Methods for mutation and selection of the ergot fungus.

A new method is described in which the Salkowski reaction is used for the rapid selection of alkaloid-producing mutants of the ergot fungus. This method was used to investigate the influence of a second mutation with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) on various mutants selected by a preliminary NTG mutation of Claviceps sp. strain SD 58. Three groups of mutants were used: high alkaloid producers, low alkaloid producers, and auxotrophs. Results indicated that a second mutation of all three types of mutants could improve alkaloid yield and vegetative vigor. In addition, a second mutation increased the frequency of auxotroph production. The difficulty of producing stable mutants from ergot strains that have multinucleated cells and that do not readily produce conidia in culture, such as an ergotamine-producing strain, was overcome by first forming protoplasts of the fungus and then subjecting them to the mutagen. Stable auxotrophs were obtained in this manner.