Fibrolytic bacteria isolated from the rumen of North American moose (Alces alces) and their potential as a probiotic for ruminants.

In order to investigate the moose rumen bacteria face-to-face, I spent two weeks at the University of Tromsø, Tromsø, Norway, in the lab of Dr. Monica A. Sundset.  There, I learned how to anaerobically isolate and culture bacteria from the digestive tract of reindeer using an anaerobic chamber.  The chamber allows you to create an enclosed environment set to your atmospheric gas specifications, in this case it was 90% nitrogen, 5% carbon dioxide, and 5% hydrogen (and no oxygen) so simulate the ambient gas in the rumen.

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Showing off my Vermont moose bacterial isolates. Photo Credit: Kristina Drobny.

Following the identification of the moose rumen microorganisms, bacteria from the rumen of VT moose were anaerobically cultured and isolated; due to the proximity of moose hunting areas in Vermont to the University of Vermont, samples were able to be frozen and transported back to the lab within hours of host death. Over 100 isolates were cultured and identified as various species of Acinetobacter, Bacillus, Escherichia, Shigella, Staphylococcus, Streptococcus, Micrococcus, and Neisseria.

At the end of April 2014, a probiotic of several fibrolytic species was inoculated into the rumen of neonatal lambs to improve fiber digestion. Twenty-four lambs were hand-reared on milk replacer, weaned onto hay and a lamb starter grain, and later transferred to another farm to be let on natural pasture for the duration of summer and mid fall. Rumen samples, as well as production data such as weights and wool growth, were routinely taken.

giving the probiotic
Administering probiotic to a lamb.  Apparently it was delicious because this guy kept asking for extra helpings.  Photo Credit: Sue Ishaq

The developing bacterial microbiome was compared between the experimental and controls groups as they changed diet over time. It was hypothesized that using pre-weaned animals which have not yet been completely colonized, and by re-administering the probiotic through weaning onto a fiber diet, would enable the inoculant to establish instead of carving out a foothold in an established bacterial arena.

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Ishaq, S.L., Kim, C.J., Reis, D., Wright, A-D.G. 2015. Fibrolytic bacteria isolated from the rumen of North American moose (Alces alces) and their potential as a probiotic for ruminants. PLoS One, 10(12).  Article

Abstract

Fibrolytic bacteria were isolated from the rumen of North American moose (Alces alces), which eat a high-fiber diet of woody browse. It was hypothesized that fibrolytic bacteria isolated from the moose rumen could be used as probiotics to improve fiber degradation and animal production. Thirty-one isolates (Bacillus, n = 26; Paenibacillus, n = 1; and Staphylococcus, n = 4) were cultured from moose rumen digesta samples collected in Vermont. Using Sanger sequencing of the 16S rRNA gene, culturing techniques, and optical densities, isolates were identified and screened for biochemical properties important to plant carbohydrate degradation. Five isolates were selected as candidates for use as a probiotic, which was administered daily to neonate lambs for 9 weeks. It was hypothesized that regular administration of a probiotic to improve fibrolysis to neonate animals through weaning would increase the developing rumen bacterial diversity, increase animal production, and allow for long-term colonization of the probiotic species. Neither weight gain nor wool quality was improved in lambs given a probiotic, however, dietary efficiency was increased as evidenced by the reduced feed intake (and rearing costs) without a loss to weight gain. Experimental lambs had a lower acetate to propionate ratio than control lambs, which was previously shown to indicate increased dietary efficiency. Fibrolytic bacteria made up the majority of sequences, mainly PrevotellaButyrivibrio, and Ruminococcus. While protozoal densities increased over time and were stable, methanogen densities varied greatly in the first six months of life for lambs. This is likely due to the changing diet and bacterial populations in the developing rumen.

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