[Effect of formate on the respiration of different microorganisms]

The cells of methylotrophic bacteria (Achromobacter parvulus 1, Pseudomonas methylica 2 and 20, Ps. fluorescens 45, Ps. oleovorans 52) and Candida methylica 101 grown in a medium with methanol take up oxygen in the presence of formiate. A. parvulus is most resistant to formiate (KM = 2.3 +/- 0.5) X 10(-3) M; Ki = 4 x 10(-1) M). When grown on Cn substrates, these microorganisms cannot oxidize formiate (with an exception of A. parvulus). Formiate also serves as a respiration substrate for E. coli K-12 and the purple bacterium Rhodopseudomonas palustris, disregarding the composition of a medium on which the cells are grown. When the cells cannot oxidize formiate, it inhibits the respiration of the cells and cell extracts in the presence of other substrates, including TMPD + ascorbate. The respiration is completely inhibited at a concentration of formiate of 10(-3)--10(-2) M. It follows therefore that formiate acts on the terminal cytochrome oxidase, regardless of whether it is cytochrome a or o.