The ability of Acinetobacter calcoaceticus MM5 to degrade heating oil was studied. Certain culture conditions relevant to the degradation of this petroleum derivative were also analyzed. Degradation of heating oil by MM5 was followed by gas chromatography during a 30-day incubation period. A. calcoaceticus MM5 degraded essentially the n-alkane components of the fuel, and left the branched hydrocarbons pristane and phytane undegraded. The degradation of heating oil was favoured by aeration of the cultures. There was an absolute nutritional requirement for nitrogen and phosphorus sources for hydrocarbon degradation. Strain MM5 degraded heating and diesel oil to a similar extent. The presence of commercial additives in the heating oil did not modify the degradation of this fuel. Infrared spectroscopy of remaining heating oil after incubation with strain MM5 showed the appearance of two new bands, corresponding to compounds with carbonyl groups derived from the metabolism of hydrocarbons.

Twenty aerobic bacterial strains were isolated from altered heating oil. Among them the strain catalogued as MM5 and identified as Acinetobacter calcoaceticus is able to grow on hydrocarbon substrates. When strain MM5 was grown on heating oil, crude oil and tetradecane, increases of protein concentration and of caprilate-lipase and acetate-esterase enzymatic activities were observed in the culture filtrate, with a simultaneous pH drop. A strong emulsification of petroleum by-products was also noticed. Degradation of heating oil was followed by gas chromatography and infrared spectroscopy. Presence of available nitrogen and phosphorus sources were essential for hydrocarbon biodegradation. Intracellular electron transparent inclusions were observed by transmission electron microscopy when strain MM5 cells were grown on hydrocarbons. Light and scanning electron microscopy showed bacteria interconnected by an extracellular polymer and attached to hydrocarbon droplets and to sheets of polymeric material. A bioemulsifier was extracted from the cell-free culture supernatants of strain MM5 grown on tetradecane. The emulsifier is a high molecular weight product that comprises proteins, sugars and fatty acids and which is resistant to high temperature. Strain MM5 should be helpful for the design of strategies for the bioremediation of hydrocarbon contaminated sites.

alpha-Galactosidases from mycelial extract and culture filtrate of Aspergillus nidulans have been purified to homogeneity and utilised to obtain polyclonal antibodies anti-alpha-galactosidase. The enzymatic characteristics and the cross reactivity of the antibodies suggest that alpha-galactosidases isolated from the two sources were the same enzyme. Thus, A. nidulans synthesized and secreted only one enzymatic form of alpha-galactosidase which is a multimeric enzyme of 370 kDa composed of four monomers of 87 kDa and a pI of 6.3. The optimum temperature of activity was 50 degrees C and the optimum pH 4-5. The enzyme was stable over a wide range of pH but quite unstable to temperature. alpha-Galactosidase of A. nidulans is a very specific enzyme, it is active only on p-nitrophenyl-alpha-D-galactoside (PNPG), melibiose and raffinose. When PNPG was utilised as substrate melibiose, raffinose, galactose and glucose were competitive inhibitors of the activity.