Investigation of the antioxidant capacity of cell-free extracts from Lactobacillus plantarum NJAU-01 obtained by different cell disruption methods

The antioxidant capacity of cell-free extracts from Lactobacillus plantarum NJAU-01 obtained by using different cell disruption methods was determined. The efficacy of various methods, including high-pressure treatment (HIP), lysozyme combined with ultrasound treatment (LCU), glycine treatment (GLY), and frozen-thawed treatment (FAT) was studied. The results showed that the bacterial suspension in the HIP group visibly had the least intact cells per visual field compared with the other groups, followed by the LCU group. The HIP group possessed 5.12 lg CFU/mL viable bacteria, which was significantly lower than that of the other groups after cell disruption from the initial 9 lg CFU/mL. The protein concentration of the cell-free extract from the HIP group was higher than that of the other groups with abundant protein bands and band intensities. The HIP group presented significantly higher total antioxidant capacity and superoxide dismutase and glutathione peroxidase activities than the other groups. Our data suggest that HIP can be a preferable method to obtain cell-free extracts with excellent antioxidant capacity for further exploring the underlying antioxidant mechanism of Lactobacillus plantarum NJAU-01.