Diversity of methanogens in the hindgut of captive white rhinoceroses, Ceratotherium simum.
BACKGROUND
The white rhinoceros is on the verge of extinction with less than 20,200 animals remaining in the wild. In order to better protect these endangered animals, it is necessary to better understand their digestive physiology and nutritional requirements. The gut microbiota is nutritionally important for herbivorous animals. However, little is known about the microbial diversity in the gastrointestinal tract (GIT) of the white rhinoceros. Methanogen diversity in the GIT may be host species-specific and, or, function-dependent. To assess methanogen diversity in the hindgut of white rhinoceroses, an archaeal 16S rRNA gene clone library was constructed from pooled PCR products obtained from the feces of seven adult animals.


RESULTS
Sequence analysis of 153 archaeal 16S rRNA sequences revealed 47 unique phylotypes, which were assigned to seven operational taxonomic units (OTUs 1 to 7). Sequences assigned to OTU-7 (64 out of 153 total sequencs - 42%) and OTU-5 (18%, 27/153) had 96.2% and 95.5% identity to Methanocorpusculum labreanum, respectively, making Methanocorpusculum labreanum the predominant phylotype in these white rhynoceroses. Sequences belonging to OTU-6 (27%, 42/153) were related (97.6%) to Methanobrevibacter smithii. Only 4% of the total sequences (6/153) were assigned to Methanosphaera stadtmanae (OTU-1). Sequences belonging to OTU-2 (4%, 6/153), OTU-3 (3%, 5/153) and OTU-4 (2%, 3/153) were distantly related (87.5 to 88,4%) to Methanomassiliicoccus luminyensis and were considered to be novel species or strains that have yet-to-be cultivated and characterized.


CONCLUSIONS
Phylogenetic analysis indicated that the methanogen species in the hindgut of white rhinoceroses were more similar to those in the hindgut of horses. Our findings may help develop studies on improving the digestibility of forage for sustainable management and better health of these endangered animals.
Key Laboratory for Animal Disease-Resistance Nutrition of China and Ministry of Education; Institute of Animal Nutrition, Sichuan Agricultural University, 625014, Ya'an, China. luoluo212@126.com.
Yu-heng
YH
Luo
André-Denis G
AD
Wright
You-long
YL
Li
Hua
H
Li
Qi-hong
QH
Yang
Ling-juan
LJ
Luo
Ming-xian
MX
Yang
D000818:Animals; D001105:Archaea / Q000145:classification* / Q000378:metabolism*; D044822:Biodiversity; D016000:Cluster Analysis; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology*; D008297:Male; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D010527:Perissodactyla / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D019641:DNA, Archaeal; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D008697:Methane