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B J Dutka

Publications and source records attributed to B J Dutka.

31 records · Page 2Linked to original sources
PubMed1981

Bacterial density in water determined by poisson or negative binomial distributions.

The question of how to characterize the bacterial density in a body of water when data are available as counts from a number of small-volume samples was examined for cases where either the Poisson or negative binomial probability distributions could be used to describe the bacteriological data. The suitability of the Poisson distribution when replicate analyses were performed under carefully controlled conditions and of the negative binomial distribution for samples collected from different locations and over time were illustrated by two examples. In cases where the negative binomial distribution was appropriate, a procedure was given for characterizing the variability by dividing the bacterial counts into homogeneous groups. The usefulness of this procedure was illustrated for the second example based on survey data for Lake Erie. A further illustration of the difference between results based on the Poisson and negative binomial distributions was given by calculating the probability of obtaining all samples sterile, assuming various bacterial densities and sample sizes.

Journal Article↗
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↗
PubMed1977

Comparison of the surface structure, metal binding, and fecal coliform recoveries of nine membrane filters.

A comparative study was made of nine commonly used membrane filters from five manufacturers, all recommended for enumeration of coliform bacteria. Bacterial recoveries and flow rates were examined from three types of water and were found to correlate with the surface pore structure determined by scanning electron microscopy. The sorption of metals was also determined. The results of these studies indicate that the five best membranes for fecal coliform recovery could be placed in two groups: Millipore HC and Gelman, followed by Johns-Manville SG and AG and Sartorius 13806.

Copper↗
PubMed1975

Relationship between various bacterial populations and coprostanol and cholesterol.

A year-long study was conducted at three different locations in Canada to evaluate the relationship between fecal sterols and bacterial populations. A statistical model was constructed to study the following: (i) seasonal variations in the sterols and bacterial parameters; (ii) the differences between morning and afternoon samples; (iii) the relationship between the two sterols (coprostanol and cholesterol) as well as their relationship to the bacterial parameters; and (iv) the geographical differences between the three sampling sites. Application of the model to the data indicated that (i) the relationship in receiving waters between coprostanol and cholesterol was found to be highly significant; (ii) at two sampling sites the relationship between fecal sterols and fecal coliforms was positively significant at the 5% level; (iii) at one sampling site there was a positive relationship between fecal sterols and the fecal coliform - fecal streptococcus ratio; and (iv) in a.m. vs. p.m. samples significant differences were noted in coliform, fecal coliform, and fecal streptococcus densities while no significant differences were found in heterotroph densities and coprostanol and cholesterol levels. Raw and treated sewage from four sewage-treatment plants were also studied to provide baseline control data. Data support the conclusion that while no consistent relationship exists between bacterial parameters and fecal sterols, fecal sterols could be considered as unequivocal indicators of the presence of fecal material in water.

Canada↗
PubMed1974

Comparison of autoclave and ethylene oxide-sterilized membrane filters used in water quality studies.

Autoclave and ethylene oxide-sterilized membrane filters manufactured by Gelman, Millipore, and Sartorius were field tested for their recovery of total coliforms, fecal coliforms, fecal streptococci, and heterotrophs. The data were analyzed by using split-plot analysis of variance and significance tests. Membranes were also tested for pH and toxicity using Escherichia coli. The mean data summaries indicated that Gelman membrane filters generally produced the highest counts during the field studies. Statistical analyses of the March data showed that there were significant differences between membrane filters at 1% level; however, statistical analyses of June data revealed no significant differences except in total coliform recoveries. Toxicity tests at 35 C indicated that Gelman and Millipore autoclaved membrane filters were able to recover 92% of the test organisms. Toxicity tests performed at 44.5 C revealed that no membranes were able to recover more than 40% of the test organisms. Since differences were found in the ability of the three brands of membrane filters to recover bacteria from natural and controlled sources, membrane filters from different manufacturers cannot be readily interchanged. There is a need for a standardized procedure for testing bacterial recovery by membrane filters.

Analysis of Variance↗