| Prevention and treatment of mold in library collections with an emphasis on tropical climates: A RAMP study |
|2.2 Environmental and nutritional factors in growth and survival|
There are three critical temperatures for mold, the temperature below which no growth occurs, the temperature above which no growth occurs, and the temperature at which most rapid growth takes place. Most microbial forms grow in temperatures ranging from 59º to 95º F (15º to 35° C), although there are forms which will grow at almost freezing and others which thrive at over 150º F. The average optimum for mold growth is usually stated to be in the vicinity of 86° F. The optimum temperature for the growth of specific molds is difficult to determine, in part because of variables in other environmental conditions, and in part because the culturing of organisms in the laboratory is a very different matter than the growth of the same organism in more natural surroundings.
It should be noted that the temperature below which no growth occurs is not synonymous with the temperature at which the potential for growth is destroyed. Many molds can survive periods of several months at sub-zero temperatures, but are less tolerant of alternating below-freezing and above-freezing temperatures.11
Sykes, speaking of bacteria, says:
Refrigeration at low temperatures...is popularly considered to be fatal to all forms of life. Whilst this may be true for the larger forms of organized life, it is certainly not true for the smaller plant life, including micro-organisms....sometimes the death rate is as high as 99% but once frozen at a sufficiently low temperature the surviving cells can be preserved for long periods.12
Given the existence of the "hold-over" spores, this undoubtedly applies to molds as well.