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Chaetomium brasiliensis requires aneurin for growth, and calcium (strontium or barium), aneurin and a low nutrient level for the formation of ascospores. Decreasing suboptimal doses of calcium progressively decrease the number of fertile perithecia until none is formed, the average perithecial size is reduced, but not the total number of perithecia. Above the optimum level, calcium delays formation of perithecia and ascospores and, ultimately, spore germination; it has no favourable effect on vegetative growth. The fungus appears able to synthesize aneurin slowly after growth is complete.

SUMMARY: The influence of certain carbohydrates, nitrogen compounds and accessory substances on the growth and sporulation of Chaetomium globosum and Memnoniella echinata has been studied. It has been confirmed that M. echinata needs an external supply of biotin, which has also a slight effect on the growth of Chaetomium globosum. For C. globosum, a very low level of soluble sugar in the medium was essential for the production of perithecia. With adequate biotin, Memnoniella echinata sporulated in the presence of considerable concentrations of sugar, but at low biotin levels no sporulation occurred until soluble sugar approached exhaustion. Jute extract stimulated growth and accelerated sporulation of Chaetomium globosum; this was not due to the presence in the extract of any of nine well-known B-group vitamins. Jute extract had no more influence on Memnoniella echinata than would be due to its biotin content.

SUMMARY: The effect of temperature and some chemical substances on the fruiting of strains of nine species of Chaetomium was studied. The optimum temperature for fruiting was generally lower than that for growth. Micro-nutrients of the nature of growth factors and starvation with respect to nutrients may both stimulate fruiting, whereas staling inhibits it, the ultimate balance between these effects determining the fruiting behaviour of a given species. These factors had no significant effect on the final amount of the vegetative growth within the conditions of the experiments.