Effect of Temperature on Growth Rate of Seven Thermophilic Fungi

Abstract

Thermophilic fungi, those with a minimum temperature required for growth of 20 C or above and a maximum temperature for growth of 50 C or above, are important in the decomposition of organic matter (3). These and similar organisms are involved in the preparation of mushroom compost (1, 3, 5, 6). Furthermore, thermophilic fungi apparently take part in thermogenesis and spontaneous combustion which cause appreciable financial losses (3). Some diseases affecting animals, including man, involve the thermophilic fungi (3). Cooney and Emerson (3), Cochrane (2), Tansey (8) and Fergus (5) have shown a need for further investigation of the influence of temperature on growth rate and development of thermophilic fungi. Of the thermophilic fungi that have been studied in this regard, only a few have been investigated in detail. Preliminary investigations (good growth and reproduction on YpSs agar at 45 C) indicated that Huimicola insolens Cooney et Emerson, Talaromyces thermophilus Stolk, Humicola grisea (Traaen) var. therm oidea Cooney et Emerson, Sporotrichtu thermophile Apinis, Malbranchea pulchella Sacc. et Penzig var. sulfurea (Miehe) Cooney et Emerson, Mucor miehei Cooney et Emerson and Papulaspora thermophila Fergus would be excellent subjects for an investigation that might extend our knowledge about the effects of temperature on growth rate and reproduction of thermophilic fungi. The organisms were supplied by Dr. C. L. Fergus. A variation of YpSs (3) medium of the following composition was used for the experiment: yeast extract, 2 g; K2HPO4, 1 g; MgSO47H20, 0.5 g; soluble starch, 4 g; distilled water, 1,000 ml; agar (Difco 542