Combinatorial Action of Different Stress Factors on the Composition of Membrane Lipids and Osmolytes of Aspergillus niger

Adaptive response (changes in the composition of osmolytes and membrane lipids) of the mycelial fungus Aspergillus niger to combinatorial action of oxidative and heat (or osmotic) shocks was studied. Oxidative shock was found to cause no significant changes in the composition of osmolytes. A combination of oxidative shock with other stressors was shown to suppress their adaptive responses, such as accumulation of trehalose (during heat shock) and polyols (during osmotic shock). A common pattern of the changes in membrane lipids observed for all the studied stress factors was an increase in the proportion of non-bilayer phosphatidic acids, which was more pronounced in the case of combinatorial stress effects. No significant changes in the degree of unsaturation of membrane phospholipids were observed. Thus, the studied combinatorial shocks did not result in an additive response and caused a decrease in the amount of osmolytes compared with individual stressors, which weakened the adaptive response of the fungus.