Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the United States America are enriched in soybean oil, composed of unsaturated fatty acids, either linoleic or oleic acid. Here, we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high or low in high-linoleic-acid soybean oil as the sole source of fat. Conventional and germfree mice gained relative fat weight and all mice consumed more calories on the high fat vs. low fat soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso-C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet and that microbial colonization influences liver sphingolipid pools regardless of diet.

使用无菌动物作为微生物定植对照的小鼠研究表明，肠道微生物组介导饮食诱发的肥胖。这些研究使用富含饱和脂肪的饮食，然而，美国的西方饮食富含大豆油，由不饱和脂肪酸（亚油酸或油酸）组成。在这里，我们探讨了微生物组是否是大豆油饮食小鼠脂肪代谢的一个变量。我们使用传统饲养的低细菌和无菌小鼠，以高或低的高亚油酸大豆油作为唯一脂肪来源，喂养 10 周。传统小鼠和无菌小鼠的脂肪重量相对增加，并且与低脂大豆油饮食相比，所有小鼠在高脂肪饮食中消耗更多的热量。血浆脂肪酸水平通常取决于饮食，微生物定植状态影响iso- C18:0、C20:3n-6、C14:0 和 C15:0 水平。定植状态（而非饮食）影响肝脏鞘脂（包括神经酰胺、鞘磷脂和二氢鞘氨醇）的水平。我们的结果证实，吸收的脂肪酸主要是饮食的反映，并且无论饮食如何，微生物定植都会影响肝脏鞘脂池。