ALTERNATIVE METHOD FOR RAPIDLY SCREENING MICROBIAL ISOLATES FOR THEIRPOTENTIAL TO DEGRADE VOLATILE CONTAMINANTS

A method is described for rapidly screening the metabolic potential of bacteria to oxidize semivolatile and volatile compounds as a sole car bon source. The method is based on an automated system that utilizes M icroplates (TM) manufactured by Biolog, Inc. (Hayward, CA, USA). This system detects bacterial respiratory activity from the oxidation of a carbon source introduced in volatile form. This is in contrast to the original design, which is based on inoculating a carbon source directl y into each well. The 96-well (MT) microtiter plates contain nutrients and a tetrazolium dye. When a bacterial species is capable of oxidizi ng a volatile carbon substrate, the dye turns purple, and a spectropho tometric plate reader quantifies the response. As a test of this metho d 150 isolates, including isolates known to degrade some of the test c ompounds and negative controls were evaluated for their potential to o xidize carbon tetrachloride, toluene, and o-xylene. Thirty-seven isola tes (25%) were qualitatively identified as contaminant oxidizers, and thirteen of these (35%) showed significant degradation capabilities fo r both toluene and o-xylene.