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At least 73 records · Page 4Linked to original sources
PubMed1986

The presence of bacteria in the oral epithelium in periodontal disease. II. Immunohistochemical identification of bacteria.

Serial histological sections of gingiva obtained from each of six advanced adult periodontitis, two localized juvenile periodontitis and two periodontally healthy patients were used for specific identification of bacteria within the oral epithelium and adjacent connective tissue. Healthy gingival biopsies served as controls. Sections from patients and control biopsies were Gram-stained and also screened with antibacterial sera associated with the peroxidase immunocytochemical technique for specific bacterial identification. The "Pop-off" electron microscopic technique was also used to further demonstrate the bacterial nature of peroxidase-stained material. In addition, the possible correlation between bacteria and areas of possible reduced keratinization was investigated. The results showed that sections of orthokeratinized healthy gingiva did not contain bacteria. Gram-stained sections from diseased sites contained large numbers of bacteria in the oral epithelium and adjacent connective tissue. Bacteroides gingivalis and to a lesser extent Capnocytophaga gingivalis were found in periodontitis, and Actinobacillus actinomycetemcomitans was found in juvenile periodontitis when the immunoperoxidase technique was used. The bacterial nature of peroxidase-stained material was confirmed by the "pop-off" technique. In the disease biopsies, bacterial presence was correlated with areas of reduced amounts of keratin suggesting that the oral epithelium may be a portal of entry for bacteria into gingival tissues.

Actinobacillus↗
PubMed2001

Multidrug-resistant bacteria: overcoming antibiotic permeability barriers of gram-negative bacteria.

Because of the permeability barrier provided by the outer membrane (OM), gram-negative bacteria are inherently resistant to many hydrophobic antibiotics. This resistance limits the arsenal of antibiotics that are effective in treating gram-negative bacterial infections. Compounding this problem, strains of gram-negative bacteria have emerged that display specific resistance mechanisms for effective antibiotics. As a means of expanding the arsenal of effective antibiotics for gram-negative bacteria, compounds that permeabilize the OM to hydrophobic substances have been developed. These compounds are typically cationic, amphiphilic molecules that can be prepared from peptides or steroids. Effective OM permeabilizers sensitize gram-negative bacteria to hydrophobic antibiotics, including erythromycin, fusidic acid, novobiocin and rifampin. These antibiotics are generally not useful in treating gram-negative bacterial infections because they traverse the OM ineffectively. The use of OM permeabilizers, in combination with hydrophobic antibiotics, may provide additional means of controlling growth of gram-negative bacteria. This review describes classes of permeabilizers, including those derived from peptides, and recently reported examples based on steroids.

Animals↗
PubMed1994

PCR primers and probes for the 16S rRNA gene of most species of pathogenic bacteria, including bacteria found in cerebrospinal fluid.

A set of broad-range PCR primers for the 16S rRNA gene in bacteria were tested, along with three series of oligonucleotide probes to detect the PCR product. The first series of probes is broad in range and consists of a universal bacterial probe, a gram-positive probe, a Bacteroides-Flavobacterium probe, and two probes for other gram-negative species. The second series was designed to detect PCR products from seven major bacterial species or groups frequently causing meningitis: Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, S. agalactiae, Escherichia coli and other enteric bacteria, Listeria monocytogenes, and Staphylococcus aureus. The third series was designed for the detection of DNA from species or genera commonly considered potential contaminants of clinical samples, including cerebrospinal fluid (CSF): Bacillus, Corynebacterium, Propionibacterium, and coagulase-negative Staphylococcus spp. The primers amplified DNA from all 124 different species of bacteria tested. Southern hybridization testing of the broad-range probes with washes containing 3 M tetramethylammonium chloride indicated that this set of probes correctly identified all but two of the 102 bacterial species tested, the exceptions being Deinococcus radiopugnans and Gardnerella vaginalis. The gram-negative and gram-positive probes hybridized to isolates of two newly characterized bacteria, Alloiococcus otitis and Rochalimaea henselii, as predicted by Gram stain characteristics. The CSF pathogen and contaminant probe sequences were compared with available sequence information and with sequencing data for 32 different species. Testing of the CSF pathogen and contaminant probes against DNA from over 60 different strains indicated that, with the exception of the coagulase-negative Staphylococcus probes, these probes provided the correct identification of bacterial species known to be found in CSF.

Bacteremia↗
PubMed2002

Contribution of cytophaga-like bacteria to the potential of turnover of carbon, nitrogen, and phosphorus by bacteria in the rhizosphere of barley (Hordeum vulgare L.).

The functional potential of bacteria isolated from the rhizosphere of barley (Hordeum vulgare L.) in May, July, and August and cultivated on nutrient-rich substrate (1/10 TSBA) and nutrient-poor substrate (cold soil extract agar) was determined. There was no significant difference in numbers of CFU when counted on nutrient rich or poor substrate. Bacterial numbers increased approximately 3-fold in the rhizosphere soil from May to August but was unchanged in bulk soil over the same period. A total of 4474 randomly isolated bacteria were screened for enzymatic activities involved in carbon turnover (amylase, cellulase, mannanase, xylanase, and chitinase), nitrogen turnover (protease, nitrate and nitrite reductase), and phosphate turnover (phosphatase). In the rhizosphere soil, bacteria carrying C and P turnover enzymes were not stimulated by the growing plant whereas protease and nitrate and nitrite reductase were stimulated by the growing plant. No changes were observed in the bulk soil. Two taxonomic groups were followed: Cytophaga-like bacteria (CLB) and fluorescent pseudomonads, the latter being abundant in the rhizosphere and important contributors to the cycling of organic matter in soil. Unexpectedly in the spring samples, CLB were around 25% of all bacteria isolated, whereas fluorescent pseudomonads made up less than 10%. The relative proportion of these bacterial groups then decreased during the plant growth season but at all times showing a clear rhizosphere effect. Furthermore, up to 70% of the isolates carrying enzymes involved in the turnover of carbon, in the May sample, were identified as CLB, indicating the importance of this group in early colonization of the rhizosphere. The fluorescent pseudomonad group contributed less than 3%.

Carbon↗
PubMed1979

A simple method for the separation of tissue-cultured plant cells from unbound bacteria: a demonstration of acquired affinity for bacteria by cells of soy bean.

Tissue-cultured cells of soy bean, grown in liquid medium and then transferred to an agar substratum in so-called tissue chambers, showed an affinity for the binding of applied bacteria (Klebsiella pneumoniae). This binding, which became greater as the plant cells remained on the agar for up to 10 days, was manifested as an increasing resistance of the bacteria to be washed from the plant cells in a standard, gentle and reproducible procedure devised for this purpose. The number of bacteria firmly bound to the cells was determined by the use of 32P-labelled bacteria and was largely independent of the concentration of bacteria in the suspension applied to the tissue-cultured cells.

Adsorption↗
PubMed2002

Impact of biocontrol strain Pseudomonas fluorescens CHA0 on rhizosphere bacteria isolated from barley (Hordeum vulgare L.) with special reference to Cytophaga-like bacteria.

AIMS: To assess the impact of the biocontrol strain Pseudomonas fluorescens CHA0 on a collection of barley rhizosphere bacteria using an agar plate inhibition assay and a plant microcosm, focusing on a CHA0-sensitive member of the Cytophaga-like bacteria (CLB). METHODS AND RESULTS: The effect of strain CHA0 on a collection of barley rhizosphere bacteria, in particular CLB and fluorescent pseudomonads sampled during a growth season, was assessed by a growth inhibition assay. On average, 85% of the bacteria were sensitive in the May sample, while the effect was reduced to around 68% in the July and August samples. In the May sample, around 95% of the CLB and around 45% of the fluorescent pseudomonads were sensitive to strain CHA0. The proportion of CHA0-sensitive CLB and fluorescent pseudomonad isolates decreased during the plant growth season, i.e. in the July and August samples. A particularly sensitive CLB isolate, CLB23, was selected, exposed to strain CHA0 (wild type) and its genetically modified derivatives in the rhizosphere of barley grown in gnotobiotic soil microcosms. Two dry-stress periods were imposed during the experiment. Derivatives of strain CHA0 included antibiotic or exopolysaccharide (EPS) overproducing strains and a dry-stress-sensitive mutant. Despite their inhibitory activity against CLB23 in vitro, neither wild-type strain CHA0, nor any of its derivatives, had a major effect on culturable and total cell numbers of CLB23 during the 23-day microcosm experiment. Populations of all inoculants declined during the two dry-stress periods, with soil water contents below 5% and plants reaching the wilting point, but they recovered after re-wetting the soil. Survival of the dry-stress-sensitive mutant of CHA0 was most affected by the dry periods; however, this did not result in an increased population density of CLB23. CONCLUSIONS: CLB comprise a large fraction of barley rhizosphere bacteria that are sensitive to the biocontrol pseudomonad CHA0 in vitro. However, in plant microcosm experiments with varying soil humidity conditions, CHA0 or its derivatives had no major impact on the survival of the highly sensitive CLB strain, CLB23, during two dry-stress periods and a re-wetting period; all co-existed well in the rhizosphere of barley plants. SIGNIFICANCE AND IMPACT OF THE STUDY: Results indicate a lack of interaction between the biocontrol pseudomonad CHA0 and a sensitive CLB when the complexity increases from agar plate assays to plant microcosm experiments. This suggests the occurrence of low levels of antibiotic production and/or that the two bacterial genera occupy different niches in the rhizosphere.

Bacteriological Techniques↗
PubMed1984

X-ray diffraction studies on chromatophore membrane from photosynthetic bacteria. II. Comparison of diffraction patterns of photosynthetic units from various purple bacteria.

Comparative X-ray diffraction studies, in conjunction with infrared absorption spectroscopy, were performed on chromatophores isolated from various purple photosynthetic bacteria in order to achieve a better understanding of the molecular structure of the photosynthetic unit. Purple non-sulfur bacteria used were Rhodospirillum rubrum, Rhodospirillum molischianum, Rhodopseudomonas sphaeroides, and Rhodopseudomonas palustris. Chromatophores of Chromatium vinosum, as a typical example of purple sulfur bacteria, were also investigated. The results were as follows. Distinct equatorial X-ray diffraction patterns were obtained from chromatophores of all the bacteria examined. They showed diffuse, continuous diffraction patterns having several maxima, and the patterns are evidently distinguished from those of either crystalline or amorphous material. The pattern indicates that the photosynthetic unit in the chromatophore has a highly organized molecular structure in the plane of the membrane. Bacteria whose major photosynthetic pigment is bacteriochlorophyll alpha can be categorized in three groups from the viewpoint of near infrared absorption spectra. X-ray diffraction patterns are also grouped accordingly, although the differences are minimal and the patterns display common features. In other words, the bacteriochlorophyll forms, which are bacteriochlorophyll-protein complexes exhibiting different near-infrared absorption spectra, show different X-ray patterns: the molecular structure of photosynthetic units is closely related to the state of pigment in each complex, although the "X-ray" molecular structure is mainly concerned with the arrangement of constituent protein molecules at the present resolution, whereas the "spectroscopic" structure reflects the local environment of pigment.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Chromatophores↗
PubMed2004

Interaction between endophytic bacteria from citrus plants and the phytopathogenic bacteria Xylella fastidiosa, causal agent of citrus-variegated chlorosis.

AIMS: To isolate endophytic bacteria and Xylella fastidiosa and also to evaluate whether the bacterial endophyte community contributes to citrus-variegated chlorosis (CVC) status in sweet orange (Citrus sinensis [L.] Osbeck cv. Pera). METHODS AND RESULTS: The presence of Xylella fastidiosa and the population diversity of culturable endophytic bacteria in the leaves and branches of healthy, CVC-asymptomatic and CVC-symptomatic sweet orange plants and in tangerine (Citrus reticulata cv. Blanco) plants were assessed, and the in vitro interaction between endophytic bacteria and X. fastidiosa was investigated. There were significant differences in endophyte incidence between leaves and branches, and among healthy, CVC-asymptomatic and CVC-symptomatic plants. Bacteria identified as belonging to the genus Methylobacterium were isolated only from branches, mainly from those sampled from healthy and diseased plants, from which were also isolated X. fastidiosa. CONCLUSIONS: The in vitro interaction experiments indicated that the growth of X. fastidiosa was stimulated by endophytic Methylobacterium extorquens and inhibited by endophytic Curtobacterium flaccumfaciens. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides the first evidence of an interaction between citrus endophytic bacteria and X. fastidiosa and suggests a promising approach that can be used to better understand CVC disease.

Actinomycetales↗
PubMed2001

Isolation of a new lytic enzyme for hiochi bacteria and other lactic acid bacteria.

A microorganism producing a lytic enzyme preparation that could rapidly lyse bacterial cells such as hiochi bacteria and other lactic acid bacteria was screened. The microorganism was identified as Streptomyces fulvissimus. The enzyme produced by this organism lysed boil-denatured cells quicker than intact cells of hiochi bacteria. A mutant strain of S. fulvissimus producing the enzyme exhibiting high activity against intact cells of hiochi bacteria was screened on plates, containing intact cells inactivated with UV irradiation. The optimal pH for lytic activity against intact cells of the hiochi bacterium Lactobacillus casei S-4 was from 3.5 to 4.0, and the optimum temperature was close to 50 degrees C. This enzyme activity was stable between pH 3.5 and pH 8.0 and up to 60 degrees C. The enzyme exhibits N-acetyl glucosaminidase and muramidase activities. The effects of adjusting the pH and using different inducers for enzyme production were investigated. Chitin was the most effective inducer of enzyme production. Intact DNA was easily isolated from the cells of many lactic acid bacteria following lysis with the enzyme. It is thought that this enzyme will be a good biotechnological tool.

Journal Article↗
PubMedDate not supplied

[Role of lactic acid bacteria in the spread of antibiotic resistant bacteria among healthy persons].

The wide use of antibiotics in livestock raising has contributed to the selection and accumulation of representatives of commensal microflora, as well as pathogenic bacteria, colonizing livestock and poultry. For this reason the problem of the possible transfer of antibiotic-resistance genes along the chain from bacteria, autochthonous for agricultural animals, to bacteria used for the production of foodstuffs, which are incorporated into normal microflora and may thus participate in the exchange of these genes with bacteria, enteropathogenic for humans, is a highly important task of medical microbiology. The article deals with the review of experimental data, indicative the possibility of the appearance of antibiotic-resistant pathogenic bacteria due to the transfer of antibiotic-resistance genes via alimentary chains.

Animal Husbandry↗
PubMed1996

Photoinactivation of bacteria. Use of a cationic water-soluble zinc phthalocyanine to photoinactivate both gram-negative and gram-positive bacteria.

The photosensitization of microorganisms is potentially useful for sterilization and for the treatment of certain bacterial diseases. Until now, any broad spectrum approach has been inhibited because, although Gram-positive bacteria can be photoinactivated by a range of photosensitizers, Gram-negative bacteria have not usually been susceptible to photosensitized destruction. In the present work, it has been shown that the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, as well as the Gram-positive bacterium Enterococcus seriolicida, can be photoinactivated when illuminated in the presence of a cationic water-soluble zinc pyridinium phthalocyanine (PPC). The degree of photoinactivation is dependent on both the concentration of PPC and the illumination time. In contrast, the three bacteria are not photoinactivated by illumination in the presence of a neutral tetra-diethanolamine phthalocyanine (TDEPC) or negatively charged tetra-sulphonated phthalocyanine (TSPC). Uptake studies have revealed that the lack of activity of TSPC is due to the fact that it has very little affinity for any of the organisms. However, the issue appears to be more complex than simply the gross levels of cellular uptake, since TDEPC and PPC are both taken up by the organisms but only PPC shows activity. This indicates that the localization and subcellular distribution of the phthalocyanines may be a crucial factor in determining their cell killing potential. Further analysis of the uptake data has revealed a cell-bound photosensitizer fraction, which remains tightly associated after several washings, and another weakly bound fraction, which is removed by successive washings. Analysis of the cell killing curves, carried out after successive washings of E. coli exposed to PPC, has revealed that it is the tightly associated fraction that is involved in the photosensitization. Taken together with other data, these results suggest that cationic photosensitizers may have a broader application in the photoinactivation of bacterial cells than the anionic or neutral photosensitizers commonly used in photodynamic therapy.

Dose-Response Relationship, Radiation↗
PubMed2006

Binding of porcine ficolin-alpha to lipopolysaccharides from Gram-negative bacteria and lipoteichoic acids from Gram-positive bacteria.

Protein(s) reactive with N-acetyl-D-glucosamine (GlcNAc) was isolated from porcine nonimmune serum. The molecular weight of the purified protein was found to be mainly 40 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. The N-terminal 10 amino acid sequence of the purified protein were found to be identical to that of porcine ficolin-alpha reported previously. In enzyme-linked immunosorbent assay, the purified protein was found to react with lipopolysaccharides (LPS) from different Gram-negative bacteria such as Esherichia coli, Salmonella typhimurium, Salmonella enteritidis, Salmonella abortus equi, Pseudomonas aeruginosa, Shigella flexeneri, and Serratia marcescens and with lipoteichoic acid (LTA) from Gram-positive bacteria such as Streptococcus sanguis, Bacillus subtilis, Streptococcus pyogenes, and Staphylococcus aureus. The purified protein also reacted with E. coli O26 isolated from food poisoning and bovine feces and heat-treated Gram-positive bacteria such as S. aureus, B. cereus, B. subtilis, Enterococcus faecium, and Corynebacterum bovis. On the other hand, porcine IgG isolated from nonimmune serum showed different reactivity with these LPS, LTA, and heat-treated bacterial cells. From the present findings, purified porcine serum protein reactive with GlcNAc is concluded to be ficolin-alpha playing an important role(s) in innate immunity against microbial infection with Gram-positive and -negative bacteria.

Amino Acid Sequence↗
PubMed1992

Isolation and identification of intestinal bacteria from Japanese tree frog (Hlya japonica) with the special reference to anaerobic bacteria.

The bacteria in the large intestines of eight Japanese tree frogs (Hlya japonica) were enumerated by using an anaerobic culture system. The microorganisms at approximately 3.1 x 10(9) bacteria per g (wet weight) of intestinal contents were present in the intestine of all the frogs tested. No difference of the total bacteria in the frog intestine was observed between two different incubation-temperatures (room temperature and 37 degrees C). Eleven genera and 16 species were isolated from the frog intestine. In most frogs, Bacteroides (B.) caccae and B. vulgatus were detected as the predominant organisms. Escherichia coli was also present in greater numbers in the intestine. Other bacteria isolated at high dilutions were strict anaerobes, including Fusobacterium and Clostridium. Enterococcus faecalis was frequently isolated from the frog intestine. However, four genera of Bifidobacterium, Eubacterium, Peptostreptococcus, and Lactobacillus were not isolated from the frog intestine.

Animals↗
PubMed1978

Oxygen and "strictly anaerobic" intestinal bacteria. II. Oxygen metabolism in strictly anaerobic bacteria.

Oxygen metabolism of "strictly anaerobic" intestinal bacteria was investigated and compared in 25 strains. Washed cell suspensions of all the bacterial strains, in which growth in a medium initially equilibrated with a gas mixture consisting of 5% O2, 5% CO2, and 90% N2 was almost the same as under anaerobic conditions, absorbed O2 at high rate. Such O2 uptake was inhibited by NaN3. Most strains in which growth was inhibited either partially or completely in the same oxygenic condition absorbed O2 at a comparably low rate, and in many cases, such O2 uptake was not inhibited by NaN3. However, in a certain strain incapable of growth in the initial presence of dissolved O2, absorption of O2 was as high as that in some aerobic bacteria, and it was inhibited by NaN3. Little interrelationship was found between the degree of oxygen tolerance and the activities of NADH-peroxidase, H2O2-splitting reaction or superoxide dismutase. A slight interrelationship seems to be present in the case of NADH oxidase even though many exceptions were recognized. All the strains studied had the activities of superoxide dismutase, the absence of which has been regarded as the enzymatic basis of strict anaerobiosis of "strictly anaerobic" bacteria. Some strict anaerobes had high an activity of this enzyme as some aerobic bacteria. The differences in the levels of this activity seem to have some interrelationship not with differences in the degree of oxygen tolerance but with those in the genus to which every strain belongs taxonomically.

Anaerobiosis↗
PubMed2002

Toxicity of tetracyclines and tetracycline degradation products to environmentally relevant bacteria, including selected tetracycline-resistant bacteria.

Tetracyclines used in veterinary therapy invariably will find their way as parent compound and degradation products to the agricultural field. Major degradation products formed due to the limited stability of parent tetracyclines (tetracycline, chlortetracycline, and oxytetracycline) in aqueous solution were theoretically identified at various environmental conditions, such as pH, presence of chelating metals, and light. Their potency was assessed on sludge bacteria, tetracycline-sensitive soil bacteria, and tetracycline-resistant strains. Several of the degradation products had potency at the same concentration level as tetracycline, chlortetracycline, and oxytetracycline on both the sludge and the tetracycline-sensitive soil bacteria. Further, both 5a,6-anhydrotetracycline and 5a,6-anhydrochlortetracycline had potency on tetracycline-resistant bacteria supporting a mode of action different from that of the parent compounds.

Bacteria↗
PubMed1977

Studies on phosphate-solubilizing bacteria in soil and rhizosphere of different plants. I. Occurrence of bacteria, acid producers, and phosphate dissolvers.

Occurrence of bacteria (total), acid producing and phosphate dissolving micro-organisms in soil, rhizosphere, and rizoplane of Egyptian cotton, peas, or maize during their different growth phases was studied. The rhizosphere effects were generally positive and differed according to type of plant, growth phase of each special plant, and type of micro-organism under study. The high densities of bacteria, acid-producers, and phosphate-dissolvers in the rhizoplane samples suggest the conclusion that roots of the studied plants are colonized with these soil micro-organisms. The role of the micro-organism and the mechanism of the noted colonization is not fully understood yet. However, the presence of high numbers of bacteria in the rhizosphere zones of all plants is undoubtedly important, since they may convert organic and inorganic substances into available plant nutrients. The acidproducing organisms were greatly stimulated in the rhizosphere of all plants. Consequently, the production of acid, especially in alkaline soils such as in Egypt, may directly or indirectly react with insoluble inorganic compounds, converting their nutrient elements into available forms for the growing plants. But not all acid-producers are considered as phosphate-dissolvers. Therefore, the presence of high numbers of phosphate-dissolving bacteria in the rhizophere zones may explain how the growing plants can obtain their requirements in such alkaline soils.

Bacteria↗
PubMed2001

Bacteria in gel probes: comparison of the activity of immobilized sulfate-reducing bacteria with in situ sulfate reduction in a wetland sediment.

A novel method was used to examine the microbial ecology of iron-rich wetland sediments receiving neutral-pH coal mine drainage. Gel probes inserted into the sediments allowed analysis of the distribution and activity of bacterial sulfate reduction (BSR). A mixed population of sulfate-reducing bacteria enriched from anoxic wetland sediments was immobilized in low temperature-gelling agarose held in grooved rods or probes. The probes were inserted vertically into sediments and were allowed to incubate in situ for 48 h. After their retrieval, the gels were sectioned and analyzed for residual BSR activity and were compared to in situ BSR rates and chemical porewater profiles. The depth distribution of residual BSR activity in the immobilized cell gel probes differed significantly from the BSR measured in situ. Approximately 51% of the total integrated residual sulfate reduction activity measured in the gel probes occurred between 0 and 7 cm of the upper 20 cm of sediment. In contrast, ca. 99% of the integrated in situ BSR occurred between 7- and 20-cm depth, and only 1% of the total integrated rate occurred between 0- and 7-cm depth. Lactate-enriched bacteria immobilized in the gel may have been atypical of the majority of sulfate-reducing bacteria in the sediment. Agarose-immobilized sulfate-reducing bacteria might also be able to proliferate in the otherwise inhospitable zone of iron reduction, where sulfate and labile carbon compounds for which they are usually outcompeted can diffuse freely into the gel matrix. Gel probes containing particulate iron monosulfide (FeS) indicated that FeS remained stable in sediments at depths greater than 2 to 3 cm below the sediment-water interface, consistent with the shallow penetration of oxygen into surface sediments.

Acrylic Resins↗
PubMed2002

Planktonic nitrate-reducing bacteria and sulfate-reducing bacteria in some western Canadian oil field waters.

Oil fields that use water flooding to enhance oil recovery may become sour because of the production of H(2)S from the reduction of sulfate by sulfate-reducing bacteria (SRB). The addition of nitrate to produced waters can stimulate the activities of nitrate-reducing bacteria (NRB) and control sulfide production. Many previous studies have focused on chemolithotrophic bacteria that can use thiosulfate or sulfide as energy sources while reducing nitrate. Little attention has been given to heterotrophic NRB in oil field waters. Three different media were used in this study to enumerate various types of planktonic NRB present in waters from five oil fields in western Canada. The numbers of planktonic SRB and bacteria capable of growth under aerobic conditions were also determined. In general, microbial numbers in the produced waters were very low (<10 ml x (-1)) in samples taken near or at wellheads. However, the numbers increased in the aboveground facilities. No thiosulfate-oxidizing NRB were detected in the oil field waters, but other types of NRB were detected in 16 of 18 produced water samples. The numbers of heterotrophic NRB were equal to or greater than the number of sulfide-oxidizing, chemolithotrophic NRB in 12 of 15 samples. These results showed that each of the oil fields contained NRB, which might be stimulated by nitrate amendment to control H(2)S production by SRB.

Animals↗