| 摘要: |
| 为了测定体外培养条件下瘤胃微生物的赖氨酸消化率及赖氨酸降解过程中谷氨酸脱氢酶（GDH）、γ-谷氨酰转肽酶(γ-GT)、谷草转氨酶（GOT）、谷丙转氨酶（GPT）和尿素氮（UN）的变化及其相关关系，经瘤胃瘘管取成年山羊瘤胃液混匀后分装至12个血清瓶中，每瓶40 mL，同时每瓶加入淀粉20 mg;血清瓶随机均分为2组，其中一组每瓶再注入8 mL 0.25 mmol/L的L-赖氨酸作为赖氨酸组，另一组每瓶再注入等体积的去离子水作为对照，一并放入39 ℃培养箱培养16 h，并于培养的0，8和16 h取培养液测定GDH、γ-GT、GOT、GPT、UN和游离氨基酸。结果表明，底物中添加赖氨酸时，培养液中UN浓度可保持稳定，否则培养16 h后的UN浓度极显著升高；GDH活性在赖氨酸的降解代谢过程中随培养时间的延长而增加；培养时间的长短显著影响GDH、γ-GT活性及UN的含量（P≤0.05）。在不添加赖氨酸的条件下，培养16 h的γ-GT与16 h的GPT和UN均呈极显著正相关（R=0.95；R=0.92）。当底物中添加赖氨酸时， 培养0 h的GDH与培养8 h的γ-GT显著相关(R=0.88)；而培养8 h的γ-GT又与8 h的UN显著相关（R=0.86）;培养0,8和16 h的赖氨酸浓度与培养0 h的GDH呈负相关，与培养8 h的GDH呈极显著负相关（R=－0.94）。对照组培养8 和16 h的赖氨酸消化率分别为31.64%和63.59%，赖氨酸组培养8和16 h的赖氨酸消化率则分别为49.24%和74.55%，均极显著高于对照组培养8 h的消化率。提示在氮源缺乏的条件下，瘤胃微生物可能通过γ-GT、GPT和GOT的共同作用增加尿素氮的积累以维持生长，瘤胃微生物的赖氨酸降解本质上属于酶解。 |
| 关键词: 成年山羊 瘤胃微生物 谷氨酸脱氢酶（GDH） γ-谷氨酰转肽酶(γ-GT) 谷草转氨酶（GOT） 谷丙转氨酶（GPT） 尿素氮（UN） 赖氨酸 消化率 |
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| 基金项目:合肥市2005年重点农业科研资助项目（2005-1011） |
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| Changes and their relationships of enzymes, urea nitrogen and lysine concentrations during mixed rumen microorganisms by using lysine in vitro |
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| Abstract: |
| In Vitro studies were conducted to examine the changes and their relationships of NADP-linked glutamate dehydrogenase (GDH),γ-glutamy transpeptidase (γ-GT),glutamic-oxalacetic transaminase (GOT),glutamic-pyruvic transaminase (GPT),urea nitrogen (UN) and lysine concentrations during mixed rumen microorganisms degrading lysine.Rumen fluids were collected from fistulated goats,then mixed and poured into 12 serum bottles.The 12 bottles were divided into two treatments (control and lysine).Each treatment had 6 bottles.Each bottle contained 40 mL of rumen fluid and 20 mg of starch.Bottles with or without 0.42 mmol lysine was respectively lysine and control treatment,and both were anaerobically incubated at 39 ℃ for 16 h.Free lysine and UN concentration,and GDH,γ-GT,GPT,GOT activities in the supernatants of the incubation for 0,8,16 h were analyzed.UN concentration kept stand in suspension with lysine,while UN concentration was significantly high (P<0.05) at incubation for 16 h.Activities of GDH increased with incubation time.Interaction of lysine concentration and incubation time significantly influenced (P<0.05) activities of GDH and γ-GT of rumen microorganisms.Incubation time factor influenced (P<0.05)activities of GDH、γ-GT and UN concentration.Activity of γ-GT for 16 h had highly significantly positive relation with GPT and UN for 16 h in culture suspension without lysine treatment（R=0.95；R=0.92）.GDH at 0 h with γ-GT for 8 h had a significantly positive relation in suspension with lysine treatment (R=0.88),the latter was significantly positively related with UN for 8 h (R=0.86).Lysine concentrations for 0,8,16 h in two treatments were negatively related with GDH for 0 h.However,there was a highly significantly negative relation with GDH in adding lysine treatment for 8 h（R=－0.94）.Digestibilities of lysine in culture suspension with and without adding lysine for 8 and 16 h were 31.64%,49.24%,and 63.59%,74.55%,respectively.The digestibilities of lysine in adding lysine group for 8 and 16 h were all highly significantly higher(P<0.01) than that of in control group for 0 h.These results implied that rumen microorganisms probably increased UN accumulation through cooperation of γ-GT,GPT and GOT to keep growth under the lack of nitrogen sources.Degradation of lysine was an enzymic degradation essentially. |
| Key words: adult goat rumen microorganisms NADP-linked glutamate dehydrogenase (GDH) γ-glutamy transpeptidase (γ-GT) glutamic-oxalacetic transaminase (GOT) glutamic-pyruvic transaminase (GPT) urea N (UN) lysine digestibility |
