Distribution of plasmids in Bacillus aneurinolyticus was studied. 11 out of 20 strains of different origins contained several groups of plasmids of the molecular sizes of 1.3Md, 4.0Md, 6.6Md and bigger than 40Md. A typical strain (B. aneurinolyticus KA17), which harboured two small plasmids of 1.3 and 4.0Md, was treated with acridine orange, ethidium bromide, or serial transfer at 42℃ in order to cure the plasmids. Partially cured strains with either one of the two original plasmids were obtained. Using the wild strains and the cured derivatives, several physiological phenotypes were tested as to whether they were coded by those plasmids. The traits studied included thiaminase production, drug resistance, bacteriocinogenic activity, restriction endonuclease activity, hemolytic activity, and sporogenic activity. B. aneurinolyticus KA17 was found to produce DNA endonuclease which cut pUB110 DNA at a single site. All B. aneurinolyticus strains tested were found to exhibit α hemolytic activity on sheep blood agar. All of those characteristics tested were observed in both wild strains and the plasmid cured strains, and indicated to be chromosome coded. plasmids of B. aneurinolyticus strains remained to be cryptic through this study.
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