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SURVIVAL AND GROWTH OF MICROCOLONIAL ROCK FUNGI AS AFFECTED BY TEMPERATURE AND HUMIDITY

1987; Wiley; Volume: 107; Issue: 1 Linguagem: Inglês

10.1111/j.1469-8137.1987.tb04889.x

1469-8137

F. Palmer, Delphine EMERY, Jayson Stemmler, James T. Staley,

Plant Pathogens and Fungal Diseases

S ummary Microcolonial rock fungi occur most typically in conditions of high temperature, sparse water, and low nutrients. This study was designed to assess their growth and survival under various conditions of temperature and relative humidity. In one set of experiments, rocks containing microcolonial fungi (MCF) from Arizona and Oregon deserts were exposed in the laboratory to different temperatures and humidities, and the survival of MCF was tested by transferring them to growth medium. The survival of MCF from Oregon and Arizona rocks was similar: many survived at 70 and 80°C even after 21 d of exposure. Those from the Sonoran Desert in Arizona which were exposed to 100°C were dead after 4 d. Low humidity favoured tolerance to high temperatures. Pure cultures of MCF from these locales in the USA as well as from Australia and Egypt were tested for growth at various temperatures and relative humidities. No isolates were able to grow at water activities below 0–95. Some strains grew at temperatures as low as 4°C, but none grew at 50°C or higher. These results indicate that these MCF are not able to grow during the hot periods encountered on desert rock surfaces regardless of the humidity, but they are able to survive for extended periods under these conditions.