3 A spore-forming Gram-positive aerobic rod isolated from a persistent periapical lesion has biofilm-like structures

Abstract

We isolated a spore-forming Gram-positive aerobic rod from a persistent periapical lesion that was identified as Bacillus subtilis using an API system, 16 S rRNA sequencing, and DNA-DNA hybridization. We named it B. subtilis strain N 38. Scanning electron microscopy revealed that this strain had dense mesh-like structures on the cell surface, which is typical of biofilm-forming bacteria. Several genes, previously reported as crucial factors for biofilm formation in B. subtilis, were detected by the polymerase chain reaction method. Compared with the ATCC 6051, which is a type strain of B. subtilis, the susceptibility of strain N 38 to anti-microbial agents did not show a particular pattern. Our data suggest that biofilm-forming B. subtilis can cause persistent periapical periodontitis.