Tolerance to high temperature and salt stress by a salt marsh isolate of Aureobasidium pullulans

Abstract

When cells of a salt marsh isolate of Aureobasidium pullulans were shifted from 25 C to 35 C, a series of proteins was observed by gel electrophoresis to increase in synthesis over time in a manner consistent with the classic heat shock response. In contrast, salt shock of 4.5% NaCl resulted in the enhancement of only three of the 12 bands observed for heat shock, whereas a simultaneous exposure to temperature and salt stress, a common occurrence in temperate salt marshes, produced an intermediate pattern of enhanced bands. The stimulation in synthesis of these proteins by sublethal stress dosages correlated with the ability of cells to survive subsequent exposures to lethal stress conditions. Not only did exposure to sublethal temperature and salt pretreatments protect against lethal temperature and salt dosages, respectively, but the pretreatments also exhibited reciprocity in their protection; an elevated temperature pretreatment protected against a lethal salt dosage and an elevated salt pretreatment protected against a lethal temperature dosage. These physiological attributes are consistent with an active role for A. pullulans in salt marsh ecosystems.

Key Words:

• heat shock
• salt shock
• salt tolerance
• thermotolerance