Product Citations and Abstracts

Required information on microbial degradation of organochlorine pesticides in estuaries will be supplied when we answer the following questions: What types of microorganisms are involved in transformation of organochlorine pesticides? Are they the same types that predominate in organic detritus formation or are they species selected by exposure to pesticide pollution? What is the degree of degradation of specific compounds? Does co-metabolism occur in the estuary, and is it a means of degrading pesticides? What effects do additional hydrocarbons, such as oil, have on microbial degradation of pesticides in the estuary? Is synergistic activity within the estuarine microflora a factor in microbial degradation of pesticides? What is the role of microbial intracellular accumulation and adsorption in biodegradation and/or biological magnification of pesticides? What environmental factors in the estuary prevent or inhibit or accelerate microbial breakdown of pesticides? What types of pesticides are easily degraded? What are the effects of degradation products on estuarine macro- and microflora and fauna? Considering all the above questions, are similar reactions, selections and effects occurring in the water column and in the sediments? Such studies will provide data for an accurate picture of the role of estuarine microorganisms on the fate of organic pollutants. Such data are needed to formulate water quality criteria for pesticide regulation in the estuarine environment.

Bourquin, Al W. 1973. Impact of Microbial Seed Cultures on the Aquatic Environment. In: Proceedings of the First Microbiology Seminar on Standardization of Methods. EPA-R4-73-022. U.S. Environmental Protection Agency, Washington, DC. Pp. 140-142. (ERL,GB 203).

Microbial seed cultures are currently being studied for application to the environment as microbiological pesticides. Viruses have been isolated which attack selectively the cabbage boll; a bacterium has been isolated as a specific pathogen of mosquitoes; and chitinoclastic bacteria have been proposed as agents against plant predators in estuarine areas. The range of impact on the aquatic environment by seed cultures must be investigated adequately before they are used on a large scale.

Bourquin, Al W. and S. Cassidy. 1975. Effect of Polychlorinated Biphenyl Formulations on the Growth of Estuarine Bacteria. Appl. Microbiol. 29(1):125-127. (ERL,GB 217).

Polychlorinated biphenyl formulations inhibited the growth of certain estuarine bacteria. The sensitive strains, although exhibiting some similar physiological characteristics, contained both gram-positive and gram-negative bacteria.

Bourquin, A.W., L.A. Kiefer, N.H. Berner, S. Crow and D.G. Ahearn. 1975. Inhibition of Estuarine Microorganisms by Polychlorinated Biphenyls. In: Developments in Industrial Microbiology, Vol. 16. American Institute of Biological Sciences, Washington, DC. Pp. 256-261. (ERL,GB 230).

Over 100 isolates of representative estuarine bacteria and fungi were screened for their ability to grow in the presence of commercial preparations of polychlorinated biphenyls (PCB). Super absorbant sensitivity discs impregnated with up to 0.5 mg of PCB were placed on the surface of freshly inoculated solid media. Twenty-six bacteria, representing both gram-positive and gram-negative strains of varying morphology, showed varying degrees of sensitivity to PCB. In contrast to insensitive isolates, sensitive strains were mainly amylolytic and proteolytic. PCB had negligible effect on the growth of fungi. The sensitivity of select cultures of heterotrophic bacteria to PCB may be of considerable importance to nutrient turnover in estuarine ecosystems.

Bourquin, A.W., S.P. Meyers and D.G. Ahearn. 1975. Impact of the Use of Microorganisms on the Aquatic Environment. EPA-660/3-75-001. U.S. Environmental Protection Agency, National Environmental Research Center, Corvallis, OR. 259 p. (ERL,GB 235). (Avail. from NTIS, Springfield, VA: PB-240 159)

This report contains the proceedings of a symposium-workshop sponsored by the EPA Gulf Breeze Environmental Research Laboratory to determine the possible impact of artificially introducing microbial insect control agents or oil-degrading agents into the aquatic environment. The efficacy and safety testing, especially against non-target aquatic organisms, for use of bacteria, viruses, fungi, and protozoa to control aquatic insect pests is discussed with remarks of panel members representing government, academia, and industry. Special attention is given to persistence of pathogens in aquatic environments as well as control of aquatic weeds and other non-insect pests. The use of microorganisms to clean up oil spills in aquatic environments is discussed by industrial, academic, and governmental scientists. Special considerations are given to selection of hydrocarbonoclastic microorganisms and use of these microorganisms in special environments--Arctic regions and Louisiana salt marshes. Summary papers are presented for each panel concerned with microbial pesticides and one summary for the session on microbial degradation of oil. Excellent bibliographies are presented with each paper and discussion.

Bourquin, Al W. 1975. Microbial-Malathion Interaction in Artificial Salt-Marsh Ecosystems--Effect and Degradation. EPA-660/3-75-035. U.S. Environmental Protection Agency, National Environmental Research Center, Corvallis, OR. 40 p. (ERL,GB 236). (Avail. from NTIS, Springfield, VA: PB-246 251)

Malathion is rapidly degraded in vitro by salt-marsh bacteria to malathion-monocarboxylic acid, malathion-dicarboxylic acid and various phosphothionates as a result of carboxyesterase cleavage. In addition, some expected phosphatase activity produces desmethyl-malathion, phosphotionates, 4-carbon dicarboxylic acids, and corresponding ethyl esters. In a simulated salt-marsh environment, malathion is degraded by the indigenous bacterial community. Numbers of bacteria capable of degrading malathion in the presence of additional nutrients increase in the sediments with increasing frequency of application and in the water column with the increasing level of treatment. Numbers of bacteria which degrade malathion as a sole carbon source are linked to the level of treatment in sediments and the frequency of treatment in the water column; however, these bacteria do not appear to play a significant role in the dissipation of malathion. I believe that frequency of treatment, increases numbers of malathion co-metabolizing bacteria which catalyze a more rapid dissipation of the compound, which results in fewer sole carbon degraders. The disappearance of malathion in the salt-marsh environment is influenced by both chemical and biological degradation; however, at temperatures below 26°C and salinities below 20 o/oo, chemical mechanisms appear to be of less importance than biological degradation.

Bourquin, A.W. 1977. Degradation of Malathion by Salt-Marsh Microorganisms. Appl. Environ. Microbiol. 33(2):356-362. (ERL,GB 291).

Numerous bacteria from a salt-marsh environment are capable of degrading malathion, an organophosphate insecticide, when supplied with additional nutrients as energy and carbon sources. Seven isolates exhibited ability (48 to 90%) to degrade malathion as a sole carbon source. Gas and thin-layer chromatography and infrared spectroscopy confirmed malathion to be degraded via malathion-monocarboxylic acid to the dicarboxylic acid and then to various phosphothionates. These techniques also identified desmethyl-malathion, phosphorothionates, and four-carbon dicarboxylic acids as degradation products formed as a result of phosphatase activity.

Bourquin, A.W., M.A. Hood and R.L. Garnas. 1977. Artificial Microbial Ecosystem for Determining Effects and Fate of Toxicants in a Salt-Marsh Environment. In: Developments in Industrial Microbiology, Vol. 18. EPA-600/J-77-075. Society for Industrial Microbiology, Washington, DC. Pp. 185-191. (ERL,GB 309). (Avail. from NTIS, Springfield, VA: PB-277 181)

An artificial laboratory environment designed to determine microbial interactions with pollutant chemicals is proposed. The system is designed to obtain maximum reproducibility between replicates by dividing a single tank into separate closed chambers. Radiolabeled toxicants are added directly to the core-chambers and monitored for metabolic breakdown. Further information is obtained easily on changes in microbial, physiological indexes induced by the toxicants. Techniques for monitoring effects of the methyl parathion on the microbial population and the fate of this chemical are given.

Bourquin, A.W. 1977. Effects of Malathion on Microorganisms of an Artificial Salt-Marsh Environment. EPA-600/J-77-065. J. Environ. Qual. 6(4):373-378. (ERL,GB 312). (Avail. from NTIS, Springfield, VA: PB-277 153)

Laboratory salt-marsh environments were treated with malathion, an organophosphate insecticide, and aerobic heterotrophic bacteria were monitored to determine changes in their microbial ecology. Several physiological activities were assayed in both treated and untreated controls; however, no reliable trends in numbers of these microorganisms were detected. On the other hand, populations of malathion sole-carbon-degrading bacteria increased significantly with increasing treatment levels and in the sediments with repeated treatment. Malathion cometabolizing bacteria increased significantly over the control systems in the water column with increasing treatment levels. Although numbers of malathion-degrading bacteria increased with higher treatment levels or frequency of treatment, these changes had no effect on the numbers of bacteria from the water or sediment. When an organochlorine insecticide, mirex, was used to treat the ecosystems, essentially no changes in the bacterial populations were detected.

Bourquin, A.W. and D.G. Ahearn. 1976. Microbiology and Chemistry of Estuarine Surface Microlayers. In: Proceedings of the International Symposium on Marine Pollution Research. EPA-600/9-76-032. Samuel P. Meyers, Editor. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. Pp. 89-96. (ERL,GB 313). (Avail. from NTIS, Springfield, VA: PB-267 601)

Organic microlayers occur at the air-water interface of most bodies of water. The microlayer or "sea slick" formation appears to be related mainly to decay of naturally occurring aquatic organisms or to their production of lipodial by-products. Sea slicks are known to influence wave action and height, air-water temperature exchange, stability of bubbles and foams, and the concentration of salt-containing micro-droplets in the marine atmosphere. In coastal regions particularly, the direct activities of man are of increasing importance in the generation of surface slicks. Industrial and municipal sewage effluents constitute the major source of films and foams, but crude oil spillage appears to be a major contributor in localized areas. In studies from our laboratories on a yeast isolated from a freshwater oil layer, the chlorinated pesticide heptachlor either stimulated or inhibited hexadecane utilization dependent upon cultural conditions. The heptachlor was bound to the yeast cells but no direct evidence for its metabolism was obtained. Stimulation of oxidation of hexadecane in the presence of a non-utilizable substrate by a fungus (Cladosporium resinae) has been shown also by Walker and Cooney (1975). Growth inhibition of estuarine microorganisms by polychlorinated biphenyl formulations has been demonstrated in laboratory studies and field and laboratory studies have shown that crude oil may diversely affect the various species of the estuarine microecosystem. The potential for alteration of the estuarine surface film microflora by hydrocarbons can be expected to increase with the advent of superports and the extension of offshore oil fields. For a better understanding of the composite phenomena affected by surface films, and their role in pollutant concentration or metabolism, a substantial increase in our knowledge of the chemical identity of surface films and of the changes in the film with microbial activity needs to be developed.

Bourquin, A.W. and V.A. Przybyszewski. 1977. Distribution of Bacteria with Nitrilotriacetate-Degrading Potential in an Estuarine Environment. Appl. Environ. Microbiol. 34(4):411-418. (ERL,GB 323).

Attempts to isolate estuarine bacteria capable of metabolizing nitrilotriacetate (NTA) as a sole carbon source from areas within Escambia Bay, Fla., were unsuccessful; however, bacteria from freshwater streams and from estuarine surface microlayers were easily adapted to degradation of NTA in freshwater medium. A Pseudomonas sp. strain (ATCC 29600), capable of growth in NTA as a sole carbon source, metabolized NTA at a reduced rate in a saline medium (15 l), compared with a freshwater medium (0 to 15 l). Microorganisms capable of degrading NTA exist in estuarine surface microlayers and in fresh subsurface waters just before entering the estuary; these data indicate an interference with NTA catabolism by some unknown factors of the estuarine environment rather than an absence of potential NTA-degrading bacteria.

Bourquin, A.W., P.H. Pritchard and W.R. Mahaffey. 1978. Effects of Kepone on Estuarine Microorganisms. In: Developments in Industrial Microbiology, Vol. 19. EPA-600/J-78-075. Society for Industrial Microbiology, Washington, DC. Pp. 489-497. (ERL,GB 345). (Avail. from NTIS, Springfield, VA: PB-290 049)

Low concn of the insecticide Kepone, approaching those found in contaminated James River sediment, were shown to be inhibitory to the growth and oxygen uptake of microorganisms randomly selected from estuarine environments. No significant correlations were noted between growth inhibition by Kepone and cell morphology, aliphatic hydrocarbon utilization, pesticide tolerance, selected enzyme activities, nitrate reduction, and urea hydrolysis. Oxygen uptake by pure cultures grown on glucose or hydrocarbons at cell densities equivalent to 103 - 104 cells/ml was decreased by 60-100% at Kepone concn of 0.02-2.0 mg/liter. Total viable counts from estuarine water or sediments grown aerobically on agar media containing 0.02 mg/liter Kepone were reduced by 8-78%. The inhibitory effect was eliminated partially when sediment populations were grown anaerobically.

Bourquin, A.W., R.L. Garnas, P.H. Pritchard, F.G. Wilkes, C.R. Cripe and N.I. Rubinstein. 1979. Interdependent Microcosms for the Assessment of Pollutants in the Marine Environment. Int. J. Environ. Stud. 13(2):131-140. (ERL,GB 348).

Laboratory microcosms are described for assessing the fate and effects of pollutants in marine and estuarine environments. These systems focus on specific ecosystem processes and interactions and are interdependent in that the results of all are necessary for a complete description of a pollutant's environmental impact. The following individual systems are described using methyl parathion as the pollutant: Environmental Fate Screening System; Eco-Core System; Continuous Flow Systems; Aquatic Gradient Avoidance Response System; Benthic Bioassay System.

Bourquin, Al W. and David T. Gibson. 1978. Microbial Degradation of Halogenated Hydrocarbons. In: Water Chlorination: Environmental Impact and Health Effects, Vol. 2. Robert L. Jolley, Hend Gorchev, and Hamilton D. Heyward, Jr., Editors. Ann Arbor Science Publishers, Ann Arbor, MI. Pp. 253-264. (ERL,GB 361).

Although little is known about the specific halogenated compounds in sea water that result from chlorination procedures, existing information relating to the microbial degradation of organohalides may be used to predict the possible fate of such molecules in marine environments.

Bourquin, Al W., Jim C. Spain and P.H. Pritchard. 1982. Microbial Degradation of Xenobiotic Compounds. In: Proceedings of the Twelfth Conference on Environmental Toxicology, 3-5 November 1981, Dayton, OH, AFAMRL-TR-81-149. Air Force Aerospace Medical Research Laboratory, Wright-Patterson AFB, OH. Pp. 354-369. (ERL,GB 437).

Microbial degradation of xenobiotic compounds in natural environments is probably the most difficult fate process to study and quantitate. Information necessary to predict biodegradation of a chemical depends on laws of chemistry, the genetic capabilities of the microbial populations, and on conditions in the environment. We have studied degradation of toxicants under conditions that maintain complexities of the natural environment and associated microorganisms. Studies with (NTA) nitrioltriacetic acid demonstrated that this compound, normally biodegradable in freshwater, persists in estuarine environments. The studies illustrate the complex interactions in natural environments that complicate our understanding of biodegradation mechanisms. Interaction with environmental conditions or lack of genetic capabilities within an environment was demonstrated further when freshwater, but not saltwater, microbial populations were shown to adapt within several days to degrade p-nitrophenol rapidly. Differences in chemical structure affect degradation of toxic chemicals in natural media with mixed microbial populations. Such structure range from compounds like methyl parathion, which is substantially metabolized, to dimilin, which partially degrades and yields nonbiodegradable products, to Kepone, which persists intact.

Bourquin, Al W. 1984. Biodegradation in the Estuarine-Marine Environments and the Genetically Altered Microbe. In: Genetic Control of Environmental Pollutants. EPA-600/D-84-051. Gilbert S. Omenn and Alexander Hollaender, Editors. Plenum Press, New York, NY. Pp. 97-115. (ERL,GB 497). (Avail. from NTIS, Springfield, VA: PB84-151315)

Historically, some organic and inorganic compounds have been considered serious environmental threats from the standpoint of quantity produced, bioaccumulation, toxicity, or adverse environmental effects. This paper documents selected examples of known introductions of toxic chemicals into marine and estuarine environments and describes how habitat differences affect biodegradation potential. Concerns regarding release of genetically altered organisms into these environments also are discussed.

Bourquin, A.W. and P.H. Pritchard, Editors. 1979. Workshop: Microbial Degradation of Pollutants in Marine Environments. EPA-600/9-79-012. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 552 p. (Also avail. from NTIS, Springfield, VA: PB-298 254)

This international workshop, held April 10-14, 1978, at Pensacola Beach, Florida, focuses on pertinent issues related to the scientific investigation of microbial degradation of organic chemicals in aquatic environments. Participants discuss methodological criteria for these investigations and the need for biodegradation studies. Speakers and contributed papers for open sessions explore these topics: (1) biochemistry of microbial degradation; (2) transformation in aquatic environments; (3) compartmentalization in aquatic environments; (4) biodegradation in microcosms; (5) degradation methodology; and (6) persistence and extrapolation. Discussions within each session are presented. These proceedings conclude with a summary report and workshop consensus reports drafted by special task groups with recommendations concerning the research, production, and regulation of potential aquatic pollutants.

Bourquin, Al W., P.H. Pritchard, William W. Walker and Rod Parrish. 1985. Proceedings of the Workshop: Biodegradation Kinetics Navarre Beach, Florida, 18-20 October 1983. EPA/600/9-85/018. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 161 p. (Also avail. from NTIS, Springfield, VA: PB85-222651)

This workshop, held October 18-20, 1983, at Pensacola Beach, Florida, focused on pertinent issues related to the scientific investigation of the microbial degradation rates of organic chemicals in natural environments. Participants discussed methodological criteria for these investigations and the need for concentrating on the kinetic aspects of biodegradation. Position papers dealing with the following topics were presented in open sessions: (1) statistical and experimental requirements for modeling decay curves; (2) the 'second order' approach assumption, limitations and research needs; (3) factors controlling biodegradation rates in microbial communities; (4) application of uptake and mineralization kinetics; (5) relationships between chemical structure and biodegradation rates; and (6) extrapolation of laboratory biodegradation data to the field. Discussions within each session are summarized by the panel members in reports that include a consensus of the direction and extent of research required for the description of biodegradation rates of xenobiotic chemicals in natural environments. These proceedings conclude with a summary report and suggestions for future research in biodegradation kinetics. This report is submitted in fulfillment of contract no. CR 810789 by Gulf Coast Research Laboratory in conjunction with Georgia State University cooperative agreement R809370 under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from April 4, 1984 to May 13, 1984, and work was completed as of June 30, 1984.

Bourquin, A.W. 1980. Discussion - Aquatic Microbial Ecology. In: Microbiology--1980. David Schlessinger, Editor. American Society for Microbiology, Washington, DC. Pp. 390-391. (ERL,GB X157).

We have been discussing the problem of how to assess environmental stress on ecosystems and the microbiological processes therein. Basically, what we have been discussing are methods--methods for measuring biomass, heterotrophic activity, biodegradation, and other indicators of environmental quality. What I would like to see discussed now is the question: 'What can we get out of these methods that can be used by regulatory agencies?' I am not sure that we are any closer to agreement on any particular method or methods that are more acceptable than others to the scientific community for assessing any environmental stress. However, I think that we have learned a lot about the various methods, including their limitations and their possible benefits. We have addressed various research needs and have just heard a very excellent presentation on this subject. What I would like to add to this is a request that we begin to apply some of this information, particularly in terms of the limitations and benefits of the various methods, to assess the so-called health of a given environment. There are environmental decisions which must be based on the available technology, because we really do not have any time and must make some decisions now. We can modify those decisions later, but a decision is needed now based on the current technology. If people such as those at this conference do not aid in determining which methods should be used with what qualifications, then less qualified people will make those decisions.

Bourquin, A.W. 1979. Regulatory Responsibility. In: Aquatic Microbial Ecology. R.R. Colwell And Joan Foster, Editor. Univ. of Maryland, College Park, MD. Pp. 401-405. (ERL,GB X301).

Whenever we are producing data involving monitoring, or data for criteria development, we are asked questions such as: So what? What does it mean? What are you going to give me? Agencies such as the Environmental Protection Agency have a number of regulatory responsibilities, only the most recent being enforcement of the Toxic Substances Control Act. Some hard decisions must be made when funding research, in-house or extramural.

Bourquin, Al and Ramon Seidler. 1986. Research Plan for Test Methods Development for Risk Assessment of Novel Microbes Released into Terrestrial and Aquatic Ecosystems. In: Biotechnology and the Environment: Research Needs. Gilbert S. Omenn and Albert H. Teich, Editors. Noyes Data Corporation, Park Ridge, NJ. Pp. 18-66. (ERL,GB X606). (AAAS)

A research plan to develop test methods and produce information for risk assessment from effects of novel organisms released into terrestrial and aquatic ecosystems is described. Test methods are required by EPA in the regulation of the biotechnology industry. Specific proposals will be developed from the research plan and a subsequent workshop will be held to define research needs of the EPA Office of Pesticides and Toxic Substances.

This paper provides a perspective on the possible interfacing of microcosm studies with both waste assimilatory capacity determinations and other less quantitative types of assessment. Some of the problems and inconsistencies in the interpretation and application of microcosm results are discussed. Conceptual ideas on how microcosms can be used in quantitative and qualitative risk analysis are presented. Two basic criteria are proposed for the development of the screening microcosm: a.) assurance that the same information cannot be obtained in some simple, laboratory systems; b.) assurance that if the screening microcosm result is not ecologically unique, it is, at least a more sensitive indicator of toxic effects or fate than other laboratory tests. Arguments are presented to support the contention that microcosms, from a quantitative risk analysis standpoint, have no predictive value by themselves. They are instead, representations of the state-of-the-whole of certain ecosystem sections which can be used as a means of verifying the environmental significance of other types of laboratory data and the correctness of kinetic expressions used to describe individual fate and effects processes. The microcosm is also a research tool which can enhance our quantitative understanding of the process interactions and metabolic networks typical of natural ecosystems.

O'Neill, Ellen J., Carol A. Monti, Parmely H. Pritchard, Al W. Bourquin and Donald G. Ahearn. 1985. Effects of Lugworms and Seagrass on Kepone (Chlordecone) Distribution in Sediment/Water Laboratory Systems. EPA/600/J-85/150. Environ. Toxicol. Chem. 4(4):453-458. (ERL,GB 488). (Avail. from NTIS, Springfield, VA: PB86-101078)

The influence of lugworms (Arenicola cristata Stimpson) and seagrass (Thalassia testudinum Koenig) on KeponeŽ (chlordecone) distribution in sediment/water systems was examined. Radiolabeled Kepone was introduced into continuous-flow sediment/water systems, and the dissolved and sorbed concentrations of Kepone were quantified. Lugworm activity decreased the Kepone concentration in the water and increased its concentration in the sediment. The presence of seagrasses did not appreciably affect the concentration of Kepone in the water. Bioturbation appeared to be the prime factor in the transport of Kepone from water to sediment.

Genthner, Fred J., Pramita Chatterjee, Tamar Barkay and Al W. Bourquin. 1988. Capacity of Aquatic Bacteria to Act as Recipients for Plasmid DNA. Appl. Environ. Microbiol. 54(1):115-117. (ERL,GB 595).

A total of 68 gram-negative freshwater bacterial isolates were screened for their ability to receive and express plasmids from Pseudomonas aeruginosa donors. The plate mating technique identified 26 of the isolates as recipient active for the self-transmissible wide-host-range plasmid R68; 10 were recipient active by R68 mobilization for the wide-host-range plasmid cloning vector R1162. Frequencies of transfer were compared by using three conjugal transfer procedures: broth, plate, and filter mating. For every recipient tested a solid environment was superior to liquid environment for transfer. The broth mating technique failed to demonstrate R68 transfer in 63% of the recipient-active isolates. Filter mating, in general, yielded the highest transfer frequencies. The more rapid plate mating procedure, however, was just as sensitive for testing the capacity of natural isolates to participate in conjugal plasmid transfer.

Barkay, Tamar, Deb Chatterjee, Stephen Cuskey, Ronald Walter, Fred Genthner and Al W. Bourquin. 1989. Bacteria and the Environment. In: Revolution in Biotechnology. Jean L. Marx, Editor. Cambridge University Press, New York, NY. Pp. 94-102. (ERL,GB 604).

Microorganisms with new functions can be constructed in the laboratory by gene cloning. This paper discusses the potential of a powerful tool for environmental management: new strains to control pests, to increase yields, and to degrade noxious pollutants. Approaches and methods are described for risk assessment based on the experiences and findings in microbial ecology. However, risk assessment criteria have yet to be established due to the unknown and potentially harmful effects of the introduced organisms on the receiving environments.

Nelson, Michael J.K., P.H. Pritchard and Al W. Bourquin. 1988. Preliminary Development of a Bench-Scale Treatment System for Aerobic Degradation of Trichloroethylene. In: Environmental Biotechnology: Reducing Risks from Environmental Chemicals Through Biotechnology. Gilbert S. Omenn et al., Editor. Plenum Press, New York, NY. Pp. 203-209. (ERL,GB 653).

Experiments with batch cultures of an environmental isolate, strain G4, indicated that the organism degraded trichloroethylene (TCE) to CO2 and inorganic chloride. Degradative activity required the presence of oxygen and the induction of an aromatic pathway. Induction was accomplished by the addition of toluene, phenol, o-cresol or m-cresol to the growth medium. Studies with water samples from estuarine, river, and groundwater environments showed that the natural microflora metabolized as much as 70% of the added TCE if stimulated by the addition of phenol or toluene under aerobic conditions. However, more complete degradation (96-100%) of TCE occurred when these samples were amended with strain G4. The results indicate TCE may be removed from contaminated water by biological treatment. Work has been initiated on a bench-scale continuous-flow treatment system for TCE-contaminated water using strain, G4 as the inoculum. Problems encountered include the need to minimize or eliminate the requirement for an aromatic inducer and to develop methods for maintaining aerobic conditions without volatilizing TCE.

Levin, Morris A., Ramon Seidler, Al W. Bourquin, John R. Fowle, III and Tamar Barkay. 1987. EPA Developing Methods to Assess Environmental Release. Bio/Technology. 5:38-45. (ERL,GB X544).

EPA biotechnology research is described. Early studies focused on characterizing the viruses and developing monitoring methods to detect and identify Baculoviruses in the area of health effects research. EPA's overall research plan focuses on risk assessment and includes development of methods and protocols for laboratory studies, evaluation and modification of methodology in microcosms, evaluation of the use of microcosm data in terms of equivalence to field data and preparation of risk assessment guidelines.