TABLE 1.

B. subtilis strains used in this study

Strain	Relevant genotype	Source or constructiona
168	trpC2	Laboratory stock
CWLBn	trpC2 cwlB::pUCNcwlB	pUCNcwlBb→168
CWLCc	trpC2 cwlC::pCAcwlC	pCAcwlCc→168
CWLHd	trpC2 cwlH::pMUTincwlH	pMUTincwlHd→168
CWLBC	trpC2 cwlB::pUCNcwlB cwlC::pCAcwlC	CWLBn→CWLCc
CWLBCH	trpC2 cwlB::pUCNcwlB cwlC::pCAcwlC cwlH::pMUTincwlH	CWLHd→CWLBC
NUCBs	trpC2 nucB::pUCSnucB	pUCSnucBe→168

^aArrows indicate transformation from donor DNA to the recipient strain.

^bFirst, to obtain the vector pUCN192 harboring the bla and neo genes, a PstI/EcoRI DNA fragment carrying the neo gene of pBEST501 (4) was blunted by treatment of the DNA with T4 DNA polymerase in the presence of deoxynucleoside triphosphates and then ligated with DNA containing the T4 DNA polymerase-treated NdeI site of pUC19 (17). pUCNcwlB is a derivative of an integrational plasmid, pUCN192, carrying a 188-bp internal segment of cwlB that was generated with primers cwlBF (5′-CCCAAGCTTAATGTGTTTTCTGGGGC-3′ [underlining indicates a restriction site]) and cwlBR (5′-CGCGGATCCTAGTGTAAAGCAATGGC-3′).

^cpCAcwlC is a derivative of an integrational plasmid, pCA191 (7), carrying a 1,176-bp internal segment of cwlC that was generated with primers cwlCF (5′-CGCGGATCCTTTTATTGATCCTGGCC-3′) and cwlCR (5′-TGCTCTAGAAATCTGCTCCCCAGTTA-3′).

^dpMUTincwlH is a derivative of an integrational plasmid, pMUTinT3 (10), carrying a 162-bp internal segment of cwlH that was generated with primers cwlHF (5′-AAGAAGCTTTAATCGTCCTGGCTATG-3′) and cwlHR (5′-GGAGGATCCATTGTTTTCCTTCATCA-3′).

^epUCSnucB is a derivative of an integrational plasmid, pUCS192 (3), carrying a 93-bp internal segment of nucB that was generated with primers nucBF (5′-CCCAAGCTTCCTGTTTCTTGCTGCAG-3′) and nucBR (5′-CGCGGATCCCTAATATGACTGCCGGT-3′).