TABLE 2.

Influence of Trypticase and amino acid addition on incorporation of ¹⁵NH₃ by three predominant cellulolytic ruminal bacteria grown on cellulose

Organism and mediuma	Final NH3 concn (g of N/liter)	Enrichment in NH3 (atom %)		Microbial N formed (g/liter)	Proportion of microbial N derived from ammonia	Mean proportion of amino acid N derived from ammonia	Mean proportion of phenylalanine N derived from ammonia
		Initial	Final
F. succinogenes BL2
A	0.086	33.2	30.0	0.035	0.91	0.90	0.89
B	0.136	31.4	30.4	0.033	0.52	0.73	0.15
C	0.198	29.1	26.6	0.061	0.42	0.50	0.10
D	0.256	38.1	24.2	0.075	0.47	0.40	0.08
R. flavefaciens 17
A	0.113	33.2	30.5	0.016	0.75	0.79	0.62
B	0.090	31.4	28.6	0.025	0.80	0.76	0.74
C	0.140	29.1	26.4	0.040	0.55	0.52	0.53
D	0.209	28.1	26.6	0.045	0.44	0.40	0.40
R. albus SY3
A	0.108	33.2	32.0	0.029	0.63	0.70	0.60
B	0.122	31.4	30.7	0.031	0.61	0.66	0.43
C	0.189	29.1	24.8	0.032	0.49	0.46	0.36
D	0.280	28.1	24.7	0.030	0.25	0.27	0.38
SEDb	0.004	0.36	0.34	0.003	0.033	0.018	0.07

^aA, basal medium; B, basal medium plus 1 g of Trypticase per liter; C, basal medium plus 10 g of Trypticase per liter; D, basal medium plus 15.5 g of amino acids per liter. 

^bResults are the means of triplicate cultures (P < 0.001).