Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard

Trine Glad,Jon Aars,Monica A Sundset,Magnus Andersen,Pål Bernhardsen,Lorenzo Brusetti,Kaare M Nielsen

doi:10.1186/1471-2180-10-10

Abstract

BackgroundPolar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81°N, 10-33°E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006.ResultsA 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 × 104 to 1.6 × 106 colony forming units (cfu)/ml for the rectum swabs and 4.0 × 103 to 1.0 × 105 cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic β-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears.ConclusionThe bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations.

Highlights

Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice
We have examined the role of polar bear gut microbiota as a potential natural reservoir of the clinically important blaTEM genes
To improve our understanding of the intestinal ecosystem of the polar bear we have studied the bacterial diversity and the prevalence of blaTEM alleles in faeces of polar bears in Svalbard, Norway (Fig. 1)

Summary

Introduction

Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. Most cultivation independent studies have been conducted on the human gastrointestinal tract, and animals including pigs, Antibiotic resistant bacteria are known to originate in populations located in environments that seem not to have been exposed to the selective pressure of pharmaceutically produced antibiotics [11]. Even though widespread in clinical settings, only few studies have determined the distribution of blaTEM genes in non-clinical environments, included the gastrointestinal tract of free ranging Arctic wild mammals [15,16,17,18,19]. We have examined the role of polar bear gut microbiota as a potential natural reservoir of the clinically important blaTEM genes

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