Showing papers on "Bacteria published in 1985"

UV inactivation of pathogenic and indicator microorganisms.

Abstract: Survival was measured as a function of the dose of germicidal UV light for the bacteria Escherichia coli, Salmonella typhi, Shigella sonnei, Streptococcus faecalis, Staphylococcus aureus, and Bacillus subtilis spores, the enteric viruses poliovirus type 1 and simian rotavirus SA11, the cysts of the protozoan Acanthamoeba castellanii, as well as for total coliforms and standard plate count microorganisms from secondary effluent. The doses of UV light necessary for a 99.9% inactivation of the cultured vegetative bacteria, total coliforms, and standard plate count microorganisms were comparable. However, the viruses, the bacterial spores, and the amoebic cysts required about 3 to 4 times, 9 times, and 15 times, respectively, the dose required for E. coli. These ratios covered a narrower relative dose range than that previously reported for chlorine disinfection of E. coli, viruses, spores, and cysts.

Characterization of Subsurface Bacteria Associated with Two Shallow Aquifers in Oklahoma

Abstract: The bacterial microflora of two shallow aquifers (saturated subsurface zones) in Oklahoma was characterized by direct observation with light and electron microscopy, by plating, and by examination of colony morphology and distribution. Isolated bacterial strains were also examined. Total cell counts varied only slightly (2.9 x 10 to 9.8 x 10 g [dry wt]) from sample to sample, whereas colony counts varied widely (6.3 x 10 to 6.5 x 10 CFU g [dry wt]). Colony counts on nutritionally rich media were lower than on low-nutrient media, especially in samples from the saturated zone. The variety of colony types growing on nutritionally rich media decreased with increasing depth and saturation. Colony counts of anaerobic bacteria also decreased with depth but were at least 100-fold lower than aerobic counts on most media. Cell morphologies of bacteria grown aerobically on plates included short rods, cocci, and actinomycete-like forms. Direct light microscopic observation of sediments revealed short, rod-shaped, and coccoid bacterial cells; endospores, actinomycete spores, and eucaryotic forms were not observed by light microscopy. Electron microscopic observation of bacteria released from the samples revealed that 85 to 90% of them were coccoid, gram-positive, Arthrobacter-like organisms, some of which were dividing or contained completed division septa; other types of gram-positive and gram-negative bacteria were present in lower numbers. Isolated bacterial strains were able to grow on both nutritionally rich and low-nutrient media. A higher proportion of gram-negative organisms was isolated than gram-positive organisms. Most of the isolates were capable of storing polyphosphate, poly-beta-hydroxybutyrate, or polysaccharide. The results of this study suggest that the microbial population of these two shallow aquifers is dominated by aerobic, nutritionally versatile bacteria that can subsist on low concentrations of organic compounds without forming specialized resting cells. Other types of microorganisms, such as facultatively anaerobic bacteria and microeucaryotes, may also be present, but they represent only a small fraction of the microflora.

Antibiotic activity of epiphytic bacteria isolated from intertidal seaweeds

Abstract: A survey of antibiotic-producing bacteria from the microbial flora attached to seaweeds and the study of their antibiotic capacities were carried out From 5 species of green and brown marine algae, 224 bacterial strains were isolated and tested for antibiotic production A total of 38 strains displayed antibiotic activity, withEnteromorpha intestinalis being the source of the highest number of producer strains All epiphytic bacteria with antibiotic activity were assigned to thePseudomonas-Alteromonas group Antagonism assays among the isolates demonstrated that each producer strain inhibits the growth of the other producers, as well as of some nonproducer strains also isolated from seaweeds Likewise, an autoinhibitory effect was observed in all antibiotic-producing strains Antibacterial spectra of all the strains include activity againstStaphylococcus, Alcaligenes, Pseudomonas, Vibrio, Pasteurella, andAchromobacter A preliminary characterization of the antibiotic substances produced by these epiphytic bacteria demonstrated that they are low molecular weight compounds, thermolabile, and anionic and are not affected by proteolytic enzymes The role that these inhibitory substances can play in the natural environment is discussed

Export and secretion of proteins by bacteria

Abstract: A wide variety of proteins are exported or secreted by a range of morphologically distinct bacteria. The processes of protein export are most extensively characterised in Escherichia coli, where recent advances have been made in the identification of genes involved in forming the export machinery. Both Gram-positive and Gram-negative bacteria secrete proteins into the medium. Gram-negative bacteria have adopted a variety of approaches in order to overcome the additional permeability of the outer membrane.

Properties of cellulolytic enzyme systems.

Abstract: Cellulolytic enzymes are synthesized by a large number of micro-organisms which include fungi, actinomycetes, gliding bacteria (myxobacteria) and true bacteria. However, only the fungi appear to excrete large amounts of cellulase enzymes in active form into culture media and not surprisingly these are the enzyme systems that have been most extensively studied. Bacterial cellulases are cell-wall bound, in the main. While many cellulases are known to solubilize the amorphous, easily hydrated areas of the cellulose, only a few appear to have the capacity for solubilizing native cellulose to an extent that denotes that the most highly ordered crystalline areas are being degraded. Notable in this regard are the cellulases of the fungi Trichoderma viride (Ogawa & Toyama, 1972), T. reesei (Mandels & Reese, 1964), T. koningii (Halliwell, 1965; Wood, 1968), Fusarium solani (Wood, 1969), Penicillium funiculosum (Wood & McCrae, 1978), Sporotrichum pulverulentum (Eriksson, 1975) and Talaromyces emersonii (Folan & Coughlan, 1979). Of the cellulolytic bacteria studied, only the anaerobe Clostridium thermocellum appears to liberate an extracellular enzyme system that effects the extensive degradation of crystalline cellulose (Johnson et al., 1982). Little is known about the properties of the cellulases of the bacteria as yet, but significant advances have been made recently in the understanding of the enzymes and their modes of operating in the fungi. It is well established, for example, that rapid dissolution of native cellulose requires the independent and cooperative action of a mixture of enzymes. The enzymes present in the mixture have been well characterized, but it is not known yet how they interact and what factors control the interactions on the face of the cellulose crystallite. These uncertainties have resulted in much speculation regarding the mechanism of cellulase action.

The internal pH of Clostridium acetobutylicum and its effect on the shift from acid to solvent formation

Abstract: Clostridium acetobutylicum was unable to keep a constant pH inside the cells when grown on a phosphatelimited synthetic medium which allowed production of organic acids in a first phase and of solvents in a second phase. At external pH values between 5.9 and 4.3, the cells kept a constant ΔpH of 0.9 to 1.3. A similar ΔpH was measured in continuous culture under solventproducing conditions. The ΔpH was abolished by protonovorous uncouplers, such as tetrachlorosalicylanilide (TCS) or carbonyl-p-trifluormethoxyphenylhydrazone (FCCP). n-Butanol at concentration of 150 mM and above led also to a complete abolition of the pH gradient.

Hydrogenase, Nitrogenase, and Hydrogen Metabolism in the Photosynthetic Bacteria

Abstract: Publisher Summary This chapter illustrates the H 2 metabolism in photosynthetic bacteria The developments in the context of the biochemistry and physiology of the photosynthetic bacteria, and their biotechnological applications are presented Photosynthetic bacteria possess a diverse and evolutionarily ancient metabolism, which is reflected in the different ways in which they can metabolize H 2 Three enzymes have been implicated in H 2 metabolism in these organisms: (1) nitrogenase, which catalyses unidirectional, ATP-dependent H 2 evolution, and can function either in the light, or in the dark under anaerobic or micro-aerobic conditions; (2) uptake hydrogenase, which is membrane-bound and, although capable of both H 2 evolution and uptake, functions physiologically in the direction of H 2 oxidation; and (3) “classical” or reversible hydrogenase, which may be either soluble or membrane bound and functions mainly during dark anaerobic fermentation The photosynthetic bacteria represent a tool of great potential in various fields of biotechnology Their rapid growth rate and their metabolic versatility enable them to survive and proliferate in a wide variety of environments

Bacterial adherence to human endothelial cells in vitro.

Abstract: Differences in the ability of bacteria to adhere to normal valvular endothelium may account for the predominance of particular species as pathogens in acute endocarditis. An in vitro adherence assay was developed to simulate the host surface encountered in acute bacterial endocarditis by using confluent monolayers of human endothelial cells. Adherence of 32 gram-positive and -negative blood culture isolates to this surface was compared. All five Staphylococcus aureus strains tested were highly adherent to endothelial cells, as was one gram-negative strain (Serratia marcescens). The remaining gram-positive and -negative isolates, including four viridans streptococci, were relatively nonadherent. Transmission electron microscopy demonstrated attachment of Staphylococcus aureus and invagination of the underlying endothelial cell membrane at 1 h followed by engulfment of large numbers of bacteria after 3 h. The intracellular bacteria appeared to be contained within vacuoles. Preferential attachment of some strains of bacteria, in particular Staphylococcus aureus, to human endothelial cells occurred in vitro, suggesting that adherence is an important determinant of bacterial pathogenicity in acute endocarditis. Active uptake of bacteria by endothelial cells may help account for the virulence of Staphylococcus aureus in endovascular infections and for the ability of this organism to establish multiple metastatic foci of infection.

Anaerobic oxidation of fatty acids by Clostridium bryantii sp. nov., a sporeforming, obligately syntrophic bacterium

Abstract: From marine and freshwater mud samples strictly anaerobic, Gram-positive, sporeforming bacteria were isolated which oxidized fatty acids in obligately syntrophic association with H2-utilizing bacteria. Even-numbered fatty acids with up to 10 carbon atoms were degraded to acetate and H2, odd-numbered fatty acids with up to 11 carbon atoms including 2-methylbutyrate were degraded to acetate, propionate and H2. Neither fumarate, sulfate, thiosulfate, sullur, nor nitrate were reduced. A marine isolate, strain CuCal, is described as type strain of a new species, Clostridium bryantii sp. nov.

Double immunofluorescence microscopic technique for accurate differentiation of extracellularly and intracellularly located bacteria in cell culture.

Abstract: A double immunofluorescence staining technique is described for differentiation between cell-attached (extracellular) and ingested (intracellular) bacteria by HEp-2 cells in cell culture monolayers. This method is based upon the observation that membranes of viable mammalian cells are impermeable for antibodies but are rendered permeable by treatment with fixatives. Consequently, extracellular bacteria can be stained by specific rhodamine-labeled antibodies before fixation, and intracellular bacteria can be visualized by treatment with specific fluorescein-labeled antibodies after fixation. The accuracy and simplicity of this method is demonstrated with HEp-2 cell culture monolayers as target cells and an isogenic pair of Yersinia enterocolitica, one of which is phagocytosis resistant and the other of which is phagocytosis sensitive. Furthermore, it is shown that this staining technique is also applicable for studying the interaction of bacteria with macrophages and fibroblasts.

Gram-positive bacteria: possible photosynthetic ancestry.

Abstract: A 16S ribosomal RNA gene has been sequenced from Heliobacterium chlorum, the recently discovered photosynthetic bacterium that contains a novel form of chlorophyll. Comparisons with other 16S ribosomal RNA sequences show that the organism belongs to the Gram-positive bacteria (one of ten eubacterial "phyla")--more precisely to the so-called low G + C (G, guanine; C, cytosine) subdivision thereof. This brings to five the number of such phyla that contain photosynthetic species, the other four being the purple bacteria and relatives, the green sulfur bacteria, the green nonsulfur bacteria, and the cyanobacteria. The finding suggests that Gram-positive bacteria may be of photosynthetic ancestry, and it strengthens the case for a common photosynthetic ancestry for all eubacteria.

In vivo evidence that bacteria in urinary tract infection grow under iron-restricted conditions.

Abstract: The outer membrane protein composition of bacteria isolated directly and without subculturing from the urine of two patients with urinary tract infections was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results indicated that the bacteria grew under iron-restricted conditions, as revealed by the expression of several high-molecular-weight outer membrane proteins which could also be observed when the same isolates were grown under iron-depleted conditions in laboratory media. The antigenicity of outer membrane components of the bacteria isolated was studied by immunoblotting with serum samples from the patients. The results indicated that the sera from the patients contained antibodies against major outer membrane components of the bacteria present in the urine, including the iron-regulated membrane proteins.

Characterization of aquatic bacteria and cloning of genes specifying partial degradation of 2,4-dichlorophenoxyacetic acid.

Abstract: Water samples from rivers, streams, ponds, and activated sewage were tested for the presence of bacteria which utilize 2,4-dichlorophenoxyacetic acid (2,4-D) as a sole source of carbon. Seventy percent of the attempted enrichments yielded pure cultures of 2,4-D-metabolizing bacteria. All but 1 of the 30 isolates were gram-negative rods, all but 2 were motile, and all were nonfermentative and oxidase and catalase positive. Nine isolates had DNA guanine-plus-cytosine values of 61.1 to 65 mol%. One isolate had a 67 mol% guanine-plus-cytosine value. The results suggest that these 2,4-D-metabolizing bacteria belong to the genus Alcaligenes. Fourteen of 23 isolates contained one or more detectable plasmids of about 20, 60, or 100 megadaltons. HindIII restriction fragment patterns showed these plasmids to be different from each other with one exception. Very similar restriction fragment patterns were revealed with a plasmid isolated from an Alcaligenes eutrophus strain obtained from Australia (pJMP397) and in an Alcaligenes sp. isolated in Oregon (pEML159). These two plasmids were about 56 megadaltons, had the same guanine-plus-cytosine value, were transmissable, and coded for 2,4-D metabolism and resistance to HgCl2. Hybridization of these two plasmids was demonstrated by using nick-translated 32P-labeled pJMP397. The vector pBR325 was used to clone HindIII fragments from pEML159. One cloned fragment of 14.8 megaldaltons expressed in Escherichia coli the ability to release 14CO2 from 2,4-D labeled in the acetate portion.

The corallopyronins, new inhibitors of bacterial RNA synthesis from Myxobacteria.

Abstract: From the culture broth of the myxobacterium, Corallococcus (Myxococcus) coralloides, three new antibiotics have been isolated: corallopyronin A, B and C. The compounds, which are chemically related to the recently discovered myxopyronins, act mainly on Gram-positive bacteria, with MIC values between 0.1 and 10 μg/ml, and only exceptionally or at much higher concentrations (MIC values; 100 and more μg/ml) on Gram-negatives. They do not inhibit eukaryotic organisms and show no toxicity for mice (sc). The corallopyronins appear to block specifically eubacterial RNA polymerase.

Murine monoclonal anti-DNA autoantibodies bind to endogenous bacteria.

Abstract: Several bacterial species (including Streptococcus faecalis, Bacillus cereus, Staphylococcus aureus, and Escherichia coli) were tested for their ability to react with monoclonal anti-DNA antibodies that were derived from MRL-lpr/lpr mice S faecalis reacted with 8/15 of such antibodies The binding was unaffected by DNase, but it was competitively inhibited by DNA F(ab')2 fragments of the monoclonal antibodies reacted with the bacteria, but Fc fragments did not Phospholipids extracted from the bacterial cells were able to bind to three representative anti-DNA antibodies that also bound to whole bacteria The results suggest that bacterial phospholipids might provide an immunogenic stimulus for the production of antibodies that cross-react with DNA We propose that some anti-DNA auto-antibodies and anti-bacterial antibodies evolve from a restricted group of antibodies with high avidity for the phosphodiester groups that occur in DNA and bacterial cells walls

Study of minimal inhibitory concentration of antibiotics on bacteria cultivated in vitro in space (Cytos 2 experiment).

Abstract: The aim of the Cytos 2 experiment, carried out during the French-Soviet manned flight in July 1982, was to study the bacteria's sensitivity to antibiotics cultivated in vitro during the orbital flight, using the bacterial method of minimal inhibitory concentration (MIC). Two species of bacteria were tested with various antibiotics: Staphylococcus aureus with Oxacillin, Chloramphenicol and Erythromycin; Escherichia coli with Colistin and Kanamycin. The results show an increase in resistance to antibiotics particularly strong in E. coli and weaker in Staphylococcus aureus. Considering these results, we think that there might be a relationship between the increase in resistance to antibiotics and a stimulating effect on growth rate by the factors of environmental space.

The significance of macroscopic aggregates marine snow as sites for heterotrophic bacterial production in the mesopelagic zone of the subtropical atlantic

Abstract: Macroscopic detrital aggregates (known as marine snow) harbor greatly enriched populations of bacteria and protozoans, suggesting that they may be an important site of heterotrophic activity in the deep sea. We collected flocculent marine snow larger than 3 mm in diameter in the mesopelagic zone of the subtropical Atlantic from the submersible, Johnson-Sea-Link. Although the bacteria inhabiting these aggregates incorporated as much or more [ 3 H]-thymidine per bacterium than free-living forms, were up to 2 orders of magnitude more abundant on marine snow than in the surrounding seawater, and were twice as large as unattached bacteria, the marine snow itself was rare, ranging from 0.5 to 4 aggregates m −3 . Thus the contribution of bacteria inhabiting flocculent marine snow to total bacterial production in the mesopelagic zone was insignificant, ranging from 0.01 to 0.39% over depths of 130 to 650 m.

Phenylobacterium immobile gen. nov., sp. nov., a Gram-Negative Bacterium That Degrades the Herbicide Chloridazon

Abstract: Bacteria which utilize the xenobiotic compounds chloridazon, antipyrin, and pyramidon as sole carbon sources were isolated from various soil samples. The 22 strains isolated are similar with respect to morphological, physiological, biochemical, serological, and genetic properties. These bacteria are aerobic gram-negative rods or coccal rods (0.7 to 1.0 by 1.0 to 2.0 μm) that occur singly, in pairs, or in short chains and are nonmotile and nonsporeforming. Physiological and biochemical characteristics and susceptibility to antibiotics were determined. The strains need vitamin B12 as a growth factor; they are catalase positive and weakly oxidase positive and show slight H2S production. All of the other tests which we performed were negative. The nutritional spectrum is extraordinarily limited, with optimal growth on chloridazon, antipyrin, pyramidon, and l-phenylalanine. Most sugars, alcohols, amino and carboxylic acids, and ordinary complex media are not utilized. The bacteria are osmotically sensitive. They are a serologically uniform group of organisms, which are harmless to rats and rabbits. Their guanine-plus-cytosine contents range between 65 and 68.5 mol%. The chloridazon-degrading bacteria are characterized as a new genus, Phenylobacterium, with a single species, Phenylobacterium immobile. The type strain Phenylobacterium immobile strain E (= DSM 1986), is not closely related to any other gram-negative bacterium, as shown by a 16S ribosomal ribonucleic acid partial sequence analysis. This organism is a member of group I of the purple nonsulfur bacteria, but is phylogenetically isolated in this group. Phenylobacterium immobile is remotely related to Pseudomonas diminuta, Rhizobium leguminosarum, rhodopseudomonads, and Aquaspirillum itersonii. Like other members of this group, Phenylobacterium immobile contains 2,3-diamino-2,3-dideoxy-d-glucose in its lipopolysaccharide. The murein equals a normal murein from a gram-negative bacterium. All citric acid cycle enzymes are detectable in Phenylobacterium immobile.

A comparison of virulence of two strains of Legionella pneumophila based on experimental aerosol infection of guinea-pigs.

Abstract: Two strains of Legionella pneumophila (LP) serogroup I, of differing virulence, were examined in terms of numbers of viable organisms in tissues, pyrexia and mortality following aerosol infection. The Corby strain was the more virulent, with pyrexia and deaths of guinea-pigs 3 to 6 days after infection. This strain multiplied very rapidly in the lungs to reach a peak of 5 X 10(11) viable organisms/lung. Organisms were present in the blood, liver, spleen and kidney. The Philadelphia-1 strain (NCTC 11192) was unable to replicate in the lung and was cleared between 14 and 21 days after infection. Pyrexia was not observed. No guinea-pigs died and viable LP was not found in any organ other than the lung. Lung lavages on aerosol infected animals were performed and the virulent Corby strain was found to be mainly intracellular. The avirulent Philadelphia-1 strain was found predominantly in the extracellular location. There were approximately 10 times the number of viable virulent LP in the lung macrophage fraction than in the lung PMNL fraction. In comparison, there were approximately equal numbers of the viable avirulent strain in the macrophages and the PMNL. Experimental evidence suggests that the macrophage preferentially supports the growth of the virulent Corby strain compared with the PMNL. The avirulent strain on the other hand appears to be destroyed by both the macrophages and the PMNL.

6 Analysis of Lipopolysaccharides of Gram-Negative Bacteria

Abstract: Publisher Summary This chapter discusses the analysis of lipopolysaccharides (LPS) of gram-negative bacteria. LPS are characteristic components of the cell wall of all Gram-negative bacteria and of at least some cyanobacteria. They are localized in the outer layer of the outer membrane, and are, in noncapsulated strains, exposed on the cell surface. They contribute to the integrity of the outer membrane and, as has been shown for enteric bacteria, protect the cell against the action of bile salts and (lipophilic) antibiotics. Isolated lipopolysaccharide, upon injection into higher organisms, exhibits a variety of biological (“endotoxic”) activities, such as the induction of fever, changes in the white blood cell count, diarrhoea, or even shock and death. Since the toxic activities are because of substances released from disintegrating bacteria, and not to an excreted exotoxin, lipopolysaccharide has been termed an endotoxin. Thus, the terms lipopolysaccharide, O-antigen, and endotoxin are used synonymously and describe either the chemical structure or discrete biological functions of the same substance.

Filamentous sulfur bacteria of activated sludge: characterization of Thiothrix, Beggiatoa, and Eikelboom type 021N strains.

Abstract: Seventeen strains of filamentous sulfur bacteria were isolated in axenic culture from activated sludge mixed liquor samples and sulfide-gradient enrichment cultures. Isolation procedures involved plating a concentrated inoculum of washed filaments onto media containing sulfide or thiosulfate. The isolates were identified as Thiothrix spp., Beggiatoa spp., and an organism of uncertain taxonomic status, designated type 021N. All bacteria were gram negative, reduced nitrate, and formed long, multicellular trichomes with internal reserves of sulfur, volutin, and sudanophilic material. Thiothrix spp. formed rosettes and gonidia, and four of six strains were ensheathed. Type 021N organisms utilized glucose, lacked a sheath, and differed from Thiothrix spp. in several aspects of cellular and cultural morphology. Beggiatoa spp. lacked catalase and oxidase, and filaments were motile. Biochemical and physiological characterization of the isolates revealed important distinguishing features between the three groups of bacteria. Strain differences were most evident among the Thiothrix cultures. A comparison of the filamentous sulfur bacteria with freshwater strains of Leucothrix was made also. Images

Preparation of a DNA gene probe for detection of mercury resistance genes in gram-negative bacterial communities

Abstract: A DNA gene probe was prepared to study genetic change mechanisms responsible for adaptation to mercury in natural bacterial communities The probe was constructed from a 26-kilobase NcoI-EcoRI DNA restriction fragment which spans the majority of the mercury resistance operon (mer) in the R-factor R100 The range of specificity of this gene probe was defined by hybridization to the DNA of a wide variety of mercury-resistant bacteria previously shown to possess the mercuric reductase enzyme All of the tested gram-negative bacteria had DNA sequences homologous to the mer probe, whereas no such homologies were detected in DNA of the gram-positive strains Thus, the mer probe can be utilized to study gene flow processes in gram-negative bacterial communities

Methanogenic bacteria, including an Acid-tolerant strain, from peatlands.

Abstract: Five pure cultures of methanogenic bacteria were isolated from Minnesota peatlands by enrichment culture techniques. One strain, identified as a member of the family Methanobacteriaceae by antigenic fingerprinting, was acid tolerant and able to produce methane at pH 3.1. Growth could not be demonstrated at pH less than 5.3.