Table 6.

ANOVA for response surface quadratic model for butanol production.

Source	Sum of squares	DF	Mean square	F value	Prob > F
Model	165.5974	9	18.39971	28.96829	<0.0001
A: glucose	91.14471	1	91.14471	143.4972	<0.0001
B: C/N ratio	0.026234	1	0.026234	0.041302	0.8430
C: butyric acid	5.238802	1	5.238802	8.247908	0.0166
A2	32.26561	1	32.26561	50.7986	<0.0001
B2	2.983714	1	2.983714	4.697524	0.0554
C2	1.864879	1	1.864879	2.936044	0.1174
AB	1.966217	1	1.966217	3.09559	0.1090
AC	7.808876	1	7.808876	12.2942	0.0057
BC	0.972474	1	0.972474	1.531052	0.2442
Residual	6.351673	10	0.635167
Lack of fit	5.680897	6	0.946816	5.64609	0.0579
Pure error	0.670776	4	0.167694
Cor total	171.9491	19
Std. dev. = 0.796	Mean = 8.99			Adequate precision	17.196
R2 = 0.96	Adj R2 = 0.93