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Biomedical subjects

R R Colwell

Publications and source records attributed to R R Colwell.

At least 235 records · Page 13Linked to original sources
PubMed1978

Enumeration of petroleum-degrading marine and estuarine microorganisms by the most probable number method.

Several media designed for use in a most probable number (MPN) determination of petroleum-degrading microorganisms were compared. The best results, i.e., largest numbers, were obtained using a buffered (32 mM PO4=) liquid medium containing 1% hydrocarbon substrate. Of 104 presumptive oil degraders tested, 20 grew on oil agar medium but did not utilize oil or a mixture of pure paraffinic hydrocarbons (C10 to C16 n-alkanes) in liquid (MPN) medium. Visible turbidity in the liquid medium was correlated with hydrocarbon utilization. Counts of petroleum degraders obtained using liquid medium (MPN) were in most cases higher than those obtained on an oil-amended silica gel medium. Both procedures yield an estimation of oil degraders, and the oil-amended agar permits growth of organisms which do not degrade crude oil. All strains of oil-degrading microorganisms examined in this study were lipolytic, but the converse was not always true.

Alkanes↗
PubMed1977

Vibrio cholerae, Vibrio parahaemolyticus, and other vibrios: occurrence and distribution in Chesapeake Bay.

Vibrio cholerae was isolated at several locations in Chesapeake Bay in fall 1976 and spring 1977. Strains induced fluid accumulation in rabbit ileal loops and positive activity in Y-1 adrenal cells. Vibrio cholerae, Vibrio parahaemolyticus, and related vibrios show a spatial and temporal distribution characteristic of Vibrio species in an estuary. The Vibrio cholerae strains isolated from Chesapeake Bay represent serotypes other than O-group I--that is, so-called nonagglutinable vibrios--and are not recognized as a serious epidemic threat, although they have caused cholera-like diarrhea sporadically.

Maryland↗
PubMed1977

Toxin isolation from a Kanagawa-phenomenon negative strain of Vibrio parahaemolyticus.

Production of a toxin by Vibrio parahaemolyticus Kanagawa-phenomenon negative strains was examined. Ammonium sulfate fractions of broth culture filtrates were dialyzed, concentrated by lyophilization, and tested for toxic effects by mouse intraperitoneal injection. One fraction, which we think is a toxin, was isolated from a broth culture filtrate of V. parahaemolyticus FC 1011 (a Kanagawa-phenomenon negative strain) and consitently produced lethal effects in mice at high concentrations and diarrhea in lower concentrations. The toxin was assayed for mouse LD50 and ability to produce diarrhea via forced feeding in mice. V. parahaemolyticus FC 1011 toxin was found to be protein, to be inactivated by heat or trypsin hydrolysis, and to produce positive skin permeability reactions in rabbits. However, it failed to induce fluid accumulation in ligated ileal loops in rabbits.

Animals↗
PubMed1977

Plasmids carried by antibiotic-resistant marine bacteria.

Antibiotic-resistant bacteria were isolated from seawater samples collected in the Atlantic Ocean off the southeastern coast of the United States. Large numbers of antibiotic-resistant bacterial strains were found to be present in harbor and inshore waters; however, the percentage of resistant strains was higher for several seawater samples collected offshore than for those collected near shore. Bacteria resistant to tetracycline, chloramphenicol, and streptomycin were found in nearly all samples collected, including samples from 200 miles (about 522 km) offshore and at depths to 8,200 m. Sediment samples, in general, were found to contain smaller populations of resistant strains as compared with the seawater samples examined. Antibiotic-resistant bacteria exhibiting phenetic characteristics common to autochthonous marine bacterial species were examined in detail, and several of the isolates exhibited unstable antibiotic resistance, which was transferable to recipient Escherichia coli cells. Deoxyribonucleic acid preparations from 10 strains examined by ethidium bromide-cesium chloride density sedimentation revealed that 6 of the strains contained covalently closed circular plasmid deoxyribonucleic acid.

Anti-Bacterial Agents↗
PubMed1977

Ambient-temperature primary nonselective enrichment for isolation of Salmonella spp. from an estuarine environment.

A primary, nonselective, ambient-temperature enrichment procedure for isolation of Salmonella spp. is described. The procedure was superior to elevated-temperature selective enrichment for Salmonella when estuarine water samples were examined. Five Chesapeake Bay stations were monitored, over an 8-month period, for the presence of salmonellae. Of 72 water and sediment samples collected, 17 (23.6%) yielded Salmonella spp. Seven serotypes were identified among the isolates. A seasonal pattern was noted for the incidence of the salmonellae. A most probable number procedure, performed by membrane filtration and nonselective enrichment, yielded Salmonella most probable number indices as high as 110 per 100 g of sediment. The results suggest that new methods, such as the one described in this report, are required for isolation of human intestinal pathogens from estuaries and coastal waters.

Bacteriological Techniques↗
PubMed1977

Numerical taxonomy and ecology of petroleum-degrading bacteria.

A total of 99 strains of petroleum-degrading bacteria isolated from Chesapeake Bay water and sediment were identified by using numerical taxonomy procedures. The isolates, together with 33 reference cultures, were examined for 48 biochemical, cultural, morphological, and physiological characters. The data were analyzed by computer, using both the simple matching and the Jaccard coefficients. Clustering was achieved by the unweighted average linkage method. From the sorted similarity matrix and dendrogram, 14 phenetic groups, comprising 85 of the petroleum-degrading bacteria, were defined at the 80 to 85% similarity level. These groups were identified as actinomycetes (mycelial forms, four clusters), coryneforms, Enterobacteriaceae, Klebsiella aerogenes, Micrococcus spp. (two clusters), Nocardia species (two clusters), Pseudomonas spp. (two clusters), and Sphaerotilus natans. It is concluded that the degradation of petroleum is accomplished by a diverse range of bacterial taxa, some of which were isolated only at given sampling stations and, more specifically, from sediment collected at a given station.

Bacteria↗
PubMed1977

Isolation of cryptic plasmid deoxyribonucleic acid from Kanagawa-positive strains of Vibrio parahaemolyticus.

Twelve strains of Vibrio parahaemolyticus was examined for plasmid deoxyribonucleic acid (DNA) by dye-buoyant gradient centrifugation. Four Kanagawa-positive strains, all isolated from the same outbreak of gastroenteritis, contained multiple plasmid species of cryptic function. However, three Kanagawa-negative strains and five Kanagawa-positive strains were not found to contain demonstrable plasmid DNA. R-plasmids were successfully transferred from Escherichia coli to V. parahaemolyticus.

Conjugation, Genetic↗
PubMed1977

Numerical taxonomy and ecology of oligotrophic bacteria isolated from the estuarine environment.

Slow-growing bacteria, isolated on nutrient-rich and nutrient-limited media, from Chesapeake Bay water and sediment samples, were examined for 119 biochemical, cultural, morphological, nutritional, and physiological characters. Those bacteria which grow on low nutrient media, termed oligotrophs, a total of 162 strains, were subjected to taxonomic analysis, as a preliminary step in determining their ecological significance. The data for all strains included in the study were examined by computer and the simple matching (S SM) and Jaccard (SJ) coefficients calculated. Clustering was achieved by the unweighted average-linkage method. From sorted similarity matrices and dendrograms, 148 strains, 90% of the total, were recovered in 24 phenetic groups defined at the 80 to 85% similarity level. Only 12 phena could be presumptively identified and these included representatives of Alcaligenes, Corynebacterium, Hyphomicrobium, Hyphomonas polymorpha, Listeria, Nocardia marina, Pedomicrobium, Planococcus citreus, Sphaerotilus, Streptothrix, and Streptomyces. Of the remaining organisms, 10% were unidentified sheathed bacteria. It is concluded that slow-growing bacteria are distributed throughout the estuarine environment and can account for a large proportion of the colonies observed on media after prolonged periods of incubation. The oligotrophic bacteria appear to predominate in areas where the concentration of available nutrients is low and are more characteristic of non-eutrophic aquatic systems.

Actinomycetales↗
PubMed1977

Numerical taxonomy of heavy metal-tolerant bacteria isolated from an estuary.

A total of 230 strains of metal-tolerant bacteria from water and sediment samples collected in Chesapeake Bay were isolated on a medium containing cobalt, lead, mercury, or molybdenum. In addition, a set of 71 cultures were simultaneously isolated on glucose tryptone yeast extract agar medium without metals. Twenty-three reference strains were also included in the numerical taxonomy study of these bacteria, bringing the grand total of strains examined to 324. All strains were examined for 112 biochemical, cultural, morphological, and physiological characters. The taxonomic data obtained were analyzed by computer and the simple matching (SSM) and Jaccard (SJ) coefficients were calculated. Clustering achieved by unweighted average linkage is presented and, from sorted similarity matrices and dendrograms, 294 strains, i.e., 97% of the total, were recovered in 12 phenetic groups defined at the 75 to 80% similarity level. Among the strains there were nine phena presumptively identified as Bacillus, Erwinia, Mycobacterium, Pseudomonas, and coryneforms. From the results of the taxonomic study, it is concluded that metal tolerance in estuarine water and sediment bacteria occurs among a restricted range of taxa distributed throughout the estuarine environment.

Actinomycetales↗
PubMed1976

Tolerance and other biological properties of Vibrio parahaemolyticus endotoxins.

Biological properties of endotoxins prepared from three strains of Vibrio parahaemolyticus were compared with reference to commercially prepared Salmonella typhi endotoxin. Endotoxin assays performed in rabbits included dermal Shwartzman reactivity, pyrogenicity, heat stability, and ability to induce tolerance as well as cross-tolerance. Mice were used for endotoxin LD50 determinations. Results showed V. parahaemolyticus endotoxins were similar to that of S. typhi strain O901. Induction of tolerance to V. parahaemolyticus strain 11590 endotoxin resulted in complete cross-tolerance to S. typhi endotoxin, and vice versa. Partial cross-tolerance to S. typhi endotoxin was demonstrated with rabbits rendered tolerant to endotoxin from V. parahaemolyticus strains Sak-3 and FC1011. Absorption spectra, nitrogen, phosphorus and carbohydrate analyses revealed additional similarities between endotoxins from V. parahaemolyticus and endotoxin from a member of the Enterbacteriaceae.

Animals↗
PubMed1976

Metabolic activities of the intestinal microflora of a deep-sea invertebrate.

The intestinal microflora of deep-sea amphipods, in enrichment culture employing starch, urea, and N-acetyl-d-glucosamine and when examined under simulated in situ conditions, exhibited growth rates and substrate conversion approximately equal to, or greater than, atmospheric controls during short-term incubation. These observations are significant since these microorganisms may play an important role in biodegradation in the deep sea.

Journal Article↗
PubMed1976

Measuring the potential activity of hydrocarbon-degrading bacteria.

[14C]hydrocarbons were utilized as a means of estimating the hydrocarbon-degrading potential of bacteria in estuarine and marine environments. Evaporation of the hydrocarbons must be considered in estimates of oxidation. Amount of mineralization of [14C]hexadecane can be equated with the total number of petroleum-degrading bacteria and the percentage of the total heterotrophic population, which they represent. Mineralization activity was found to be related to the activity of the bacterial populations during in situ incubation. Rates of mineralization were observed, as follows, for [14C]hexadecane greater than [14C]naphthalene greater than [14C]toluene greater than [14C]cyclohexane. Increased rates of uptake and mineralization were observed for bacteria in samples collected from an oil-polluted harbor compared with samples from a relatively unpolluted, shellfish-harvesting area, e.g., turnover times of 15 and 60 min for these areas, respectively, using [14C]hexadecane.

Bacteria↗
PubMed1976

Enumeration of petroleum-degrading microorganisms.

A variety of factors, including concentration of oil, antibiotics, dyes, and inoculum washes, were examined to determine their effect on the total counts of microorganisms on oil-containing media. The media found to be best for enumerating petroleum-degrading microorganisms contained 0.5% (vol/vol) oil and 0.003% phenol red, with Fungizone added for isolating bacteria and streptomycin and tetracycline added for isolating yeasts and fungi. Washing the inoculum did not improve recovery of petroleum degraders. Specifically, silica gel-oil medium and a yeast medium are recommended for enumeration of petroleum-degrading bacteria and yeasts and fungi, respectively. It is suggested that counts of petroleum degraders be expressed as percentage of the total population rather than total numbers of petroleum degraders per se. Incubation temperature and presence of oil was found to influence the numbers of petroleum-degrading microorganisms at a given sampling site.

Amphotericin B↗
PubMed1976

Heterotrophic utilization of glucose and glutamate in an estuary: effect of season and nutrient load.

Uptake of 14C-labeled glucose and glutamate was studied at several sites in Baltimore Harbor, Eastern Bay, and the Rhode River. Levels of uptake of 14C-labeled glutamate, measured over a period of 1 year during September, December, April, May, and June to estimate seasonal effects on heterotrophic utilization of selected nutrients, were highest in May and lowest in December. In a comparison of visibly polluted and unpolluted sites, the greatest amount of incorporation of glucose or glutamate and the highest Vmax values were observed at those sites where the microorganisms were exposed to varied and higher levels of pollutants, suggesting that Vmax may function as an indicator of relative pollution. Mineralization values ranged from 30 to 43%. A range of 0.44 to 2.32 mumol of C/liter per day was calculated for glutamate uptake.

Bacteria↗