BACKGROUND The rumen contains a myriad of microbes whose primary role is to degrade and ferment dietary nutrients, which then provide the host with energy and nutrients. Rumen microbes commonly attach to ingested plant materials and form biofilms for effective plant degradation. Quorum sensing (QS) is a well-recognised form of bacterial communication in most biofilm communities, with homoserine lactone (AHL)-based QS commonly being used by Gram-negative bacteria alone and AI-2 Lux-based QS communication being used to communicate across Gram-negative and Gram-positive bacteria. However, bacterial cell to cell communication in the rumen is poorly understood. In this study, rumen bacterial genomes from the Hungate collection and Genbank were prospected for QS-related genes. To check that the discovered QS genes are actually expressed in the rumen, we investigated expression levels in rumen metatranscriptome datasets. RESULTS A total of 448 rumen bacterial genomes from the Hungate collection and Genbank, comprised of 311 Gram-positive, 136 Gram-negative and 1 Gram stain variable bacterium, were analysed. Abundance and distribution of AHL and AI-2 signalling genes showed that only one species (Citrobacter sp. NLAE-zl-C269) of a Gram-negative bacteria appeared to possess an AHL synthase gene, while the Lux-based genes (AI-2 QS) were identified in both Gram-positive and Gram-positive bacteria (191 genomes representing 38.2% of total genomes). Of these 192 genomes, 139 are from Gram-positive bactreetteria and 53 from Gram-negative bacteria. We also found that the genera Butyrivibrio, Prevotella, Ruminococcus and Pseudobutyrivibrio, which are well known as the most abundant bacterial genera in the rumen, possessed the most lux-based AI-2 QS genes. Gene expression levels within the metatranscriptome dataset showed that Prevotella, in particular, expressed high levels of LuxS synthase suggesting that this genus plays an important role in QS within the rumen. CONCLUSION This is the most comprehensive study of QS in the rumen microbiome to date. This study shows that AI-2-based QS is rife in the rumen. These results allow a greater understanding on plant-microbe interactions in the rumen.

中文翻译：

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瘤胃细菌可以互相交流吗？

背景技术瘤胃中含有无数微生物，其主要作用是降解和发酵膳食营养，然后为宿主提供能量和营养。瘤胃微生物通常附着在摄入的植物材料上并形成生物膜，以有效地降解植物。在大多数生物膜群落中，群体感应（QS）是一种公认​​的细菌传播形式，仅基于革兰氏阴性细菌通常使用基于高丝氨酸内酯（AHL）的QS，而基于AI-2 Lux的QS交流被用于传播跨革兰氏阴性和革兰氏阳性细菌。但是，对瘤胃中细菌细胞间的通讯了解甚少。在这项研究中，从Hungate收集品和Genbank获得的瘤胃细菌基因组有望用于QS相关基因。为了检查发现的QS基因是否在瘤胃中真正表达，我们调查了瘤胃元转录组数据集中的表达水平。结果分析了来自Hungate收集和Genbank的448个瘤胃细菌基因组，包括311革兰氏阳性，136革兰氏阴性和1革兰氏染色可变细菌。AHL和AI-2信号基因的丰度和分布表明，只有一种革兰氏阴性菌（柠檬杆菌NLAE-zl-C269）似乎具有AHL合酶基因，而基于Lux的基因（AI-2在革兰氏阳性和革兰氏阳性细菌（191个基因组占总基因组的38.2％）中都鉴定出QS）。在这192个基因组中，有139个来自革兰氏阳性菌，有53个来自革兰氏阴性细菌。我们还发现Butyrivibrio，Prevotella，Ruminococcus和Pseudobutyrivibrio属 众所周知，它们是瘤胃中最丰富的细菌属，具有最基于勒克斯的AI-2 QS基因。元转录组数据集内的基因表达水平表明，Prevotella尤其表达高水平的LuxS合酶，表明该属在瘤胃内的QS中起重要作用。结论这是迄今为止对瘤胃微生物组中QS的最全面的研究。这项研究表明，基于AI-2的QS在瘤胃中盛行。这些结果使人们对瘤胃中植物与微生物的相互作用有了更深入的了解。结论这是迄今为止对瘤胃微生物组中QS的最全面的研究。这项研究表明，基于AI-2的QS在瘤胃中盛行。这些结果使人们对瘤胃中植物与微生物的相互作用有了更深入的了解。结论这是迄今为止对瘤胃微生物组中QS的最全面的研究。这项研究表明，基于AI-2的QS在瘤胃中盛行。这些结果使人们对瘤胃中植物与微生物的相互作用有了更深入的了解。