Monsma D J, Marlett J A
Department of Nutritional Sciences, University of Wisconsin-Madison 53706, USA.
J Nutr. 1996 Feb;126(2):554-63. doi: 10.1093/jn/126.2.554.
The differential fermentative capacities of microflora from two regions of the large bowel and how fermentation was altered by prior exposure of the microflora to the substrate to be fermented were studied using an in vitro fermentation system. Bacterial inocula were prepared from cecal contents and feces from three groups of rats fed purified diets containing 100 g/kg dietary fiber from canned peas or psyllium seed husk, or a nonpurified diet containing 170 g/kg dietary fiber. The substrate for all fermentations was ileal excreta from colectomized rats fed a purified diet containing 100 g/kg dietary fiber from canned peas. Anaerobic fermentations were conducted for 0, 3, 6, 12, 24, 48 and 96 h. Sugars of the unfermented polysaccharides were measured by gas chromatography following acid hydrolysis; disappearance was the measure of fermentation. Independent of inoculum source, > 90% of the starch and arabinose and 75% of the uronic acids, but < 30% of non-starch glucose (the measure of cellulose), were fermented by 24 h. Cecal inocula fermented arabinose and uronic acids more quickly (P < 0.05) and fermented more (P < 0.05) non-starch glucose than fecal inocula. Inocula adapted to psyllium seed husk fermented starch faster (P < 0.05) and non-starch glucose, arabinose and uronic acids more slowly (P < 0.05) than inocula adapted to peas or nonpurified diet. Bacterial efficiency of carbohydrate utilization, the increase in muramic acid/mole carbohydrate fermented, was greatest (P < 0.05) with cecal inocula adapted to peas. We conclude that using cecal microflora as the inoculum source provides a more accurate index of fermentation during transit through the large bowel and that noncellulosic and storage polysaccharides of the plant cell wall are utilized before cellulose.
利用体外发酵系统研究了来自大肠两个区域的微生物群的不同发酵能力，以及微生物群预先接触待发酵底物后发酵是如何改变的。细菌接种物取自三组大鼠的盲肠内容物和粪便，这三组大鼠分别喂食含有100 g/kg来自罐装豌豆或车前草籽壳膳食纤维的纯化日粮，或含有170 g/kg膳食纤维的非纯化日粮。所有发酵的底物是喂食含有100 g/kg来自罐装豌豆膳食纤维的纯化日粮的结肠切除大鼠的回肠排泄物。进行厌氧发酵0、3、6、12、24、48和96小时。酸水解后通过气相色谱法测量未发酵多糖的糖含量；消失量作为发酵的指标。与接种物来源无关，到24小时时，超过90%的淀粉和阿拉伯糖以及75%的糖醛酸被发酵，但非淀粉葡萄糖（纤维素的指标）被发酵的比例不到30%。盲肠接种物比粪便接种物更快地发酵阿拉伯糖和糖醛酸（P<0.05），并且发酵更多的非淀粉葡萄糖（P<0.05）。适应车前草籽壳的接种物比适应豌豆或非纯化日粮的接种物更快地发酵淀粉（P<0.05），而发酵非淀粉葡萄糖、阿拉伯糖和糖醛酸更慢（P<0.05）。碳水化合物利用的细菌效率，即每摩尔发酵碳水化合物中胞壁酸的增加量，在适应豌豆的盲肠接种物中最大（P<0.05）。我们得出结论，使用盲肠微生物群作为接种物来源可提供在大肠转运过程中更准确的发酵指标，并且植物细胞壁的非纤维素和储存多糖在纤维素之前被利用。
