Or-Rashid M M, Onodera R, Wadud S, Oshiro S, Okada T
Laboratory of Animal Nutrition and Biochemistry, Division of Animal Science, Faculty of Agriculture, Miyazaki University, Japan.
Amino Acids. 2001 Dec;21(4):383-91. doi: 10.1007/s007260170003.
In vitro studies were conducted to examine the metabolism of methionine (Met) and threonine (Thr) using mixed ruminal bacteria (B), mixed ruminal protozoa (P), and a combination of these two (BP). Rumen microorganisms were collected from fistulated goats fed with lucerne cubes (Medicago sativa) and a concentrate mixture twice a day. Microbial suspensions were anaerobically incubated with or without 1 mM each of the substrates at 39 degrees C for 12h. Met, Thr and their related amino compounds in both the supernatants and microbial hydrolyzates of the incubation were analyzed by HPLC. Met was degraded by 58.7, 22.1, and 67.3% as a whole in B, P, and BP suspensions, respectively, during 12h incubation. In the case of Thr, these values were 67.3, 33.4, and 76.2% in B, P, and BP, respectively. Met was catabolized by all of the three microbial suspensions to methionine sulfoxide and 2-aminobutyric acid. Catabolism of Thr by B and BP resulted in the production of glycine and 2-aminobutyric acid, while P produced only 2-aminobutyric acid. From these results, the existence of diverse catabolic routes of Met and Thr in rumen microorganisms was indicated.
开展了体外研究，以使用混合瘤胃细菌（B）、混合瘤胃原生动物（P）以及二者的组合（BP）来检测蛋氨酸（Met）和苏氨酸（Thr）的代谢情况。瘤胃微生物取自每天饲喂两次苜蓿块（紫花苜蓿）和精料混合物的带瘘管山羊。微生物悬浮液在有或无1 mM各底物的情况下，于39℃厌氧培养12小时。通过高效液相色谱法分析培养物上清液和微生物水解产物中的Met、Thr及其相关氨基化合物。在12小时培养期间，Met在B、P和BP悬浮液中的整体降解率分别为58.7%、22.1%和67.3%。对于Thr，B、P和BP中的这些值分别为67.3%、33.4%和76.2%。所有三种微生物悬浮液都将Met分解代谢为甲硫氨酸亚砜和2-氨基丁酸。B和BP对Thr的分解代谢产生了甘氨酸和2-氨基丁酸，而P仅产生2-氨基丁酸。从这些结果可以看出，瘤胃微生物中Met和Thr存在多种分解代谢途径。
