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Project Description: 

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are common environmental contaminants that can cause adverse health effects in humans. BTEX contamination is of particular concern in groundwater, as leaking underground gasoline storage tanks are often the culprit of BTEX groundwater plumes. Because groundwater is often a sole or supplemental source of drinking water, it is imperative to remove BTEX compounds from groundwater. One method of removal, called bioremediation, involves the use of microorganisms to degrade the BTEX to less harmful substances. This project display demonstrates the use of a bacteria, Rhodococcus Rhodochrous ATCC 21198, to degrade BTEX compounds both individually and in a mixture. Batch tests were carried out to test if 21198 could degrade BTEX compounds, and if so, how quickly. A variety of growth substrates were used to grow 21198 used in these batch tests, namely isobutane, 1-butanol, and 2-butanol. Isobutane is 21198's primary growth substrate, but 1-butanol and 2-butanol are alternative substrates that 21198 is still capable of growing on. However, 21198's activity differs between growth substrates, therefore these batch tests were needed to determine the viability of using an alternative growth substrate to sustain 21198 as it transforms BTEX compounds. Results from the individual contaminant and contaminant mixture tests indicate that 21198 is not only capable of transforming BTEX compounds, but also does so rapidly. To the authors' knowledge, this is the first demonstration of BTEX degradation by 21198. Comparisons between activity on different growth substrates reveal that 2-butanol is the superior alternative growth substrate for 21198 when the goal is degrading BTEX compounds. This research positions 21198 as a promising candidate for use in future BTEX bioremediation applications. 

Juliana Huizenga and Lewis Semprini

Juliana Huizenga