猪肠道微生物区系-代谢物-宿主肌内脂肪沉积的相互调控机制

Wujin pigs as Yunnan excellent local breeds with special characteristics of higher intramuscular fat content, is the raw material to produce Xuanwei ham. The traits of higher intramuscular fat content in Wujin pigs are closely related to the special intestinal microflora. On the basis of our previous studies and combined with the domestic and foreign research focus, The project intends to use Wujin pigs as experimental materials and Landrace as control. Intramuscular fat content was determined in Longissimus dorsi muscle. Fatty acid concentrate in different intestinal segment will be detected firstly by high pressure liquid chromatography (HPGC). Microbial flora diversity will be measured using 16S rRNA and metagenomic analysis technology. The different intestinal microflora between Wujin and Landrace pigs would be analyzed and to screen the microbial flora which may be associated with the content of metabolites and intramuscular fat. The abundance of microbial communities would be determined by real time PCR technology. The results of this study will enrich the molecular mechanism theory of intramuscular fat deposition in Wujin pig and provide the theoretical basis to mine and use Wujin pigs resources, to develop the safe, health of Yunnan plateau characteristics of animal products. The study would provide new ideas and feasible ways through nutrition regulation and control measures of gut microbes to increase porcine intramuscular fat deposition, improve meat quality.

大河乌猪具有肌内脂肪含量高的种质特性，是制作云南高原特色畜产品—宣威火腿的原料。大河乌猪肌内脂肪含量高的种质特性必然与其肠道微生物密切相关。本项目拟以大河乌猪为试验材料，以长白猪为对照，首先测定背最长肌肌内脂肪含量，利用HPGC检测回肠、空肠和盲肠各肠段短链脂肪酸含量，采用16S rRNA和宏基因组学测序比较大河乌猪与长白猪肠道微生物群落及基因功能差异，关联分析微生物区系-代谢物及肌内脂肪含量，筛选可能与肌内脂肪含量相关的微生物菌群及优势群落基因；利用real time PCR技术定量检测差异微生物群落基因丰度，从而阐明猪肠道微生物区系-代谢物及宿主肌内脂肪沉积间相互调控机制，该研究结果将丰富乌金猪肌内脂肪沉积的分子机制理论，为深度挖掘和高效利用乌金猪优良种质资源，开发安全、健康的畜产品提供理论依据，为通过营养措施调控肠道微生物，增加猪肌内脂肪沉积，改善猪肉品质，提供新的思路和可行的途径。

动物肠道栖息着高度复杂的微生物群落，这些群略在调控宿主生理反应方面发挥着至关重要的作用。然而，关于肠道微生物群如何影响猪脂肪沉积的机制尚不清楚。本研究以脂肪型猪-大河猪和瘦肉型猪-长白猪两个品种的猪为研究对象，检测了肌内脂肪含量并通过油红O染色法观察了肌内脂肪细胞中脂滴大小的形态学；分析了猪消化道不同肠段食糜的pH值和有机酸含量；通过16S rRNA测序技术检测了肠道微生物区系，比较分析了微生物组成、多样性和功能预测，筛选肠道不同肠段的优势菌群。结果表明，大河猪肌内脂肪含量和脂滴数量显著大于长白猪（P<0.05）。猪消化道食糜处于弱酸性的环境，约为6.0左右，且大河猪的回肠、结肠和盲肠中总短链脂肪酸和乙酸的含量均显著低于长白猪（P<0.05），且随着肠段下移，pH逐渐降低的趋势。回肠的优势菌门是变形菌门和厚壁菌门，总占比超过了90%。结肠和盲肠的优势菌群为盲肠和结肠的优势菌门是厚壁菌门和拟杆菌门，占比约为90%和88%。与长白猪相比，大河猪回肠、盲肠和结肠微生物群落更为丰富和多样性。预测的大河猪微生物功能富集磷酸转移酶系统、丙酮酸代谢、氧化磷酸化和脂类代谢；长白猪富集氨基糖和核苷酸糖代谢、肽聚糖生物合成、氨酰-tRNA生物合成和核糖体等。优势菌群的定量检测显示大河猪回肠和盲肠中的优势菌群显著大于长白猪（P<0.05）。相关性分析指出，优势菌群与有机酸含量关联。总之，大河猪肠道丰富多样的微生物菌群，有助于有机酸的产生，促进脂肪沉积。该研究结果为干预肠道方式实现微生物-代谢物-宿主的对话，达到生产优质肉质的生态调控策略提供了理论依据。