title: Role of oxidative stress in Sclerotial differentiation and aflatoxin B1 biosynthesis in Aspergillus flavus.
abstract: We show here that oxidative stress is involved in both sclerotial differentiation (SD) and aflatoxin B1 biosynthesis in Aspergillus flavus. Specifically, we observed that (i) oxidative stress regulates SD, as implied by its inhibition by antioxidant modulators of reactive oxygen species and thiol redox state, and that (ii) aflatoxin B1 biosynthesis and SD are comodulated by oxidative stress. However, aflatoxin B1 biosynthesis is inhibited by lower stress levels compared to SD, as shown by comparison to undifferentiated A. flavus. These same oxidative stress levels also characterize a mutant A. flavus strain, lacking the global regulatory gene veA. This mutant is unable to produce sclerotia and aflatoxin B1. (iii) Further, we show that hydrogen peroxide is the main modulator of A. flavus SD, as shown by its inhibition by both an irreversible inhibitor of catalase activity and a mimetic of superoxide dismutase activity. On the other hand, aflatoxin B1 biosynthesis is controlled by a wider array of oxidative stress factors, such as lipid hydroperoxide, superoxide, and hydroxyl and thiyl radicals.
authors.affiliation: Biochemistry Laboratory, Section of Genetics, Cell and Developmental Biology, Department of Biology, University of Patras, Patras, Greece Metabolic Engineering and Systems Biology Laboratory, Institute of Chemical Engineering Sciences, Foundation for Research and Technology-Hellas, Patras, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Grintzalis
authors.affiliation: Metabolic Engineering and Systems Biology Laboratory, Institute of Chemical Engineering Sciences, Foundation for Research and Technology-Hellas, Patras, Greece.
authors.forename: Spyros I
authors.initials: SI
authors.lastname: Vernardis
authors.affiliation: Metabolic Engineering and Systems Biology Laboratory, Institute of Chemical Engineering Sciences, Foundation for Research and Technology-Hellas, Patras, Greece Department of Chemical and Biomolecular Engineering and Department of Bioengineering, University of Maryland, College Park, Maryland, USA.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Klapa
authors.affiliation: Biochemistry Laboratory, Section of Genetics, Cell and Developmental Biology, Department of Biology, University of Patras, Patras, Greece c.georgiou@upatras.gr.
authors.forename: Christos D
authors.initials: CD
authors.lastname: Georgiou
mesh_terms: D016604:Aflatoxin B1 / Q000096:biosynthesis*; D001231:Aspergillus flavus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D016604:Aflatoxin B1; D006861:Hydrogen Peroxide