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Biomedical subjects

N C Dondero

Publications and source records attributed to N C Dondero.

12 recordsLinked to original sources
PubMed1977

Salmonella in surface waters of central New York state.

Six tributary streams and southern Cayuga Lake in central New York state were sampled for the presence of Salmonella on swabs immersed for 4 days. Of a total of 322 swabs, 39% yielded salmonellae. Swabs were cultured in tetrathionate enrichment at 41.5 degrees C. Isolations were made from brilliant green agar. Salmonellae were isolated from many sites on the streams and from some lake sites. Twenty-five serotypes (11 somatic antigen groups) and a distinct biotype of S. typhimurium (H2S negative) were found. Most frequent isolates, in order of decreasing occurrence, were S. typhimurium, S. thompson, S. oranienburg, and S. enteritidis. Several uncommon isolates also appeared. When tested for mouse infectivity, the isolates generally showed little or no virulence. The incidence of clinical salmonellosis among humans was low in the area and the variety of serotypes had not been noted among cattle. The presence of Salmonella in waters ranging in classification from potable to agricultural and industrial indicated the existence of a low level and undefined reservoirs of the bacteria in the region.

Escherichia coli↗
PubMed1970

Aerobic heterotrophic bacterial populations of sewage and activated sludge. IV. Adaptation of activated sludge to utilization of aromatic compounds.

An activated sludge from a sewage treatment plant and a laboratory activated sludge developed on an artificial waste were compared for their ability to utilize 11 aromatic compounds. There were several significant differences between them. The laboratory sludge contained higher numbers of organisms and metabolized the aromatics to a greater extent. Laboratory activated sludges acclimated to utilization of the aromatics differed from each other in population structure and the pattern of oxygen consumption with aromatic substrates. The oxidative patterns of uncontrolled mixed populations were unreliable for investigating metabolic pathways. Extracts of the various sludges elevated the plate counts of the sludges.

Adaptation, Physiological↗
PubMed1970

Aerobic heterotrophic bacterial populations of sewage and activated sludge. V. Analysis of population structure and activity.

Two procedures, the confidence interval method and Mountford's index, were tested in analyses of the microbial populations of 11 laboratory activated sludges acclimated to aromatic compounds. The two methods gave somewhat different results but indicated that the populations were quite dissimilar. The activity of seven of the sludges correlated well with the population structure. Some considerations in analysis of microbial population structure are discussed.

Adaptation, Physiological↗
PubMed1968

Calcium nutrition of Sphaerotilus growing in a continuous-flow apparatus.

Sphaerotilus natans required calcium for the production of sheaths and probably requires calcium for growth as well, though at a lower concentration. Neither strontium nor barium substituted for calcium. S. natans grew attached to the culture vessels of the continuous-flow apparatus even when no sheaths were produced. Tentative evidence showed that the requirement for calcium is shared by the manganese-oxidizing species S. discophorus.

Bacteriological Techniques↗
PubMed1967

Aerobic heterotrophic bacterial populations of sewage and activated sludge. I. Enumeration.

Agar plating media containing solely activated sludge extracts yielded, in general, higher viable counts of activated sludge bacteria than any other culture medium tested. Activated sludge extracts made from different treatment plants varied in efficacy in evoking maximal viable counts. Frequently, homologous plating, i.e., plating inocula of activated sludges on extracts made from the same activated sludges, tended to yield lower counts than the heterologous platings tried in this investigation. The counts obtained by homologous plating of activated sludge were not significantly lower and sometimes were even significantly higher than the counts obtained on standard Nutrient Agar, which had been found by previous workers to be a good medium for counting activated sludge bacteria. The higher counts obtained with activated sludge extracts set objectives for formulating reproducible or defined culture media for the enumeration of activated sludge bacteria.

Bacteria↗
PubMed1967

Aerobic heterotrophic bacterial populations of sewage and activated sludge. II. Method of characterization of activated sludge bacteria.

The replica-plating technique and Lochhead's nutritional method were combined in exploratory experiments to test their feasibility as useful means for characterizing the aerobic heterotrophic flora of activated sludge and to minimize the burdensome process of isolation, purification, and testing of isolates. In the test run, the method was about 86% reliable at the 0.05 level of significance. About 40% of the total number of bacteria able to grow on an aqueous extract of activated sludge did not grow on media containing glucose, amino acids, growth factors, and inorganic salts. The requirement for activated sludge extract suggested the existence of a requirement for unidentified nutrients contained in the activated sludge extract.

Agar↗
PubMed1967

Aerobic Heterotrophic Bacterial Populations of Sewage and Activated Sludge: III. Adaptation in a Synthetic Waste.

The nature and behavior of the microbial population developed on a synthetic waste containing salts and sorbitol are compared to that of a treatment-plant activated sludge. The population of the adapted sludge developed on the synthetic waste consisted approximately of only six kinds of bacteria. Experiments with radioactive sorbitol indicate that the microbial population developed on the synthetic waste showed the effects of repression by glucose on the metabolism of sorbitol; in contrast, the activated sludge from a plant treating primarily domestic waste was able to attack both substrates immediately and simultaneously.

Journal Article↗