Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
The Friedman School of Nutrition Science & Policy, Tufts University, Boston, MA, USA.
Gut Microbes. 2021 Jan-Dec;13(1):1-16. doi: 10.1080/19490976.2021.1887721.
Vitamins have well-established roles in bacterial metabolism. Menaquinones (MKn, n = prenyl units in sidechain) are bacterially produced forms of vitamin K produced by the gut microbiota and consumed in the diet. Little is known about the influence of dietary vitamin K quinones on gut microbial composition and MKn production. Here, male and female C57BL6 mice were fed a vitamin K deficient diet or vitamin K sufficient diets containing phylloquinone (PK, plant-based vitamin K form), MK4, and/or MK9. DNA was extracted from cecal contents and 16S sequencing conducted to assess microbial composition. Cecal microbial community composition was significantly different in vitamin K deficient female mice compared to females on vitamin K sufficient diets (all < .007). Parallel trends were seen in male mice, but were not statistically significant (all > .05 but <0.1). Next, stable isotope-labeled vitamin K quinones were supplemented to male and female C57BL6 mice (HPK, CMK4, HMK7, HMK9) and to an fermentation model inoculated with human stool (HPK, HMK4, HMK9, or vitamin K precursor H-menadione). Vitamin K quinones in feces and culture aliquots were measured using LC-MS. , supplemented vitamin K quinones were remodeled to other MKn (H- or C-labeled MK4, MK10, MK11, and MK12), but only the precursor H-menadione was remodeled to HMK4, HMK9, HMK10, and HMK11. These results suggest that dietary vitamin K deficiency alters the gut microbial community composition. Further studies are needed to determine if menadione generated by host metabolism may serve as an intermediate in dietary vitamin K remodeling .
维生素在细菌代谢中具有明确的作用。menaquinones（MKn，侧链中 prenyl 单位的 n 个）是由肠道微生物群产生并在饮食中消耗的细菌产生的维生素 K 形式。关于饮食中维生素 K 醌对肠道微生物组成和 MKn 产生的影响知之甚少。在这里，雄性和雌性 C57BL6 小鼠分别喂食维生素 K 缺乏饮食或维生素 K 充足饮食，其中含有叶绿醌（PK，植物来源的维生素 K 形式）、MK4 和/或 MK9。从盲肠内容物中提取 DNA 并进行 16S 测序以评估微生物组成。与维生素 K 充足饮食组相比，维生素 K 缺乏的雌性小鼠盲肠微生物群落组成有显著差异（均 <0.007）。雄性小鼠也出现了类似的趋势，但无统计学意义（均 >0.05 但 <0.1）。接下来，向雄性和雌性 C57BL6 小鼠（HPK、CMK4、HMK7、HMK9）以及接种人粪便的发酵模型（HPK、HMK4、HMK9 或维生素 K 前体 H- menadione）补充稳定同位素标记的维生素 K 醌。使用 LC-MS 测量粪便和培养物等分试样中的维生素 K 醌。结果表明，补充的维生素 K 醌被重塑为其他 MKn（H-或 C-标记的 MK4、MK10、MK11 和 MK12），但只有前体 H- menadione 被重塑为 HMK4、HMK9、HMK10 和 HMK11。这些结果表明，饮食中维生素 K 的缺乏改变了肠道微生物群落组成。需要进一步的研究来确定宿主代谢产生的 menadione 是否可以作为饮食中维生素 K 重塑的中间产物。
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