title: 6-pentyl-alpha-pyrone production by Trichoderma harzianum: the influence of energy dissipation rate and its implications on fungal physiology.
abstract: The influence of the agitation conditions on biomass growth, morphology, carbon metabolism, viability, and 6-pentyl-alpha-pyrone (6PP) production by Trichoderma harzianum were studied in an extractive fermentation system. Batch spore-inoculated cultures developed at dissolved oxygen concentrations above 35% of air saturation were carried out in a 14 L bioreactor. The effect of energy dissipation rate over culture performance was assessed using two sets of three Rushton turbines (having different diameters) operated at different agitation speeds. Higher mechanical stress enhanced cellular differentiation (i.e., sporulation), while yielding lower specific growth rates and increased specific CO(2) production rates (CPRs) at relatively constant specific glucose consumption rates. In addition, fungal viability and clump mean diameter decreased gradually at higher energy dissipation rates. 6PP biosynthesis was growth associated and its specific productivity showed a bell-shaped relationship with the energy dissipation rate. T. harzianum physiology was, therefore, strongly influenced by the prevailing hydrodynamic conditions as it triggered cellular metabolism and differentiation shifts.
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, 62210 Morelos, México.
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Rocha-Valadez
authors.forename: Mainul
authors.initials: M
authors.lastname: Hassan
authors.forename: Gabriel
authors.initials: G
authors.lastname: Corkidi
authors.forename: Celia
authors.initials: C
authors.lastname: Flores
authors.forename: Enrique
authors.initials: E
authors.lastname: Galindo
authors.forename: Leobardo
authors.initials: L
authors.lastname: Serrano-Carreón
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D002245:Carbon Dioxide / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D003198:Computer Simulation; D004734:Energy Metabolism / Q000502:physiology; D004735:Energy Transfer / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008954:Models, Biological; D010865:Pilot Projects; D011753:Pyrones / Q000378:metabolism*; D014242:Trichoderma / Q000166:cytology / Q000502:physiology*
chemical_list: C008798:6-pentylpyrone; D011753:Pyrones; D002245:Carbon Dioxide; D005947:Glucose