FIG. 1.

(A) Southern hybridization of HindIII-digested DNA from Tn917-lac biofilm-defective S. gordonii nosX::Tn917-lac mutant. A digoxigenin-labeled pTV32-OK containing Tn917-lac (which has two HindIII sites) was used as the probe. Three hybridizing bands were produced in HindIII-digested DNA, demonstrating the presence of a single transposon insertion. (B) Biofilm phenotypes of S. gordonii Challis 2 and nosX::Tn917-lac mutant as determined by the polystyrene microtiter plate assay and direct observation of biofilms formed on borosilicate glass surfaces by phase-contrast microscopy. Cells were grown in BM for 24 h at 37°C under anaerobic conditions.