Folate-producing bifidobacteria: metabolism, genetics, and relevance.

Folate (the general term for all bioactive forms of vitamin B9) plays a crucial role in the evolutionary highly conserved one-carbon (1C) metabolism, a network including central reactions such as DNA and protein synthesis and methylation of macromolecules. Folate delivers 1C units, such as methyl and formyl, between reactants. Plants, algae, fungi, and many bacteria can naturally produce folate, whereas animals, including humans, must obtain folate from external sources. For humans, folate deficiency is, however, a widespread problem. Bifidobacteria constitute an important component of human and many animal microbiomes, providing various health advantages to the host, such as producing folate. This review focuses on bifidobacteria and folate metabolism and the current knowledge of the distribution of genes needed for complete folate biosynthesis across different bifidobacterial species. Biotechnologies based on folate-trophic probiotics aim to create fermented products enriched with folate or design probiotic supplements that can synthesize folate in the colon, improving overall health. Therefore, bifidobacteria (alone or in association with other microorganisms) may, in the future, contribute to reducing widespread folate deficiencies prevalent among vulnerable human population groups, such as older people, women at child-birth age, and people in low-income countries.

Potential Applications of Essential Oils for Environmental Sanitization and Antimicrobial Treatment of Intensive Livestock Infections.

The extensive use of antibiotics has contributed to the current antibiotic resistance crisis. Livestock infections of Salmonella spp, Clostridium spp. and E. coli antimicrobial-resistant bacteria represent a public threat to human and animal health. To reduce the incidence of these zoonoses, essential oils (EOs) could be effective antibiotic alternatives. This study aims at identifying EOs safe for use, effective both in complementary therapy and in the environmental sanitization of intensive farming. Natural products were chemo-characterized by gas chromatography. Three S. Typhimurium, three C. perfringens and four E. coli strains isolated from poultry and swine farms were used to assess the antimicrobial properties of nine EOs and a modified GR-OLI (mGR-OLI). The toxicity of the most effective ones (Cinnamomum zeylanicum, Cz; Origanum vulgare, Ov) was also evaluated on porcine spermatozoa and Galleria mellonella larvae. Cz, Ov and mGR-OLI showed the strongest antimicrobial activity; their volatile components were also able to significantly inhibit the growth of tested strains. In vitro, Ov toxicity was slightly lower than Cz, while it showed no toxicity on G. mellonella larvae. In conclusion, the study confirms the importance of evaluating natural products to consolidate the idea of safe EO applications in reducing and preventing intensive livestock infections.

In Vitro Activity of Tea Tree Oil Vaginal Suppositories against Candida spp. and Probiotic Vaginal Microbiota.

The aim of this work is to evaluate the in vitro microbicidal activity of vaginal suppositories (VS) containing tea tree oil (TTO-VS) towards Candida spp. and vaginal probiotics. A total of 20 Candida spp. strains, taken from patients with vaginitis and from an established type collection, including reference strains, were analysed by using the CLSI microdilution method. To study the action of VS towards the beneficial vaginal microbiota, the sensitivity of Bifidobacterium animalis subsp. lactis (DSM 10140) and Lactobacillus spp. (Lactobacillus casei R-215 and Lactobacillus acidophilus R-52) was tested. Both TTO-VS and TTO showed fungicidal activity against all strains of Candida spp. whereas placebo-VS or the Aloe gel used as controls were ineffective. The study of fractional fungicidal concentrations (FFC) showed synergistic interaction with the association between Amphotericin B and TTO (0.25 to 0.08 µg/ml, respectively) against Candida albicans. Instead, the probiotics were only affected by TTO concentration ≥ 4% v/v, while, at concentrations < 2% v/v, they remained viable. TTO-VS exhibits, in vitro, a selective fungicidal action, slightly affecting only the Bifidobacteriun animalis strain growth belonging to the vaginal microbiota. In vivo studies are needed to confirm the efficacy to prevent acute or recurrent vaginal candidiasis.