Further Studies on the Water Relations of Xerophilic Fungi, Including Some Halophiles

Germination and growth of six fungi, Basipetospora halophila, Polypaecilum pisce, Aspergillus penicilloides, A. wentii, Eurotium repens and Exophiala werneckii, isolated from salt fish, and two new undescribed species from other sources, a Geomyces sp. and a Eurotium sp., were examined on media in which water activity (a w) was controlled over a wide range by glucose/fructose, glycerol or NaCl. Three species, B. halophila, P. pisce and Ex. werneckii, grew more rapidly on media containing NaCl in comparison with glucose/fructose, and hence can be considered to be halophilic. Two other species, A. penicilloides and A, wentii, were also unusually tolerant of NaCl: A. penicilloides could grow on media saturated with NaCl, while A. wentii grew more rapidly on NaCl-based media down to 0.82 a w than any other xerophile examined so far. In contrast, the Geomyces sp. was intolerant of salt. The Eurotium sp. was obligately xerophilic, with growth confined to the range 0.935-0.68 a w.