Regulation of CcpA on the growth and organic acid production characteristics of ruminal Streptococcus bovis at different pH

Table 3 Effect of the absence of ccpA gene on organic acid production in S. bovis S1 at different pH (n = 3)

Items	Wild-type strain		ccpA-knockout strain		SEM¹	P-value²
Items	pH 6.5	pH 5.5	pH 6.5	pH 5.5	SEM¹	Strain	pH	Strain×pH
Lactic acid (mM)	41.10	39.20	38.78	35.98	0.561	< 0.001	< 0.001	0.107
Formic acid (mM)	5.63	5.29	8.40	7.74	0.404	< 0.001	0.002	0.200
Acetic acid (mM)	3.69^c	3.43^d	5.69^a	4.70^b	0.273	< 0.001	< 0.001	0.004
Total organic acids(mM)	50.42^b	47.91^c	52.87^a	48.42^c	0.603	0.001	< 0.001	0.014
Lactic acid (%)	81.51	81.81	73.35	74.31	1.190	< 0.001	0.049	0.260
Formic acid (%)	11.17	11.04	15.88	15.98	0.731	< 0.001	0.933	0.549
Acetic acid (%)	7.33^c	7.15^c	10.77^a	9.71^b	0.473	< 0.001	0.010	0.041

¹ SEM, standard error of mean
² Strain, strain effect; pH, pH effect; Strain × pH, the interaction between strain and pH
^a,b,c,d Means within a row with different superscripts differ significantly (P < 0.05)

ISSN: 1471-2180