Biochemical Alterations of Dermatophytes during Growth.

Alterations in the biochemical constituents of mycelia were studied during the growth, development, and starvation of Microsporum quinckeanum. On the basis of dry weight, growth of this dermatophyte could be divided into four phases: lag, log, stationary, and death. The percentage of total nitrogen, inorganic phosphorus, ribonucleic acid (RNA), and protein increased rapidly during the lag phase. The percentage of protein remained constant after the initial increase; however, inorganic phosphate and RNA decreased in older mycelia. Acid-soluble materials in the cells increased in concentration as the organism aged. Chitin was present in the spores at a much higher concentration than in the mycelia. The percentage of this compound decreased rapidly until the end of the lag phase. An increase and subsequent decrease in per cent chitin occurred during the log phase. Inorganic phosphorus in the mycelia increased from the value in the spore stage to a maximum in the early log phase, and then decreased rapidly during the remainder of the growth cycle. Compounds involved in protein synthesis increased rapidly during the lag phase of growth. Changes in chemical composition of the mold during starvation indicate that carbohydrate does not form the principal endogenous reserve of M. quinckeanum, whereas lipids may represent the primary reserve material.