The effects of oxygen on fermentation in Tritrichomonas foetus KV1 and its variant 1MR-100 with defective hydrogenosomes

Lloyd, David ORCID: https://orcid.org/0000-0002-5656-0571, James, Christopher J., Lloyd, Alun L. ORCID: https://orcid.org/0000-0002-5656-0571, Yarlett, Nigel and Yarlett, Nuriza C. 1987. The effects of oxygen on fermentation in Tritrichomonas foetus KV1 and its variant 1MR-100 with defective hydrogenosomes. Microbiology 133 (5) , pp. 1181-1186. 10.1099/00221287-133-5-1181

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Abstract

The effects of low concentrations of O2 on fermentation in the cattle parasite Tritrichomonas foetus KV1 and its variant 1MR-100 were compared using membrane inlet mass spectrometry to measure simultaneously and continuously ethanol, CO2 and H2. In strain KV1 glucose-supported H2 and CO2 production were stimulated by O2 concentrations < 1·4 μM but were inhibited at higher concentrations. Damped oscillatory responses in H2 production indicated the operation of a feedback control system. Measurement of the O2-dependence of O2 consumption rates confirmed the presence of a high-affinity terminal oxidase (apparent K m = 1·6 μM-O2 at 37 °C) and substrate inhibition by O2 at > 8 μM-O2. Successive periods of exposure to O2 resulted in decreased O2 scavenging capacity, as indicated by increasing apparent K m values for O2. The variant strain 1MR-100 which lacks pyruvate: ferredoxin oxidoreductase and hydrogenase showed quite different characteristics: H2 production was not detectable, ethanol formation was inhibited by O2 (K 1 = 1 μM) and O2-dependence of O2 consumption indicated that no high-affinity oxidase was present (apparent K m = 33 μM-O2). Progressive increases in respiration rates on repeated exposure to low O2 concentrations indicated a capacity for adaptation to aerobiosis.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences
Publisher:	Microbiology Society
ISSN:	1350-0872
Last Modified:	26 Oct 2022 08:34
URI:	https://orca.cardiff.ac.uk/id/eprint/127791

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