Litmocidin, a New Antibiotic Substance Produced by Proactinomyces cyaneus.

In a search for new antibiotic substances a soil actinomycete was isolated by us from a sample of south Russian soil that produces a powerful antibiotic substance of a new type. In this article a description of this organism is given, together with some details concerning the production of the antibiotic substance and its action upon pathogenic bacteria. A subsequent paper by M. G. Brazhnikova treats of the isolation and purification of litmocidin and outlines its chemical nature. The antagonist. The strain of actinomycete isolated by us is close to Actinococcus cyaneus, isolated by Beijerinck from garden soil in Holland in 1913. It forms well-developed mycelium which later disintegrates into single cells. Colonies produce deep-blue water-soluble pigment, which becomes red at an acid reaction, and blue at an alkaline reaction. A similar litmuslike pigment was recorded by Beijerinck. However, the conditions for the production of a litmuslike pigment by our microbe and by the Actinococcus of Beijerinck are very different. The latter readily produced pigment upon a mineral medium containing glucose and ammonium nitrate. Upon this medium our microbe is unable to produce a litmuslike pigment. The conditions for pigment production by our microbe are outlined in table 1. It is clear that either peptone or tryptone (still better both of them) is required for pigment production in our strain. In view of important differences in pigment production between our microbe and the Actinococcus of Beijerinck, and because of the strong antibiotic action of the litmuslike pigment produced by our microbe (nothing like this is reported by Beijerinck), it is proposed to designate the strain as a new variety, var. antibioticus. According to modern classification (Krasilnikov, 1945) the generic name Actinococcus should be replaced by Proactinomyces, and the complete name of the organism should be Proactinomyces cyaneus-antibioticus. It is to be pointed out that the production of a litmuslike pigment occurs in different groups of actinomycetes, and has been particularly well studied in Actinomyces coelicolor. As Kriss (1936) has shown, the pigment of the latter species belongs to the anthocyanines. It is also remarkable that the litmuslike pigment of A. coelicolor is devoid of antibiotic action (Krasilnikov, 1945). The anthocyanine pigments of plants are also devoid of antibiotic action, according to our experience. In the light of all this evidence it appears probable that the antibiotic, litmuslike pigment observed by us represents some specific modification of the common litmuslike pigment. As will be shown in the subsequent paper, the antibiotic