Transformation and transfection in lysogenic strains of Bacillus subtilis: evidence for selective induction of prophage in competent cells

Abstract

Lysogenic strains of Bacillus subtilis 168 were reduced in their level of transformation as compared to non-lysogenic strains. The level of transformation decreased even further if the competent lysogenic cells were allowed to incubate in growth media prior to selection on minimal agar. This reduction in the frequency of transformation was attributable to the selective elimination of transformed lysogenic cells from the competent population. Concurrent with the decrease in the number of transformants from a lysogenic competent population was the release of bacteriophage by these cells. The lysogenic bacteria demonstrated this dramatic release of bacteriophage only if the cells were grown to competence. Both the selective elimination of transformed lysogens and the induction of prophage was prevented by the inhibition of protein synthesis. Additionally, competent lysogenic cells released significantly higher amounts of exogenous donor transforming deoxyribonucleic acid than did competent nonlysogenic cells or competent lysogenic cells incubated with erythromycin. These data establish that the induction of the prophage from the competent lysogenic cells was responsible for the selective elimination of the lysogenic transformants. A model is presented that accounts for the induction of the prophage from competent lysogenic bacteria via the induction of a repair system. It is postulated that a repair system is induced or derepressed by the accumulation of gaps in the chromosomes of competent bacteria. This hypothetical enzyme(s) is ultimately responsible for the induction of the prophage and the selective elimination of transformants. Lysogenic conversion can markedly influence the capacity of a wide range of bacterial species to undergo deoxyribonucleic acid (DNA) mediated transformation and transfection. For instance, Staphylococcus aureus can be made competent only in the presence of temperate bacteriophage 441 (29, 34). Similarly, Bacillus stearothermophilus requires the temperate bacteriophage TP-12 for the development of competence (N. E. Welker and M. E. Eager, Abstr. Annu. Meet. Amer. Soc. Microbiol. 1972, V98, p. 201). Apparently this virus enables the cell to produce the competence factor(s) required for the binding of DNA to the cytoplasmic membrane (38). On the other hand, in Bacillus subtilis (27, 44, 45, 47) and streptococci (25), lysogeny inhibits DNA-mediated transformation. Although transformation is reduced in competent lysogenic cultures of B. subtilis,

More than a hole: the holin lethal function may be required to fully sensitize bacteria to the lytic action of canonical endolysins

“…T4 DNA ligase and the 1 kb Plus DNA Ladder were from Invitrogen (Thermo Fisher Scientific, USA). Development of competence and transformation of E. coli and B. subtilis strains was as described by Chung et al (1989) and Yasbin et al (1975), respectively. Constructs were confirmed by DNA sequencing (GATC Biotech, Germany).…”

Bacillus subtilis strain deficient for the protein‐tyrosine kinase PtkA exhibits impaired DNA replication

“…Transformability of B. subtilis strains (wild type, DptkA and DptpZ) was assayed according to Yasbin et al (1975). B. subtilis cells were transformed with 1 mg of the plasmid pDG-268neo (Mijakovic et al, 2006), and different dilutions were plated on LB plates (supplemented with appropriate antibiotics) for colony counting.…”

Transfection of Enterobacteriaceae and its applications.

“…Similarly, rec+ lysogens of H. influenzae were induced to release phage by treatment of competent cells with transforming DNA (347). Finally, it was found that making B. subtilis lysogens competent induced these cells to produce a burst of progeny phage (124,465). Thus what looked like a fundamental difference between competence for transformation and transfection turned out to be an artefact produced by the killing of lysogenic competent cells after phage induction.…”