In Vitro Activity of Lactobacilli with Probiotic Potential Isolated from Cocoa Fermentation against Gardnerella vaginalis.

Study of the probiotic potential of microorganisms isolated from fermented foods has been increasing, especially studies related to lactobacilli. In intestinal models, lactobacilli have demonstrated beneficial properties, such as anti-inflammatory activity and increased antibody production, but the molecular mechanisms involving probiotic and antagonistic action as well as their effect on human vaginal cells have not yet been fully elucidated. The aim of this study was to evaluate the functional and antagonistic properties of three strains of lactobacilli isolated from cocoa fermentation (Lactobacillus fermentum 5.2, L. plantarum 6.2, and L. plantarum 7.1) against Gardnerella vaginalis. Our results show that the lactobacilli have potential use as probiotics, since they have high hydrophobicity and autoaggregation properties and effectively adhere to vaginal cells. Metabolites secreted into the culture medium and whole cells of the strains under study are capable of interfering with the growth of G. vaginalis to different degrees. The elucidation of the antagonistic mechanisms as well as their effect on human cells may be useful in the development of a product containing such microorganisms or products secreted by them.

Inhibition of Staphylococcus aureus biofilm by Lactobacillus isolated from fine cocoa.

BACKGROUND: Biofilm production represents an important virulence and pathogenesis factor for Staphylococcus aureus. The formation of biofilms on medical devices is a major concern in hospital environments, as they can become a constant source of infection. Probiotic bacteria, such as Lactobacillus fermentum and L. plantarum, have been found to inhibit biofilm formation; however little is known about the underlying mechanism. In this study, we tested the activity of supernatants produced by L. fermentum TCUESC01 and L. plantarum TCUESC02, isolated during the fermentation of fine cocoa, against S. aureus CCMB262 biofilm production. We measured inhibition of biofilm formation in vitro and analyzed biofilm structure by confocal and electronic microscopy. Additionally, we quantified the expression of S. aureus genes icaA and icaR involved in the synthesis of the biofilm matrix by real-time PCR. RESULTS: Both Lactobacillus supernatants inhibited S. aureus growth. However, only L. fermentum TCUESC01 significantly reduced the thickness of the biofilm, from 14 µm to 2.83 µm (at 18 mg∙mL-1, 90 % of the minimum inhibitory concentration, MIC), 3.12 µm (at 14 mg∙mL-1, 70 % of the MIC), and 5.21 µm (at 10 mg∙mL-1, 50 % of the MIC). Additionally, L. fermentum TCUESC01 supernatant modulated the expression of icaA and icaR. CONCLUSIONS: L. fermentum TCUESC01 reduces the formation of S. aureus biofilm under subinhibitory conditions. Inhibition of biofilm production probably depends on modulation of the ica operon.