies and to determine whether resazurin was more effective in estimating microbial growth than turbidity alone (i.e. no res azurin) or use of the dye, methylene blue. Methods and Results: Resazurin was incubated with a range of organic chemic als that were used as substrates in an MPN assay. Only 1,2-dichlorobenzene, 2,4-D, glycol sulphite and sulphinol reacted to generate false positives. Resazurin was also used to estimate, micro-organisms in a series of bioreme diation studies. Conclusions: The results showed that resazurin was more sensitive than meth ylene blue or turbidity alone as an indicator of microbial growth. Significance and Impact of the Study: The significance of the current study is that resazurin should be used in MPN assays for estimating contaminant- degrading micro-organisms instead of turbidity alone or other dyes such as methylene blue.