The metabolism of 51 strains within the 'Mycoplasma mycoides cluster' was investigated by measuring oxygen uptake following the addition of organic substrates to washed cell suspensions. There were extensive differences between strains in the range of substrates utilized, the relative rates of oxidation and the observed saturation constants for substrates, which ranged from a f e w pM to several mM. M. mycoides subsp. Capri and M. mycoides subsp. mycoides LC (large colony) strains were diverse and could not be distinguished by substrate utilization patterns. However, there were consistent differences in the patterns of substrate utilization between other groups of the M. mycoides cluster, suggesting that these patterns may be useful in identification. In particular, SC (small colony) strains of M. mycoides subsp. mycoides were distinguished by their inability to oxidize maltose, trehalose and (at low concentrations) mannose and glucosamine. Surprisingly, the type strain, M. F38, of Mycoplasma capricolum subsp. capripneumoniae and two further isolates differed from all other strains in that they did not oxidize glucose or other sugars. They did, however, oxidize pyruvate, lactate and 2-oxobutyrate a t high rates. The marked metabolic differences between these strains and M. capricolum subsp. capricolum strains is in contrast to the genetic evidence that was used to support the designation of the M. F38 group as a subspecies of M. capricolum.

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Alcohol metabolism by Acholeplasma and Mycoplasma cell suspensions was determined using changes in dissolved oxygen tension to monitor oxygen uptake. All seven Acholeplasma test species oxidised ethanol and (where tested) propanol, butanol and pentanol. The rate of oxidation, at any particular substrate concentration, decreased with increasing alcohol molecular mass. Amongst 20 Mycoplasma species tested, M. agalactiae, M. bovis, M. dispar, M. gallisepticum, M. pneumoniae and M. ovipneumoniae oxidised ethanol. Propanol was also oxidised by M. dispar and isopropanol by M. agalactiae, M. bovis and M. ovipneumoniae. Isopropanol was oxidised at particularly high rates (V(max)100 nmol O(2) taken up min(-1) mg cell protein(-1)) and with a relatively high affinity (K(m) value<2 mM); oxygen uptake was consistent with oxidation to acetone. The significance of alcohol oxidation is unclear, as it would not be predicted to lead to ATP synthesis.