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Front. Microbiol. | doi: 10.3389/fmicb.2018.00575

Comparative Analysis of the Microbiota between Sheep Rumen and Rabbit Cecum Provides New Insight into their Differential Methane Production

Lan Mi1, 2, Bin Yang1, Xialu Hu1, Yang Luo1,  Jianxin Liu1,  Zhongtang Yu2* and  Jiakun Wang1*
  • 1Zhejiang University, China
  • 2Department of Animal Sciences, The Ohio State University, United States

The rumen and the hindgut represent two different fermentation organs in herbivorous mammals, with the former producing much more methane than the latter. The objective of this study was to elucidate the microbial underpinning of such differential methane outputs between these two digestive organs. Methane production was measured from 5 adult sheep and 15 adult rabbits, both of which were placed in open-circuit respiratory chambers and fed the same diet (alfalfa hay). The sheep produced more methane than the rabbits per unit of metabolic body weight, digestible neutral detergent fiber, and acid detergent fiber. pH in the sheep rumen was more than 1 unit higher than that in the rabbit cecum. The acetate to propionate ratio in the rabbit cecum was more than 3-fold greater than that in the sheep rumen. Comparative analysis of 16S rRNA gene amplicon libraries revealed distinct microbiota between the rumen of sheep and the cecum of rabbits. Hydrogen-producing fibrolytic bacteria, especially Butyrivibrio, Succiniclastium, Mogibacterium, Prevotella, and Christensenellaceae, were more predominant in the sheep rumen, whereas non-hydrogen producing fibrolytic bacteria, such as Bacteroides, were more predominant in the rabbit cecum. The rabbit cecum had a greater predominance of acetogens, such as those in the genus Blautia, order Clostridiales, and family Ruminococcaceae. The differences in the occurrence of hydrogen-metabolizing bacteria probably explain much of the differential methane outputs from the rumen and the cecum. Future research using metatranscriptomics and metabolomics shall help confirm this premise and understand the factors that shape the differential microbiota between the two digestive organs. Furthermore, our present study strongly suggests the presence of new fibrolytic bacteria in the rabbit cecum, which may explain the stronger fibrolytic activities therein.

Keywords: Acetogen, Cecum, Fibrolytic bacteria, Hydrogen, Methane, microbiota, pH, Rumen

Received: 18 Dec 2017; Accepted: 13 Mar 2018.

Edited by:

Diana E. Marco, National Scientific Council (CONICET), Argentina

Reviewed by:

Stephan Schmitz-Esser, Iowa State University, United States
SANJAY KUMAR, University of Pennsylvania, United States
Wang Min, Institute of Subtropical Agriculture (CAS), China  

Copyright: © 2018 Mi, Yang, Hu, Luo, Liu, Yu and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Zhongtang Yu, The Ohio State University, Department of Animal Sciences, Columbus, Ohio, United States,
Prof. Jiakun Wang, Zhejiang University, Hangzhou, China,