Uncoupling Effect of Fatty Acids in Halo- and Alkalotolerant Bacterium Bacillus pseudofirmus FTU

I. V. Popova, M. E. Bodrova, E. N. Mokhova, and M. S. Muntyan^*

Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; fax: (7-095) 939-3181; E-mail: muntyan@genebee.msu.su

^* To whom correspondence should be addressed.

Received May 31, 2004

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Natural uncouplers of oxidative phosphorylation, long-chain non-esterified fatty acids, cause uncoupling in the alkalo- and halotolerant bacterium Bacillus pseudofirmus FTU. The uncoupling effect in the bacterial cells was manifested as decrease of membrane potential and increase of respiratory activity. The membrane potential decrease was detected only in bacterial cells exhausted by their endogenous substrates. In proteoliposomes containing reconstituted bacterial cytochrome c oxidase, fatty acids caused a “mild” uncoupling effect by reducing membrane potential only at low rate of membrane potential generation. “Free respiration” induced by the “mild” uncouplers, the fatty acids, can be considered as possible mechanism responsible for adaptation of the bacteria to a constantly changed environment.

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KEY WORDS: fatty acids, bacteria, uncouplers, proteoliposomes, membrane potential, caa₃ type oxidase

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