Biostatistics Group, Department of Genetics, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland.
Key Laboratory of Animal Genetics, Breeding and Reproduction, MARA; National Engineering Laboratory for Animal Breeding; College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China.
BMC Microbiol. 2022 Jul 5;22(1):171. doi: 10.1186/s12866-022-02576-0.
Humans have been influencing climate changes by burning fossil fuels, farming livestock, and cutting down rainforests, which has led to global temperature rise. This problem of global warming affects animals by causing heat stress, which negatively affects their health, biological functions, and reproduction. On the molecular level, it has been proved that heat stress changes the expression level of genes and therefore causes changes in proteome and metabolome. The importance of a microbiome in many studies showed that it is considered as individuals' "second genome". Physiological changes caused by heat stress may impact the microbiome composition.
In this study, we identified fecal microbiota associated with heat stress that was quantified by three metrics - rectal temperature, drooling, and respiratory scores represented by their Estimated Breeding Values. We analyzed the microbiota from 136 fecal samples of Chinese Holstein cows through a 16S rRNA gene sequencing approach. Statistical modeling was performed using a negative binomial regression. The analysis revealed the total number of 24 genera and 12 phyla associated with heat stress metrics. Rhizobium and Pseudobutyrivibrio turned out to be the most significant genera, while Acidobacteria and Gemmatimonadetes were the most significant phyla. Phylogenetic analysis revealed that three heat stress indicators quantify different metabolic ways of animals' reaction to heat stress. Other studies already identified that those genera had significantly increased abundance in mice exposed to stressor-induced changes.
This study provides insights into the analysis of microbiome composition in cattle using heat stress measured as a continuous variable. The bacteria highly associated with heat stress were highlighted and can be used as biomarkers in further microbiological studies.
人类通过燃烧化石燃料、养殖牲畜和砍伐热带雨林等方式影响气候变化，导致全球气温上升。这种全球变暖问题通过引起热应激，对动物的健康、生物功能和繁殖产生负面影响。在分子水平上，已经证明热应激会改变基因的表达水平，从而导致蛋白质组和代谢组的变化。许多研究都证明了微生物组的重要性，它被认为是个体的“第二基因组”。热应激引起的生理变化可能会影响微生物组的组成。
在这项研究中，我们通过三个指标——直肠温度、流口水和呼吸评分（代表其估计育种值）来确定与热应激相关的粪便微生物群。我们通过 16S rRNA 基因测序方法分析了 136 份中国荷斯坦奶牛的粪便样本中的微生物群。使用负二项式回归进行统计建模。分析揭示了与热应激指标相关的 24 个属和 12 个门的总数。根瘤菌和拟丁酸弧菌是最重要的属，而酸杆菌门和芽单胞菌门是最重要的门。系统发育分析表明，三个热应激指标量化了动物对热应激反应的不同代谢方式。其他研究已经发现，那些属在暴露于应激诱导变化的小鼠中丰度显著增加。
本研究为使用连续变量测量的热应激对牛的微生物组组成进行分析提供了思路。突出了与热应激高度相关的细菌，可以作为进一步微生物学研究的生物标志物。
