β-酪蛋白不同基因型荷斯坦奶牛瘤胃微生物群落特征和功能分析

Characteristic and Functional Analysis of Rumen Microbial Communities inHolstein Cows with Different β-Casein Genotypes

β-酪蛋白是乳汁中最重要的蛋白质之一,在荷斯坦奶牛中存在A1和A2这2种主要基因型。为探究β-酪蛋白不同基因型荷斯坦奶牛瘤胃微生物群落的差异,试验选取体况良好、第1胎次的A1A1、A1A2和A2A2基因型荷斯坦奶牛各15头(各基因型奶牛乳脂率和乳蛋白率相近),采集瘤胃液后通过Illumina HiSeq 2000平台进行宏基因组测序,并利用Diamond 0.9.7软件进行分类和功能注释,分析3种基因型奶牛瘤胃微生物群落的组成和功能。结果表明:1)A1A1基因型奶牛瘤胃中特征微生物有Intestinibaculum、戴阿利斯特杆菌属(Dialister)、克雷伯氏菌属(Klebsiella)和不动杆菌属(Acinetobacter)等;A1A2基因型奶牛瘤胃中特征微生物有普雷沃氏菌科(Prevotellaceae)的帕拉普雷沃氏菌属(Paraprevotella)和Paraprevotella xylaniphila;A2A2基因型奶牛瘤胃中特征微生物包括醋杆菌属(Acetobacter)和黄单胞菌属(Xanthomonas)等。2)A1A2和A2A2基因型奶牛瘤胃中富含与木质纤维素和纤维素降解相关的酶;A1A2基因型奶牛瘤胃参与淀粉和蔗糖代谢、脂肪酸生物合成、蛋白质消化与吸收、精氨酸和脯氨酸代谢以及RNA降解通路的基因数量更多;A2A2基因型奶牛瘤胃参与炎症介质调节通路的基因数量更多。由此可知,A1A1基因型荷斯坦奶牛的瘤胃标志物微生物是Intestinibaculum和戴阿利斯特杆菌属,可能与减少甲烷排放和A1型β-酪蛋白以及部分疾病存在潜在关联;A1A2基因型奶牛的瘤胃标志微生物是普雷沃氏菌科,可能对饲粮消化有促进作用;A2A2基因型奶牛的瘤胃标志微生物是醋杆菌属,其相对丰度对乳脂含量有调节作用。

β-casein is one of the most important proteins in milk,and there are two major genotypes,A1 and A2,in Holstein cows.In order to investigate the differences of rumen microbial communities of Holstein cows with differentβ-casein genotypes,15 Holstein cows with genotypes A1A1,A1A2 and A2A2 in good condition and the first parity were selected in the experiment(milk fat percentage and milk protein percentage of all genotypes were similar).After rumen fluid collection,metagomic sequencing was performed by Illumina HiSeq 2000 platform,Diamond 0.9.7 software was used for classification and functional annotation,and the composition and function of rumen microbial communities of three genotypes of dairy cows were analyzed.The results showed as follows:1)the characteristic microorganisms in rumen of cows with genotype A1A1 were Intestinibaculum,Dialister,Klebsiella and Acinetobacter,and so on;the characteristic microorganisms in rumen of cows with genotype A1A2 were Paraprevotella and Paraprevotella xylaniphila of Prevotellaceae;and the characteristic microorganisms in rumen of cows with genotype A2A2 were Acetobacter and Xanthomonas,and so on.2)The rumen of cows with genotypes A1A2 and A2A2 was rich in enzymes related to lignocellulose and cellulose degradation;the number of genes involved in starch and sucrose metabolism,fatty acid biosynthesis,protein digestion and absorption,arginine and proline metabolism and RNA degradation pathways were more in rumen of cows with genotype A1A2,and the rumen of cows with genotype A2A2 had more genes involved in the regulatory pathway of inflammatory mediators.It can be concluded that the rumen marker microorganisms of Holstein cows with genotype A1A1 are Intestinibaculum and Dealisteria,which may be potentially associated with reduced methane emissions andβ-casein type A1,as well as some diseases;the rumen marker microorganism of cows with genotype A1A2 is Prevotellaceae,which may promote dietary digestion;and the rumen marker microorganism of cows with genotype A2A2 is Acetobacter,and its relative abundance has a regulating effect on milk fat content.