The production of alamethicins by Trichoderma spp.

The production of polypeptides containing a high percentage of 2-methylalanine residues by a number of isolates of Trichoderma spp. has been examined. It has been shown that good yields (0.5-1.0 g L-1) can be achieved on synthetic media provided an insoluble carbohydrate is included and provided single-spore isolates that have this production ability are selected from time to time. Such yields could not be obtained on any single nitrogen source investigated, but a mixture of potassium nitrate, glutamine, and 2-methylalanine was effective. It was shown that at least eight polypeptides were produced in shake-flask or tank fermentation and that the proportions of these metabolites depended on the fermentation temperature, its pH, age, and aeration. Fermentation conditions for enhancing the production (independently) of two of the metabolites at the expense of the others are given. These two metabolites have been obtained in crystalline form and details of some of their physical and chemical properties are given.