Species-specific effects of the introduction of Aspergillus nidulans gfdB in osmophilic aspergilli

Industrial fungi need a strong environmental stress tolerance to ensure acceptable efficiency and yields. Previous studies shed light on the important role that Aspergillus nidulans gfdB, putatively encoding a NAD(+)-dependent glycerol-3-phosphate dehydrogenase, plays in the oxidative and cell wall integrity stress tolerance of this filamentous fungus model organism. The insertion of A. nidulans gfdB into the genome of Aspergillus glaucus strengthened the environmental stress tolerance of this xerophilic/osmophilic fungus, which may facilitate the involvement of this fungus in various industrial and environmental biotechnological processes. On the other hand, the transfer of A. nidulans gfdB to Aspergillus wentii, another promising industrial xerophilic/osmophilic fungus, resulted only in minor and sporadic improvement in environmental stress tolerance and meanwhile partially reversed osmophily. Because A. glaucus and A. wentii are phylogenetically closely related species and both fungi lack a gfdB ortholog, these results warn us that any disturbance of the stress response system of the aspergilli may elicit rather complex and even unforeseeable, species-specific physiological changes. This should be taken into consideration in any future targeted industrial strain development projects aiming at the fortification of the general stress tolerance of these fungi.

Automated summary

Industrial fungi require strong environmental stress tolerance for optimal efficiency and yields. Previous research has highlighted the crucial role played by Aspergillus nidulans gfdB, which encodes a NAD(+)-dependent glycerol-3-phosphate dehydrogenase, in the stress tolerance of this filamentous fungus. Introducing A. nidulans gfdB into Aspergillus glaucus enhanced its stress tolerance, while transferring it to Aspergillus wentii resulted in limited improvement and partial reversal of osmophily, indicating the complex and species-specific changes that can occur in the stress response system of aspergilli.