Biomedical subjects

M J McInerney

Publications and source records attributed to M J McInerney.

42 records · Page 3Linked to original sources

PubMed1982

Effect of O2 limitation on growth and respiration of the wild type and an ascorbate-tetramethyl-p-phenylenediamine-oxidase-negative mutant strain of Azotobacter vinelandii.

Azotobacter vinelandii strain AVOP (wild type) and an ascorbate-N,N,N',N'-tetramethylene-p-phenylenediamine oxidase-negative mutant (AV11) were each grown in O2-limited chemostat cultures. The results showed that the mutant strain grew and used O2 less efficiently than the wild-type strain. Respiration rates of membrane particles with NADH or malate as the substrate were similar for each strain. Succinate oxidase activity was about fourfold lower in membrane particles prepared from mutant than from wild-type strain. Cyanide at a concentration that completely inhibited ascorbate-TMPD oxidase activity resulted in a 50% inhibition of NADH oxidase activity in membrane particles of AVOP. These data suggest that the cytochrome o, a1, oxidase branch of the respiratory chain may be important in the physiology of A. vinelandii under O2-limiting growth conditions.

Azotobacter↗

PubMed1981

Anaerobic Degradation of Lactate by Syntrophic Associations of Methanosarcina barkeri and Desulfovibrio Species and Effect of H(2) on Acetate Degradation.

When grown in the absence of added sulfate, cocultures of Desulfovibrio desulfuricans or Desulfovibrio vulgaris with Methanobrevibacter smithii (Methanobacterium ruminantium), which uses H(2) and CO(2) for methanogenesis, degraded lactate, with the production of acetate and CH(4). When D. desulfuricans or D. vulgaris was grown in the absence of added sulfate in coculture with Methanosarcina barkeri (type strain), which uses both H(2)-CO(2) and acetate for methanogenesis, lactate was stoichiometrically degraded to CH(4) and presumably to CO(2). During the first 12 days of incubation of the D. desulfuricans-M. barkeri coculture, lactate was completely degraded, with almost stoichiometric production of acetate and CH(4). Later, acetate was degraded to CH(4) and presumably to CO(2). In experiments in which 20 mM acetate and 0 to 20 mM lactate were added to D. desulfuricans-M. barkeri cocultures, no detectable degradation of acetate occurred until the lactate was catabolized. The ultimate rate of acetate utilization for methanogenesis was greater for those cocultures receiving the highest levels of lactate. A small amount of H(2) was detected in cocultures which contained D. desulfuricans and M. barkeri until after all lactate was degraded. The addition of H(2), but not of lactate, to the growth medium inhibited acetate degradation by pure cultures of M. barkeri. Pure cultures of M. barkeri produced CH(4) from acetate at a rate equivalent to that observed for cocultures containing M. barkeri. Inocula of M. barkeri grown with H(2)-CO(2) as the methanogenic substrate produced CH(4) from acetate at a rate equivalent to that observed for acetate-grown inocula when grown in a rumen fluid-vitamin-based medium but not when grown in a yeast extract-based medium. The results suggest that H(2) produced by the Desulfovibrio species during growth with lactate inhibited acetate degradation by M. barkeri.

Journal Article↗

PubMed1981

Syntrophic association of a butyrate-degrading bacterium and methanosarcina enriched from bovine rumen fluid.

An anaerobic butyrate-degrading bacterium, morphologically similar to Syntrophomonas wolfei, was isolated in coculture with Desulfovibrio strain G11 from an enrichment of bovine rumen fluid. A Methanosarcina species was the major H2-using organism in the enrichment. The results are discussed in relationship to the absence of Methanospirillum hungatei, the H2-using methanogen usually found in association with S. wolfei, and the finding of Methanosarcina rather than Methanobrevibacter ruminantium as the major H2-using bacterium in the enrichments. The finding of butyrate degraders in the rumen suggests that, if the retention time of the rumen contents becomes more prolonged, butyrate and longer-chained fatty acids might be significantly degraded.

Animals↗

PubMed1981

Syntrophomonas wolfei gen. nov. sp. nov., an Anaerobic, Syntrophic, Fatty Acid-Oxidizing Bacterium.

An anaerobic, nonphototrophic bacterium that beta-oxidizes saturated fatty acids (butyrate through octanoate) to acetate or acetate and propionate using protons as the electron acceptor (H(2) as electron sink product) was isolated in coculture with either a non-fatty acid-degrading, H(2)-utilizing Desulfovibrio sp. or methanogens. Three strains of the bacterium were characterized and are described as a new genus and species, Syntrophomonas wolfei. S. wolfei is a gram-negative, slightly helical rod with round ends that possesses between two to eight flagella laterally inserted along the concave side of the cell. It has a multilayered cell wall of the gram-negative type. The presence of muramic acid, inhibition of growth by penicillin, and increased sensitivity of the cells to lysis after treatment with lysozyme indicate that peptidoglycan is present in the cell wall. Cells of S. wolfei contain poly-beta-hydroxybutyrate. Isoheptanoate was degraded to acetate, isovalerate, and H(2). Carbohydrates, proteinaceous materials, alcohols, or other tested organic compounds do not support growth. Common electron acceptors are not utilized with butyrate as the electron donor. Growth and degradation of fatty acids occur only in syntrophic association with H(2)-using bacteria. The most rapid generation time obtained by cocultures of S. wolfei with Desulfovibrio and Methanospirillum hungatei is 54 and 84 h, respectively. The addition of Casamino Acids but neither Trypticase nor yeast extract stimulated growth and resulted in a slight decrease in the generation time of S. wolfei cocultured with M. hungatei. The addition of H(2) to the medium stopped growth and butyrate degradation by S. wolfei.

Journal Article↗

PubMedDate not supplied

Properties of the biosurfactant produced by Bacillus licheniformis strain JF-2.

The activity of the biosurfactant produced by Bacillus licheniformis strain JF-2 was quantified using a unit defined as the amount of the acid-precipitated biosurfactant that lowered the surface tension by 10 mN/m. One unit was equivalent to 37 micrograms/ml of the acid-precipitated biosurfactant. Acid precipitation was very effective in the removal of the biosurfactant from the spent medium. Among the solvents tested methanol was the most efficient in extracting the surfactant activity from acid-precipitated material. Thin-layer chromatography of the acid-precipitated biosurfactant revealed four components, two of which contained a lipid moiety and one of which contained an amino group. The methanol-soluble fraction also contained these four components. Studies suggested that all four components were needed for full activity. The lowest interfacial tensions against octane were observed when NaC1 concentrations were 50 g/l or greater. Calcium concentrations greater than 25 g/l significantly increased the interfacial tension.

Anaerobiosis↗

PubMedDate not supplied

Direct mail intervention to increase retinal examination rates in Medicare beneficiaries with diabetes.

The objective of this study was to identify the baseline frequency of eye examinations for Medicare beneficiaries with diabetes in Montana and to determine whether a direct mail reminder increased eye examinations. Using Medicare Part A and Medicare Part B claims data, a cohort of Medicare beneficiaries with diabetes was defined. Eye examination claims were identified using billing codes specific for retinal examinations, as well as visits to ophthalmologists and optometrists during which retinal exams were likely to have been performed. A random sample of the identified beneficiaries with diabetes received a letter encouraging regular annual retinal examinations. In the first 3-month period after the mailing, the billed eye examination rate for those to whom letters were sent was 2.2 percentage points greater than the rate for those to whom letters were not sent (19.4% vs 17.2%; relative risk, 1.13; 95% confidence interval, 1.01-1.26). However, 6 months after the letters were sent, there was no longer a significant difference in the rates for these 2 groups (32.9% vs 32.4%; relative risk, 1.02; 95% confidence interval, 0.94-1.10). In this study, direct mail outreach initially influenced the proportion of Medicare beneficiaries receiving an eye examination, but this pattern was not sustained over the 6-month follow-up period.

Aged↗