Controlled cellular redox, repressive hemin utilization and adaptive stress responses are crucial to metronidazole tolerance of Porphyromonas gingivalis persisters.

Li, Peng; Fung, Yi‐Man Eva; Yin, Xiaohui; Seneviratne, Chaminda J.; Che, Chi‐Ming; Jin, Lijian

Background: Antimicrobial‐tolerant microbial persisters critically account for various infections and inflammation. This study identified the characteristics of Porphyromonas gingivalis persisters, and explored their underlying survival mechanisms through proteomic profiling. Methods: Porphyromonas gingivalis cultured with different concentrations of hemin was treated with 100 μg/ml of metronidazole (MTZ). The viability of P. gingivalis persisters was determined by colony‐forming unit assay and LIVE/DEAD staining. The proteomic signature of P. gingivalis persister fractions was examined using LC‐MS/MS and bioinformatic analysis. Results: A small fraction of P. gingivalis persisters survived from lethal MTZ treatment without heritability. At late exponential phase, the frequency of these persisters significantly increased when incubated with 1 μg/ml of hemin compared to 10 μg/ml. Higher levels of P. gingivalis persisters formed at stationary phase than the late exponential phase. High‐throughput proteomic analysis showed that the persisters markedly downregulated multiple proteins involved in electron transfer and heme/iron utilization essential for redox regulation and MTZ activation. Moreover, the persisters enabled to shut down major cellular activities (e.g. translation) and overexpress stress proteins. Conclusion: The presence and survival of metronidazole‐tolerant P. gingivalis persisters may be dominated by regulation of cellular redox state and enhanced via repression of heme/iron utilization, dormancy and stress responses.

METRONIDAZOLE; PORPHYROMONAS gingivalis; MULTIDRUG tolerance (Microbiology); OXIDATION-reduction reaction; HEMIN; PHYSIOLOGICAL stress; PHYSIOLOGICAL adaptation; PROTEOMICS; BACTERIAL diseases; IRON; LIQUID chromatography; MASS spectrometry; REPRESSION (Psychology); SURVIVAL; BIOINFORMATICS; METALLOPORPHYRINS; GRAM-negative anaerobic bacteria; THERAPEUTICS

Journal of Clinical Periodontology, 2018, Vol 45, Issue 10, p1211

0303-6979

Academic Journal

10.1111/jcpe.13002