MINERALIZATION OF [C-14] OCTACOSANE BY ACINETOBACTER-CALCOACETICUS S30

Acinetobacter calcoaceticus S30 could grow (doubling time, 7 h) on oct acosane (C-28) and degraded about 70% of the substrate during growth. Octacosanol, octacosanoic acid, and other lower carboxylic acids were identified during degradation of octacosane. Acinetobacter calcoacetic us S30 could also grow on intermediate metabolites, namely octacosanol and octacosanoic acid, although the doubling time was greater on octa cosanoic acid (72 h on octacosanol and 120 h on octacosanoic acid). Wh ole cells of A. calcoaceticus S30 using [18-C-14]octacosane mineralize d 65% of the octacosane to (CO2)-C-14 and 30% of the radiolabel was re tained in the cell biomass in 24 h. Acinetobacter calcoaceticus S30 co nverts octacosane to octacosanol through an oxidation step, which is t hen oxidized to octacosanoic acid and then beta-oxidized to CO2. Among several metabolic inhibitors, those of the sulphydryl group greatly i nhibited the uptake of octacosanol and octacosanoic acid at much lower concentrations. The electron transport inhibitors were potent inhibit ors of octacosane, octacosanol, and octacosanoic acid uptake, suggesti ng that the oxidation of these substrates is an energy-dependent proce ss.