中文摘要：

目的：研究新生仔猪从7日龄至35日龄（断奶后2周）胃中细菌及乳酸杆菌的菌群变化。方法：利用Dilution-PCR半定量法比较仔猪胃中细菌和乳酸杆菌数量变化，采用PCR／DGGE及16S rDNA序列分析技术，比较细菌和乳酸杆菌菌群的变化。结果：仔猪哺乳期胃内食糜维持较低的pH值，断奶后pH值显著上升。Dilution-PCR分析发现，仔猪在哺乳期胃中细菌数量很低，而断奶后总细菌数量显著上升，乳酸杆菌数量则略有上升；DGGE图谱显示，哺乳期胃中细菌条带较单一，优势菌为相对高Gc含量细菌，断奶后图谱中出现一些新的优势条带，序列分析表明，它们分别属于Escherichia fergusonii，Escherichia coli，Streptococcus gordonii和Streptococcus suis；乳酸杆菌DGGE图谱相似性分析显示，仔猪断奶前、后胃中乳酸杆菌变化较小。结论：仔猪断奶应激，引起胃pH值显著上升，并造成潜在病原菌在胃中大量增生。

英文摘要：

Objective： To study bacterial and lactobacilli communities in stomach of neonatal piglets from 7 to 35 （two weeks after weaning） days of age. Methods： The semi-quantitative Dilution-PCR, PCR-DGGE and sequencing were used to analyze the shifts of stomach total bacterial and lactobacilli community. Resuits ： Stomach pH value was around 3.0 before weaning and increased apparently after weaning. Dilution-PCR showed that bacterial concentration in stomach of piglet was very low before weaning and increased significantly after weaning. The DGGE profiles from total bacteria in stomach showed that the bands of samples before weaning were very simple and the predominant band belonged to high GC bacterium. After weaning, some new predominant bands appeared and the previous high GC bacteria disappeared simultaneously. Sequence analysis indicated that these new bands were Escherichia fergusonii ,Escherichia coli, Streptococcus gordonii and Streptococcus suis ,all of which were potential pathogens for piglets. The similarity of DGGE profiles from stomach lactobacilli showed weaning stress had no obvious effect on lactobacilli community. Conclusion ： Weaning stress could cause stomach pH increase apparently and induce potential pathogens proliferation in stomach of piglets.