Myxobacteria in soils and composts: their distribution, number and lytic action on bacteria

sp. are widely distributed in the soils of Great Britain including some treated only with artificial fertilizers. Myxococcus Wirescens and Chondrococeecs exiguus appear to be the dominant species. The numbers of myxobacteria ranged from 2000 to 76,4OO/g. of soil. In an actively decomposing compost of sludge and straw the number of Myxococcus fulvus was found to be over 500,00O/g.; M. virescens and Chondrococcus exiguus were also present, but less abundantly. Variation of pH between 4.0 and 8.8 does not affect the growth of My~ococcus fulvus, M. virescens and Chondrococcus exiguus, and normal fruiting bodies were produced in the presence of suitable bacteria. Myxococcus fulvus and M. virescens do not attack filter paper. Both Gram-positive and Gram-negative bacteria growing on solid media may be lysed by extracellular secretions of M. virescens, M. fulvus and Chondrococcus exiguus. Of forty-seven Gram-positive and forty-seven Gram-negative strains of bacteria tested with three species of myxobacteria, a higher percentage of Gram-negative than of Gram-positive strains was attacked. Pigmented strains of bacteri