Limosilactobacillus reuteri AJCR4: A Potential Probiotic in the Fight Against Oral Candida spp. Biofilms

Oral candidiasis is one of the most common infections in the immunocompromised. Biofilms of Candida species can make treatments difficult, leading to oral infection recurrence. This research aimed to isolate a Lactobacillus with anti-Candida effects from the oral cavity. An oral Lactobacillus was isolated in caries-free individuals. The best isolate was evaluated against Candida spp. planktonic and biofilm forms. The bacterial impacts on Candida biofilms’ adhesion to acrylic discs were analyzed through an in vitro test. L. reuteri AJCR4 had the best anti-Candida activity in the preliminary screening. Results were promising in both planktonic and biofilms, particularly with C. albicans SC5314 and C. tropicalis ATCC750, where no viable cells were detected when using the cell-free supernatant (undiluted). In C. glabrata ATCC2001 and C. parapsilosis ATCC22019 biofilms, reductions of 3 Log10 and more than 2 Log10, respectively, were noted when using a cell suspension of L. reuteri ACJR4 (108 CFU/mL). On polymethyl methacrylate acrylic discs, the cell-free supernatant reduced Candida adhesion, resulting in no viable cell detection on the surface. In conclusion, L. reuteri AJCR4 demonstrated notable antifungal activity against Candida biofilms. This oral isolate and its postbiotic can be a potential alternative strategy to oral candidiasis, especially to treat recalcitrant infections.