Using a previously reported conditional expression system for use in
Bacillus subtilis(A. P. Bhavsar, X. Zhao, and E. D. Brown, Appl. Environ. Microbiol. 67:403–410, 2001), we report the first precise deletion of a teichoic acid biosynthesis ( tag) gene, tagD,in B. subtilis. This teichoic acid mutant showed a lethal phenotype when characterized at a physiological temperature and in a defined genetic background. This tagDmutant was subject to full phenotypic rescue upon expression of the complementing copy of tagD.Depletion of the tagDgene product (glycerol 3-phosphate cytidylyltransferase) via modulated expression of tagDfrom the amyElocus revealed structural defects centered on shape, septation, and division. Thickening of the wall and ultimately lysis followed these events.