Search PubMed⌕ Search

Biomedical subjects

B J Dutka

Publications and source records attributed to B J Dutka.

At least 19 recordsLinked to original sources
PubMed1995

A modified SOS-Chromotest procedure to test for genotoxicity and cytotoxicity in sediments directly without extraction.

A modified SOS-Chromotest bioassay using a chromogenic pad (pad procedure) was developed to test for genotoxicity in sediments directly without extraction. This test is based on the de novo synthesis of beta-galactosidase enzyme by a genetically-engineered E. coli strain PQ37. In the bioassay, an exponential growth phase antibiotic-containing culture of the test bacterium is introduced into a series of tubes with the first tube containing 0.1 gram of sediment. Serial dilutions are then made and the tubes of sediment plus bacterial culture are incubated at 37 degrees C for four hours, followed by placing a drop of each mixture on a chromogenic pad and additional incubation for 20 hours at 37 degrees C. The solid particulates are then washed off with tap water and positive (genotoxic) activity is noted by the presence of a distinctive blue colour on the pad. The SOS-Chromotest pad procedure may be best used as a relative measure of genotoxicity by comparing results to a reference sample. In addition it can also determine sediment cytotoxicity by comparing samples spiked with a genotoxic standard (i.e., 4-nitroquinoline-N-oxide). Preliminary results suggest that this new bioassay is highly sensitive, consistent and discriminating.

4-Nitroquinoline-1-oxide↗
PubMed1995

Toxicity of organomercury compounds: bioassay results as a basis for risk assessment.

A former mercury plant, where mercury salts and organomercurials for pesticide use were produced, caused soil contamination in high concentrations. Typical organomercurial products included ethylmercury, phenylmercury, methoxyethylmercury and ethoxyethylmercury compounds. Risk assessment of these sites must be carried out before any major clean-up processes can be planned. A sensitive speciation technique for the various organomercury species in environmental matrices is a prerequisite for toxicity investigations. In this connection, a high-performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) technique has been developed to differentiate between and determine the presence of eight organomercury compounds in environmental samples. Using this technique, methylmercury, ethylmercury and phenylmercury and some unknown organomercury species were found in soil samples collected from the sites of an old mercury products producing plant. With regard to risk assessment, it is necessary to assess the toxicity of the organomercurials. As different microbial metabolic pathways react differently to mercury and its compounds, batteries of bioassays are, therefore, useful to evaluate the toxicity of pollutants. To describe the toxicity and genotoxicity of MeHg+, MeOEtHg+, EtHg+, EtOEtHg+ and PhHg+, p-tolymercury chloride, nitromersol and Hg2+ six bioassays were used: resazurin reduction method, Spirillum volutans test, nematode toxicity assay Panagrellus redivivus, Toxi-Chromotest and SOS-Chromotest. A ranking of the toxicity of the organomercurial is shown. The SOS-Chromotest indicated genotoxicity for 5-7 organomercurials.

Animals↗
PubMed1988

Incidence of coliphage in potable water supplies.

Samples of drinking water from different sources in greater Cairo, Egypt, and bottled drinking water were tested for total coliform, fecal coliform, and coliphage populations. Of the 147 samples tested, 4 samples were positive for both total coliforms and coliphage, 65 samples were negative for total coliforms, fecal coliforms, and coliphage, and 78 samples were positive for coliphage and negative for total coliforms and fecal coliforms. The incidence of coliphage in these potable water supplies reflects the probability of human pathogenic virus survival in these waters also.

Coliphages↗
PubMed1987

Enumeration of Klebsiella spp. in cold water by using MacConkey-inositol-potassium tellurite medium.

MacConkey-inositol-potassium tellurite agar was field tested for its ability to selectively enumerate Klebsiella species from the waters of the Saint John River Basin, which include fresh and marine waters. Water temperature varied from 1 to 6 degrees C during the survey period. Results of the study indicated that 77% of the typical colonies on MacConkey-inositol-potassium tellurite medium were Klebsiella species, but the total Klebsiella population enumerated was greatly underestimated.

Culture Media↗
PubMed1984

The fate and impact of oil and oil-dispersant mixtures in freshwater pond ecosystems: introduction.

Oil and oil-dispersant mixtures were added to the surface waters of a series of man-made ponds. The fate of the oil and dispersant (Norman Wells crude and Corexit 9527 respectively) were studied as well as the impact of the added chemicals on the ponds' ecosystems. Elements of the ecosystems studied include bacteria, fungi, phytoplankton, periphyton , proto- and mesozooplankton , zoobenthos and surface insects. In addition a number of water quality parameters were regularly monitored. Comparisons were made between oil-treated and control ponds, as well as oil-dispersant treated and oil and/or control ponds. This paper describes the experimental set up and provides a summary of the findings reported in the following five papers.

Animals↗
PubMed1984

Study of long term effects of oil and oil-dispersant mixtures on freshwater microbial populations in man made ponds.

In this paper, the results of a 19 month investigation of microbial communities subjected to the effects of oil and oil plus dispersant additions in man made ponds are reported. Microbial biomass estimations by ATP (adenosine triphosphate) and microscopic procedures using epifluorescence indicated that oil and oil plus dispersants had little or no effect on these parameters, and any effect noted was stimulatory. However, detailed examination of specific populations indicated that oil and oil plus dispersant additions were stimulatory for short periods of time to the populations studied. Seven days after the oil and dispersant additions to the ponds, no mutagenic or toxic activities to bacteria were noted.

Adenosine Triphosphate↗
PubMed1984

Incidence of Legionella organisms in selected Ontario (Canada) cities.

The distribution of Legionella pneumophila in water inside buildings was examined by means of culture methods. Cooling tower sumps and condenser valves harboured the organism at the highest frequency and in the highest concentrations. The bacterium was also frequently isolated from potable water systems, including hot and cold mixed taps, drinking water fountains and showers. When water quality parameters were examined, only elevated pH, total particulate nitrogen and alkalinity were correlated with the occurrence of L. pneumophila. Survival of the organism in water was increased at slightly basic pH and lower temperatures. The proliferation of the organism in water within buildings is probably due to a number of interrelated environmental factors that influence its survival and growth.

Culture Media↗
PubMed1984

Sensitivity of Legionella pneumophila to sunlight in fresh and marine waters.

Studies were carried out to assess the sunlight sensitivity of Legionella pneumophila suspended in fresh and marine waters. Comparison studies on sunlight sensitivity of lake water bacteria, Pseudomonas aeruginosa, Escherichia coli and Streptococcus faecalis, were also undertaken. The effects of full sunlight and polyacrylic-screened sunlight were monitored in the study. Results indicate that L. pneumophila cells are slightly more sensitive to sunlight in seawater than in fresh water. Enumeration of sunlight-stressed bacteria in fresh water was found to be dependent on the medium used, and the following order of sensitivity to sunlight, from least to most sensitive, was noted: natural lake water bacteria, L. pneumophila, P. aeruginosa, E. coli, and S. faecalis.

Culture Media↗
PubMed1980

Microbiological water and effluent sample preservation.

A study, using four types of water samples ranging from relatively pure stream water to water containing industrial and domestic effluents, was carried out to investigate the effect of storage temperature on four bacterial parameters: total coliform, fecal coliform, fecal streptococcus, and heterotrophic bacteria. In the study, each water sample was cooled immediately after collection to approximately 1.5 degrees C by storage in crushed ice. At 2-, 24-, 30-, and 48-h intervals, the sample was mixed, and a subsample was removed and tested. Three separate analyses for each parameter were made on each subsample. The data available for statistical analyses contained, in some cases, the values obtained for the three subsamples and, in others, the means of the three values. The data were analysed as replicated data and as part of the entire set. The analysed data indicated (i) that with the exception of heterotrophic populations, more than 75% of the samples were microbiologically stable for at least 24 h, (ii) that at least 50% of samples tested for heterotrophic densities were stable for a minimum period of 24 h, (iii) that the original water temperature and bacterial load do not appear to be consistent factors in the preservation of samples for microbiological analysis, and (iv) that nutrient levels, also, do not seem to be consistent factors in the preservation of water samples for microbiological analyses.

Bacteria↗
PubMed1979

The occurrence of Candida Albicans in Lake Ontario bathing beaches.

There are inherent weaknesses associated with currently used bacterial fecal pollution indicator systems. Fecal pollution indicator data would be more meaningful if supplemented with information relating to the occurrence of pathogens in recreational water. Through surveys of four bathing beaches on Lake Ontario, it was established that the opportunistically pathogenic yeast Candida albicans occurs in near shore waters. The beaches surveyed could be differentiated on the basis of bacterial fecal pollution indicator levels and numbers of the pathogens C. albicans and Pseudomonas aeruginosa. The occurrence of C. albicans and P. aeruginosa appeared to be related to elevated fecal pollution indicator levels. Maximum numbers of all parameters were observed in July and August in association with peak bather loads at the beaches. In only one instance does the data suggest that a beach was subjected to human fecal contamination.

Bathing Beaches↗
PubMed1978

Health--indicator bacteria in water--surface microlayers.

The distribuution patterns of a variety of bacteria in the surface microlayer, 20 cm and 100 cm below the surface of rivers, open lake waters, and off docks are presented. Implications of this three-season study are that conventional sampling techniques underestimate the true microbiol densities.

Fungi↗
PubMed1977

Confirmation of the single-step membrane filtration procedure for estimating Pseudomonas aeruginosa densities in water.

The efficiency of two procedures, membrane filtration and most probable number, to resuscitate and enumerate Pseudomonas aeruginosa have been compared at two temperatures and varying incubation periods. Data indicate that the membrane filtration procedure using mPA or mPA medium B is more efficient than the most-probable-number procedure in estimating P. aeruginosa populations. It was also found that the specificity of the membrane filtration procedure was such that 92 to 99% of the colonies counted as P. aeruginosa were confirmed, whereas only 2.7 to 10% of the nontypical colonies were confirmed as P. aeruginosa. Furthermore, the data indicate that mPA medium B combined with a 3- to 4-day incubation period at 4.15 degrees C is slightly more specific than mPA medium and is a valid single-step procedure for the resuscitation and enumeration of P. aeruginosa from water or sewage effluent.

Culture Media↗