TABLE 4.

Influence of amino acids on incorporation of ¹⁵NH₃ by S. ruminantium HD4^a

Parameter	Value for growth medium					SEDc
	Basal	Basal + amino acids (1 g/liter)	Basal + amino acids (5 g/liter)	Basal + amino acids (10 g/liter)	Basal + amino acids (30 g/liter)
NH3 concn (g of N/liter)
Initial	0.214	0.209	0.247	0.304	0.592	0.004
Final	0.117	0.145	0.257	0.313	0.701	0.008
Enrichment in NH3 (atom%)
Initial	37.7	37.8	35.1	32.6	26.7	0.36
Final	35.8	33.7	30.0	27.1	19.2	1.13
Microbial N formed (g/liter)	0.083	0.093	0.109	0.154	0.169	0.004
Enrichment in microbial N (atom%)	39.0	25.5	10.7	8.6	5.3	0.62
Proportion of microbial N derived from ammonia	1.06	0.71	0.33	0.29	0.23	0.016
Proportion of microbial amino acids derived from ammoniab
Ala	0.96	0.50	0.37	0.32	0.24
Gly	0.99	0.52	0.04	0.05	0.03
Val	0.93	0.50	0.12	0.05	0.01
Leu	0.93	0.58	0.24	0.12	0.03
Ile	0.94	0.59	0.25	0.12	0.02
Pro	0.98	0.08	0	0	0
Ser	0.98	0.53	0.03	0.06	0.09
Thr	0.97	0.56	0.21	0.18	0.07
Phe	0.87	0.55	0.14	0.12	0.08
Asp	0.98	0.69	0.43	0.33	0.16
Glu	0.98	0.70	0.48	0.41	0.33
Tyr	0.89	0.57	0.26	0.17	0.08
Mean proportion of amino acid N derived from ammonia	0.95	0.53	0.22	0.16	0.10	0.009

^aResults are mean values from three separate cultures. 

^bStandard errors of difference for proportion of individual microbial amino acids derived from ammonia are as follows: treatment, 0.005; amino acid, 0.007; treatment × amino acid, 0.016 (degrees of freedom, 118). 

^cSED, standard errors of differences of means.