title: Intracellular pH responses in the industrially important fungus Trichoderma reesei.
abstract: Preserving an optimal intracellular pH is critical for cell fitness and productivity. The pH homeostasis of the industrially important filamentous fungus Trichoderma reesei (Hypocrea jecorina) is largely unexplored. We analyzed the impact of growth conditions on regulation of intracellular pH of the strain Rut-C30 and the strain M106 derived from the Rut-C30 that accumulates L-galactonic acid-from provided galacturonic acid-as a consequence of L-galactonate dehydratase deletion. For live-cell measurements of intracellular pH, we used the genetically encoded ratiometric pH-sensitive fluorescent protein RaVC. Glucose and lactose, used as carbon sources, had specific effects on intracellular pH of T. reesei. The growth in lactose-containing medium extensively acidified cytosol, while intracellular pH of hyphae cultured in a medium with glucose remained at a higher level. The strain M106 maintained higher intracellular pH in the presence of D-galacturonic acid than its parental strain Rut-C30. Acidic external pH caused significant acidification of cytosol. Altogether, the pH homeostasis of T. reesei Rut-C30 strain is sensitive to extracellular pH and the degree of acidification depends on carbon source.
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland. Electronic address: mari.valkonen@vtt.fi.
authors.forename: Mari
authors.initials: M
authors.lastname: Valkonen
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Penttilä
authors.affiliation: Laboratory of Biotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia; Centre of Excellence EN-FIST, 1000 Ljubljana, Slovenia. Electronic address: mojca.bencina@ki.si.
authors.forename: Mojca
authors.initials: M
authors.lastname: Benčina
mesh_terms: D003593:Cytoplasm / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D025301:Hyphae / Q000254:growth & development / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D007785:Lactose / Q000378:metabolism; D013011:Sorbic Acid / Q000378:metabolism; D013400:Sugar Acids / Q000378:metabolism; D014242:Trichoderma / Q000254:growth & development / Q000378:metabolism*
chemical_list: D006603:Hexuronic Acids; D013400:Sugar Acids; C012991:galactonic acid; C007819:galacturonic acid; D006836:Hydro-Lyases; C019607:galactonate dehydratase; D005947:Glucose; D007785:Lactose; D013011:Sorbic Acid
keywords: Dual sequential scanning microscopy; Filamentous fungus Trichoderma reesei; Genetically encoded pH sensor RaVC; Ratiometric indicator; pH homeostasis