Novel Rumen Bacterial Diversity in Two Geographically Separated Sub-Species of Reindeer

Abstract

Svalbard reindeer (Rangifer tarandus platyrhynchus) live under austere nutritional conditions on the high-arctic archipelago of Svalbard, while semi-domesticated Norwegian reindeer (R. tarandus tarandus) migrate between lush coastal summer pastures and inland winter pastures with lichens on mainland Norway. Svalbard reindeer are known to have high rumen concentrations of cellulolytic bacteria, ranging from 15% of the viable population in summer to 35% in winter, compared to only 2.5% in Norwegian reindeer. Their rumen bacterial diversity was investigated through comparative analyses of 16S rRNA gene sequences ( approximately 1.5 kb in length) generated from clone libraries (n = 121) and bacterial isolates (n = 51). LIBSHUFF comparisons of the composition of the two 16S rRNA libraries from Norwegian reindeer showed a significant effect of artificial feeding compared to natural pasture, but failed to yield significant differences between libraries from Norwegian reindeer and Svalbard reindeer. The combined sequences from reindeer were not significantly different from those reported in wild Thompson's gazelle in Kenya but did differ from those reported in domestic cattle in Japan. A total of 90 distinct operational taxonomic units (OTUs) were identified by employing a criterion of 97% similarity, while the Chao1 index estimated the reindeer bacterial rumen population richness at 698 OTUs. The majority of the clone library sequences (92.5%) represented novel strains with <97% identity to any known sequence in the public database, most of them affiliated with the bacterial phylum Firmicutes (low G+C Gram-positives) related to the order Clostridiales (76.7%), while Gram-negative bacteria in the Bacteriodales (Prevotella-Bacteroides group) contributed to 22.5%. Also, six of the isolates were putatively novel strains, possibly representing new species in the Clostridium subphylum (cluster XIVa), Actinomyces and Butyrivibrio.

Functional Characterization Reveals Novel Putative Coding Sequences in Prevotella ruminicola Genome Extracted from Rumen Metagenomic Studies

“…The dominance of the Bacteroidetes and the Firmicutes phyla observed in the metagenomic results was in accordance with a number of earlier studies [Jami et al, 2014;Sundset et al, 2007] related to gut and rumen of cattle [Kalyuzhnaya et al, 2008;Kong et al, 2010] and buffalo [Singh et al, 2012]. Of these, relatively few analyzed bacterial diversity using high-throughput next-generation sequencing.…”

Molecular profiling of bacterial species in the geese cecum

“…In the study, we found that there were 80 cloned sequences (50%) with less than 97% of relatedness to database sequences unidentified in the goose gut previously. Sundset et al (2007) suggested that less than 97% of relatedness to database sequences may represent a new species. Moreover, the physiological role of many more bacteria than newly sequenced bacteria should be investigated.…”

Eubacterium rangiferina, a novel usnic acid-resistant bacterium from the reindeer rumen

“…Anaerobic culture methods were those of Bryant (1972) using Hungate culture tubes (Bellco, Vineland, NJ, USA) sealed with butyl rubber septa. Bacteria were maintained on a modified M8V medium (Sundset et al 2007) in Petri dishes in an anaerobic chamber (Coy Laboratory Products, Ann Arbor, MI, USA) in an atmosphere of N 2 (90%), CO 2 (5%), and H 2 (5%). A palladium catalyst was present to remove O 2 , and the temperature in the chamber was kept at 39°C.…”

“…The bacteria were cultured under a CO 2 atmosphere in sealed boxes inside the chamber. The M8V medium contained an anaerobic M8 buffer (Olsen et al 1994) in which the rumen fluid had been replaced by a mixture of fatty acids (3.1 ml/1,000 ml medium) as described for the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ, Braunschweig, Germany) medium 330 (Kopečný et al 2003) and 0.1% (wt/vol) of the following carbohydrates: xylan from Birchwood, cellobiose, glucose, starch, and maltose (Sundset et al 2007). Vitamins (1% vol/vol;Roché et al 1973) were filter sterilized through a Millex R-GS single-use filter unit (0.22 μm; Millipore, Molsheim, France) and added to the medium before use.…”

“…As ruminants, they depend on symbiotic rumen microorganisms for the degradation of plant cell wall carbohydrates (Mathiesen et al 2005), and molecular studies indicate that they host rumen bacteria different from those found in domestic sheep and cattle (Mackie et al 2003;Sundset et al 2007). Foregut fermentation may enable detoxification and thus protection from plant secondary metabolites.…”