Abstract: This study aimed at investigating the effect of Met or Lys as sole Nitrogen (N) and Carbon (C) sources on Glutamic Oxaloacetic Transaminase (GOT), Glutamic Pyruvic Transaminase (GPT) and Amino Acid (AA) metabolism of rumen microorganisms in vitro. Three fistulated goats were used as a source of ruminal microorganisms. Microbial suspensions with or without Met or Lys as substrate were anaerobically incubated at 39°C for 16 h. Free AA and transaminases in the supernatants of the incubation were analyzed by HPLC and an automatic biochemistry analyzer, respectively. When Met was used as a unique source of N and C, the content of free Val and His were significantly (p<0.01 and p<0.05) reduced but Gly was increased (p<0.01). No significant differences in the other free AA were found as well as for GOT and GPT activities. When Lys was used as a sole source of N and C, the content of free His and activities of GOT and GPT were significantly lower (p<0.01) than that of controls however Tyr was significantly increased (p<0.05). The results indicated that Val and Cys are probably the most important AA of rumen microorganisms when Met serves as the only source of N and C. But when Lys serves as a sole source of N and C, His becomes the most important AA. At the same time, GPT plays a weaker role when Met serves as a sole source of N and C.
L.M. Li, H. Diao, X.L. Ding, K. Qian and Z.J. Yin, 2011. Effects of Methionine or Lysine Served as Sole Nitrogen and Carbon Sources on Level of Free Amino Acids and Activity of Transaminases at in vitro Incubation of Rumen Microorganisms. Journal of Animal and Veterinary Advances, 10: 1588-1591.