Abstract
Nitrogen is known to be a limiting factor in polluted environments, however many studies overlook the potential role for nitrogen to significantly influence the removal rate and efficiency with which microorganisms can degrade aromatic hydrocarbons. In this study, inoculated and uninoculated aerated soil microcosms containing different s-triazines were examined for their ability to efficiently and rapidly treat contaminated soils containing naphthalene, nitrobenzene, and toluene (NNT), via a microbial consortium consisting of Pseudomonas, Rhodococcus, and Aeromonas. After an experimental period of 14 days, greater than 90% degradation of NNT supplemented with different s-triazines, at concentrations of 1000-3000 ppm was observed. A difference in the degradation of NNT was seen in inoculated box reactors supplemented with cyanuric acid, melamine, and atrazine in comparison to uninoculated box reactors. Combined usage of 16s rDNA and 16s rRNA analysis was then applied to study the bacterial communities, and determine the abundance and survival of inoculated strains within box reactors contaminated with NNT. The bacterial diversity within clone libraries obtained illustrated a dominance of proteobacteria and gram positive bacteria. Analysis from clone libraries also showed that inoculated strains did survive within each condition, but were not the most predominant members present in the communities. This research shows that significant removal of NNT can be achieved in two weeks with the supplementation of one of the s-triazines. However, differences in degradation and the microbial populations present within contaminated communities will be seen depending on which nitrogen sources are used and whether or not environments are bioaugmented or not.
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