Inhibition of Candida albicans biofilm formation and modulation of gene expression by probiotic cells and supernatant.

Oral candidiasis is a disease caused by opportunistic species of Candida that normally reside on human mucosal surfaces. The transition of Candida from budding yeast to filamentous hyphae allows for covalent attachment to oral epithelial cells, followed by biofilm formation, invasion and tissue damage. In this study, combinations of Lactobacillus plantarum SD5870, Lactobacillus helveticus CBS N116411 and Streptococcus salivarius DSM 14685 were assessed for their ability to inhibit the formation of and disrupt Candida albicans biofilms. Co-incubation with probiotic supernatants under hyphae-inducing conditions reduced C. albicans biofilm formation by >75 % in all treatment groups. Likewise, combinations of live probiotics reduced biofilm formation of C. albicans by >67 %. When live probiotics or their supernatants were overlaid on preformed C. albicans biofilms, biofilm size was reduced by >63 and >65 % respectively. Quantitative real-time PCR results indicated that the combined supernatants of SD5870 and CBS N116411 significantly reduced the expression of several C. albicans genes involved in the yeast-hyphae transition: ALS3 (adhesin/invasin) by 70 % (P < 0.0001), EFG1 (hyphae-specific gene activator) by 47 % (P = 0.0061), SAP5 (secreted protease) by 49 % (P < 0.0001) and HWP1 (hyphal wall protein critical to biofilm formation) by >99 % (P < 0.0001). These findings suggest the combination of L. plantarum SD5870, L. helveticus CBS N116411 and S. salivarius DSM 14685 is effective at both preventing the formation of and removing preformed C. albicans biofilms. Our novel results point to the downregulation of several Candida genes critical to the yeast-hyphae transition, biofilm formation, tissue invasion and cellular damage.

Probiotic lactobacilli: a potential prophylactic treatment for reducing pesticide absorption in humans and wildlife.

Numerous pesticides are used in agriculture, gardening, and wildlife-control. Despite their intended toxicity to pests, these compounds can also cause harm to wildlife and humans due to their ability to potentially bioaccumulate, leach into soils, and persist in the environment. Humans and animals are commonly exposed to these compounds through agricultural practices and consumption of contaminated foods and water. Pesticides can cause a range of adverse effects in humans ranging from minor irritation, to endocrine or nervous system disruption, cancer, or even death. A convenient and cost-effective method to reduce unavoidable pesticide absorption in humans and wildlife could be the use of probiotic lactobacilli. Lactobacillus is a genus of Gram-positive gut commensal bacteria used in the production of functional foods, such as yoghurt, cheese, sauerkraut and pickles, as well as silage for animal feed. Preliminary in vitro experiments suggested that lactobacilli are able to degrade some pesticides. Probiotic Lactobacillus rhamnosus GR-1-supplemented yoghurt reduced the bioaccumulation of mercury and arsenic in pregnant women and children. A similar study is warranted to test if this approach can reduce pesticide absorption in vivo, given that the lactobacilli can also attenuate reactive oxygen production, enhance gastrointestinal barrier function, reduce inflammation, and modulate host xenobiotic metabolism.

Preliminary investigations of the colonisation of upper respiratory tract tissues of infants using a paediatric formulation of the oral probiotic Streptococcus salivarius K12.

A powder preparation of the oral probiotic Streptococcus salivarius K12 has been given to 19 young otitis media-prone children following a 3-day course of amoxicillin administered as a preliminary to ventilation tube placement. In two subjects, the use of strain K12 appeared to effect the expansion of an indigenous population of inhibitory S. salivarius. In other children, strain K12 colonisation extended beyond the oral cavity to also include the nasopharynx or adenoid tissue. The relatively low proportion (33%) of subjects that colonised was attributed to failure of the amoxicillin pre-treatment to sufficiently reduce the indigenous S. salivarius populations prior to dosing with strain K12 powder.