Biologia futura: combinatorial stress responses in fungi.

In the ever-changing fungal environment, fungi have to cope with a wide array of very different stresses. These stresses frequently act in combination rather than independently, i.e.

Autolytic hydrolases affect sexual and asexual development of Aspergillus nidulans.

Radial growth, asexual sporulation, and cleistothecia formation as well as extracellular chitinase and proteinase formation of Aspergillus nidulans were monitored in surface cultures in order to study the physiological role of extracellular hydrolase production in carbon-stressed cultures. We set up carbon-stressed and carbon-overfed experimental conditions by varying the starting glucose concentration within the range of 2.5 and 40 g/L.

Antifungal activity of extracellular hydrolases produced by autolysing Aspergillus nidulans cultures.

Carbon-starving Aspergillus nidulans cultures produce high activities of versatile hydrolytic enzymes and, among these, ChiB endochitinase and EngA β-1,3-endoglucanase showed significant antifungal activity against various fungal species. Double deletion of engA and chiB diminished the antifungal activity of the fermentation broths and increased conidiogenesis and long-term viability of A. nidulans, but decreased the growth rate on culture media containing weak carbon sources.

MeaB-dependent nutrition sensing regulates autolysis in carbon starved Aspergillus nidulans cultures.

Carbon starvation induced autolysis is an active process of self-digestion and is under complex regulation in Aspergillus nidulans. In this study we investigated how autolysis depends on the composition of the culture medium, especially on the presence of yeast extract. We demonstrated that the rate of autolytic cell wall degradation as well as the extracellular chitinase and proteinase productions significantly decreased in the presence of this nutrient.

[Study of the effects of alkali metals on some virulence characteristics of Candida albicans].

The effects of the alkali metals sodium, potassium and lithium on the growth and on certain virulence factors (adhesion, cell-surface hydrophobicity and the germinating ability) of Candida albicans were investigated. It can be concluded that high concentrations of alkali metals possessed an inhibitory effect on the growth of the Candida cells and preincubation in the presence of alkali metals had a negative effect on all the virulence factors studied. It is worth emphasizing that the changes induced during the preincubation persisted even when the high concentrations of the alkali metals were removed from the cell suspension.