Table 3: Mutoxitest—Number of Trp+ revertants/plate (mean ± SD). Aliquots (100 L) of exponentially growing cultures were mixed with 100 L of different concentrations of the papain or 0.9% NaCl, as negative control, and mixed with 2.5 mL molten top agar at 45C and plated on minimal glucose agar plates supplemented with 0.5 mg tryptophan/litre. The mutagenic responses were expressed as the absolute number of Trp+ revertants/plate, after incubation at 37C, for 48 hours. Values are the mean of 3 independent experiments with standard deviations not exceeding 15%.
Number of Trp+ revertants/plate (mean ± SD)
Agent (g/plate)
E. coli IC203 uvrA oxyR
E. coli IC204 uvrA umuDC
Papain 5
158 ± 26.0
15 ± 3.0
Papain 25
162 ± 16.0
17 ± 3.0
Papain 50
154 ± 26.0
12 ± 3.0
Papain 100
129 ± 24.0
14 ± 3.0
Papain 125
178 ± 10.0
16 ± 3.0
Papain 250
162 ± 25.0
17 ± 3.0
Papain 500
149 ± 24.0
18 ± 3.0
Positive control H2O2 (300)
853* ± 70.2
15a ± 1.9
Negative control 0.9% NaCl (50 L/plate)
141 ± 28.0
16 ± 4.0
Number of H2O2-induced revertants equivalent to that found with other genotoxic agents used by Blanco et al. in 1998. when compared to negative control (0.9% NaCl).