Evaluation of phenol-degradation activity of Rhodococcus opacus 1CP using immobilized and intact cells

Abstract

Phenol is among the most distributed pollutants; phenol biodegradation is one of the most efficient and cost-effective pollutants degradation technologies. To estimate phenol-degradation activity of actinobacterium Rhodococcus opacus 1CP, the pollutant-degrading microorganism, evaluation of the activity of phenol hydroxylase and other systems for phenol degradation was performed in this study. For the first time, phenol hydroxylase activity and activity of phenol transporting cellular systems of R. opacus 1CP cells were assessed using biosensor technique based on the immobilized cells of the culture of interest. For phenol-induced cells and cells grown in the enriched medium, the responses to a substrate were compared. Two non-specific systems of phenol transport into 1CP cells were detected. These systems differed in the degree of affinity for phenol. It was shown for phenol-induced 1CP cells that phenol was transported into the cell by simple diffusion at phenol concentrations above 0.1 µM. For R. opacus 1CP phenol hydroxylase, Km app, obtained with immobilized cells, was not greater than 1 µM. For the first time, immobilized cells-based technique (estimation of the responses to a substrate using immobilized and intact cells) was applied to predict the presence of at least two isozymes of phenol hydroxylases, which play metabolic and regulatory roles, and of a few differentially regulated catechol 1,2-dioxygenases in cells of this culture. This study confirmed that biosensor technique is simple, rapid and useful method for investigation of substrate metabolism.