Improved medium for recovery and enumeration of Pseudomonas aeruginosa from water using membrane filters.
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A modified mPA medium, designated mPA-C, was shown to recover Pseudomonas aeruginosa from a variety of water sources with results comparable to those with mPA-B and within the confidence limits of a most-probable-number technique. Enumeration of P. aeruginosa on mPA-C was possible after only 24 h of incubation at 41.5 degrees C, compared with 72 h of incubation required for mPA-B and 96 h of incubation for a presumptive most probable number. (+info)
Effects of dispersed recreational activities on the microbiological quality of forest surface water.
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The microbiological quality of forest surface waters in the Greenwater River watershed was examined to investigate the influence of heavy motorized camping in an area with no sanitary facilities. Indicator densities increased during weekend human-use periods when compared to weekdays. Increases in indicator densities were also noted downstream from heavily used camping areas when compared to upstream sites. Seasonal, weekly, and diurnal fluctuations in indicator densities were observed. This study suggests that potential health hazards exist in this watershed during periods of human use. (+info)
Fecal coliform elevated-temperature test: a physiological basis.
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The physiological basis of the Eijkman elevated-temperature test for differentiating fecal from nonfecal coliforms was investigated. Manometric studies indicated that the inhibitory effect upon growth and metabolism in a nonfecal coliform at 44.5 degrees C involved cellular components common to both aerobic and fermentative metabolism of lactose. Radioactive substrate incorporation experiments implicated cell membrane function as a principal focus for temperature sensitivity at 44.5 degrees C. A temperature increase from 35 to 44.5 degrees C drastically reduced the rates of [14C]glucose uptake in nonfecal coliforms, whereas those of fecal coliforms were essentially unchanged. In addition, relatively low levels of nonfecal coliform beta-galactosidase activity coupled with thermal inactivation of this enzyme at a comparatively low temperature may also inhibit growth and metabolism of nonfecal coliforms at the elevated temperature. (+info)
How a fungus escapes the water to grow into the air.
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Fungi are well known to the casual observer for producing water-repelling aerial moulds and elaborate fruiting bodies such as mushrooms and polypores. Filamentous fungi colonize moist substrates (such as wood) and have to breach the water-air interface to grow into the air. Animals and plants breach this interface by mechanical force. Here, we show that a filamentous fungus such as Schizophyllum commune first has to reduce the water surface tension before its hyphae can escape the aqueous phase to form aerial structures such as aerial hyphae or fruiting bodies. The large drop in surface tension (from 72 to 24 mJ m-2) results from self-assembly of a secreted hydrophobin (SC3) into a stable amphipathic protein film at the water-air interface. Other, but not all, surface-active molecules (that is, other class I hydrophobins and streptofactin from Streptomyces tendae) can substitute for SC3 in the medium. This demonstrates that hydrophobins not only have a function at the hyphal surface but also at the medium-air interface, which explains why fungi secrete large amounts of hydrophobin into their aqueous surroundings. (+info)
Legionnaires' disease on a cruise ship linked to the water supply system: clinical and public health implications.
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The occurrence of legionnaires' disease has been described previously in passengers of cruise ships, but determination of the source has been rare. A 67-year-old, male cigarette smoker with heart disease contracted legionnaires' disease during a cruise in September 1995 and died 9 days after disembarking. Legionella pneumophila serogroup 1 was isolated from the patient's sputum and the ship's water supply. Samples from the air-conditioning system were negative. L. pneumophila serogroup 1 isolates from the water supply matched the patient's isolate, by both monoclonal antibody subtyping and genomic fingerprinting. None of 116 crew members had significant antibody titers to L. pneumophila serogroup 1. One clinically suspected case of legionnaires' disease and one confirmed case were subsequently diagnosed among passengers cruising on the same ship in November 1995 and October 1996, respectively. This is the first documented evidence of the involvement of a water supply system in the transmission of legionella infection on ships. These cases were identified because of the presence of a unique international system of surveillance and collaboration between public health authorities. (+info)
Haloanaerobacter salinarius sp. nov., a novel halophilic fermentative bacterium that reduces glycine-betaine to trimethylamine with hydrogen or serine as electron donors; emendation of the genus Haloanaerobacter.
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A novel halophilic fermentative bacterium has been isolated from the black sediment below a gypsum crust and a microbial mat in hypersaline ponds of Mediterranean salterns. Morphologically, physiologically and genetically this organism belongs to the genus Haloanaerobacter. Haloanaerobacter strain SG 3903T (T = type strain) is composed of non-sporulating long flexible rods with peritrichous flagella, able to grow in the salinity range of 5-30% NaCl, with an optimum at 14-15%. The strain grows by fermenting carbohydrates or by using the Stickland reaction with either serine or H2 as electron donors and glycine-betaine as acceptor, which is reduced to trimethylamine. The two species described so far in the genus Haloanaerobacter are not capable of Stickland reaction with glycine-betaine + serine; however, Haloanaerobacter chitinovorans can use glycine-betaine with H2 as electron donor. Strain SG 3903T thus represents the first described strain in the genus Haloanaerobacter capable of the Stickland reaction with two amino acids. Although strain SG 3903T showed 67% DNA-DNA relatedness to H. chitinovorans, it is physiologically sufficiently different from the two described species to be considered as a new species which has been named Haloanaerobacter salinarius sp. nov. (+info)
Roseovarius tolerans gen. nov., sp. nov., a budding bacterium with variable bacteriochlorophyll a production from hypersaline Ekho Lake.
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Eight Gram-negative, aerobic, pointed and budding bacteria were isolated from various depths of the hypersaline, heliothermal and meromictic Ekho Lake (Vestfold Hills, East Antarctica). The cells contained storage granules and daughter cells could be motile. Bacteriochlorophyll a was sometimes produced, but production was repressed by constant dim light. The strains tolerated a wide range of temperature, pH, concentrations of artificial seawater and NaCl, but had an absolute requirement for sodium ions. Glutamate was metabolized with and without an additional source of combined nitrogen. The dominant fatty acid was C18:1; other characteristic fatty acids were C18:2, C12:0 2-OH, C12:1 3-OH, C16:1, C16:0 and C18:0. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. The DNA G+C base composition was 62-64 mol%. 16S rRNA gene sequence comparisons showed that the isolates were phylogenetically close to the genera Antarctobacter, 'Marinosulfonomonas', Octadecabacter, Sagittula, Sulfitobacter and Roseobacter. Morphological, physiological and genotypic differences to these previously described and distinct genera support the description of a new genus and a new species, Roseovarius tolerans gen. nov., sp. nov. The type strain is EL-172T (= DSM 11457T). (+info)
Phylogeny of marine and freshwater Shewanella: reclassification of Shewanella putrefaciens NCIMB 400 as Shewanella frigidimarina.
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Dissimilatory Fe(III) reduction by Shewanella putrefaciens and related species has generated considerable interest in biochemical characterization of the pathways for anaerobic electron transfer in this organism. Two strains, MR-1 and NCIMB 400, have been extensively used, and several respiratory enzymes have been isolated from each. It has become apparent that significant sequence differences exist between homologous proteins from these strains. The 16S rRNA from NCIMB 400 was sequenced and compared to the sequences from MR-1 and other Shewanella strains. The results indicate that NCIMB 400 is significantly more closely related to the newly identified Shewanella frigidimarina than to the S. putrefaciens type strain. It is therefore proposed that NCIMB 400 should be reclassified as S. frigidimarina. (+info)