Adaptive response of Bacillus sp. F26 to hydrogen peroxide and menadione.

The adaptive and cross-protection responses to oxidants were investigated in Bacillus sp. F26. The cells were treated with sublethal concentrations of either H(2)O(2) or menadione (a superoxide-generating agent) to induce an adaptive response. The results showed that the cells treated with menadione exhibited cross-protection against, but in another case, those cells treated with H(2)O(2) did not show significant resistance to menadione. It suggests that Bacillus sp. F26 possesses two separate adaptive responses that respond to the two different kinds of oxidants. The adaptability is regarded as that which is accompanied by the inductions of some antioxidant enzymes. It was found that catalase (CAT) production was increased about 1.6-fold after treatment with 600 microM: H(2)O(2), whereas the presence of 50 microM: menadione induced CAT, superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), and glutathione reductase (GR) by 2-, 2-, 2-, and 1.6-fold, respectively. The results can be used to explain why menadione-treated cells have higher adaptability to lethal concentrations of oxidants than that of those H(2)O(2)-treated. In addition, it was found that growing Bacillus sp. F26 in high-salinity media causes it to become more resistant to H(2)O(2) and menadione stress, which may be partially due to the induction of CAT and SOD production under high NaCl concentration.