Nosiheptide (9671 R.P.) isolated from Streptomyces actuosus 40037 (NRRL 2954) is a sulfur-containing polypeptidic antibiotic, quite different from all the other members of this family. Very active in vitro against gram-positive bacteria, it is inactive in vivo in experimentally infected mice. Not toxic, even at high dose, it may be used as a feed additive for chickens and pigs and it shows a favourable effect on the growth and conversion index.

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SummaryThe research carried out by several scientists has made possible the industrial preparation of B-carotene by fermentation. A fungus, Blakeslea trispora, abundantly synthesizes carotenoids when its two opposite forms are cultivated together in a special fatty medium. When ionones or other natural substances are introduced into the culture, a very obvious increase in the biosynthesis of carotenoids, more specifically of p-carotene, is obtained.Our own work has shown that: (1) several synthetic products chemically related to p-ionone, such as 2,6,6-trimethyl-l-acetylcyclohexene, can advantageously replace either partially or totally t.he ionones as inductors of the biosynthesis of p-carotene; (2) various nitrogen-containing substances when added to the culture medium can considerably enhance the biosynthesis of carotenoids while sometimes very specifically orienting it. Their action comes on top of that of the ionones or their substitutes; actually this action is unexplained.Thus certain amides, imides, lactams, hydraaides, or substituted pyridines, and in particular succinimide and isonicotinoylhydrazine, have produced a two or threefold increase in the quantity of @-carotene present in the culture media of Blakeslea trispora.Conversely some heterocyclic substances such as pyridine itself or imidazole totally inhibit the biosynthesis of 6-carotene but induce the production of very important quantities of lycopene.

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