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Novel vitamin B12-producing Enterococcus spp. and preliminary in vitro evaluation of probiotic potentials

Li, Ping, Gu, Qing, Wang, Yuejiao, Yu, Yue, Yang, Lanlan, Chen, Jieyan V.
Applied microbiology and biotechnology 2017 v.101 no.15 pp. 6155-6164
Enterococcus faecium, GRAS substances, Lactobacillus, antibiotic resistance, bile salts, environmental factors, ethanol, feces, food industry, gastric acid, human cell lines, humans, in vitro studies, lactic acid bacteria, osmotic stress, pH, probiotics, reversed-phase high performance liquid chromatography, temperature, virulence, vitamin B12
Vitamin B₁₂ is an essential nutrient required for crucial metabolic processes in humans. Vitamin B₁₂-producing lactic acid bacteria (LAB) have been attracting increased attentions currently because of the generally recognized as safe (GRAS) status. Most of recent studies focused on Lactobacillus, and little is known about B₁₂-producing Enterococcus. In the present study, five Enterococcus strains isolated from infant feces were identified as vitamin B₁₂ producers. Among them, Enterococcus faecium LZ86 had the highest B₁₂ production (499.8 ± 83.7 μg/L), and the B₁₂ compound from LZ86 was identified as the biological active adenosylcobalamin, using reversed phase high-performance liquid (RP-HPLC) chromatogram. We examined basic probiotic and safety properties of E. faecium LZ86 and found that it was able to survive harsh environmental conditions (hot temperature, cold temperature, ethanol and osmotic stresses), tolerate gastric acid (pH 2.0, 3 h) and bile salts (0.3%), and adhere to Caco-2 cells. We also showed that E. faecium LZ86 is devoid of transferable antibiotic resistance and potential virulence factors. Together, here we report a B₁₂-producing E. faecium strain LZ86 firstly, which has desirable probiotic properties and may serve as a good candidate for vitamin B₁₂ fortification in food industry.