TRANSPOSON MUTAGENESIS IN DESULFOVIBRIO-DESULFURICANS - DEVELOPMENT OF A RANDOM MUTAGENESIS TOOL FROM TN7

The transposons Tn5, Tn7, Tn9, and Tn10 or their derivatives have been examined for transposition in the sulfate-reducing bacterium Desulfov ibrio desulfuricans G20, Tn7 inserted with a frequency of 10(-4) to 10 (-3) into a unique attachment site that shows strong homology with tho se sites identified in other gram-negative bacteria. Inactivation of t he tnsD gene in Tn7, encoding the function directing insertion into th e unique site, yielded a derivative that transposed essentially random ly with a frequency of ca. 10(-6) per donor, Derivatives of Tn5, but n ot wild-type Tn5, were also found to undergo random transposition at a similar frequency, No evidence was obtained for transposition of Tn9 or Tn10.