Mapping and disruption of the cybB gene coding for cytochrome b561 in Escherichia coli

Abstract The cybB gene on a plasmid encoding cytochrome b ₅₆₁ in Escherichia coli was disrupted by insertion of Km^rl determinant DNA. The cromosomal cybB gene was replaced by the inactivated cybB gene on the plasmid by homologous recombination using λ phage lysogenization and heat-induction. The replacement was confirmed by Southern and Western blotting analyses. Deficiency on the cybB gene product did not affect the growth properties of the cells, and the oxidase activities of the cells dependent on various substrates were similar to those of the parental strain. Cytochrome b ₅₆₁ is concluded to be expressed in E. coli , but may not play a major role in cell growth. In the genetic map of E. coli , the cybB gene was determined by conjugational and transductional crosses to be at 31 min between trg and terC .     

Distribution of Clostridium botulinum in Japan and in Shinkiang district of China

Soil specimens obtained from several areas of Japan, which are closely located to or facing the Continental land of China, were examined for the distribution of Clostridium botulinum, especially pertaining to types A and B. A total of 266 specimens of Japan, when cultured, showed no type A or B toxicity, although 30 (11.3%), 4 (1.5%), and 10 (3.8%) of the specimens showed C1, C2, and type E toxicities, respectively. On the contrary, types A and/or B toxicities were shown, by the same method, in 14 of 20 specimens of Shinkiang district, China. The highest number of C. botulinum cells found in one gram of soil specimen was 25 for type A and 10 for type B.