[Amplification of the riboflavin operon genes of Bacillus subtilis in Escherichia coli cells].

Amplification of Bacillus subtilis DNA fragments was performed in Escherichia coli using plasmid RSF2124. The main principle of isolation and cloning hybrid plasmids was described using genes of riboflavin operon as a model. Bac. subtilis DNA was treated with restriction endonuclease EcoR; followed by the agarose gel electrophoretic separation of the resulting fragments. Gels were sliced, DNA was eluted from the corresponding slices and used to transform Bac. subtilis auxotrophs rib A72, rib S110 and rib D107. DNA fraction with the molecular weight 7 . 10(6) daltons restored prototrophy of these mutants. DNA of this fraction was ligated with EcoRI treated plasmid RSF2124 DNA and used for transformation of E. coli rk-mk+. Ampicillin resistant transformants which had lost the colicin production ability, were selected. The presence of riboflavin genes within the hybrid plasmids was detected by transformation of B. subtilis auxotrophs. Three hybrid plasmids (pPR1, pPR2 and pPR3), containing a fragment of Bac. subtilis DNA with the molecular weight 6.8 . 10(-6) daltons including riboflavin operon, were selected. The analysis of the transformation activity of Bac. subtilis DNA and plasmid pPR1 DNA revealed, that there was no restriction activity of Bac. subtilis cells against plasmid DNA amplified in E. coli. Heteroduplex analysis has shown that plasmids pPR1 and pPR2 differ in the orientation of Bac. subtilis DNA fragment. DNA of these plasmids restored prototrophy of the several studied E. coli riboflavin auxotrophs.