野血牦牛和家养牦牛瘤胃发酵参数及微生物多样性的比较分析

Comparative analysis of rumen fermentation parameters and microbial diversity of wild blood yaks and domestic yaks

为了比较野血牦牛和家养牦牛瘤胃发酵参数及微生物组成的差异,试验选取年龄、体重相近且健康的野血牦牛和家养牦牛各10头(公母各半),分别为野血牦牛组和家养牦牛组,两组屠宰后采集瘤胃液,测定瘤胃发酵参数(氨态氮、尿素氮、总氮、微生物蛋白和挥发性脂肪酸),并基于细菌16S rDNA基因序列比较分析两组瘤胃微生物组成的差异。结果表明:野血牦牛组瘤胃液中总氮含量、微生物蛋白质量浓度极显著高于家养牦牛组(P<0.01),氨态氮质量浓度、尿素氮浓度与家养牦牛组差异不显著(P>0.05);总挥发性脂肪酸浓度和正丁酸摩尔百分比极显著低于家养牦牛组(P<0.01),正戊酸摩尔百分比显著低于家养牦牛组(P<0.05),乙酸摩尔百分比极显著高于家养牦牛组(P<0.01),丙酸摩尔百分比显著高于家养牦牛组(P<0.05);异丁酸、异戊酸摩尔百分比及乙酸/丙酸与家养牦牛组差异不显著(P>0.05)。两组瘤胃共有1 963个核心操作性分类单元(operational taxonomic units,OTUs),野血牦牛组和家养牦牛组特有的OTUs分别为18 542个和16 514个。在门水平上,两组的优势菌门均为拟杆菌门(Bacteroidete)和厚壁菌门(Firmicutes),二者占微生物总数的98%以上。在属水平上,野血牦牛组瘤胃中的优势菌属(相对丰度>2%)包括普氏菌属1(Prevotella_1)、细菌F082(Bacterium F082)、理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)、克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)、拟杆菌目BS11肠道群(Bacteroidales_BS11_gut_group)和瘤胃球菌科NK4A214群(Ruminococcaceae_NK4A214_group),相对丰度分别为24.50%、14.68%、12.88%、6.50%、2.77%和2.70%;家养牦牛组瘤胃中的优势菌属分别为理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)、克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)、瘤胃球菌科NK4A214(Ruminococcaceae_NK4A214_group)、琥珀酸菌(Succiniclasticum)、细菌F082(Bacterium F082)和拟杆菌目RF16群(Bacteroidales_RF16_group),相对丰度分别为22.69%、13.87%、10.46%、6.93%、4.07%和3.96%。在门水平上,野血牦牛组瘤胃中拟杆菌门(Bacteroidete)相对丰度显著高于家养牦牛组(P<0.05),厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、髌骨细菌门(Patescibacteria)、互养菌门(Synergistetes)和疣微菌门(Verrucomicrobia)相对丰度显著低于家养牦牛组(P<0.05)。在属水平上,野血牦牛组瘤胃中普氏菌属1(Prevotella_1)相对丰度极显著高于家养牦牛组(P<0.01),细菌F082(Bacterium F082)和拟杆菌目BS11肠道群(Bacteroidales_BS11_gut_group)相对丰度显著高于家养牦牛组(P<0.05),克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)、瘤胃球菌科NK4A214群(Ruminococcaceae_NK4A214_group)和琥珀酸菌(Succiniclasticum)相对丰度极显著低于家养牦牛组(P<0.01),理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)相对丰度显著低于家养牦牛组(P<0.05)。说明野血牦牛和家养牦牛瘤胃发酵参数及微生物多样性存在明显差异;野血牦牛瘤胃中拟杆菌门相对丰度更高,对非纤维植物多糖和蛋白质的消化能力更强;而家养牦牛瘤胃厚壁菌门相对丰度更高,对纤维类物质的消化能力更强。

In order to compare the differences of rumen fermentation parameters and microbial composition between wild blood yaks and domestic yaks,10 healthy wild blood yaks and domestic yaks with similar age and body weight were selected as wild blood yak group and domestic yaks group,respectively.Rumen fluid was collected after slaughter in the two groups.Rumen fermentation parameters(ammonia nitrogen,urea nitrogen,total nitrogen,microbial protein and volatile fatty acids) were determined,and the differences of rumen microbial composition between the two groups were compared on the basis of bacterial 16S rDNA gene sequence.The results showed that the total nitrogen content and microbial protein mass concentration in rumen fluid of wild blood yak group were extremely significantly higher than those of domestic yak group(P<0.01),but there were no significant differences in ammonia nitrogen mass concentration and urea nitrogen concentration between wild blood yak group and domestic yak group(P>0.05).The total volatile fatty acid concentration and molar percentage of n-butyric acid were extremely significantly lower than those in domestic yak group(P<0.01);the molar percentage of N-valeric acid was significantly lower than that in domestic yak group(P<0.05);the molar percentage of acetic acid was significantly higher than that in domestic yak group(P<0.01),and the molar percentage of propionic acid was significantly higher than that in domestic yak group(P<0.05).There were no significant differences in molar percentage of isobutyric acid,isovaleric acid and acetic acid/propionic acid between wild blood yak group and domestic yak group(P>0.05).There were 1 963 core operational taxonomic units(OTUs)in the rumen of the two groups,and 18 542 and 16 514 unique OTUs in the wild blood yak group and domestic yak group,respectively.At the phylum level,Bacteroidete and Firmicutes were the dominant bacteroidete and Firmicutes in both groups,accounting for more than 98% of the total microorganisms.At the generic level,the dominant bacteria genera(relative abundance >2%) in the rumen of wild blood yaks group included Prevotella 1,Bacteria F082,Rienaceae_RC9_gut_group,Christensenaceae_R-7_ group,Bacteroideae BS11_gut_group and Rumenococcaceae_NK4A214_gut.The relative abundances were 24.5%,14.68%,12.88%,6.50%,2.77% and 2.70%,respectively.The dominant rumen bacteria in domestic yaks group were Rikenellaceae_RC9_gut_group,Christensenaceae_R-7_group,Ruminococcaceae_NK4A214_group,Succiniclasticum,Bacterium F082 and Bacteroidales_RF16_group of Ruminococcaceae,with relative abundances of 22.69%,13.87%,10.46%,6.93%,4.07% and 3.96%,respectively.At the phylum level,the relative abundance of Bacteroidete in rumen of wild blood yak group was extremely significantly higher than that of domestic yak group(P<0.05).The relative abundance of Firmicutes,Proteobacteria,Patescibacteria,Synergistetes and Verrucomicrobia was significantly lower than that of domestic yaks(P<0.05).At the generic level,the relative abundance of Prevotella_1 in rumen of wild blood yak group was significantly higher than that of domestic yak group(P<0.01).The relative abundance of Bacterium F082 and Bacteroidales_BS11_gut_group was significantly higher than that of domesticated yak group(P<0.05).The relative abundances of Christensenellaceae_R-7_group,Ruminococcaceae_NK4A214_group and Succiniclasticum were extremely significantly lower than those of the family(P<0.01).The relative abundance of Rikenellaceae_RC9_gut_group in yak raising group was significantly lower than that in domestic yak raising group(P<0.05).The results indicated that there were significant differences in rumen fermentation parameters and microbial diversity between wild blood yaks and domesticated yaks.The relative abundance of Bacteroidetes in rumen of wild blood yaks was higher,and the digestion ability of non-fiber plant polysaccharide and protein was stronger.The relative abundance of firmicutes in rumen of domesticated yaks was higher,and the digestibility of fibrous substances was stronger.