Studies on Nonfruiting Myxobacteria

Abstract

C.johnsonae is a chitin-decomposing myxobacterium which was isolated from soil by means of aerobic chitin enrichment cultures. It appears to be a common member of the chitin-decomposing micro-flora of soil. All strains proved to be nutritionally unspecial-ized; they developed well in mineral media containing any one of a wide variety of heat-sterilized carbohydrates, and also in carbohydrate-free peptone media. The morphology is variable, and in some respects atypical. Creeping motility, although evidenced on suitable media, can be entirely su-pressed by high nutrient concentrations; under such conditions, the organisms simulate eubacteria. The factors influencing colony form were analyzed, and it was shown that the cone, of nutrients and the gel strength play important roles in this respect. Following a discussion of the means of differentiation between cytophagas and Gram-negative, rod-shaped eubacteria, the present taxonomic status of the Cytophaga group is reviewed.