(b) Effect of papain associated with talc on the survival of E. coli strains. Exponentially growing cultures were centrifuged, washed with 0.9% NaCl, and suspended in the same solution. Aliquots (1 mL) of these suspensions were incubated with different papain concentrations (associated or not with talc) or 0.9% NaCl for 60 minutes, at 37°C, with shaking. Afterwards, aliquots (100 μL) were taken, diluted and plated onto LB medium for determining surviving fractions (SF = N₆₀/N₀) for each strain. Values are the mean of 3 independent experiments (6 determinations) with standard deviations not exceeding 15% (mean ± SD). 5% significance level was adopted to compare data.

	E. coli strains (SF = N60/N0)
Agents	AB1157 (WT)	BW9091 (xthA)
0.9% NaCl (negative control)	1.00 ± 0.02	1.00 ± 0.04
Papain (500 μg/mL)	1.00 ± 0.03	0.93 ± 0.03
Papain associated with talc (500 μg/mL)	0.80 ± 0.01	0.96 ± 0.03
Talc (500 μg/mL)	0.90 ± 0.01	0.87 ± 0.02
H2O2 (10 Mm) (positive control)	0.20* ± 0.004	0.003* ± 0.00004

The results are not significantly different (p > 0.05) when compared to negative control.

*The results are significantly different (p < 0.05) when compared to negative control.