PhD, University of Cincinnati, 2017, Engineering and Applied Science: Environmental Engineering

Disinfection by products (DBPs) resulted from the reactions between the chlorine and natural organic substances which increased the formation of trihalomethanes (THMs). DBPs are carcinogens or have been known to cause health risks. Chloroform (CF) is the most abundant of all THMs with a maximum contaminant level (MCL) of 0.070 mg/L. In addition, CF and other THMs could also originate from sources other than by-products of water disinfection. Several physical and chemical removal methods are used to treat chloroform, which are expensive and could generate secondary pollutants. Biofiltration is one of the most proven technologies for volatile organic compound (VOC) control as it is environment–friendly, cost effective and releases fewer byproducts. In this study, an integrated technology was proposed. The integrated technology consists of nitrogen or air stripping followed by anaerobic or aerobic bio-trickling Filter (BTF). This study evaluated first CF only and secondly mixtures of THMs (CF and dichlorobromomethane (DCBM)). A co metabolite (ethanol) and surfactant (Tomadol 25 – 7) have been used to improve the biodegradation process. In addition, surfactin a bio surfactant was seeded within the BTF and its effectiveness has been investigated. Finally, microbial analysis was conducted to determine the dominant and responsible microbes for the BTFs performance.

Committee: George Sorial Ph.D. (Committee Chair); Ashraf Aly Hassan Ph.D. (Committee Member); Margaret Kupferle Ph.D. P.E. (Committee Member); E Sahle-Demessie Ph.D. (Committee Member); David Wendell Ph.D. (Committee Member) Subjects: Environmental Engineering

Master of Science (MS), Ohio University, 2009, Environmental Studies (Arts and Sciences)

Toluene is a major component of gasoline and is a widely used industrial solvent. It contaminates surface and groundwater and poses a menacing threat to human health. Toluene is not a carcinogen; however, in mixtures it enhances the effect of carcinogens. This research uses a molecular approach to study toluene biodegradation by the facultative, denitrifier Thauera aromatic strain T1 (T.aromatica strain T1). This strain is able to degrade toluene into non aromatic compounds under anaerobic conditions and use it as a sole carbon and energy source. Previous work identified the tutE tutFDGH gene cluster as essential for the first step of anaerobic toluene biodegradation. The aim of this research is to determine the role of selected amino acids in the function of the TutH protein in toluene biodegradation by T.aromatica strain T1. This work determined if changes can be made to certain amino acids in the TutH protein without disrupting protein function. We identified amino acids of interest by computer analysis and used site-directed mutagenesis to generate the desired changes. Based on computer analysis, I formed a hypothesis that changing the amino acid leucine at position 266 into valine , changing serine at position 5 into theronine, or changing tyrosine at position 283 into phenyalanine will not disrupt the TutH protein function. We performed site-directed mutagenesis on TutH and determined that two of these altered proteins (L266V and S5T) failed to complement a strain unable to produce TutH while altered protein containing Y283F succeeded in complementing a strain unable to produce TutH. It is important to identify tolerated amino acids because researchers can use them to change the range of substrates. This research will further the understanding of the toluene metabolism in the environment and may help in the remediation of contaminated sites. Also, this research will contribute to the development of a more efficient toluene bio-degradation pathway. Ideal (open full item for complete abstract)

Committee: Peter Coschigano (Advisor); Michele Morrone (Committee Chair); Erin Murphy (Committee Member) Subjects: Microbiology

Doctor of Philosophy (PhD), Ohio University, 2007, Biological Sciences (Arts and Sciences)

Toluene is an aromatic hydrocarbon that is widely used in our everyday life. It is a major water-soluble constituent of petroleum and can pollute surface as well as ground waters. The toxic nature of toluene is responsible for causing severe health hazards. The study of toluene degrading bacteria has attracted attention because of their potential to clean up spills. Thauera aromaticastrain T1 is one such bacterium capable of degrading toluene under anaerobic conditions. The tutE tutFDGHgene cluster is essential for the first step of anaerobic toluene degradation in T. aromaticastrain T1. The tutF, tutDand tutGgenes are proposed to code for the three subunits of the enzyme benzylsuccinate synthase, which is involved in the initial step of anaerobic toluene degradation pathway. The tutEgene is proposed to code for the enzyme benzylsuccinate synthase activase. The precise role of the tutHgene in toluene degradation is currently unknown, but it is proposed to have an ATP/GTP binding domain and is assumed to be involved in benzylsuccinate synthase complex formation. This is consistent with its proposed role as a chaperone of “ATPases Associated with a Variety of Cellular Activities” (AAA) class. Work presented here demonstrates that the gene tutHis essential for toluene metabolism. A plasmid carrying an in-frame tutHdeletion was unable to produce wild-type TutH protein in a tutGchromosomal deletion background (chromosomal deletion in tutGdoes not result in production of TutH due to a polar effect on downstream genes). The resultant construct was unable to complement a polar tutGchromosomal mutation, indicating the importance of tutHin toluene degradation. Further, site-directed mutagenesis was used to identify amino acids in TutH that are essential for toluene metabolism. The TutH putative ATP/GTP binding domain was disrupted by changing glycine, lysine and serine at positions 52, 53 and 54 to alanine, arginine and alanine respectively. Additionally, other amino acids wh (open full item for complete abstract)

Committee: Peter Coschigano (Advisor) Subjects: