摘要
      大象是濒临灭绝的物种。它们是单胃草食性的，后肠发酵器，它们的消化策略要求它们消耗大量低质量的饲料。肠道微生物组对它们的新陈代谢、免疫调节和生态适应都很重要。我们的研究调查了相同饮食条件下圈养非洲象和亚洲象肠道微生物群的结构和功能以及抗生素耐药性基因（ARGs）。结果表明，圈养的非洲象和亚洲象的肠道细菌组成不同。MetaStats分析显示，圈养的非洲象和亚洲象在门水平上的螺旋体类（FDR=0.00）和疣毛象属（FDR=0.01）以及在科水平上的Spirochaeteae（FDR=01）和Akkermansiaceae（FDR=0.02）的相对丰度各不相同。在京都基因和基因组百科全书（KEGG）数据库第2级（57种子途径）的前十个功能亚类中，细胞群落原核生物的相对基因丰度、膜转运、，和碳水化合物代谢显著低于亚洲象（0.98对1.03%，FDR=0.04；1.25对1.43%，FDR=0.03；3.39对3.63%；FDR=0.02），MetaStats分析显示，与亚洲象相比，非洲象具有更高的糖苷水解酶家族28（GH 28）的相对基因丰度（0.10对0.08%，FDR=0.03）。关于肠道微生物携带的抗生素抗性基因，MetaStats研究显示，非洲象的vanO（FDR=0.00）、tetQ（FDR=0.04）、，和efrA（FDR=0.04）分别比编码糖肽、四环素和大环内酯类/利福霉素/氟喹诺酮类抗生素耐药性的亚洲象高。总之，相同饮食的圈养非洲象和亚洲象具有不同的肠道微生物群落。我们的发现为未来改善圈养大象肠道健康的研究奠定了基础。
Abstract
Elephants are endangered species and threatened with extinction. They are monogastric herbivorous, hindgut fermenters and their digestive strategy requires them to consume large amounts of low quality forage. The gut microbiome is important to their metabolism, immune regulation, and ecological adaptation. Our study investigated the structure and function of the gut microbiota as well as the antibiotic resistance genes (ARGs) in captive African and Asian elephants on the same diet. Results showed that captive African and Asian elephants had distinct gut bacterial composition. MetaStats analysis showed that the relative abundance of Spirochaetes (FDR = 0.00) and Verrucomicrobia (FDR = 0.01) at the phylum level as well as Spirochaetaceae (FDR = 0.01) and Akkermansiaceae (FDR = 0.02) at the family level varied between captive African and Asian elephants. Among the top ten functional subcategories at level 2 (57 seed pathway) of Kyoto Encyclopedia of Genes and Genomes (KEGG) database, the relative gene abundance of cellular community-prokaryotes, membrane transport, and carbohydrate metabolism in African elephants were significantly lower than those in Asian elephants (0.98 vs. 1.03%, FDR = 0.04; 1.25 vs. 1.43%, FDR = 0.03; 3.39 vs. 3.63%; FDR = 0.02). Among the top ten functional subcategories at level 2 (CAZy family) of CAZy database, MetaStats analysis showed that African elephants had higher relative gene abundance of Glycoside Hydrolases family 28 (GH 28) compared to Asian elephants (0.10 vs. 0.08%, FDR = 0.03). Regarding the antibiotic resistance genes carried by gut microbes, MetaStats analysis showed that African elephants had significantly higher relative abundance of vanO (FDR = 0.00), tetQ (FDR = 0.04), and efrA (FDR = 0.04) than Asian elephants encoding resistance for glycopeptide, tetracycline, and macrolide/rifamycin/fluoroquinolone antibiotic, respectively. In conclusion, captive African and Asian elephants on the same diet have distinct gut microbial communities. Our findings established the ground work for future research on improving gut health of captive elephants.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9978182/