Table 3.

ANOVA and regression analysis of second-order polynomial model developed according to the results of the surface response methodology for the production of biomass and EPS by A. brasilense Ab-V5.

Factora	Biomass			EPS
	RCb	t-value	p-value	RCb	t-value	p-value
β0	8.809**	57.433	0.000	0.842**	11.430	0.000
β1	−0.213	−1.275	0.226	−0.200*	−2.497	0.028
β2	−0.298	−1.784	0.100	0.0824	1.027	0.325
β4	0.367*	2.195	0.049	0.141	1.760	0.104
β12	−0.474*	−2.838	0.015	−0.032	−0.401	0.696
β14	0.573**	3.429	0.005	0.085	1.064	0.308
β24	0.558**	3.339	0.006	0.426**	5.307	0.000
MSR	0.447			0.103
R2	0.772			0.769
EEc	= 8.80895 + (−0.213125 X1) + (−0.298125 X2) + (0.366875 X4) + (−0.474375 X1X2) + (0.573125 X1X4) + (0.558125 X2X4)			= 0.842053 + (−0.200438 X1) + (0.0824375 X2) + (0.141312 X4) + (−0.0321875 X1X2) + (0.0854375 X1X4) + (0.426063 X2X4)

^aβ linear estimates of coefficients for glycerol (β₁), sucrose (β₂), K₂HPO₄(β₄) and respective interactions; MSR, mean square residual.

^bRC, regression coefficient.

^cEE, expanded equation; X₁ glycerol concentration (% w/v), X₂ sucrose concentration (% w/v), X₄ K₂HPO₄ concentration (% w/v).

Asterisks denote levels of statistical significance:

^*p < 0.05,

^**p < 0.01.