title: Temperature-stress tolerance of the fungal strain Aspergillus niger 26: physiological and ultrastructural changes.
abstract: The study focuses on the morphological and physiological cell responses to oxidative stress induced by high temperature treatment in the industrially relevant fungus Aspergillus niger 26. Temperatures above 30 °C lead to growth suppression and changes in morphological characteristics: decrease in the size of hyphal elements and increase in "active length" by switching from slightly branched long filaments to a multitude of branched forms containing active cytoplasm. Transmission electron microscopy of fungal cultures heated at 40 °C demonstrated abnormal wavy septation with reduced amount of chitin (as shown by WGA-gold labelling), intrahyphal hyphae development, disintegration of mitochondria and extensive autolysis. Temperature-dependent decrease in the total intracellular protein content and a sharp increase (six to tenfold) in oxidatively damaged proteins were also demonstrated. Elevated temperatures caused a two and threefold increase in catalase and superoxide dismutase activities, respectively.
authors.affiliation: The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, 26 Acad. Georgi Bonchev Str., 1113, Sofia, Bulgaria.
authors.forename: Radoslav
authors.initials: R
authors.lastname: Abrashev
authors.forename: Stoyanka
authors.initials: S
authors.lastname: Stoitsova
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Krumova
authors.forename: Svetlana
authors.initials: S
authors.lastname: Pashova
authors.forename: Tsvetelina
authors.initials: T
authors.lastname: Paunova-Krasteva
authors.forename: Spassen
authors.initials: S
authors.lastname: Vassilev
authors.forename: Pavlina
authors.initials: P
authors.lastname: Dolashka-Angelova
authors.forename: Maria
authors.initials: M
authors.lastname: Angelova
mesh_terms: D001234:Aspergillus niger / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure*; D018533:Biomass; D002374:Catalase / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D006358:Hot Temperature; D025301:Hyphae / Q000254:growth & development / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D018384:Oxidative Stress / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D002374:Catalase; D013482:Superoxide Dismutase