Rhodes A N, Urbance J W, Youga H, Corlew-Newman H, Reddy C A, Klug M J, Tiedje J M, Fisher D C
NSF Center for Microbial Ecology, Michigan State University, East Lansing 48824-1101, USA.
Appl Environ Microbiol. 1998 Feb;64(2):651-8. doi: 10.1128/AEM.64.2.651-658.1998.
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 that Rahnella 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.
在古代沉积物挖掘过程中出土的乳齿象（美洲乳齿象）遗骸通常仅由骨骼材料组成，这是因为软组织会被微生物在死后分解。然而，最近在俄亥俄州和密歇根州的缺氧沉积物中进行的两次骨骼遗骸挖掘，发现了似乎分别是小肠和大肠残余物的有机团块。对这些团块成分的宏观植物学检查揭示了植物材料组合，其放射性碳年代测定为距今约11500年前，被认为是这种已灭绝哺乳动物未完全消化的食物残余。我们试图使用各种通用和选择性培养基，从肠道内容物、与骨骼相关的沉积物以及远离遗骸的沉积物中培养和鉴定细菌。总共培养了295个分离株，并通过脂肪酸甲酯（FAME）谱和生化特征（API - 20E）鉴定出38个不同的分类单元。通过16S核糖体DNA（rDNA）测序确认了所选肠道菌和专性厌氧菌的分类地位。结果表明，肠道和与骨骼相关的样本中细菌分类单元的多样性最大，肠杆菌科成员占所有分离株的41%，在肠道团块和骨骼附近的沉积物中占主导地位，但在背景沉积物中不常见。阴沟肠杆菌是最常鉴定出的分离株，部分rDNA测序表明，FAME谱显示为小肠结肠炎耶尔森菌的菌株的正确身份是水生拉恩菌。未回收拟杆菌属或预期的肠道厌氧菌。唯一回收的专性厌氧菌是梭菌，且未从小肠团块中回收。这项研究的微生物学证据支持了其他宏观植物学数据，表明这些团块的肠道来源。然而，这些微生物是否是原始肠道微生物群的直接后代尚无法确定。
