Fifth Stenhouse‐Williams Memorial Lecture Oxygen and the Obligate Anaerobe

Morris, Jonathan

doi:10.1111/j.1365-2672.1976.tb04171.x

Cited by 71 publications

(13 citation statements)

References 50 publications

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“…Products toxic to anaerobic organisms are known to rapidly build up in culture media exposed to air and may actually arise from agents added to the medium to lower the oxidation-reduction potential (36,37). These reactive products may damage cell components such as sulfhydryl and metaloprotein groups, cause a rise in the particular oxidation-reduction potential within the cell, and inhibit the electron transport system, thus consuming the cell's reducing power.…”

Section: Destruction Of Tissue Culture Monolayers By Trophozoites Of mentioning

confidence: 99%

Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.

Bracha¹,

Mirelman²

1984

The Journal of Experimental Medicine

187

148

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The association of axenically grown trophozoites of Entamoeba histolytica strains HK-9 or HM-1:IMSS with various types of gram-negative bacteria for relatively short periods markedly increased their virulence, as evidenced by their ability to destroy monolayers of tissue-cultured cells. Interaction of trophozoites with bacteria that were heat inactivated, glutaraldehyde fixed, or disrupted by sonication, or bacteria treated with inhibitors of protein synthesis, did not augment amebic virulence. Lethally irradiated bacteria, however, retained their stimulative properties and trophozoites that ingested bacteria were protected from the toxic effects of added hydrogen peroxide. An increase in virulent properties of amebae was also found in experiments carried out under microaerobic conditions (5% O2, 10% CO2). The augmentation of amebic virulence due to association with bacteria was specifically blocked by metronidazole, but not by tetracycline or aminoglycosides, and the rate of metronidazole uptake in stimulated trophozoites was two to three times higher. The results obtained suggest that virulence of axenically grown E. histolytica trophozoites may depend to a considerable extent on the cell's reducing power. Both microaerobic conditions and the association with bacteria apparently stimulate the electron transport system of the ameba. Bacteria may function as broad range scavengers for oxidized molecules and metabolites through the contribution of enzymatic systems, components, or products.

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Section: Destruction Of Tissue Culture Monolayers By Trophozoites Of mentioning

confidence: 99%

Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.

Bracha¹,

Mirelman²

1984

The Journal of Experimental Medicine

187

148

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“…They contain high concentrations of 0,-labile compounds and require a relatively low redox potential for growth (Mah & Smith, 1981 ;Morris, 1976;Vogels et al, 1988). Although methanogens may possess some enzymic self-defence against 0,-toxicity, growth in pure cultures is completely blocked in the presence of 0, (Jones et al, 1983;Kengen et al, 1991;Kiener et al, 1988;Kiener & Leisinger, 1983;Kirby et al, 1981;Patel et al, 1984;Roberton & Wolfe, 1970;Smith & Hungate, 1958;Zehnder & Wuhrmann, 1977).…”

Section: Introductionmentioning

confidence: 99%

Two-membered mixed cultures of methanogenic and aerobic bacteria in O2-limited chemostats

Gerritse¹,

Gottschal²

1993

Journal of General Microbiology

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Three different co-cultures composed of a methanogenic and a strictly aerobic bacterium were grown under 0,-limitation in continuous cultures. The combinations used were (1) Methanobacterium formicicum with the aerobic heterotroph Comamonas testosteroni; (2) M. formicicum with a methanotrophic Methylocystis species; and (3) Methanosarcina barkeri with C. testosteroni. Although true steady-states were not obtained, growth and metabolic activity of the methanogenic and aerobic organisms occurred during 0,-limited growth of these mixed cultures over extended periods of time. Co-cultures with C. testosteroni were considerably more stable than those with Methylocystis. Co-cultures with M. barkeri were less 0,-sensitive than those with M. formicicum. C. testosteroni exhibited a higher 0,-affinity than Methylocystis, resulting in a lower dissolved oxygen tension and a superior protection of the methanogenic bacteria against 0,-poisoning than in mixed cultures with Methylocystis. The dissolved O,-concentrations in the mixed cultures were below the detection limit of the 0,-probes used (0-2 p~). Calculations based on growth properties of pure cultures of C. testosteroni, M. barkeri and M. formicicum suggested that the dissolved 0,-concentrations in the mixed cultures, as well as the 0,-inhibition constants (apparent p) of the methanogens were in the nanomolar range.

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“…The cyanide sensitivity of oxygen uptake by 2. mobilis led BELAICR and SENEZ [18] to the suggestion that a complete respiratory chain was present. Presence of a respiratory chain in addition to the protective enzymes, catalase [13] and superoxide dismutase [14] should rend2r 2. mobilis as aerotolerant as yeast or facultative anaerobic bacteria [19]. In fact, however, oxygen inhibits growth as can be judged from its effect on the growth yield (Tab.…”

Section: Effects Of Ozygenmentioning

confidence: 99%

Continuous ethanol production by zymomonas mobilis on an industrial scale

Sahm

Bringer‐Meyer

1987

Acta Biotechnologica

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The specific growth rate of the ethanol producing bacterium Zymomonas mobilis was lower in the presence of oxygen than under aniierobic conditions. Aerobically, considerable amounts of acetaldehyde and acetic acid were formed in addition to the normal fermentation products, ethanol and carbon dioxide. This bacterium contains considerable amounts of pentacyclic triterpenoids, mainly 1, 2, 3,4-tetrahydroxypentane-29-hopane. It seems that stability and permeability of the cytoplasmic membrane of this rather ethanol tolerant organism is achieved by the hopanoid content. A continuous culture of Zymomonas mobilis produced 60 g/1 ethanol over a test period of 39 days. This strain was used for ethanol production from an enzymatically hydrolyzed wheat starch fraction on an industrial scale of 100 nP.

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Fifth Stenhouse‐Williams Memorial Lecture Oxygen and the Obligate Anaerobe

Cited by 71 publications

References 50 publications

Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.

Virulence of Entamoeba histolytica trophozoites. Effects of bacteria, microaerobic conditions, and metronidazole.

Two-membered mixed cultures of methanogenic and aerobic bacteria in O2-limited chemostats

Continuous ethanol production by zymomonas mobilis on an industrial scale

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