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.

A purple pigment, named cochliodinol, C32H32N2O4, has been isolated from three isolates of Chaetomium cochliodes and from two isolates of Chaetomium globosum. The pigment is produced intracellularly on a wide range of media in quantities up to 0.45 mg/ml. The rate of production for a given isolate is proportional to its growth but such proportionality is not observed when one isolate is compared to another. A second, fluorescent pigment, C32 H28N2O4, is produced by those isolates that produce cochliodinol but in 1/500 of the yield.

Laboratory cultures of Trichoderma hamatum produce metabolites that are characterized by an isocyanide functionality. Three such metabolites predominate. One is the known compound trichoviridin (I). The other two, described here for the first time, are 3-(3-isocyano-6-oxabicyclo[3,1,0]hex-2-en-5-yl)acrylic acid (II) and a very unstable compound 3-(3-isocyanocyclopent-2-enylidene-)propionic acid (III). Production of these three metabolites by a random sample of wild isolates of the fungus has been examined. At least one of these isocyanides was isolated from all cultures in which the culture broth inhibited the growth of Micrococcus luteus. The relative amounts of the three isocyanides produced by individual isolates were not the same and cultures were found in which I, II, or III was the main product. The isocyanide III was produced by all wild isolates which had antibiotic activity in their culture broth, and it was present in the concentration range 2-40 mg X L-1.

SUMMARYThe growth of ewe lambs of the Shropshire breed declined and in some cases ceased at the end of July, when they grazed permanent pastures at the Experimental Farm, Nappan, Nova Scotia. This decline in growth coincided with a decrease of about three orders of magnitude in the numbers of viable rumen bacteria. At the end of July an increase of one to two orders of magnitude was observed in the numbers of viable fungi collected from the pastures. Lambs grazing pastures developed from tidal marsh of the Bay of Fundy had a better growth performance than lambs grazing adjacent pastures developed from mixed conifer-deciduous forest. The forest soils supported a greater fungal population than the marshland soil, and several species were found predominantly on the forest soil.

Polyporic acid, atromentin, bovinone, and oosporein are common metabolic products of a number of species of fungi. The related compound cochliodinol and its congeners are produced by several Chaetomium spp. These quinonoid metabolites have been shown to inhibit the growth and metabolism of a range of bacterial genera. The antibiotic activity of the quinones depends on the substituents at the 3 and 6 positions of the 2,5-dihydroxy-1,4-benzoquinone ring; in aerobic systems the activity appears to be inversely proportional to the polarity of the metabolite. It has been shown that reduction of the quinone to the hydroquinone changes the antibiotic activity of these metabolites but does not abolish it. Contrary to previous reports, the activity of these hydroquinones is not reversed by cysteine.