Mating behaviour of Ctenomyces serratus.

Nineteen isolates of Ctenomyces serratus including three pairs of tester strains were crossed in all possible combinations on diluted Pablum cereal agar with added salts, oatmeal salts agar-Medium E, and soil and hair medium. Out of 190 crosses, 18 were fertile and the remaining 172 were sterile. Of the 19 isolates, seven were '-' mating type, 11 were '+' mating type, and one (UAMH 1959) was non-fertile with the other isolates. The high degree of non-fertile crosses among the 19 isolates shows that the use of mating reactions for the identification of conidial isolates of C. serratus may not be a practical tool, unless a large number of isolates belonging to both the mating types are employed. The production of exudate droplets in the fertile crosses seemed to be correlated with the degree of mating response. Ascocarp morphology corresponded closely to that of a cleistothecium, because of the completely closed nature. Ascospores were quite alike in their size, but they differed in shape, depending on their orientation.