THE GROWTH OF AEROBIC THERMOPHILIC BACTERIA

The thermophilic microbes are usually defined as organisms capable of growing at high temperatures. Such a definition does not imply that life at high tem-perature is actually linked with a modified physiology of nutrition, reproduction, etc. The microbes adapt themselves not only to high temperatures, but also to the physico-chemical peculiarities of their habitat at these temperatures. Such an ecological approach suggests that the thermophiles represent a rather isolated group of microbes differing somewhat in their biology from mesophilic bacteria. It was pointed out in previous publications that the biochemical activity of thermophilic bacteria is extremely high (Imsenecki, 1941a, 1941b). The leading role among the causes underlying this increased activity belongs to rapid growth of thermophiles, and for this reason the present study deals with the peculiarities of reproduction of the sporulating aerobic thermophilic bacteria. Someparallel experiments were also conducted with mesophilic bacteria. The Behavior of Thermophilic Bacteria at Relatively Low Temperatures Thermophilic bacteria very often occur at temperatures lower than those necessary for their growth. Hence it is commonly held that under such condi-tions the thermophiles are in a resting state (mostly in the spore state) and do not participate in the mineralization of organic matter. Revival of the thermophiles and the beginning of their active life is caused by a rise of temperature as linked, e.g., with heating of the superficial layers of the soil by sunlight or with self-heating of the disintegrating organic matter. Yet, inactivity of thermophiles at relatively low temperatures is sometimes denied. It was shown in a number of studies that the thermophiles are able to propagate not only at high but also at low temperatures, such as 20 to 30