Semester of Graduation

Spring 2023


Master of Civil Engineering (MCE)


Civil and Environmental Engineering

Document Type



Production of the aromatic hydrocarbon toluene can be biologically mediated via the decarboxylation of phenylacetate, a reaction catalyzed by the enzyme phenylacetate decarboxylase. This study analyzed metagenome assembled genomes from a toluene-producing enrichment culture that originated from a Superfund Site in south Louisiana. Sequencing and assembly revealed two high quality (>90% complete, Azospira inquinatastrain Azo-3T, which was previously isolated from the same enrichment culture. It lacked the phenylacetate decarboxylase genes necessary for toluene production. The second MAG was found to have relatively high similarity to, but was distinct from, a bacterium from the phylum Acidobacteriota- referred to in the literature as strain Tolsyn. The Superfund site MAG assembly contained two distinct phenylacetate decarboxylase operons.

Metabolic pathway analysis of the Acidobacteriota MAG from the enrichment culture suggests the potential for growth in media supplemented with lactate and glycerol under aerobic conditions. Based on these results, experiments were performed with multiple toluene-producing enrichment cultures to observe how these supplements affect toluene production. An enrichment culture derived from freshwater sediments collected from the Blackwater River near Milton, Florida accumulated aqueous phase toluene when air occupied the gas headspace, although at lower concentrations than when grown in anoxic media. Among the medium supplements tested with air in serum bottle gas headspaces, media supplemented with lactate yielded the highest aqueous phase toluene accumulation. Supplementing the growth medium with lactate may prove useful in future attempts to isolate the toluene-producing bacteria.



Committee Chair

Moe, William



Available for download on Wednesday, April 03, 2030