摘要:

AbstractData on the decomposition of 2,4‐dichlorophenoxyacetic acid (2,4‐D) by pure cultures ofAlcaligenes eutrophusJMP134 and in soil were obtained to investigate the validity of the Eq. (1),c=c0‐k1t1/2for decomposition at a decreasing rate by a constant amount of enzymes, and Eq. (2),c=c0‐k1t1/2, for decomposition at an increasing rate by an exponentially increasing amount of cells. In the equations,cis the concentration of 2,4‐D at timet, c0is the initial concentration of 2,4‐D,qis the maximum metabolic rate,N0is the initial amount of 2,4‐D‐degrading microorganisms, andk1andk2are rate constants. Equation 2 satisfactorily described the data on decomposition of 2,4‐D byA.eutrophusatc0of 100–400 μg mL−1, withN0of 0.33‐11.8 × 107cells mL−1, and at initial pH values between 7.1 and 8.4. At an initial pH of 6.1 there was accumulation of 2,4‐dichlorophenol (DCP), and the pattern of decomposition of 2,4‐D was sigmoidal. When approximately 20 μg of DCP mL−1had accumulated, the kinetics of decomposition switched from Eq. (2) to Eq. (1). Growth and DCP accumulation then also became linear witht1/2. Equation (1) was also valid for decomposition of 2,4‐D under conditions of nitrogen starvation. In soil, Eq. (1) was valid when the number of 2,4‐D degrading microorganisms was constant, and Eq. (2) was valid when the number increased exponentially. It is concluded that several occurring patterns of decomposition are described mathematically by Eq. (1), by Eq. (2), or by the sum of these equations. Sigmoidal curves are described by combining the equations in a sequence, thus providing an alternative to models where decomposition curves

ISSN:0884-8181    

DOI:10.1002/tox.2540040402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractA toxicant interaction method was used to study the effects of various bioassay parameters on interaction responses obtained in microbial bioassays. The fungusPythium ultimumwas employed as the test organism, and was exposed to various combinations of the fungicide captan and several organic solvents, using a poisoned agar technique. In all cases the fungicide and solvents interacted synergistically toward culture growth. For most experiments acetone was used as the test solvent. Where pH and temperature were altered, the magnitude of the interaction response between captan and acetone increased dramatically as the pH or temperature was raised from 4.5 to 7.5, or 15 to 30°C, respectively. This corresponded to similar increases in the culture growth rate and decreases in the toxicity of captan. When the medium composition was changed, interaction magnitudes were again greatest in media eliciting the fastest growth rate. These media also yielded the lowest captan toxicity. The largest interaction magnitudes occurred with V8 juice agar, followed by corn meal agar, potato dextrose agar, and malt extract agar. When the solvent used in the interaction experiments was changed, a similar response was obtained, in that the greatest interaction magnitudes occurred in systems eliciting the lowest captan toxicity. The largest magnitudes were measured with acetone, followed by hexane, ethanol, dimethylformamide, methanol, and dimethyl sulfoxide. The significance of these data in toxicant interaction bioassays is discussed

ISSN:0884-8181    

DOI:10.1002/tox.2540040403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractKlebsiella pneumoniaestrains isolated from different clinical and environmental sources were examined for resistance to antibiotics, pentachlorophenol, and heavy metals using intracellular ATP measurements. Resistance to kanamycin, neomycin, gentamicin, and tobramycin was noted for the hospital strain but not for the environmentally derived isolates. On the other hand, strains isolated from pulp and paper mill effluents and receiving waters exhibited a higher degree of pentachlorophenol and heavy metal resistance. Chromosomal restriction endonuclease analysis (REA) digests of three environmental strains produced patterns that were different and readily distinguishable. Plasmids were detectable in these same environmental isolates; two of the three carried a 70 × 106Da plasmid that is thought to mediate both antibiotic and heavy metal resistance

ISSN:0884-8181    

DOI:10.1002/tox.2540040404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThere are several advantages to the use of planktonic rotifers as freshwater bioassay organisms, yet few studies report toxicological data for these taxa. The goal of the present study was to evaluate the 24‐h acute toxicity responses ofBrachionus calycifiorusto six heavy metals, and to compare metal tolerance of this species to published results for other aquatic organisms. Metal toxicity toB. calyciflorus, in decreasing order, was Hg>Cu>Cd>Zn>Fe>Mn. This order follows the theoretical ranking by affinity for anionic radicals based on Lewis acid‐base classification. While not quite as sensitive asDaphnia magna, B. calyciflorusis potentially useful as a bioassay species because it is easy to culture and manipulate, and is widely distributed in alkaline waters of eastern North Amer

ISSN:0884-8181    

DOI:10.1002/tox.2540040405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe interaction between microorganism and chemical mixture was studied using resazurin reduction to delineate the microbial response to toxic substances. Two chemical mixtures, one consisting of two similar chemicals (2,3‐dichlorophenol and pentachlorophenol) and another of two dissimilar compounds (mercuric chloride and 2,3‐dichlorophenol), were tested on three pure bacterial isolates. Various toxicity patterns encompassing synergistic, neutral, and antagonistic effects on test bacteria were observed, demonstrating that the observed toxicity response from a chemical mixture does not always match the summed toxicity responses of the chemicals tested individually. No overall pattern regarding the interaction between microorganism and chemical mixture's toxicity could be drawn, implying that the traditional philosophy of setting water quality standards based on the toxicity assessment of individual chemicals should be readdressed to reflect the complexity of managing toxic substances in the aquatic environm

ISSN:0884-8181    

DOI:10.1002/tox.2540040406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of CuSO4on O2consumption in sediment samples and a pure culture ofAeromonas hydrophilawere examined using an O2electrode. Maximum inhibition of O2consumption in sediment samples was 85% at Cu concentrations ranging from 400 to 500 μg/g sediment. In contrast, O2consumption byA. hydrophilacell suspensions was inhibited 100% at Cu concentrations of 150 μg/mL in stream water and 250 μg/mL in sediment extract, respectively. Nonbiological (chemical) O2consumption also occurred in sediment samples during the bioassay. This was demonstrated by respiration insensitive to KCN (metabolic inhibitor) and the observation that chemical O2consumption occurred in autoclaved sediment samples. Caution should be taken when interpreting O2consumption data in environmental samples as nonbiological reactions may interfere with the bioass

ISSN:0884-8181    

DOI:10.1002/tox.2540040407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractToxins contained inMicrocystisspecies were examined for natural samples of water bloom collected from several lakes in Japan. The toxins were identified as microcystins (cyanoginosins)‐LR,‐YR, and ‐RR. The amounts of the three toxins were estimated after adsorption to a C18 cartridge, eluted with methanol, and subjected to high performance liquid chromatography using an octa decylsilanized column. Microcystins‐RR and ‐LR were the main components of the toxins contained in natural samples ofMicrocystisbloom, while YR was not detected in more than half of the samples analyzed. Six samples were also examined in relation to LD50values and species composition ofMicrocystis. The highest total amount of the three toxins was obtained for the sample with the lowest LD50value and composed mostly of cells ofM. aeruginosa. The relation between LD50values and total contents of the three toxins was well fitted to the formulaY= 1100 × X−1.079, where Y is the LD50value and X is the total amount of the

ISSN:0884-8181    

DOI:10.1002/tox.2540040408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractCyanobacterial blooms from several British freshwaters have been toxic by mouse bioassay each year since annual sampling began in 1981. Toxic blooms ofMicrocystis aeruginosa, Anabaenaspp.,Gloeotrichia echinulata, Oscillatoriaspp., andAphanizomenon flos‐aquaeoccur, with peptide toxin‐producingMicrocystisandAnabaenabeing most often encountered. We are developing a range of detection and quantification methods for cyanobacterial peptide and alkaloid toxins to supplement the standard mouse bioassay. Both types of toxins can be readily assayed by high performance liquid chromatography, and we have developed facile high performance thin layer chromatographic procedures for their detection from natural blooms and laboratory cultures. We have also produced polyclonal and monoclonal antibodies for the assay ofMicrocystistoxins by enzyme‐linked immunosorbent assay and have developedin vitrofibroblast cytotoxicity assays for the toxins ofMicrocystisand other cyanobac

ISSN:0884-8181    

DOI:10.1002/tox.2540040409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540040410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540040411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY