No abstract

No abstract

Clostridium barkeri sp. n. has been described, and its relationship to other clostridia is discussed.

NOTES magnitude of about one-tenth. The other genera are generally less active, with some of the leuconostocs and the lactobacilli displaying only feeble, though readily demonstrable, catalase activity. There is some evidence for slight azide inhibition in preparations of cells grown in the absence of azide. This phenomenon is reminiscent of the findings of Whittenbury (Nature 187:433, 1960), who observed the formation of a catalase in certain heterofermentative lactic acid bacteria, apparently through the coupling of an apocatalase with free hematin or the hematin from blood. With the preparations of Lactobacillus, Leuconostoc, and Streptococcus obtained from cultures grown in the presence of sodium azide, the insensitivity seems absolute. We conclude, therefore, that these s-stems, as with Pediococcus, do not contain heme iron, or at least (lo not involve heme-iron components. We are indebted to our colleague, C. S. Pederson, to C. F. Niven of the Amiierican Meat Institute Foundation, anid to C. W1'. Langston of the U. S. Department of Agriculture, Beltsville laboratories, all of wvhom furnished cultures for our current work.

Thirty-one soil samples were examined for the presence of organisms capable of inhibiting growth and toxin production of strains of Clostridium botulinum type A. Such organisms were found in eight samples of soil. Inhibiting strains of C. perfringens were found in five samples, of C. sporogenes in three and of Bacillus cereus in three. Three of the C. perfringens strains produced an inhibitor effective on all 11 strains of C. botulinum type A against which they were tested, seven of eight proteolytic type B strains, one nonproteolytic type B strain, five of nine type E strains and all seven type F strains, whether proteolytic or nonproteolytic. They did not inhibit any of 26 type C strains, 6 type D strains, 4 type E strains, or 24 C. sporogenes strains. In mixed culture, an inhibitor strain of C. perfringens repressed growth and toxin production by a C. botulinum type A strain even though it was outnumbered by the latter about 40 times. It also repressed growth and toxin production of C. botulinum in mixed culture of soils in which this latter organism naturally occurred when cooked meat medium but not when trypticase medium was used.