Stress situations induce cyanide-resistant respiration in spoilage yeasts

Aims: To investigate the conditions that promote the expression of cyanide-resistant respiration (CRR) in the spoilage yeasts Pichia membranifaciens and Debaryomyces hansenii. Methods and Results: CRR was detected by sensitivity of oxygen consumption to salicylhydroxamic acid. It was absent in both yeasts in the early exponential phase, but was triggered by several stress situations. Starvation under aerobic conditions, decreasing pH or incubation of the culture in a narrow temperature range below the maximum temperature for growth promoted the emergence of CRR in both yeasts. In D. hansenii, CRR was also induced by 1.5-2 mol l(-1) NaCl. Although the presence of H2O2 and menadione induced CRR, radical scavengers had no effect on the emergence of CRR. Also, the level of reactive oxygen species did not vary with the CRR activity. Conclusions: Under aerobic conditions, a respiratory pathway alternative to the cytochrome chain is triggered by stress conditions in P. membranifaciens and D. hansenii. Significance and Impact of the Study: The relationship between stress situations and CRR must be taken into account in studies on the performance of spoilage yeasts in the food processing environments where several forms of stress are common.