title: [Mechanism of Hansenula polymorpha reaction to the pulsed addition of a limiting substrate].
abstract: As was shown in experiments with a Hansenula polymorpha culture, a temporary drop in the pH of the medium in response to a pulse addition of a limiting substrate (organic or mineral) is not related to NH4+ uptake from the medium. The response is similar in media with NH4+ and in distilled water without NH4+. The pH drop caused by a pulse addition of certain substrates appears to result from the extrusion of H+ ions in the process of antiport: K+/H+ and Mg2+/H+. It is likely that the response to a substrate pulse is the extrusion of H+ ions for maintaining the membrane potential decreased owing to the uniport of either NH4+ or K+. Protons may be extruded in response to a substrate pulse during glycolysis of respiration. It is possible that an addition of organic substrates activates the metabolism; inorganic ions may also have a stimulating action. The lag time from the moment of substrate addition to the beginning of a decrease in the pH of the medium seems to include transport to the cytoplasmic membrane, transport into the cell and, possibly, the first steps of metabolism of the added substrate.
mesh_terms: D001203:Ascomycota / Q000378:metabolism*; D001692:Biological Transport; D003470:Culture Media / Q000378:metabolism; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D010843:Pichia / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
chemical_list: D003470:Culture Media; D000644:Quaternary Ammonium Compounds; D006859:Hydrogen; D008274:Magnesium; D011188:Potassium
vernacular_title: O mekhanizme reaktsii Hansenula polymorpha na impul'snuiu dobavku limitiruiushchego substrata.