Intracellular oxidative damage due to antibiotics on gut bacteria reduced by glutathione oxidoreductase-derived antioxidant molecule GM15.

The human gut consists of > 1000 different bacterial species for the smooth functioning of the gut. In normal conditions, the antioxidant system present in cells minimize the effects of reactive oxygen species. Upon exposure to antibiotics, there is a rise in ROS level which induces oxidative stress to the cells, ultimately killing the cells. Two broad-spectrum antibiotics, streptomycin and gentamicin at a concentration of 50 µM and 25 µM, were treated with Bacillus subtilis SRMIST201901 (MN726522) and B. cereus SRMIST201902 (MN726923); the treatment reduced the cell counts. Considering the bacterial defense property which relies on the antioxidant mechanism, in this study, we have reported an antioxidant peptide (GM15) derived from glutathione oxidoreductase of spirulina (or called cyanobacteria) Arthrospira platensis (Ap) which reduced the intracellular oxidative stress. Cellular ROS detection was confirmed by fluorescent-associated cell sorting (FACS) using the DCFDA dye. Resazurin dye test also confirmed the activity of peptide on the growth of the Bacillus sp. Based on the results obtained, it was concluded that there was a significant (P < 0.05) reduction in the intracellular oxidative stress on treating with GM15 peptide. Overall, the study indicates the influence of antioxidant peptide on the intracellular oxidative stress, leading to the development of an antioxidant drug from glutathione oxidoreductase of A. platensis against oxidative-related stresses.