Protective effects of α-tocopherol and β-carotene on para-nonylphenol-induced inhibition of cell growth, cellular respiration and glucose-induced proton extrusion of bacteria

para-Nonylphenol (NP) showed a dose-dependent inhibition against the cell growth of Bacillus subtilis, Micrococcus luteus, Pseudomonas aeruginosa and Staphylococcus aureus at 5-100 mu M. However, other typical plastic-derived endocrine disrupters such as bisphenol A and di-2-ethylhexyl phthalate (DEHP) did not significantly affect the cell growth of these bacteria at 5-100 mu M. The NP-induced cell growth inhibition was restored when concomitantly supplemented with lipohilic antioxidants such as alpha-tocopherol and beta-carotene, but not with hydrophilic antioxidants, ascorbic acid and (-)-epigallocatechin gallate (EGCG). NP also suppressed. in a dose-dependent manner cellular oxygen consumption and glucose-induced proton extrusion of these bacteria at 10-100 mu M. Both effects were prevented when added with alpha-tocophorol and beta-carotene, but not with ascorbic acid and EGCG. The significance of these results is discussed from the viewpoint of environmental microbiology and a possible biochemical mechanism of the inhibitory effect of NP is suggested. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.