Application of response surface methodology to improve the production of antimicrobial biosurfactants by Lactobacillus paracasei subsp. tolerans N2 using sugar cane molasses as substrate

Bioresources and Bioprocessing

Table 2 ANOVA of the different responses assessed for the Plackett-Burman design

Factors	Inhibition diameter				Surface tension				Yield
Factors	DF	Sum of squares	F-value	p-value	DF	Sum of squares	F-value	p-value	DF	Sum of squares	F-value	p-value
X ₁	1	603.501	30.050	0.031*	1	55.900	21.580	0.043*	1	1.387	27.630	0.034*
X ₂	1	61.200	3.050	0.223	1	17.040	6.580	0.124	1	0.158	3.160	0.217
X ₃	1	0.300	0.010	0.913	1	0.520	0.200	0.697	1	0.001	0.020	0.891
X ₄	1	281.301	14.010	0.064	1	22.687	8.760	0.097	1	0.790	15.750	0.058
X ₅	1	643.868	32.060	0.029*	1	222.741	86.000	0.011*	1	1.346	26.820	0.035*
X ₆	1	397.901	19.810	0.046*	1	204.188	78.840	0.012*	1	1.009	20.100	0.046*
X ₇	1	48.400	2.410	0.260	1	8.500	3.280	0.211	1	0.080	1.590	0.334
X ₈	1	96.900	4.820	0.159	1	3.307	1.280	0.375	1	0.235	4.680	0.163
Lack of fit	4	52.829	0.660	0.677	4	43.422	4.190	0.201	4	0.133	0.660	0.675
Pure error	2	40.166			2	5.180			2	0.100
Total (corr.)	14	2226.37			14	583.489			14	5.242
R ²			95.82				91.67				95.34
Adjusted R²			90.25				80.56				89.60

X₁: Temperature; X₂: time; X₃: agitation speed; X₄: inoculum concentration; X₅: sugar cane molasses concentration; X₆: peptone concentration; X₇: yeast extract concentration; X₈: K₂HPO₄ concentration; DF: degrees of freedom; *significant at p < 0.05