Influence of cytochrome composition on the energy conservation of acinetobacter calcoaceticus 69‐V

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Abstract
Acinetobacter calcoaceticus 69‐V contained cytochromes b, o, d and traces of cytochrome a1 after growth on ethanol. Cytochromes o, d, and a1 are known to be potentially capable of functioning as terminal oxidases. After growth on acetate only smaller amounts of cytochromes b and o were detectable. Cytochrome spectra of acetate plus glucose‐grown cells resembled more those of ethanolgrown cells. Cytochrome spectra of acetate plus ethanol‐grown cells were more similar to those of acetate‐grown cells but already showed small amounts of cytochrome d.Ethanol‐grown cells were energized only by the oxidation of glucose. But the velocity of ATP synthesis was so low that the P/O quotient amounted to practically zero. The stoichiometries of ATP synthesis of the otherwise‐grown cells were generally higher for the oxidation of glucose than for the oxidations of succinate and D‐lactate. Similar high P/O quotients were measured for the oxidations of glucose and ethanol in acetate plus ethanol‐grown cells.No significant energization could be observed during the oxidations of gluconate and acetate.The findings indicate that electrons delivered by the PQQ‐dependent glucose as well as by NAD+‐ dependent ethanol oxidations have probably a common place of entry into the respiratory chain. Glucose and NADH appeared to be energetically equivalent although at least two energetically different pathways might be involved in substrate oxidation.