DISTRIBUTION OF GEOPHILIC DERMATOPHYTES AND OTHER KERATINOPHILIC FUNGI IN RELATION TO PH OF SOIL

Keratinophilic fungi have been isolated from 178 (71.3 %) out of 250 soil samples taken from different sites in the surroundings of Berlin. The pH-values of the soils recorded vary within a range from 3.0 to 8.0. Most of the soils with the lowest pH (3.0-4.5) do not yield keratinophilic fungi while almost all of them with a pH higher than 5 do contain 1 to 6 kerationphilic species. The average pH of soils negative for these fungi is pH 4.1, the average pH of positive samples is 5.8. The distribution of individual species is also influenced by the pH of the soil. Only Kerationmyces ajelloi is recovered in the same rate from soils with pH lower and higher than 6, the other species more frequently occur in weakly acid to weakly alkaline reacting soils. The development of keratinophilic and keratinolytic fungi generally seems to be favoured under nearly neutral to weakly alkaline conditions. A similar range of pH has proved to be the most favourable to several metabolic activities of these fungi. The pH-optima of enzymes excreted by dermatophytes have been found to be within this range. Enzyme activity is inhibited if the pH of the substrate decreases below 4.0. The absence of keratinophilic fungi in strongly acid soils may therefore be due to the inhibition of enzyme activities under these conditions. © 1969 Dr. W. Junk N.V.