Nitrite inhibits hydrogen production and kills the cattle parasite Tritrichomonas foetus

摘要

Aims: To investigate the effects of NaNO_2 on the microaerophilic flagellated protozoan, Tritrichomonas foetus KV1, an economically important cattle parasite that inhabits the vagina and can spread rapidly through herds of animals by sexual transmission and leads to abortion of foetal calves. Methods and Results: Growth of the parasite was inhibited by 50% in the presence of 4 mM NaNO_2; immediate killing occurred at 10 mM. Mass spectrometric monitoring of gases showed that H_2 and CO_2 evolution were inhibited by NaNO_2, and electron paramagnetic resonance spectrometry revealed a signal similar to that of a thiolate-iron-NO complex. Growth with sublethal concentrations of NaNO_2 yielded organisms that produced ethanol rather than H_2. Conclusions: NaNO_2 probably inactivates FeS proteins(s) of hydrogenosomes so as to inhibit the conversion of pyruvate (derived from maltose in the growth medium) to H_2 and acetate. Significance and Impact of the Study: The sue of NaNO_2 as a topical antitrichomonal agent in veterinary practice is a possibility. At present, slaughter of infected animals is the favoured method of control.