Response of Fungi to Diurnal Temperature Extremes

Abstract

REPEATED freezing and thawing of bacteria is generally considered to be lethal^1,2, but Aerobacter aerogenes and a Pseudomonas species have survived and grown well in experiments simulating Martian temperature extremes of about +25° C to −75° C (ref. 3). The bacteria spent only about 4.5 h above 0° C with a maximum near 25° C in each 24 h cycle. Growth rates in liquid media were found to be comparable with the non-cycled controls held at 25° C. In similar work with desert algal-lichen soil crusts⁴, the algae survived repeated freezing and thawing but did not grow during the treatment. The algae were grown later on a modified Pochon solution incubated at 27° C–30° C. The diurnal temperature extremes were −79° C or −195° C for 15 h and 22° C for 9 h for periods of 1–7 days. As far as is known, no comparable work has been done on the response of fungi to diurnal temperature extremes.