TABLE 1.

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

Organism and mediumb	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 phenylalamine N derived from ammonia
	Initial	Final	Initial	Final
F. succinogenes BL2
A	NGc
B	0.134	0.128	31.1	33.7	0.025	0.87	0.81	0.02
C	0.257	0.142	29.8	28.3	0.083	0.57	0.61	0.02
D	0.306	0.167	28.1	26.0	0.131	0.52	0.51	0.01
R. flavefaciens 17
A	0.129	0.094	32.1	32.3	0.021	1.01	1.02	0.96
B	0.134	0.079	31.3	30.8	0.032	0.93	0.89	0.77
C	0.257	0.090	29.8	26.9	0.078	0.72	0.62	0.59
D	0.306	0.125	28.1	26.1	0.160	0.58	0.51	0.52
R. albus SY3
A	0.129	0.057	32.1	32.3	0.063	1.09	1.02	0.74
B	0.134	0.042	31.1	30.2	0.076	0.93	0.92	0.65
C	0.257	0.096	29.8	26.9	0.122	0.75	0.74	0.56
D	0.306	0.124	28.1	24.1	0.141	0.68	0.67	0.71
SEDd	0.006	0.012	0.4	0.6	0.003	0.04	0.01	0.04

^aResults are the means of triplicate cultures. 

^bA, 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. 

^cNG, no growth. 

^dP < 0.001.