The use of transposon Tn917 and Tn917-lacZ-cat fusions to study sporulation in Bacillus megaterium QM B1551

Abstract

Transposon Tn917 and Tn917-lacZ-cat, carried on plasmid pTV1 and pTV53 respectively, were introduced into B̲a̲c̲i̲l̲l̲u̲s̲ m̲e̲g̲a̲t̲e̲r̲i̲u̲m̲ and were induced to transpose. Insertional mutants were isolated in at least nine different auxotrophic loci and four sporulation loci. Pour Tn917 insertion s̲p̲o̲ mutants were found by transmission electron microscopy (TEM) to be blocked at stage III or stage V. In addition, a s̲p̲o̲::Tn9̲1̲7-l̲a̲c̲Z̲-c̲a̲t̲ mutant was further characterized by TEM as a s̲p̲o̲O̲ or probably s̲p̲o̲I̲I̲ mutant. B-galactosidase activity, encoded by the transcriptional fusion of the l̲a̲c̲Z̲ gene, began to appear at about t₇. The delayed expression of the s̲p̲o̲ gene was shown to be because of the host strain, since a transductant, obtained from crossing the spo locus to a normal sporulation strain, showed B-galactosidase activity beginning at t₂. The s̲p̲o̲ locus is cotransduced with t̲r̲p̲B̲, and with t̲r̲p̲E̲. This study has indicated very good prospects for the use of the Tn917 system to study sporulation in this species at both the molecular and genetic levels.