Genomic sequencing of a Porphyromonas gingivalis W50 PG1879 mutant

Porphyromonas gingivalis is a keystone pathogen in chronic periodontitis. A P. gingivalis mutant, lacking the predicted inner membrane (IM)-associated patatin/PLA2 superfamily member PG1879, did not exhibit a death phase, but instead a prolonged stationary phase. The surviving cells exhibited intact cell membranes and 11-day-old culture regrowth. Contrastingly, the wild type entered death phase, showed a compromised IM and did not regrow under identical conditions. Lipidomic analysis revealed 29 lipid classes, with 16 being novel, and common membrane lipid remodelling that enabled survival during stationary phase. Sequencing of the genome of the PG1879 mutant was undertaken to look for any secondary mutations that could result in the observed phenotype; the mutant was also complemented.