Functionality and prevalence of trehalose‐based oligosaccharides as novel compatible solutes in ascospores of N eosartorya fischeri ( A spergillus fischeri ) and other fungi

Abstract

Summary Ascospores of N eosartorya , B yssochlamys and T alaromyces can be regarded as the most stress‐resistant eukaryotic cells. They can survive exposure at temperatures as high as 85° C for 100 min or more. N eosartorya fischeri ascospores are more viscous and more resistant to the combined stress of heat and desiccation than the ascospores of T alaromyces macrosporus which contain predominantly trehalose. These ascospores contain trehalose‐based oligosaccharides ( TOS ) that are novel compatible solutes, which are accumulated to high levels. These compounds are also found in other members of the genus N eosartorya and in some other genera within the order Eurotiales that also include B yssochlamys and T alaromyces . The presence of oligosaccharides was observed in species that had a relatively high growth temperature. TOS glasses have a higher glass transition temperature ( T g ) than trehalose, and they form a stable glass with crystallizing molecules, such as mannitol. Our data indicate that TOS are important for prolonged stabilization of cells against stress. The possible unique role of these solutes in protection against dry heat conditions is discussed.

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