Probiotic bacteria from asymptomatic necrotic tooth can regulate the microbiome homeostasis

This study was performed to identify and isolate the dominant bacteria from a chronic asymptomatic necrotic root canal and investigate in vitro its potential postbiotics effect at the biofilm maturation maintaining root canal microbiome homeostasis.

For bacterial identification of an in vivo root canal sample, metagenomic analysis was applied, followed by single colony isolation and PCR analysis. Cell free supernatant (CFS) was then cultivated through serial L paracasei culture procedures prior antibiofilm analysis. Antibiofilm effects of the CFS product were evaluated using in vitro biofilm analysis against S. mutans and E. faecalis. Biofilm mass analysis was measured by using colorimetric approach with cresyl-vast violet staining, morphological appearance was observed using both phase-contrast and scanning electron microscope (SEM). Shapiro-Wilk analysis was applied for normality test, followed by the ANOVA to compare multiple groups or a student t-test for independent two groups mean comparisons.

The isolated root canal bacteria produced biofilm mass that was similar to the Enterococcus faecalis control pathogenic biofilm. From the morphological analysis suggested that population of the isolated bacteria were predominantly occupied by rod-shaped rather than cocci-shaped inhabitants. Further metagenomic analysis indicated that the isolated dominant bacteria in the mixed culture were mainly identified as probiotic bacteria, Lacticaseibacillus paracasei. Moreover, the functional analysis revealed that the L. paracasei cell free supernatant product (CFS) exhibited a promising positive effect in biofilm structure integrity disturbances of S. mutans and E. faecalis.

The isolated Lacticaseibacillus paracasei from the root canal of a chronic asymptomatic necrotic tooth, produces potential postbiotic products that demonstrated a disruptive ability against Streptococcus mutans and Enterococcus faecalis biofilm integrity.