Improved xenobiotic-degrading activity of Rhodococcus opacus strain 1cp after dormancy

The goals of the present work were as follows: to obtain the dormant forms of R. opacus 1cp; to study the phenotypic variability during their germination; to compare phenotypic variants during the growth on selective and elective media; and to reveal changes in the ability of the strain to destruct xenobiotics that had not been degradable before dormancy. It was shown that Rhodococcus opacus 1cp (the strain degrading chlorinated phenols) became able to utilize a broader spectrum of xenobiotics after storage in the dormant state. Germination of the dormant forms of R. opacus 1cp on an agarized medium was followed by emergence and development of phenotypic variants that could grow on 4-chlorophenol and 2,4,6-trichlorophenol without adaptation. The cells of R. opacus 1cp phenotypic variants also utilized all of the tested chlorinated phenols: 2,3-, 2,5-, and 2,6-dichloro-, 2,3,4- and 2,4,5-trichloro-, pentachlorophenol, and 1,2,4,5-tetrachlorobenzene in concentrations up to 60 mg/L, though at the lower rates than 4-CP and 2,4,6-TCP. The improved degradation of chlorinated phenols by R. opacus strain 1cp exposed to the growth arrest conditions demonstrates the significance of dormancy for further manifestation of the adaptive potential of populations. A new principle of selection of variants with improved biodegradative properties was proposed. It embraces introduction of the dormancy stage into the cell life cycle with subsequent direct inoculation of morphologically different colonies into the media with different toxicants, including those previously not degraded by the strain.     

The electron density distribution in pyridinium and bipyridylium compounds and its relevance to their adsorption by expanding lattice clays

Abstract

Charge distributions in 1, 1'‐ethylene‐2, 2'‐bipyridylium (diquat), 1,1'‐dimethyl‐4,4'‐bipyridylium (paraquat) and 1‐methylpyridinium organocations were calculated by a Complete Neglect of Differential Overlap semi‐empirical quantum mechanical procedure. The data show that the positive charges in the organocations are distributed around the molecules and are greatest in the positions ortho and para to the heterocyclic nitrogen atoms. Earlier interpretations of the mechanisms of adsorption of paraquat and diquat by soils and clays assumed that the charges were located in the heterocyclic nitrogen atoms. Here some consideration is given to the influence of the charge delocalizations on the processes of adsorption by montmorillonite and vermiculite clay preparations.     

Effect of some xenobiotics on kynurenine hydrolase and kynurenine aminotransferase of mouse liver

Abstract

The effects of some xenobiotics on the activity of the B₆‐dependent kynurenine hydrolase (KH) and kynurenine aminotransferase (KATE) in mouse liver, were investigated. Polychlorinated biphenyl (Aroclor 1254) (400mg/kg/day ×4) markedly decreased the activity of both enzymes. Benzo(a)pyrene (BP) and 3‐methylcholanthrene (3‐MC) (40mg/Kg/day ×1) as well as phénobarbital (PB) (75mg/kg/day ×3) did not alter the activity of KH, while that of KATE was mildy reduced. The response of the two enzymes to treatment with chlorpromazine (CPZ) (5mg/Kg/day ×5) were opposite with marked elevation of KH and inhibition of KATE activities. Treatment with B‐naphthoflavone (B‐NF) (80mg/Kg/day ×2), Pyrazole (200mg/Kg/day ×1) or indole (400mg/kg/day ×1) produce no change in the activity of either enzyme. It, seems therefore, that Aroclor(1254) and chlorpromazine may cause disordered kynurenine metabolism through alterations in the activities of its metabolizing enzymes. This, in turn, might affect nicotinamide adenine dinucleotide biosynthesis and/or the accumulation of some tryptophan metabolites suspected of being carcinogenic or co‐carcinogenic.     

Hazardous Waste Minimization: Part IV Waste Reduction in the Metal Finishing Industry

The metal finishing industry uses over 40 production processes to produce a wide range of metal products. Waste streams generated include wastewater, waste oils, spent solvents, and spent process solutions. Currently a wide variety of techniques which minimize waste are available. Cost-effective methods to reduce electroplating wastewater contamination include water conservation and drag-out reduction, recovery and management. Ways to cost-effectively reduce the generation of spent metal-working fluids include establishing a fluid management program and installing a fluid recovery system. However, before any techniques are selected, a waste reduction survey should first be conducted.     

A Management Systems Review of the Superfund RI/FS: Opportunities for Streamlining

The Management Systems Review is an important component of EPA’s quality assurance program. MSRs enable managers to assess the effectiveness of environmental data operations and the quality assurance/ quality control activities designed to ensure that the results are of the expected quality. These reviews inform managers about aspects of the environmental data operation that are working well and those which may warrant some improvement. A recent review of the Superfund remedial investigation/feasibility study (RI/FS) has shown that the MSR is an excellent tool for providing a systematic definition of complex environmental data operations and for enabling a thorough analysis of these operations. The MSR utilized information gathered from interviews of Regional staff and management and from case studies of recently completed RI/FSs. The findings indicated that environmental data play an important role in most RI/FS decisions and that thorough and structured scoping is critical to the effectiveness of the RI/ FS. Analysis of the RI/FS process using a comprehensive flow model identified several opportunities for changes that may increase efficiency in data collection and the reliability of RI/FS decisions. These changes provide for more effective scoping activities, a streamlined feasibility study, and increased use of treatability studies during the RI. A pilot demonstration of these process changes is being planned for a Regional RI/FS.     

Radon Risk Communication Research: Practical Lessons

Those responsible for state and local radon programs often express frustration about the small share of homes that have been tested for radon, and the small share of those with high readings that have been mitigated. There are now a number of completed studies that have examined how well alternative ways of communicating about radon risk have accomplished the goals of motivating appropriate testing and mitigation. This paper summarizes the research results that are most crucial for planning and implementing effective radon risk communication programs. We identify six reasons why people do not respond to radon as a serious threat and provide some remedies suggested by radon studies.     

Comparison of the Annular Denuder System and the Transition Flow Reactor for Measurements of Selected Dry Deposition Species

An intensive field study was conducted in Research Triangle Park, North Carolina in the fall of 1986. Ambient concentrations of the following constituents were obtained: nitric acid, nitrous acid, nitrogen dioxide, sulfur dioxide, ammonia, hydrogen ion, and particulate nitrate, sulfate, and ammonium. Results collected using the annular denuder system (ADS) and the transition flow reactor (TFR) are presented and compared.

Both types of samplers had operational detection limits on daily (22-hour) samples that were generally below 1 μg m_-3 suggesting that both samplers can provide sensitive measurements for most of the constituents of interest. Both the ADS and TFR show reasonable (>25 percent) within-sampler precision for most of the measured species concentrations, except TFR fine particulate nitrate measurements where results were frequently negative (The TFR fine particulate nitrate measurement is calculated using subtraction of positive numbers).

Comparison of ADS and TFR daily results showed good agreement for total particulate sulfate, the sum of total (coarse plus fine) particulate and gaseous nitrate, and ammonia. As a result of different inlet particle collection efficiencies, the ADS fine particulate sulfate exceeded the TFR (5 percent). In the absence of a filter to collect volatilized particulate ammonium in the ADS, the sum of total particulate and gaseous ammonium in the TFR exceeded that in the ADS. Of potentially more importance, ADS measurements of SO₂ and H⁺ exceeded those of the TFR, while TFR measurements of HNO₃ exceeded those of the ADS. Results of this study suggest that the TFR may provide biased measurements of SO₂, H⁺, HNO₃, and Fine NO₃ ^- that cannot be corrected without modifications to the fundamental design of the sampling system.     

The Mutagenic Activity of Particulate Organic Matter Collected with a Dilution Sampler at Coal-Fired Power Plants

The Deep Creek Lake Study of 1983 provided an opportunity to obtain emission samples from coal-fired power plants with a dilution sampler for mutagenicity testing. Stack and ambient samples of particulate matter were collected with a dilution sampler at three coal-fired power plants in West Virginia. Samples were sequentially extracted with cyclohexane (CX), dichloromethane (DCM) and acetone (ACE) and tested for mutagenicity in the Ames Salmonella/microsome assay using TA98 (-S9). For the stack samples, the CX, DCM and ACE fractions constituted 1.0, 0.7 and 98.1 percent of the total extractable organic material (EOM), respectively, compared to 28.5, 7.4 and 64.1 percent for the ambient samples. In contrast, the mutagenic activity of the organic fractions was concentrated in the CX and DCM fractions.

The cyclohexane- and dichloromethane-soluble fractions of the stack samples from all locations exhibited mutagenicity when tested in the plate incorporation assay. No significant response was observed with the acetone fraction. When tested with Kado's modification of the preincubation assay, the acetone-soluble fraction did exhibit mutagenic activity comparable to that of the other fractions when expressed in units of revertants per milligram of particular matter. Chemical analyses of one of the acetone-soluble fractions indicated that half of the mass was sulfuric acid while the remainder consisted of C, H and O. More than 30 peaks were detected in the high pressure liquid chromatogram of this fraction.

Although little mutagenic activity was detected in the polar ACE fraction of the diluted stack emissions samples with this single bioassay, in view of the large mass of this fraction, further investigation of the chemical composition and genotoxic activity of this fraction would be prudent.