Influence of growth temperature on lipid and soluble carbohydrate synthesis by fungi isolated from fellfield soil in the maritime Antarctic

Abstract

The effects of growth temperature on soluble carbohydrate and lipid content of Humicola marvinii, Geomyces pannorum and Mortierella elongata isolated from the Antarctic (Signy Island; 60° 43′S, 45° 38′W) were investigated. Each of these fungi responded differently to suboptimal growth temperatures. At low temperatures Humicola marvinii accumulated cryoprotective carbohydrates (trehalose intracellularly and glycerol extracellularly), whereas Geomyces pannorum responded by altering its lipid composition with increases in unsaturated lipid content and overall unsaturation index. In the case of Mortierella elongata, features that may influence its ability to grow at low temperatures included the absence of detectable ergosterol, the presence of stearidonic acid and increased amounts of intracellular trehalose when grown at lower temperatures. The relative importance of lipid and carbohydrate metabolism in adaptation to temperature stress in these fungi is discussed.

Key Words:

• Geomyces
• Humicola
• Mortierella
• psychrophilic
• temperature adaptation