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The metabolic potentialities of an Acinetobacter radioresistens strain, isolated from the soil adjacent to an activated sludge plant, were investigated. Among 26 aromatic substrates tested, only phenol, benzoate and catechol were metabolized. Since this strain possessed abundant plasmid DNA, the antibiotic and heavy metal resistance was examined, and the bacterial cells proved to be sensitive to all metals (Ni, Tl, Pb, Cd, Ag, Co, Zn) and antibiotics tested except for Fosfomycin and chloramphenicol. The degradation kinetics for phenol and benzoate as the sole carbon/energy source (pH 7, 30 degrees C) displayed different trends, confirmed by the bacterial growth curve. Crude extracts from phenol-grown cultures showed both phenol hydroxylating activity and catechol dioxygenating activity. Phenol hydroxylase possessed a reductase component able to reduce nitroblue tetrazolium (NBT) and cytochrome C, thus exhibiting differences from previously reported monocomponent phenol hydroxylases from the same genus. Catechol dioxygenase is an intradiol-cleaving enzyme recognizing also substituted catechols.

A strain of Acinetobacter radioresistens was able to utilize phenol as the only carbon and energy source, after an acclimatization period of 3 days in which increasing phenol concentrations from 50 to 200 mg/l were supplied. At 30 degrees C, the complete phenol utilization in batch degradation tests occurred in 2.5-3 h at pH 7 and 8, but it increased strongly at pH 6 (over 40 h). No microbial growth was detected at 40 degrees C, while at 20 degrees C (pH 7-8) the time necessary for complete phenol degradation was about twofold longer than that at 30 degrees C (pH 7-8) revealing a good capability of the strain as a seed-micro-organism for enhancing phenol degradation. The bacterial growth in acclimatized cultures, evaluated with the viable cell count, always displayed a trend consistent with the use of phenol as a substrate with an eventual lag phase and then an exponential phase, while in the non-acclimatized cultures an initial stage of cellular death was observed.

High acetate content in a wine, after strong clarification of the must, is due to depletion in the yeast cells of important metabolites (normally present in non-clarified musts) such as metals, amino acids, polyphenolic compounds and unsaturated fatty acids. These substances were added separately to a synthetic medium, comparable in composition to the clarified must, which was then inoculated with a high acetate producer strain. No effects were observed after the addition of various metals and amino acids. The addition of unsaturated fatty acids (Tween 80) caused a significant (p = 0.01) decrease in acetate content. Similar results have been obtained in the presence of polyphenols (catechins and anthocyans): their mechanism of action is probably due to direct inhibition of the enzyme aldehyde dehydrogenase. Control experiments were performed with a low acetate producer strain, and a reduction in acetate content was detected. No differences in the glyceropyruvic metabolism of the two strains was evident.

Twenty five strains of Staphylococcus aureus of human and environmental origin were tested for their enzymatic patterns. All human strains possessed acid phosphatase, while only 25% of the environmental staphylococci demonstrated acid phosphatase activity. In addition, the enzyme alpha-glucosidase was present only in the methicillin resistant-multiresistant strains, in spite of their origin. This work suggests a possible role of the enzyme on penicillin-binding protein mediated methicillin-resistance and stresses the importance of external habitat in the expression of enzymatic activity of bacteria. The enzymatic pattern may confirm or exclude cross-infection, when a single species, with uniformly antibiotic responses, is involved.

The link between loss of protein A and methicillin-resistance, and the presence of both characters in relation to the hosts from which S. aureus strains have been isolated, was examined. The majority of methicillin-resistant strains lost protein A. Normal hosts were generally infected with methicillin-sensitive protein A positive strains, while in immunocompromised patients the finding of multiresistant-protein A deficient strains was more frequent. The importance of the host's immune system, together with the antibiotic pressure in selecting these mutants, is discussed.