title: Buffering capacity and membrane H+ conductance of neutrophilic and alkalophilic gram-positive bacteria.
abstract: Buffering capacity and membrane H+ conductance were examined in three gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, and Bacillus alcalophilus. An acid pulse technique was used to measure both parameters. The buffering capacity and membrane H+ conductance of B. alcalophilus are influenced by the pH of the medium and the culture conditions. Suspensions of B. alcalophilus cells from both H. A. medium and L-malate medium cultures grown at pH 10.5 exhibited higher values for these parameters than cells grown at pH 8.5. B. alcalophilus grown aerobically had a lower buffering capacity and a lower membrane conductance for protons than the neutrophilic bacteria S. aureus and B. subtilis. Fermenting cells exhibited significantly higher values for both variables than respiring cells.
authors.affiliation: Departament de Microbiologia i Parasitologia Sanitàries, Universitat de Barcelona, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Rius
authors.forename: J G
authors.initials: JG
authors.lastname: Lorén
mesh_terms: D001407:Bacillus / Q000254:growth & development / Q000378:metabolism; D001412:Bacillus subtilis / Q000254:growth & development / Q000378:metabolism; D002021:Buffers; D002462:Cell Membrane / Q000378:metabolism; D003470:Culture Media; D004553:Electric Conductivity; D006094:Gram-Positive Bacteria / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D011522:Protons; D013045:Species Specificity; D013211:Staphylococcus aureus / Q000254:growth & development / Q000378:metabolism
chemical_list: D002021:Buffers; D003470:Culture Media; D011522:Protons