Rumen microbial diversity in Svalbard reindeer, with particular emphasis on methanogenic archaea

Abstract

Ruminal methanogens, bacteria and ciliate protozoa of Svalbard reindeer grazing natural pastures in October (late fall) and April (late winter) were investigated using molecular-based approaches. The appetite of the Svalbard reindeer peaks in August (summer) and is at its lowest in March (winter). Microbial numbers, quantified by real-time PCR, did not change significantly between October and April, when food intakes are at similar levels, although the numbers of methanogens tended to be higher in October (P=0.074), and ciliate numbers tended to be higher in April (P=0.055). Similarly, no change was detected in the bacterial and protozoal population composition by rRNA gene-based denaturing gradient gel electrophoresis analysis. Dominant methanogens were identified using a 16S rRNA gene library (97 clones) prepared from pooled PCR products from reindeer on October pasture (n=5). Eleven of the 22 distinct operational taxonomic units (OTUs) generated exhibited a high degree of sequence similarity to methanogens affiliated with Methanobacteriales (eight OTUs), Methanomicrobiales (one OTU) and Methanosarcinales (two OTUs). The remaining 11 OTUs (53% of the clones) were associated with a cluster of uncultivated ruminal archaea. This study has provided important insights into the rumen microbiome of a high-arctic herbivorous animal living under harsh nutritional conditions, and evidence suggesting that host type affects the population size of ruminal methanogens.

Diversity of gut methanogens in herbivorous animals

“…In the literature, this group has variably been referred to as 'rumen cluster C', 'uncultured novel order' or 'ThermoplasmatalesAffiliated Lineage C (TALC)'. Not only are they consistently identified in the gut of herbivores, but these methanogens can represent a very highly prevalent type of archaea in the gut environment (Wright et al, 2006 andEvans et al, 2009;Sundset et al, 2009b). These results have generated a great deal of interest in Thermoplasmatales-affiliated methanogens, and efforts are underway to successfully cultivate isolates from this group and determine their genome sequence.…”

“…Other than Methanobrevibacter-related methanogens, Thermoplasmatales-affiliated archaea were found at a frequency of 9.3%. In contrast, Thermoplasmatales-affiliated archaea were the most prevalent (53.6%) rumen methanogens in reindeer from the high-arctic desert island Svalbard that were sampled in late fall (Sundset et al, 2009b). Methanobrevibacter-related methanogens were less abundant in Svalbard reindeer than in Norwegian reindeer (42.3%), and they were predominantly represented by M. millerae (26.8%) and unassigned Methanobrevibacter species (13.4%).…”

“…Reindeer represents an interesting model for this purpose because it is adapted to survive in a harsh environment where diet consists of vegetation of poor nutritional quality, the abundance of which is controlled by seasonal weather changes. Rumen methanogen studies have so far been published on Norwegian (Sundset et al, 2009a) and Svalbard reindeer (Sundset et al, 2009b). In the rumen of Norwegian reindeer grazing on late summer pastures consisting of woody plants, graminoids, mosses and lichens, Methanobrevibacterrelated methanogens were found to be the most prominent (83.3%; Sundset et al, 2009a).…”

The use of direct-fed microbials for mitigation of ruminant methane emissions: a review

“…Although they are categorised as a minor group based on the meta-analysis of partial 16S rRNA sequences by Janssen and Kirs (2008), recent studies showed that they are ubiquitous members of the rumen in different ruminant species, fed different diets and at various geographical locations (Franzolin et al, 2012;St-Pierre and Wright, 2012). Methanomicrococcus and Methanosarcina were also retrieved from several rumen clone libraries (Whitford et al, 2001;Sundset et al, 2009), but not in significant numbers. Instead, the rumen cluster C group is one of the major methanogen groups (Janssen and Kirs, 2008) sometimes contributing up to 80% of the total clones analysed (Wright et al, 2006).…”

Examination of the Rumen Bacteria and Methanogenic Archaea of Wild Impalas (Aepyceros melampus melampus) from Pongola, South Africa

“…Previous studies that observed the microbiome of wild ruminants included the Svalbard reindeer (Rangifer tarandus platyrhynchus), moose (Alces alces), yak (Bos grunniens), elk (Cervus canadensis), white-tailed deer (Odocoileus virginianus), and the semi-domesticated Norwegian reindeer (Rangifer tarandus tarandus) [9][10][11][12][13]. The exploration of the rumen microbiota in wild animals, such as the impala, aims to improve our understanding of their rumen microorganisms in comparison to their domesticated relatives.…”