Interaction of protoplasts, L forms, and bacilli of Bacillus subtilis with 12 strains of bacteriophage

Abstract

The interaction of 12 phage strains with bacilli, protoplasts, and L forms of Bacillus subtilis 168 and with eight of its mutants and two of its lysogens is described qualitatively and quantitatively. After removal of the cell wall from B. subtilis 168, 11 of the 12 phage strains can still adsorb to the protoplasts, nine kill their wall-less host cells, and five multiply in the naked bacteria, forming plaques on L form lawns. Individual gene mutations can have similarly pleiotropic effects, strongly dependent upon the plating medium. Thus, the gta A mutation, which causes loss of glucosylation of the wall teichoic acid, results in loss of wall adsorption sites for phi (but not membrane sites) and for phi105. Phages phi25, SP82G and phie can still adsorb to gta A bacilli and plaque in unstabilized and sorbitol-stabilized lawns of this mutant, but they can not plaque in sucrose-stabilized lawns. The lysogenized wild type, B. subtilis 168 (SPO2), also exhibits a pleiotropic pattern, showing different levels of resistance to phages SPO2, phi1, phie, and phi25. Its resistance pattern is very similar to that of wild-type protoplasts. On the basis of such patterns, the bacterial mutants and strain B. subtilis 168 (SPO2) could be ordered into four classes and the phage strains classified into four to six groups. Together, they form four to six interaction complexes, based partly on adsorption sites and perhaps partly on metabolic blocks in phage development.