Identification of Bacterial Isolates Obtained from Intestinal Contents Associated with 12,000-Year-Old Mastodon Remains

Abstract

Mastodon (Mammut americanum) remains unearthed during excavation of ancient sediments usually consist only of skeletal material, due to postmortem decomposition of soft tissues by microorganisms. Two recent excavations of skeletal remains in anoxic sediments in Ohio and Michigan, however, have uncovered organic masses which appear to be remnants of the small and large intestines, respectively. Macrobotanical examinations of the composition of these masses revealed assemblages of plant material radiocarbon dated to approximately 11,500 years before the present and thought to be incompletely digested food remains from this extinct mammal. We attempted to cultivate and identify bacteria from the intestinal contents, bone-associated sediments, and sediments not in proximity to the remains using a variety of general and selective media. In all, 295 isolates were cultivated, and 38 individual taxa were identified by fatty acid-methyl ester (FAME) profiles and biochemical characteristics (API-20E). The taxonomic positions of selected enteric and obligately anaerobic bacteria were confirmed by 16S ribosomal DNA (rDNA) sequencing. Results indicate that the intestinal and bone-associated samples contained the greatest diversity of bacterial taxa and that members of the family Enterobacteriaceae represented 41% of all isolates and were predominant in the intestinal masses and sediments in proximity to the skeleton but were uncommon in the background sediments. Enterobacter cloacae was the most commonly identified isolate, and partial rDNA sequencing revealed thatRahnella aquatilis was the correct identity of strains suggested by FAME profiles to be Yersinia enterocolitica. No Bacteroides spp. or expected intestinal anaerobes were recovered. The only obligate anaerobes recovered were clostridia, and these were not recovered from the small intestinal masses. Microbiological evidence from this study supports other, macrobotanical data indicating the intestinal origin of these masses. Whether these organisms are direct descendants of the original intestinal microbiota, however, cannot be established.

Environmental reconstruction inferred from the intestinal contents of the Yamal baby mammoth Lyuba (Mammuthus primigenius Blumenbach, 1799)

“…Supposedly, this enabled the uptake of modern carbon by these microbes. Such phenomena have been observed before, for example in 12,000 years old Mastodon remains (Rhodes et al, 1998). The AMS radiocarbon date obtained for a properly treated large sample (41,700 (þ700/À550) BP) is accepted as a final date for the intestinal contents of a baby mammoth.…”

Evidence for the diet and habitat of two late Pleistocene mastodons from the Midwest, USA

“…The putative intestinal material consisted of a zone of finely ground plant debris several centimeters thick in most places, surrounding the lateral and lower aspect of a hemispherical mass of sand and gravel about 30 cm in plan diameter (see figs. 1B and 2 in Rhodes et al, 1998). This hemisphere is inferred to have originally been a spheroidal mass of sand and gravel, surrounded on all sides by a zone of finely ground plant debris, all retained within tissue of the large intestine.…”

“…Bacteriological analyses showed that the lake sediment contained taxa known to occur in sediment and/or freshwater environments, whereas the cylindrical mass included species common in mammalian intestinal tracts (Lepper et al, 1991). More refined microbiological analysis by Rhodes et al (1998) was more quantitative and uncovered greater bacterial diversity. Enterobacteriaceae characteristic of intestines were found by culture and confirmed by DNA and ribosomal sequencing.…”

The Natural Antibiotic Resistances of the Enterobacteriaceae Rahnella and Ewingella

“…It is frequently found in the rhizosphere and tightly associated with roots and tubers of plants (Berge et al, 1991;Heulin et al, 1994;Jafra et al, 2009;Rozhon et al, 2010) but is also present on other parts of plants including leaves (Hamilton-Miller & Shah, 2001;Hashidoko et al, 2002), fruits (Lindow et al, 1998) and seeds (Cankar et al, 2005;Iimura & Hosono, 1996). Other sources are water (Brenner et al, 1998;Gavini et al, 1976;Niemi et al, 2001), soil (Martinez et al, 2007) and the intestine of snails, slugs (Brenner et al, 1998) and even American mastodon remains (Rhodes et al, 1998). Recently, Rahnella was also found at a high frequency in the gut of ghost moths (Yu et al, 2008) and to be associated with larvae and adults of the mountain pine beetle (Winder et al, 2010).…”