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Biomedical subjects

R R Colwell

Publications and source records attributed to R R Colwell.

At least 217 records · Page 12Linked to original sources
PubMed1980

Isolation, enumeration, and characterization of Aeromonas from polluted waters encountered in diving operations.

Counts of total viable, aerobic, heterotrophic bacteria, indicator organisms, and Aeromonas spp. were made at a diver training site on the Anacostia River in Washington, D.C. The numbers of Aeromonas cells in Anacostia River sediment and water increased during periods of elevated water temperature, to maxima of 4 x 10(5) cells per g of sediment and 300 cells per ml of water. Correspondingly, Aeromonas counts dropped 2 to 4 logs as the water temperature decreased to 0 to 0.5 degrees C. Cultures taken by sterile swabs from the ears and face masks of divers after a 30-min swim in the Anacostia River yielded bacterial types and numbers similar to those found in the river. The nasal passages of the divers apparently did not become contaminated by swimming, possibly because of the protective effect of the face masks used by the divers. Properties associated with virulence in Aeromonas hydrophila and Aeromonas sobria strains isolated from the river, sediment, and divers were investigated. Nearly 40% of the strains of both species collected during the study produced cytotoxic activity for mouse Y-1 adrenal cells, as well as elastase. Enterotoxin activity, as detected by the Y-1 assay, was observed in 3% (1 of 35) of the strains of A. sobria and in 6% (19 of 330) of the A. hydrophila strains. Fluid accumulation in rabbit ileal loops induced by both species of Aeromonas varied greatly among the 17 strains examined. Fluid accumulation of at least 0.4 ml/cm was correlated with positive cytotoxin- or enterotoxin-like response in the Y-1 tissue culture assay.

Aeromonas↗
PubMed1980

Distribution and identification of luminous bacteria from the sargasso sea.

Vibrio fischeri and Lucibacterium harveyi constituted 75 of the 83 luminous bacteria isolated from Sargasso Sea surface waters. Photobacterium leiognathi and Photobacterium phosphoreum constituted the remainder of the isolates. Luminescent bacteria were recovered at concentrations of 1 to 63 cells per 100 ml from water samples collected at depths of 160 to 320 m. Two water samples collected at the thermocline yielded larger numbers of viable, aerobic heterotrophic and luminous bacteria. Luminescent bacteria were not recovered from surface microlayer samples. The species distribution of the luminous bacteria reflected previously recognized growth patterns; i.e., L. harveyi and V. fischeri were predominant in the upper, warm waters (only one isolate of P. phosphoreum was obtained from surface tropical waters).

Journal Article↗
PubMed1980

Biochemical characteristics and virulence of environmental group F bacteria isolated in the United States.

Bacteria phenotypically resembling Aeromonas hydrophila, but requiring NaCl for growth, have been isolated form the New York Bight. The bacteria proved to be identical to group F organisms isolated from cases of human diarrhea in Indonesia and Bangladesh. Anaerogenic strains initiated responses in Y-1 tissue culture and rabbit ileal loop, consistent with those associated with cytotoxin- and enterotoxin-producing Aeromonas spp. strains. Separation on the basis of production of gas from glucose by group F strains was correlated with differences in mean guanine-plus-cytosine deoxyribonucleic acid base composition and in deoxyribonucleic acid relative reassociation. Both aerogenic and anaerogenic strains reassociated to a significantly greater extent with Vibrio spp. than with Aeromonas spp. and indeed should be considered a new species of the genus Vibrio.

Base Composition↗
PubMed1980

Species composition and barotolerance of gut microflora of deep-sea benthic macrofauna collected at various depths in the atlantic ocean.

The bacterial flora of marine animals collected at depths of 570 to 2,446 m was examined for population size and generic composition, and the barotolerant characteristics of selected bacterial isolates were determined. Total numbers of culturable, aerobic, heterotrophic bacteria were found to be low in animals collected at the greatest ocean depths sampled in this study. Vibrio spp. were predominant in 10 of 15 samples examined, and Photobacterium spp. and yeasts were the major components of the remainder. Pseudomonas, Achromobacter, and Flavobacterium spp. comprised minor components of the gut flora of deep-sea fish. Forty-six pure cultures isolated from samples of seven animals were tested for growth or viability after incubation for 1 week under pressures ranging from 100 to 750 atm. Strains of bacteria isolated from samples of fish intestine were more barotolerant than those from the stomach (P<0.01). When incubated at a pressure of 600 atm, viability of bacterial cultures originally isolated from fish caught at a depth of 570 m was significantly decreased in comparison with viability of cultures from animals caught at depths of 1,393 and 2,446 m (P<0.01). From results of this study, it is concluded that the gut microflora of animals that dwell in the deeper regions of the ocean are adapted to an increased hydrostatic pressure environment, that is, the gut microflora is less inhibited by elevated hydrostatic pressure with increasing depth from which the host animal was collected.

Journal Article↗
PubMed1980

An estuarine agar medium for enumeration of aerobic heterotrophic bacteria associated with water, sediment, and shellfish.

A plate count agar was formulated for use in bacteriological analysis of estuarine samples and was tested together with standard plate count agar and an estuarine salts yeast extract agar for growth of aerobic, heterotrophic bacteria in water, sediment, and oysters. The estuarine agar was found to be efficient for enumerating aerobic, heterotrophic bacterial populations of water, sediment, and oysters, and is recommended for plate counts of estuarine samples.

Agar↗
PubMed1979

Microbial impact of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus) on aquatic ecosystems.

Quantitative and qualitative analyses of the intestinal bacterial flora of Canada geese and whistling swans were carried out with the finding that wild birds harbor significantly more fecal coliforms than fecal streptococci. The reverse was typical of captive and fasting birds. Neither Salmonella spp. nor Shigella spp. were isolated from 44 migratory waterfowl that were wintering in the Chesapeake Bay region. Enteropathogenic Escherichia coli were detected in seven birds. Geese eliminated 10(7) and swans 10(9) fecal coliforms per day. Results of in situ studies showed that large flocks of waterfowl can cause elevated fecal coliform densities in the water column. From the data obtained in this study, it is possible to predict the microbial impact of migratory waterfowl upon aquatic roosting sites.

Animals↗
PubMed1979

Ecology, serology, and enterotoxin production of Vibrio cholerae in Chesapeake Bay.

A total of 65 isolates of Vibrio cholerae, serotypes other than O--1, have been recovered from water, sediment, and shellfish samples from the Chesapeake Bay. Isolations were not random, but followed a distinct pattern in which salinity appeared to be a controlling factor in V. cholerae distribution. Water salinity at stations yielding V. cholerae (13 out of 21 stations) was 4 to 17 0/00, whereas the salinity of water at stations from which V. cholerae organisms were not isolated was less than 4 or greater than 17 0/00. From results of statistical analyses, no correlation between incidence of fecal coliforms and V. cholerae could be detected, whereas incidence of Salmonella species, measured concurrently, was clearly correlated with fecal coliforms, with Salmonella isolated only in areas of high fecal coliform levels. A seasonal cycle could not be determined since strains of V. cholerae were detectable at low levels (ca. 1 to 10 cells/liter) throughout the year. Although none of the Chesapeake Bay isolates was agglutinable in V. cholerae O group 1 antiserum, the majority for Y-1 adrenal cells. Furthermore, rabbit ileal loop and mouse lethality tests were also positive for the Chesapeake Bay isolates, with average fluid accumulation in positive ileal loops ranging from 0.21 to 2.11 ml/cm. Serotypes of the strains of V. cholerae recovered from Chesapeake Bay were those of wide geographic distribution. It is concluded from the data assembled to date, that V. cholerae is an autochthonous estuarine bacterial species resident in Chesapeake Bay.

Ecology↗
PubMed1979

Comparative study of the aerobic, heterotrophic bacterial flora of Chesapeake Bay and Tokyo Bay.

A comparative study of the bacterial flora of the water of Chesapeake Bay and Tokyo Bay was undertaken to assess similarities and differences between the autochthonous flora of the two geographical sites and to test the hypothesis that, given similarities in environmental parameters, similar bacterial populations will be found, despite extreme geographic distance between locations. A total of 195 aerobic, heterotrophic bacterial strains isolated from Chesapeake Bay and Tokyo Bay water were examined for 115 biochemical, cultural, morphological, nutritional, and physiological characters. The data were analyzed by the methods of numerical taxonomy. From sorted similarity matrices, 77% of the isolates could be grouped into 30 phena and presumptively identified as Acinetobacter-Moraxella, Caulobacter, coryneforms, Pseudomonas, and Vibrio spp. Vibrio and Acinetobacter species were found to be common in the estuarine waters of Chesapeake Bay, whereas Acinetobacter-Moraxella and Caulobacter predominated in Tokyo Bay waters, at the sites sampled in the study.

Aerobiosis↗
PubMed1979

Bacteria associated with the surface and gut of marine copepods.

Little is known about the nature of bacteria associated with the surface and gut of marine copepods, either in laboratory-reared animals or in the natural environment. Nor is it known whether such animals possess a gut flora. The present report deals with studies of microorganisms isolated from healthy, laboratory-reared copepods of the species Acartia tonsa Dana, from several species of wild copepods collected from a marine or estuarine environment, and from laboratory dishes containing moribund copepods. Evidence for a unique gut flora in laboratory-reared animals is presented; the predominant bacteria were represented by the genus Vibrio. Other organisms such as Pseudomonas and Cytophaga were found less abundantly associated with the copepods and not specifically associated with the gut.

Journal Article↗
PubMed1979

Aerobic and facultatively anaerobic bacteria associated with the gut of Canada geese (Branta canadensis) and whistling swans (Cygnus columbianus columbianus).

Aerobic and facultatively anaerobic bacteria from the intestinal tracts of swans and geese were isolated and characterized as part of a larger study of the microbiological effects of migratory waterfowl on water quality. A total of 356 isolates were identified by using rapid identification methods and classified by using numerical taxonomy. A diverse population of bacteria was recovered from the waterfowl, and representative strains could be classified into 21 phena. The majority of the aerobic, heterotrophic bacteria found in the gut of the waterfowl were species of Enterobacteriaceae. Streptococcus. Lactobacillus, and Bacillus. Unfortunately, the birds that were examined did not harbor significant numbers of any waterfowl-specific bacterial species. Thus, it may not be possible to assess microbiological impact of migratory waterfowl by using and "indicator" species since avian fecal pollution could not be distinguished from animal and human fecal pollution.

Aerobiosis↗
PubMed1979

Role of plasmids in mercury transformation by bacteria isolated from the aquatic environment.

Eight mercury-resistant bacterial strains isolated from the Chesapeake Bay and one strain isolated from the Cayman Trench were examined for ability to volatilize mercury. Mercury volatilization was found to be variable in the strains tested. In addition, plasmids were detected in all strains. After curing, two of the bacterial strains lost mercury resistance, indicating that volatilization is plasmid mediated in these strains. Only two cultures demonstrated ability to methylate mercuric chloride under either aerobic or anaerobic conditions. Methylation of mercury, compared with volatilization, appears to be mediated by a separate genetic system in these bacteria. It is concluded that mercury volatilization in the estuarine environment can be mediated by genes carried on plasmids.

Anti-Bacterial Agents↗
PubMed1979

Medium for the presumptive identification of Aeromonas hydrophila and Enterobacteriaceae.

A medium was devised for the rapid presumptive identification of Aeromonas hydrophila. It also offered good differentiation of Klebsiella, Proteus, and other enteric species. Mannitol fermentation, inositol fermentation, ornithine decarboxylation and deamination, indole production, motility, and H2S production from sodium thiosulfate and cysteine could be recorded in a single tube of the medium.

Aeromonas↗
PubMed1979

Aeromonas primary wound infection of a diver in polluted waters.

Two separate species of Aeromonas, A. sobria (not listed as a species in Bergey's Manual of Determinative Bacteriology, 8th ed.) and A. hydrophila, were primary pathogens isolated from the leg wound of a diver conducting operations in polluted waters. This is the first recorded instance of a primary infection of soft tissue in a human caused by two species of Aeromonas, one of which was resistant to tetracycline. Because of the very rapid development of this wound infection, cytotoxicity of these organisms was examined in several biological systems. A. sobria was hemolytic for sheep erythrocytes, cytotoxic for Y-1 adrenal cells, and enterotoxic in rabbit ligated intestinal loops, whereas A. hydrophila was hemolytic and cytotoxic. Pertinent clinical, bacteriological, and environmental features of the case are presented.

Adult↗
PubMed1979

Analysis of Vibrio parahaemolyticus soluble antigens by employing passive hemagglutination.

The passive hemagglutination assay was explored as a sensitive test of immunological reactivity of endotoxin and other antigens prepared from selected strains of Vibrio parahaemolyticus. The tannic acid procedure for passive hemagglutination, commonly used with protein antigens, was the only procedure yielding good results with V. parahaemolyticus protein extracts, endotoxins, and related preparations. These results were probably due to the presence of large amounts of protein in the V. parahaemolyticus endotoxins as determined by earlier work referenced in the text. Glucose and galactose as possible antigenic determinants in the endotoxin of a Vibrio strain were tested by inhibition tests. Cross-reactions were observed between endotoxin preparations, but were low in hemagglutination, suggesting reactions of common generic antigens. The ability of V. parahaemolyticus endotoxins to stimulate production of antibodies was determined.

Antibodies, Bacterial↗
PubMed1979

Ecology and taxonomy of bacteria attaching to wood surfaces in a tropical harbor.

Water, sediment, and wooden pilings, samples of which were collected from a harbor in Puerto Rico during the course of a long-term study of biofouling of wood treated with creosote and related compounds, were found to support growth of microbial populations, the dominant taxa of which included Hyphomicrobium, Hyphomonas, Pseudomonas, Vibrio, and Bacillus. New wood exposed to the harbor water was rapidly colonized by Hyphomicrobium vulgare. Old pilings in an advanced stage of biodeterioration maintained a diverse bacterial microflora, representatives of which were also found widely distributed in the water column and sediment. Evidence for bacterial species succession was obtained, indicating that microbial interactions are important for attachment to, and subsequent colonization of, wood surfaces in the marine environment.

Bacteria↗
PubMed1978

Effects of microbial activity on aquatic pollutants.

Bacteria and fungi present in estuarine and marine water and sediment accomplish significant degradation of crude oil, refined oils, polychlorinated biphenyls, and organomercurials, with the rate and extent of degradation varying with species, geographic source, temperature, and other biologic and environmental parameters. Our biodegradation studies have been extended to determine if physical weathering and/or microbial degradation of oil by microorganisms present in Chesapeake Bay water and sediment produces potentially carcinogenic substances. Water and sediment from an area in Chesapeake Bay that receives heavy input of oil and from a relatively nonpolluted site have been assayed for mutagenic ability by use of the Ames method, which is a bacterial assay and is highly sensitive. Preliminary findings indicate the presence of mutagenic substances in samples collected from the polluted site. Extracts of oil subjected to microbial degradation under controlled laboratory conditions did not yield detectable mutagenic activity. In situ studies are in progress.

Animals↗
PubMed1978

Evaluation of the accuracy and precision of enumerating aerobic heterotrophs in water samples by the spread plate method.

Factors associated with accuracy and precision in the enumeration of aquatic aerobic heterotrophs by the spread plate method were evaluated by using a nested analysis of variance experimental design. Variances associated with individual components of the spread plate procedure were isolated, and optimal replications of each step were allocated. A practical scheme for optimal allocation of resources is proposed, consisting of four subsamples and two plates per subsample and yielding a total variance decrease of 70% from a single-subsample, 10-plate series. Data transformation was, in general, unnecessary for intraexperiment or intrasample statistical analysis, whereas interexperiment or intersample comparisons may require transformation of data. Rapid changes in the numbers of organisms in stored water samples were observed that were not reproducible and did not follow detectable trends, with increases or decreases in counts occurring in samples regardless of whether they were stored at room temperature or refrigerated, or stored in plastic or glass containers. Rapid sample handling is strongly recommended to minimize variations in the microbial populations of samples for aquatic environments.

Journal Article↗