The method for the extraction of antioxidant enzymes in the
microbial cells was described by Azcón et al. (2010). Bacterial cells
were homogenized in a cold mortar with 4 mL 50 mM phosphate
buffer (pH 7.8) containing 1 mM EDTA, 8 mM MgCl2, 5 mM
dithiothreitol (DTT), and 1% (w/v) polyvinylpolypyrrolidone
(PVPP). The homogenate was centrifuged at 6000 rpm for 15 min
at 4 C, and the supernatant was used for enzyme activity
determination. Catalase (CAT) activity was measured as described
by Aebi (1984), conducted in 2 mL reaction volume containing
50 mM potassium phosphate buffer (pH 7.0), 10 mM H2O2 and
50mL of enzyme extract. It was determined the consumption of
H2O2 and followed by decrease in absorbance at 240 nm for 1 min