Department of Microbiology and Risk Assessment, National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
BMC Microbiol. 2010 Jan 20;10:13. doi: 10.1186/1471-2180-10-13.
Our study was part of the large European project ISAFRUIT aiming to reveal the biological explanations for the epidemiologically well-established health effects of fruits. The objective was to identify effects of apple and apple product consumption on the composition of the cecal microbial community in rats, as well as on a number of cecal parameters, which may be influenced by a changed microbiota.
Principal Component Analysis (PCA) of cecal microbiota profiles obtained by PCR-DGGE targeting bacterial 16S rRNA genes showed an effect of whole apples in a long-term feeding study (14 weeks), while no effects of apple juice, purée or pomace on microbial composition in cecum were observed. Administration of either 0.33 or 3.3% apple pectin in the diet resulted in considerable changes in the DGGE profiles.A 2-fold increase in the activity of beta-glucuronidase was observed in animals fed with pectin (7% in the diet) for four weeks, as compared to control animals (P < 0.01). Additionally, the level of butyrate measured in these pectin-fed animal was more than double of the corresponding level in control animals (P < 0.01). Sequencing revealed that DGGE bands, which were suppressed in pectin-fed rats, represented Gram-negative anaerobic rods belonging to the phylum Bacteroidetes, whereas bands that became more prominent represented mainly Gram-positive anaerobic rods belonging to the phylum Firmicutes, and specific species belonging to the Clostridium Cluster XIVa.Quantitative real-time PCR confirmed a lower amount of given Bacteroidetes species in the pectin-fed rats as well as in the apple-fed rats in the four-week study (P < 0.05). Additionally, a more than four-fold increase in the amount of Clostridium coccoides (belonging to Cluster XIVa), as well as of genes encoding butyryl-coenzyme A CoA transferase, which is involved in butyrate production, was detected by quantitative PCR in fecal samples from the pectin-fed animals.
Our findings show that consumption of apple pectin (7% in the diet) increases the population of butyrate- and beta-glucuronidase producing Clostridiales, and decreases the population of specific species within the Bacteroidetes group in the rat gut. Similar changes were not caused by consumption of whole apples, apple juice, purée or pomace.
我们的研究是大型欧洲项目 ISAFRUIT 的一部分，旨在揭示水果在流行病学上确立的健康效应的生物学解释。目的是确定苹果和苹果产品的摄入对大鼠盲肠微生物群落组成的影响，以及对一些可能受微生物群改变影响的盲肠参数的影响。
通过针对细菌 16S rRNA 基因的 PCR-DGGE 对盲肠微生物群进行主成分分析（PCA），结果表明，在长期喂养研究（14 周）中，整个苹果有作用，而苹果汁、果泥或果渣对盲肠微生物组成没有作用。饮食中添加 0.33%或 3.3%的苹果果胶会导致 DGGE 图谱发生很大变化。与对照组动物（饮食中 7%）相比，连续四周喂食果胶的动物的β-葡糖苷酸酶活性增加了两倍（P < 0.01）。此外，在这些喂食果胶的动物中测量的丁酸盐水平是对照组动物的两倍多（P < 0.01）。测序结果表明，在果胶喂养的大鼠中被抑制的 DGGE 条带代表属于拟杆菌门的革兰氏阴性厌氧菌，而变得更为突出的条带主要代表属于厚壁菌门的革兰氏阳性厌氧菌，以及特定属于梭菌属 14 簇的物种。定量实时 PCR 证实，在果胶喂养的大鼠以及在为期四周的研究中，苹果喂养的大鼠中，特定的拟杆菌种类的数量减少（P < 0.05）。此外，通过定量 PCR 检测到果胶喂养动物粪便样本中梭菌 coccoides（属于 14 簇）的数量增加了四倍以上，以及编码参与丁酸产生的丁酰辅酶 A CoA 转移酶的基因数量增加了四倍以上。
我们的研究结果表明，食用苹果果胶（饮食中 7%）会增加丁酸和β-葡糖苷酸产生的梭状芽胞杆菌的数量，并减少大鼠肠道中拟杆菌组内特定物种的数量。而食用整个苹果、苹果汁、果泥或果渣则不会导致这种情况。
