title: Bioenergetics and the role of soluble cytochromes C for alkaline adaptation in gram-negative alkaliphilic Pseudomonas.
abstract: Very few studies have been conducted on alkaline adaptation of Gram-negative alkaliphiles. The reversed difference of H(+) concentration across the membrane will make energy production considerably difficult for Gram-negative as well as Gram-positive bacteria. Cells of the alkaliphilic Gram-negative bacterium Pseudomonas alcaliphila AL15-21(T) grown at pH 10 under low-aeration intensity have a soluble cytochrome c content that is 3.6-fold higher than that of the cells grown at pH 7 under high-aeration intensity. Cytochrome c-552 content was higher (64% in all soluble cytochromes c) than those of cytochrome c-554 and cytochrome c-551. In the cytochrome c-552-dificient mutant grown at pH 10 under low-aeration intensity showed a marked decrease in μ max⁡ [h(-1)] (40%) and maximum cell turbidity (25%) relative to those of the wild type. Considering the high electron-retaining abilities of the three soluble cytochromes c, the deteriorations in the growth of the cytochrome c-552-deficient mutant could be caused by the soluble cytochromes c acting as electron storages in the periplasmic space of the bacterium. These electron-retaining cytochromes c may play a role as electron and H(+) condenser, which facilitate terminal oxidation at high pH under air-limited conditions, which is difficult to respire owing to less oxygen and less H(+).
authors.affiliation: Laboratory of Environmental Microbiology, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan ; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi Toyohira-ku, Sapporo 062-8517, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Matsuno
authors.affiliation: Laboratory of Environmental Microbiology, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan ; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi Toyohira-ku, Sapporo 062-8517, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Yumoto
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D000468:Alkalies / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis; D003574:Cytochrome c Group / Q000096:biosynthesis; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D011549:Pseudomonas / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
chemical_list: D000468:Alkalies; D001426:Bacterial Proteins; D003574:Cytochrome c Group; C017167:cytochrome C(551); C022302:cytochrome C-552