Cotransduction and cotransformation of genetic markers in Bacillus subtilis and Bacillus licheniformis.

Bacteriophage SP-15, a large generalized transducing phage of Bacillus, was compared with phages PBS-1 and SP-10 for the ability to cotransduce pairs of genetic markers exhibiting different degrees of linkage. When auxotrophs of B. subtilis W-23 were used as recipients, SP-15 and PBS-1 effected a much higher frequency of cotransduction than did SP-10 with markers that were not closely linked. With more closely linked loci, the differences were not as great. SP-15 cotransduced linked markers at a higher mean frequency than PBS-1, suggesting that SP-15 is able to transfer a larger fragment of the Bacillus genome than any phage heretofore described. The frequency of the joint transfer of genetic markers in B. licheniformis was lower via transforming deoxyribonucleic acid than by transduction with phage SP-10. The availability of three procedures for genetic exchange-transduction by SP-15 and SP-10 as well as transformation-each of which reveals a different degree of linkage, makes B. licheniformis 9945A especially amenable to genetic analysis.