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R Blakemore

Publications and source records attributed to R Blakemore.

7 recordsLinked to original sources
PubMed1998

Reduction of diverse electron acceptors by aeromonas hydrophila

Aeromonas hydrophila ATCC 7966 grew anaerobically on glycerol with nitrate, fumarate, Fe(III), Co(III), or Se(VI) as the sole terminal electron acceptor, but did not ferment glycerol. Final cell yields were directly proportional to the amount of terminal electron acceptor provided. Twenty-four estuarine mesophilic aeromonads were isolated; all reduced nitrate, Fe(III), or Co(III), and five strains reduced Se(VI). Dissimilatory Fe(III) reduction by A. hydrophila may involve cytochromes. Difference spectra obtained with whole cells showed absorption maxima at wavelengths characteristic of c-type cytochromes (419, 522, and 553 nm). Hydrogen-reduced cytochromes within intact cells were oxidized by the addition of Fe(III) or nitrate. Studies with respiratory inhibitors yielded results consistent with a respiratory chain involving succinate (flavin-containing) dehydrogenase, quinones and cytochromes, and a single Fe(III) reductase. Neither anaerobic respiration nor dissimilatory metal reduction by members of the genus Aeromonas have been reported previously.

Journal Article↗
PubMed1996

Synergistic iron reduction and citrate dissimilation by Shewanella alga and Aeromonas veronii

Two bacterial isolates from Great Bay Estuary, New Hampshire, in co-culture carried out anaerobic dissimilation of citric acid with Fe(III) as the terminal electron acceptor. Neither isolate oxidized citrate with Fe(III) anaerobically in axenic culture. The Fe(III) reducer, Shewanella alga strain BrY, did not grow anaerobically with citrate as an energy source. The citrate utilizer, Aeromonas veronii, did not reduce iron axenically with a variety of electron donors including citrate. The onset of iron reduction by the co-culture occurred after initiation of citrate dissimilation and just prior to initiation of growth by either organism (as measured by viable plate counts). Anaerobic culture growth rates and final cell densities of each bacterial strain were greater in co-culture than in axenic cultures. By 48 h of growth, the co-culture had consumed 27 mM citrate as compared with 12 mM dissimilated by the axenic culture of A. veronii. By 48 h the co-culture produced half as much formate (6 mM) and twice as much acetate (40 mM) as did A. veronii grown axenically (12 mM and 20 mM, respectively). Formate produced from citrate by A. veronii appeared to have supported growth and Fe(III) reduction by S. alga.Although not obligatory, nutrient coupling between these two organisms illustrates that fermentative (A. veronii-type) organisms can convert organic compounds such as citrate to those used as substrates by dissimilatory Fe(III) reducers, including S. alga. This synergism broadens the range of substrates available for iron reduction, stimulates the extent and rate of organic electron donor degradation (and that of iron reduction) and enhances the growth of each participant.

Journal Article↗
PubMed1979

Reduction by cimetidine of acute gastric hemorrhage caused by reinfusion of blood after exposure to exogenous acid during gastric ischemia in rats.

The present study has been made in anesthetized rats to characterize conditions of exposure to acid and extent of ischemia which determine the development of gastric hemorrhage. Gastric hemorrhage occurred in rats subjected to shock during exposure of the gastric lumen to acid after the reinfusion of withdrawn blood. When the acid concentration was constant, bleeding was dependent on the degree of shock. When hemorrhage shock was constant, bleeding from the stomach appeared pH dependent, although this did not quite achieve statistical significance. Cimetidine 2 x 10(-6) mol kg-1 min-1 (30 mg kg-1 hr-1) and 1 x 10(-5) mol kg-1 min-1 (150 mg kg-1 hr-1) significantly reduced gastric hemorrhage whether given prophylactically before gastric injury or therapeutically after completion of gastric injury. Because protection can be demonstrated against an injury involving exogenous acid and after the injury has been established, it is probable that the effectiveness of cimetidine in these studies is independent of its antisecretory effects.

Acute Disease↗
PubMed1975

Magnetotactic bacteria.

Bacteria with motility directed by the local geomagnetic field have been observed in marine sediments. These magnetotactic microorganisms possess flagella and contain novel structured particles, rich in iron, within intracytoplasmic membrane vesicles. Conceivably these particles impart to cells a magnetic moment. This could explain the observed migration of these organisms in fields as weak as 0.5 gauss.

Bacteria↗