Anaerobic growth of psychrophilic bacteria.

Upadhyay, J. (Washington State University, Pullman) and J. L. Stokes. Anaerobic growth of psychrophilic bacteria. J. Bacteriol. 83:270-275. 1962.-Facultatively anaerobic psychrophilic bacteria are widely distributed in nature and can be readily isolated from a variety of foods, soil, sewage, and other habitats. Strictly anaerobic psychrophiles, however, could not be isolated. Temperature and oxygen have striking effects on the growth and metabolism of the psychrophiles. Sugars which are fermented at 20 C may not be fermented at 0 C or gas may not be produced. Under both aerobic and anaerobic conditions, decreases in incubation temperatures increase the duration of the lag, exponential, stationary, and death phases. Elimination of O(2) increases the lag period, allows the cells to survive much longer at low temperatures (but accelerates their death at 20 C and higher), and, finally, reduces the extent of growth. Maximal cell populations are obtained aerobically at 5 C and anaerobically at 25 C. Growth is most rapid in the range of 20 to 35 C, and maximal growth temperatures range from 25 to 45 C. Neither of these cardinal temperatures is appreciably affected by the presence or absence of O(2).