title: Active transport in phototrophic bacteria.
abstract: Phototrophic bacteria utilize light-driven, cyclic electron flow to pump protons out of their cytoplasm, creating an electrochemical proton gradient, ΔμH+, outside acid and positive. These bacteria exchange external protons for internal cations (Na(+), K(+) and Ca(+2)), allowing the cells to maintain a nearly constant internal pH while maintaining the electrical component of ΔμH+. Na(+)/H(+) exchange also establishes an electrochemical Na(+) gradient. Phototrophic bacteria are able to utilize these electrochemical gradients as energy sources for the uptake of a wide variety of metabolites (e.g., sugars, organic acids and amino acids) via metabolite/cation symports.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, 79409-4260, Lubbock, Texas, (U.S.A.).
authors.forename: D B
authors.initials: DB
authors.lastname: Knaff