Phosphoenolpyruvate (PEP) carboxykinase was identified to be the only C3-carboxylating enzyme in Alcaligenes eutrophus. The enzyme requires GDP or inosine diphosphate (GTP or inosine triphosphate) for activity. Pyruvate- and other PEP-dependent CO2-fixing enzyme activities were not detected, regardless of whether the cells were grown autotrophically or heterotrophically. It is suggested that two pathways are present in the organism for the formation of PEP from C4 dicarboxylic acids. Besides decarboxylation of oxaloacetate by PEP carboxykinase, the consecutive action of NADP+-malic enzyme and PEP synthetase can also accomplish this synthesis. An oxaloacetate decarboxylase activity observed in the cell extracts may also contribute to the latter route. The properties of a mutant deficient in PEP synthetase supported the biochemical data. This mutant was unable to grow on pyruvate or lactate and grew slower than the wild type on direct or indirect metabolites of the tricarboxylic acid cycle such as succinate, glutamate, or acetate. Growth on fructose and autotrophic growth were not affected by the enzyme defect. The findings suggest that, depending on the growth substrate utilized, PEP carboxykinase can serve a dual physiological function in A. eutrophus, an anaplerotic function in oxaloacetate synthesis from PEP, or a gluconeogenic function in PEP synthesis from oxaloacetate.

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Mutants of Alcaligenes eutrophus were isolated on the basis of their inability to grow on succinate as the sole source of carbon and energy. The mutants also failed to grow on other gluconeogenic substrates, including pyruvate, acetate, and citrate. Simultaneously, they had lost their capability for autotrophic growth. The mutants grew, but slower than the wild type, on fructose or gluconate. Growth retardation on gluconate was more pronounced. The mutants lacked phosphoglycerate mutase activity, and spontaneous revertants of normal growth phenotype had regained the activity. The physiological characteristics of the mutants indicate the role of phosphoglycerate mutase in heterotrophic and autotrophic carbon metabolism of A. eutrophus. Although the enzyme is necessary for gluconeogenesis during heterotrophic growth on three- or four-carbon substrates, its glycolytic function is not essential for the catabolism of fructose or gluconate via the Entner-Doudoroff pathway. The enzyme is required during autotrophic growth as a catalyst in the biosynthetic route leading from glycerate 3-phosphate to pyruvate. It is suggested that the mutants accomplish the complete degradation of fructose and gluconate mutase lesion. The catabolically produced triose phosphates are converted to fructose 6-phosphate which is rechanneled into the Entner-Doudoroff pathway. This carbon recycling mechanism operates less effectively in mutant cells growing on gluconate.

Domestic invasive mycoses are typically present as secondary diseases in patients definitely immunocompromised. This truth should not obscure the fact that a transient overload of the immune system, e.g. in the polytrauma patients, may likewise favour the development of mycoses. The two groups of patients show a comparable course of infection and, to some extent, diagnostic signs: surveillance cultures and monitoring of antibodies are more helpful with trauma patients and less reliable in the typically immunocompromised patients. In the latter, however, antigen tests may yield more reliable results than in the trauma patients. The different functional capacities of the immune system in the two groups of patients may also affect the appearance of fungal elements, particularly of aspergilli, in secretions and biopsies.

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