- 學位論文
分離產高三甲胺表現型之相關菌種與其功能分析 (II)
Isolation and functional analysis of bacterial species associated with high trimethylamine producing phenotype (II)
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摘要
心血管疾病是全球一大死因，近年來已經有許多論文報導它的致病機制其中之一是由於腸道菌產生的小分子代謝物導致。當人類攝食動物性食物，例如：紅肉、雞蛋、貝類以及魚類等富含膽鹼 (choline) 和左旋肉鹼 (L-carnitine)，這些物質會被一些腸道菌分解產生三甲胺 (trimethylamine, TMA)，而三甲胺藉由肝臟酵素形成氧化三甲胺 (trimethylamine-N-oxide, TMAO) 進入血液循環，若氧化三甲胺累積濃度高可能導致心血管疾病的發生。本研究室的合作團隊利用16S 核醣體DNA次世代定序分析血漿中有高濃度氧化三甲胺的受試者之腸道菌株，其中與產氧化三甲胺高度相關的菌株包含Alistipes timonensis、埃氏類桿菌 (Bacteroides eggerthii)和Ihubacter massiliensis，因此本研究利用受試者糞便檢體培養腸道微生物及聚合酶連鎖反應技術進行分離A. timonensis、B. eggerthii和I. massiliensis。實驗結果顯示無法分離出A. timonensis，B. eggerthii則在糞便檢體O13中成功分離，並將其命名為B. eggerthii O13，而I. massiliensis仍在分離中。之後對B. eggerthii O13進行膽鹼、肉鹼及γ-丁基甜菜鹼 (γ-Butyrobetaine, γ-BB) 之代謝利用實驗，結果顯示B. eggerthii O13不具有代謝膽鹼、肉鹼或γ-丁基甜菜鹼產生三甲胺的功能。本研究另探討先前由本實驗室分離出可能為低三甲胺生成相關的菌株Flavonifractor plautii是否對代謝γ-丁基甜菜鹼為三甲胺的Emergencia timonensis具抑制能力，將兩種菌株共同培養進行γ-丁基甜菜鹼代謝利用競爭實驗，結果顯示雖然F. plautii可能藉由抑制E. timonensis生長而降低三甲胺生成，但不具有顯著差異。
並列摘要
Cardiovascular disease is one of main cause of death in the world. In recent years, many researches have showed that one of its pathogenic mechanisms is caused by small molecular metabolites produced by gut microbiota. Some gut microbiota can metabolize choline, L-carnitine or γ-butyrobetaine (γ-BB) to trimethylamine (TMA), then TMA converts to trimethylamine-N-oxide (TMAO) through liver enzymes and enters the blood circulation. If the cumulative concentration of TMAO is high, it may lead to cardiovascular disease. Our cooperating lab used 16S ribosomal DNA next-generation sequencing to analyze the gut microbiota strains of subjects with high concentrations of TMAO in the plasma. Alistipes timonensis, Bacteroides eggerthii, and Ihubacter massiliensis were identified. In this study, we want to isolate A. timonensis, B. eggerthii and I. massiliensis to investigate whether they have the ability of metabolizing choline, carnitine or γ-BB to TMA. Our results showed that A. timonensis could not be isolated, while B. eggerthii was successfully isolated from stool sample O13. We are still working on the isolation of I. massiliensis. However, we also found that B. eggerthii could not metabolize choline, carnitine or γ-BB to TMA. On the other hand, we want to explore whether the previously isolated strain Flavonifractor plautii, a low TMA producing-associated bacteria, has inhibitory ability against Emergencia timonensis, which can metabolize γ-BB to TMA. In the γ-BB metabolism and competition experiment, although F. plautii reduced the production of TMA and inhibited the growth of E. timonensis when co-cultured with E. timonensis, the content did not have a significant difference.
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