Cabotaje L M, López-Guisa J M, Shinnick F L, Marlett J A
Department of Nutritional Sciences, University of Wisconsin-Madison 53706.
Appl Environ Microbiol. 1990 Jun;56(6):1786-92. doi: 10.1128/aem.56.6.1786-1792.1990.
Separating dietary fiber from other polysaccharides in digesta and feces is necessary to understand its mechanisms of action. A gravimetric method that separates fecal plant and bacterial matter based on size and density was evaluated and modified to determine the plant and bacterial mass of lyophilized whole and blended rat and human feces. Three screen mech combinations (150 and 75 microns, 150 and 35 microns, 35 microns) were used with rat feces. Filtration of a homogenized rat fecal slurry sequentially through 150- and 35-microns-mesh screens versus 150- and 75-microns-mesh screens decreased the gravimetric recovery of bacteria from congruent to 35 to congruent to 25% of fecal dry weight and increased the plant fraction weight. Neutral sugar composition, determined by gas chromatography of alditol acetates, and bacterial counts of the fractions suggested that the decreased yield of bacterial fraction represented removal of plant material and not a loss of bacteria. Rat excreta contained 29.5% (dry weight) total neutral sugar, 88% of which was recovered in the plant material. Human feces containing wheat bran, fractionated with the 150- and 35-microns-mesh screens, was 21% neutral sugar, congruent to 65% of which was in the plant fraction. The plant fractions had more xylose and arabinose and less glucose than the bacterial fractions. Processing samples in a Waring blender had no adverse effect on the rat or human fecal bacterial counts. The use of this gravimetric method in combination with the sugar analysis of the fractions provided a better measure of plant and bacteria than only gravimetric yield.
将膳食纤维与消化物和粪便中的其他多糖分离，对于理解其作用机制至关重要。一种基于大小和密度分离粪便中植物和细菌物质的重量法经过评估和改进，用于测定冻干的大鼠和人类全粪便及混合粪便中的植物和细菌质量。对大鼠粪便使用了三种筛网组合（150微米和75微米、150微米和35微米、35微米）。将匀浆后的大鼠粪便悬浮液依次通过150微米和35微米筛网，相较于通过150微米和75微米筛网，细菌的重量回收率从粪便干重的约35%降至约25%，同时植物部分的重量增加。通过糖醇乙酸酯气相色谱法测定的中性糖组成以及各部分的细菌计数表明，细菌部分产量的降低代表植物物质的去除，而非细菌的损失。大鼠排泄物中总中性糖含量为29.5%（干重），其中88%在植物物质中回收。用150微米和35微米筛网分级的含麦麸的人类粪便，中性糖含量为21%，其中约65%在植物部分。植物部分的木糖和阿拉伯糖比细菌部分多，葡萄糖比细菌部分少。在韦林搅拌器中处理样品对大鼠或人类粪便细菌计数没有不利影响。与仅通过重量产量相比，使用这种重量法结合各部分的糖分析能更好地衡量植物和细菌。
