Dr. Joe E Lepo

This study is a component of the "Assessment of Environmental Pollution and Community Health in Northwest Florida, " supported by a USEPA Cooperative Agreement award X-9745502 to The University of West Florida (Project Director: Dr. K. Ranga Rao). The contents of this report are solely the responsibility of the authors and do not necessarily represent the official views of the USEPA. The study was undertaken because of the increasing concern for environmental pollution and potential impacts on human health in Northwest Florida. It was designed to assess environmental impacts of toxic pollutants in Bayou Texar with an emphasis on possible superfund site impacts upon the bayou. Kristal Flanders managed the spatial databases for the project and drafted the maps. Her assistance has been invaluable. Alan Knowles, Jason Moore, Jeff Seebach, Kevin Bradley, and Tony DiGirolamo helped with the fieldwork and some laboratory procedures. We wish also to thank Michael Lewis, Ecosystem Assessment Branch of the US EPA Gulf Ecology Division for discussing some data from US EPA studies on Bayou Texar with us.

Test systems that simulate oil slicks on open water or oiled sandy beaches were developed to test the effectiveness of commercial oil spill bioremediation agents (CBAs). Gravimetric
and gas chromatographic-mass spectrometric analytes (e.gv selected n-alkanes, isoprenoids, and aromatic compounds) were used to provide efficacy endpoints for comparing CBA-treated test systems with untreated control systems. The resulting test systems, and protocols for their use, .were evaluated using a variety of CBAs. Aquatic chronic estimator toxicology tests provided information on the environmental risks posed by the bioremediation agent itself as well as by the effluent,from CBA-treated test systems. Selected CBAs produced only minimal losses of analytes in the open-water test system after 7 days and somewhat greater, losses from the beach test system after 28 days. The use of a positive control consisting of selected oil degrading bacteria and nutrients enhanced degradation of certain oil components. The environmental safety protocols were also tested with a variety of CBAs; their intrinsic toxicity was relatively low (>75 ppm), and effluent exiting open-water test systems in which CBA and oil were allowed to interact was toxic for only one out of six products. A variety of research topics related to the development of CBA test system protocols were also investigated.

Several hundred bacterial cultures isolated from a variety of natural sites were screened for their ability to desulfurize the model coal organosulfur compounds, dibenzothiophene (DBT) and DBT-sulfone. A sulfur-stress assay, in which DBT-sulfone was the only bioavailable source of sulfur, was used to screen and select for organisms that selectively desulfurized the organic-sulfur substrate. Only two new isolates, UMX9 and UMX3, and strain IGTS-8, a Rhodococcus rhodochrous provided by the Institute for Gas Technology (Chicago, USA.) as a reference culture, would grow on DBT or DBT-sulfone as a sole source of sulfur. Under sulfur-stress conditions, a desulfurized product identified as 2-hydroxybiphenyl (2-phenylphenol) was detected only for UMX9 and IGTS-8. Biodesulfurization activity for all three organisms occurred only for growing cultures, and was depressed by free sulfate, although more so for UMX3 and IGTS-8 than for UMX9. None of the three cultures exhibited good growth on DBT, DBT-sulfone, or 2-phenylphenol as sole sources of carbon. Taxonomic studies revealed UMX3 to be similar to IGTS-8, whereas UMX9 only exhibited Rhodococcus-like features. Comparative tests for carbohydrate utilization revealed that only UMX9 would grow on glucose, and that only IGTS-8 would grow on L-arabinose. Assays of biodesulfurization activity as a function of temperature or pH revealed further differences between UMX9 and UMX3/IGTS-8. Under optimized assay conditions for each organism, UMX9 exhibited up to 30% greater biodesulfurization activity than did IGTS-8 and UMX3, which were similar in activity.