Temperate and virulent forms of phage theta attacking Bacillus licheniformis |
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Authors: | J Doskocil J Forstová J Stokrová |
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Institution: | (1) Czechoslovak Academy of Sciences, Institute of Molecular Genetics, Flemingovo n.2, 166 10 Praha 6, Czechoslovakia |
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Abstract: | Summary Clear-plaque phage c, attacking bacitracin-producing strains of B. licheniformis, yields spontaneous temperate mutants at high frequency; the temperate mutants fall into several classes phenotypically different in plaque morphology and properties of lysogenised bacteria. The most common phenotype 3 has DNA restriction fragment patterns identical with those of the parent c; some less common temperate forms, i.e. 1 and 2, produce different restriction fragment patterns, sugesting that a part of the original c DNA has been reorganized or replaced by some foreign genetic material. The changed fragment pattern remains stable upon subsequent passaging of the phage or of the lysogenic bacteria. Neither class of temperate phage mutants gives clearplaque revertants at measurable frequency. Lysogenisation of bacteria with any class of temperate phage confers immunity to all temperate forms and to c; virulent mutants vir, which plate with 100% efficiency on lysogens for 1 and 2 but not for 3, occur in stocks of c at a frequency of 10–7. The mutation from c to vir is not accompanied by any change of the restriction fragment patterns of DNA. |
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