Bacterial Chemotaxis toward Environmental Pollutants: Role in Bioremediation

The increasing release of organic pollutants by industries cause many health-related problems. However, increased awareness of the harmful effects of environmental pollution has led to a dramatic increase in research on various strategies that may be employed to clean up the environment. It is now realized that microbial metabolism provides a safer, more efficient, and less expensive alternative to physicochemical methods for pollution abatement (27). In the past few decades, a vast range of xenobiotic compounds have been found to be susceptible to microbial mineralization. In most instances where mineralization has been demonstrated, the catabolic pathway and its regulation have also been determined. Bacterial chemotaxis, movement under the influence of a chemical gradient, either toward (positive chemotaxis) or away (negative chemotaxis) from the gradient helps bacteria to find optimum conditions for their growth and survival. However, this aspect has received little attention, even though some microorganisms with the chemotactic ability toward different xenobiotic compounds have been isolated and characterized (8, 19, 23, 41, 53). In many cases, the chemoattractant is a compound that serves as carbon and energy source, whereas a chemorepellent is toxic for the bacteria. We describe here recent discoveries in bacterial chemotaxis toward pollutants and how they may be explored and exploited for bioremediation applications.