Lactobacillus acidophilus impairs the establishment of pathogens in a subgingival multispecies biofilm

Abstract

The present study evaluated the antibiofilm effects of Lactobacillus acidophilus within a subgingival multispecies biofilm. Lactobacillus acidophilus (La5) at 1 × 10², 1 × 10⁴, and 1 × 10⁶ were included at the beginning of biofilm formation, which lasted 7 days. The biofilms comprised 33 periodontitis-related bacterial species and the Calgary Biofilm device was used. At the end, DNA-DNA hybridization (checkerboard) was performed. A Kruskal-Wallis test followed by a Dunn post hoc test were performed (p ≤ 0.05). La5 at 1 × 10⁴ and 1 × 10⁶ reduced the total counts of biofilm and the proportions of red and green complexes when compared to the control biofilm without La5 (p ≤ 0.05). La5 at 1 × 10⁴ increased the proportions of Actinomyces complex compared to the controls (p ≤ 0.05). Both La5 at 1 × 10⁴ and 1 × 10⁶ decreased levels of 20 and 14 distinct species, respectively, including Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum polymorphum, and Parvimonas micra compared to the control (p ≤ 0.05). Only La5 at 1 × 10⁴ reduced the levels of Tannerella forsythia, Fusobacterium periodonticum, and Aggregatibacter actinomycetencomytans compared to the control (p ≤ 0.05). L. acidophilus inhibited establishing periodontic pathogens from red complex such as P. gingivalis and T. forsythia in a subgingival multispecies biofilm.

Keywords: Lactobacillus acidophilus; bacteria; periodontitis; probiotics; subgingival biofilm.

Figure 1

Mean counts of La5 after 7 days of biofilm formation within a multispecies biofilm. Different letters indicate statistical significance between groups by Kruskal–Wallis followed by Dunn's post hoc test (p ≤ 0.05). La5 × 10² means initial inoculum with La5 × 10² CFU/mL; La5 × 10⁴ means initial inoculum with La5 × 10⁴ CFU/mL; and La5 × 10⁶ means initial inoculum with La5 × 10⁶ CFU/mL.

Figure 2

Mean total counts of multispecies biofilm without any treatment (control) and treated with La5 × 10², La5 × 10⁴, and La5 × 10⁶. Different letters indicate statistical significance between groups by Kruskal–Wallis followed by Dunn's post hoc test (p ≤ 0.05). La5 × 10² means initial inoculum with La5 × 10² CFU/mL; La5 × 10⁴ means initial inoculum with La5 × 10⁴ CFU/mL; and La5 × 10⁶ means initial inoculum with La5 × 10⁶ CFU/mL.

Figure 3

Mean proportions of bacterial complexes multispecies biofilm without any treatment (control) and treated with La5 × 10⁴ and La5 × 10⁶. The colors represent different microbial complexes described by Socransky et al. (17). Different letters mean statistical significance among groups within the same complex. Statistical analysis performed using Kruskal–Wallis followed by Dunn post hoc (p ≤ 0.05). La5 × 10² means initial inoculum with La5 × 10² CFU/mL; La5 × 10⁴ means initial inoculum with La5 × 10⁴ CFU/mL; and La5 × 10⁶ means initial inoculum with La5 × 10⁶ CFU/mL.

Figure 4

Mean total counts of the species included in the biofilm without any treatment (control) and treated with La5 × 10⁴ and La5 × 10⁶. Statistical analysis was performed by the Kruskal–Wallis test followed by Dunn post hoc test (p ≤ 0.05). Letter “a” indicates statistical difference between La5 × 10⁴ and control but without statistical difference between La5 × 10⁴ and La5 × 10⁶; “b” indicates statistical difference between La5 × 10⁶ and control but without statistical difference between La5 × 10⁴ and La5 × 10⁶; and “c” indicate statistical difference among La5 × 10⁴ and the two other groups.