Thesis (Ph. D.)--Georgia State University, 2006. / Title from title screen. George E. Pierce,committee chair; Eric S. Gilbert, Sidney A. Crow, committee members. Electronic text (135 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Aug. 20, 2007. Includes bibliographical references (p. 120-124).

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental contaminants with two or more aromatic rings and originating from different emission sources. They are extremely toxic, carcinogenic and mutagenic to human, animals and plants. Consequently, the need to expand economical and practical remediation technologies for PAH contaminated sites is evident. In this study, the effect of biotic and abiotic factors on degradation of PAH was studied. The degradation was studied on the key model PAH (phenanthrene, anthracene, fluoranthene and pyrene) in J. Arthur Bower’s top soil. The hypothesis for this study was that roadside soil would contain PAH degrading bacteria; pH would influence the microbial degradation of PAH, chemical oxidation of PAH would be as efficient as microbial breakdown of PAH and mobilising agents, would move PAH throughout soil, potentially making the PAH more available for biodegradation. The greatest degradations were found for the lowest molecular weight PAH, phenanthrene and anthracene; whilst lowest degradation was observed for higher molecular weight PAH, fluoranthene and pyrene. Twelve bacteria genera were isolated and identified by biochemical and molecular techniques from the roadside soil with the four PAHs as the sole carbon source. However, potentially new PAH biodegrader bacteria species and a novel were found in this study, which was not reported in the literature. The effect of pH between 5.0 and 8.0 at half pH intervals on biodegradation of the four PAHs and on bacterial populations in the soil over 32 days was monitored. The greatest population of bacteria and greatest biodegradation for the four PAHs was found at pH of 7.5. It is likely that the general increase in population was also linked with greater metabolic activities of bacteria at basic pHs which assists pollutant biodegradation. Although there is high pollutant mobility at low pHs, the biodegradation was limited due to reduced microbial activity. High pHs resulted in greater PAH biodegradation suggesting that pH manipulation by liming may be an effective way of stimulating biodegradation of PAH. The effect of potassium permanganate on oxidation of the four PAHs in the soil was examined. Studies in this thesis, indicated that potassium permanganate had a significant (p<0.05) effect on oxidation of the four PAHs at pH 7.5 over 35 days. However in comparison to biodegradation, chemical oxidation has significantly (p<0.05) less effect. Finally, the effect of Tween 20 only on translocation and biodegradation of the four PAHs at pH 7.5 over 35 days was examined. Studies indicated that Tween 20 had significantly (p<0.05) enhanced translocation of the four PAHs in the sterile soil. Moreover, the greatest biodegradation was found in the soil inoculated with only the roadside soil microorganisms but without Tween 20. This suggested that Tween 20 had a significant (p<0.05) inhibitory effect on the roadside soil microorganisms and therefore less microorganism were grown in the soil containing Tween 20. This indicated that Tween 20 was translocated PAH, but inhibited breakdown. This study indicated microbial biodegradation was the most effective technique for removing of the PAH from contaminated soil, which was cost effective and easier to perform in comparison to the other two techniques. Microbial biodegradation could be improved by adjusting pH through liming if soil was acid.

Submitted by orjuela@ibilce.unesp.br (orjuela@ibilce.unesp.br) on 2016-02-17T12:16:38Z No. of bitstreams: 1 Isolamento de bactérias degradadoras de hidrocarbonetos aromáticos 1-107.pdf: 3940758 bytes, checksum: c39dfe1dada0d918848470d3f0de5b83 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-17T13:16:08Z (GMT) No. of bitstreams: 1 orjuela_gl_dr_rcla.pdf: 3940758 bytes, checksum: c39dfe1dada0d918848470d3f0de5b83 (MD5) / Made available in DSpace on 2016-02-17T13:16:08Z (GMT). No. of bitstreams: 1 orjuela_gl_dr_rcla.pdf: 3940758 bytes, checksum: c39dfe1dada0d918848470d3f0de5b83 (MD5) Previous issue date: 2016-02-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este documento foi organizado em dois capítulos. O Capítulo I é um artigo de revisão intitulado “Metabolic Pathways for Aromatic Compounds Degradation by Bacteria”, no qual são descritas as fontes naturais e antrópicas dos hidrocarbonetos aromáticos e suas características químicas. Relacionaram-se os fatores ambientais que afetam a degradação aeróbia e anaeróbia desses compostos por bactérias e os principais compostos intermediários produzidos. É descrita passo a passo a sequência de preparação e desaromatização do anel benzênico e os compostos finais dessa degradação. O artigo foi publicado no volume 237 da série Reviews of Environmental Contamination and Toxicology em janeiro de 2016 (Springer http://dx.doi.org/10.1007/978-3-319-23573-8_5). O Capítulo II contém os resultados da pesquisa desenvolvida. O objetivo geral foi isolar cepas bacterianas de amostras de solo e avaliar o potencial degradador de fenol e outros hidrocarbonetos aromáticos. Foram realizadas coletas de amostras de solo de cinco postos de combustíveis, para a seleção das cepas bacterianas e para análises químicas e granulométricas. Alíquotas das amostras de solo foram transferidas para meio de cultura seletivo contendo querosene como única fonte de carbono. Testes morfológicos e bioquímicos indicaram que as cepas isoladas são Gram negativas, móveis, catalase positivas, produtoras de cápsula e de biossurfactantes. O sequenciamento do gene 16S rRNA mostrou 99 a 100% de similaridade com o gênero Pseudomonas sp. Todas as cepas degradaram o fenol em concentração de 120 mg L-1 em menos de 24 horas. Testes da atividade enzimática mostraram que algumas das cepas expressaram a catecol 1,2-dioxigenase que catalisa a orto-clivagem do anel benzênico e outras expressaram a catecol 2,3 dioxigenase da meta-clivagem do anel aromático. Uma cepa não apresentou atividade para nenhuma dessas duas enzimas e uma apresentou atividade de ambas. Todas as cepas foram capazes de crescer em presença de fenantreno, fluoranteno e pireno. / This document is organized in two chapters. The Chapter I is a review paper entitled “Metabolic Pathways for Aromatic Compounds Degradation by Bacteria” in which are described natural and anthropogenic sources of aromatic hydrocarbons and their chemical characteristics. There are listed environmental factors that affect the aerobic and anaerobic degradation by bacteria and the central intermediates yielded. It is described step to step of sequence of preparation and dearomatization of benzene ring and the final metabolites of breakdown. The manuscript was publicated in the volume 237 of Reviews of Environmental Contamination and Toxicology in January of 2016 (Springer http://dx.doi.org/10.1007/978-3- 319-23573-8_5). Chapter II has the results of developed research. The general objective was to isolate bacterial strains from samples of soil and to evaluate the potential of them for breakdown hydrocarbons. Soil samples from five gas stations were collected to isolate the bacterial strains and chemical and granulometric analysis was made. Aliquots of the soil samples were cultured with selective media with kerosene as only carbon and energy sources. Morphological and biochemical tests showed that bacterial strains were Gram negatives, motile, positive catalase, capsule-producers and biosurfactant producers. The sequencing of 16S rRNA gene showed 99 to 100% similarity with Pseudomonas sp genera. All bacterial strains were able to degrade phenol 120 mg L-1 in less than 24 hours. Tests of enzymatic activity showed that some bacteria expressed the catecol 1,2-dioxygenase that catalyze ortoclivage of benzene ring, others showed activity for the catecol 2,3-dioxygenase that catalyze the meta-cleavage of the ring. One strain did not show activity for any of these enzymes and one strain had activity for both. All strains were able to growth with fenantrene, fluoranthene and pyrene. / CNPq: 140704/2012-4