摘要:

AbstractThe effects of copper, nickel, and iron on survival, growth, nutrient uptake (NH 4+, NO 3−, and PO 4−3), carbon fixation, nitrate reductase, nitrogenase (CH2reduction assay), glutamine synthetase (transferase), and alkaline phophatase activities ofAnabaena doliolumwere studied. About 50% survival of the test alga was scored at 8.0 × 10−3, 8.6 × 10−3, and 0.36 mM of Cu, Ni, and Fe, respectively. However 45, 59, and 57% reductions in final yield were scored, respectively, at LD50concentrations of Cu, Ni, and Fe. On the basis of the LD50of the test metals, Ni was the most inhibitory for nutrient uptake. However, the LD50concentrations of Cu, Ni, and Fe showed different levels of inhibition for different processes. Although metal concentrations higher than LD50were found to be more inhibitory, 0.54 mM iron generated maximum inhibitory effect as compared to Cu and Ni. The present study demonstrates that the test cyanobacterium exhibits metal and dose‐specific responses toward different physiological and bioc

ISSN:0884-8181    

DOI:10.1002/tox.2540050302

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

年代:1990

数据来源: WILEY

摘要:

AbstractDecolorization and biodegradation of the azo dye methyl red (2′‐carboxy‐4‐N,N‐dimethylamino‐azobenzene) in shaking and static cultures of the strict aerobeAcetobacter liquefaciensS‐1 were demonstrated by the disappearance of the brownish orange color of the methyl red containing medium (pH 7.5), by the decrease in absorption maximum of methyl red, and by the identification of two compounds 2‐aminobenzoic acid (anthranilic acid) and N,N′‐dimethyl‐p‐phenylene diamine (4‐N,N‐dimethylamino‐aniline) formed by reductive cleavage of methyl red in parallel with incubation time. Decolorization of methyl red was essentially completed within 17 h of incubation in both shaking and static cultures, which contained 1 g/L of (NH4)2SO4as nitrogen source, 1% ethanol as carbon source, and up to 400 ppm of methyl red. Cells ofA. liquefaciensS‐1 were able to metabolize methyl red as sole nitrogen source for growth, although the time required to achieve high decolorization efficiency (98%) of methyl red was considerably lon

ISSN:0884-8181    

DOI:10.1002/tox.2540050303

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe Arabian Gulf offers a suitable location for investigating the potential impact of toxic chemicals on marine life, because it is a semienclosed, relatively shallow, small body of water. This study was carried out to evaluate the relative sensitivity, precision, and accuracy of three published microbial bioassay procedures to ascertain their ability to detect toxicity in the marine environment of Kuwait.The bioassay procedures used were dissolved oxygen depletion (DOD), viable plate count (VPC), and optical density (OD). Mixed marine bacteria isolated from the local seawater of Kuwait was used, and test samples (pollutants) investigated include mercuric chloride (HgCl2), lindane, and a wastewater samples.The DOD technique was evaluated as best for sensitivity of testing toxicity. In both brief and extended exposures, activity quotient values given by this technique were much lower than the LC50and IC50values given by the VPC and OD techniques. However, both VPC and OD techniques showed better reproducibility than the DOD technique, as indicated by lower coefficient of variation (CV) values. When evaluating complexity, the OD assay would be considered the least complex, then the DOD, and last would be the VPC.Although both VPC and OD assays showed better reproducibility than the DOD technique, as indicated by lower CV values, the DOD demonstrated a higher sensitivity in detecting toxicity, and showed several other advantages such as rapidity and lower expenditure of routine assay requirements. However, the initiation of short‐term bioassay in Kuwait for predicting effect of pollutants in the marine environment is of necessity and importanc

ISSN:0884-8181    

DOI:10.1002/tox.2540050304

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe use of bacteria as test organisms in rapid ecotoxicity assays is under investigation in several laboratories worldwide. However, little attention has been given to the question of permeability of the outer membrane of gram‐negative bacteria to toxicants of environmental interest. We have investigated the effect of physical, chemical, and genetic alterations on the sensitivity ofEscherichia colito environmental toxicants, as measured via inhibition of β‐galactosidase biosynthesis. Polymyxin treatment (2 mg/L) was the most promising treatment tested, significantly increasing the sensitivity of wild‐typeE. colito pentachlorophenol and sodium dodecyl sulfate. A mutant strain ofE. coli(EW1b), with an outer membrane protein alteration (tol Cgene), was found to be the most sensitive to hydrophobic compounds and to detergent. EW1b, further sensitized via polymyxin treatment, appears to be a sensitive microorganism for toxicant

ISSN:0884-8181    

DOI:10.1002/tox.2540050305

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

年代:1990

数据来源: WILEY

摘要:

AbstractCollection system and nonchlorinated secondary effluent samples from a large municipal wastewater system were fractionated using a scheme that included filration, EDTA treatment, C18solid‐phase extraction columns, and air stripping. Microtox required less time thanCeriodaphnia dubiabioassay for determining the toxicity of the numerous test samples generated by the fractionation procedure. Its usefulness was limited to collection system samples, however. Secondary effluent samples, which caused significant mortality ofC. dubia, were nontoxic to Microtox. Diazinon was tentatively identified as one of the causative toxicants present. Its LC50toC. dubia(0.5 μg/L) is within the range of concentrations detected (0.1–0.6 μg/L), whereas the EC50of diazinon to Microtox is much higher (>18,000

ISSN:0884-8181    

DOI:10.1002/tox.2540050306

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

年代:1990

数据来源: WILEY

摘要:

AbstractA microcapillary assay technique was developed to assess effects of pollutants on the chemoattraction of the ciliate,Tetrahymena pyriformis. Parameters in the protocol such as starvation period, exposure period, and trough design were standardized in an effort to obtain consistent results.Cadmium, phenol, and naphthalene were tested for effects on ciliates' chemoattraction to 0.15% yeast extract. All three toxicants inhibited chemoattraction; cadmium had the greatest effect, followed by naphthalene and phenol, respectively. The percent inhibition of chemoattraction for each concentration was used to determine EC50values for both 1 and 5 h exposures.Results show that the chemoattraction assay may provide a rapid, inexpensive, and sensitive asessment of aquatic toxicity. Inclusion of a protozoan assay fills the existing taxonomic gap in the routine battery of toxicity tests used for many hazard evaluations.

ISSN:0884-8181    

DOI:10.1002/tox.2540050307

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

年代:1990

数据来源: WILEY

摘要:

AbstractEcological effects of selenium (as sodium selenite) on naturally derived microbial communities were evaluated in laboratory microcosms and in outdoor experimental streams at the U.S. Environmental Protection Agency (U.S. EPA) Monticello Ecological Research Station (MERS). Microcosms were continuously dosed for 21 days at selenium concentrations ranging from 0 to 160μg Se/L. Outdoor streams were continuously dosed at 0, 10, and 30 μg Se/L, the highest concentration approximating the current U.S. EPA water quality criterion. In laboratory microcosms, protozoan species richness was reduced by 20%, and chlorophyll and hexosamine levels were reduced by 40% at μ80 μg Se/L. Total biomass and carbohydrate levels decreased with increasing Se, but these effects were not significant. Selenium had no effect on microcosm production to respiration ratios. In outdoor streams, microbial community biomass collected on artificial substrata was 2–3 times greater than in the laboratory. In general, adverse effects were not observed, confirming laboratory estimates of no adverse effects at<80 μg Se/L. However, low doses (10μg Se/L) consistently stimulated microbial biomass (protein, chlorophyll, hexosamine) and elevated production to biomass (P/B), consistent with reports of Se stimulation of algal growth. The highest Se dose (30 μg/L) caused decreased primary production and decreased P/B compared to controls. Experiments showed that ecological responses of laboratory microcosms and outdoor experimental ecosystems are similar, and are at least as sensitive as standard toxicological r

ISSN:0884-8181    

DOI:10.1002/tox.2540050308

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

年代:1990

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540050309

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

年代:1990

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540050301

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

年代:1990

数据来源: WILEY