Isolation of thermophilic streptomycetes.

The thermophilic streptomycetes, growing in the temperature range of 55 to 65 C, have remained a little known group of microorganisms. Since their discovery in 1888 by Golbig, their physiology, metabolism, metabolic products, natural habitat, and even their morphology have remained unknown or in the realm of conjecture. It was only in the latest edition of Bergey's Manual of Determinative Bacteriology (Breed et al., 1957) that Waksman introduced 2 new species and only in the last 6 years has any attempt been made to study their metabolism and physiology (Erikson and Webley, 1953; Erikson, 1952, 1955; Reed, 1956; Webley, 1954). Erikson reports only 7 isolates in her collection (Erikson, 1953), whereas Reed lists 2. The existence of other collections of any size are unknown to the authors. The methods of isolation and cultivation outlined by Waksman et al. (1939) and Erikson (1952) led the authors to believe that lack of interest in the group and want of knowledge concerning it depended on the difficulties entailed in isolation and cultivation of the organisms. A few cultures were isolated in this department by methods recommended by Waksman and Erikson, but the process of obtaining them was laborious. Growth was scant, many cultures were lost in transfer, and sporulation was poor. The process of isolating and cultivating these organisms left much to be desired. As a preliminary step in a study of the streptomyeetes growing at 60 C, isolation and cultivation techniques were studied to make procurement and maintenance of cultures in luxuriant growth relatively simple. Waksman and Erikson had made isolations in petri dishes on an agar medium, but such a technique was hampered by spreading thermophilic bacteria. It was learned by observation that during prolonged incubation at 60 C, the strepto-