title: Surface imaging of the filamentous fungus Penicillium simplicissimum growing in a solid-state fermentation system.
abstract: A comparative study on the lipase-producing fungus Penicillium simplissicimum, grown on a tray type solid-state fermentation (SSF) bioreactor, was performed using stereoscopy, focus Z-stacking stereoscopic images, field emission scanning electron microscopy (FE-SEM) and environmental scanning electron microscopy (ESEM) to better characterize the morphology of filamentous fungi in SSF and their distribution over the solid matrix. The imaging of live fungal samples using a stereomicroscope with focus Z-stacking showed differences in colonization between a static SSF and an intermittent agitated SSF. A comparison of the stereomicroscopy, hi-vacuum and environmental scanning electron microscopy results obtained using different protocols for sample processing showed that fixation with osmium tetroxide vapor and subsequent hydrated imaging is the best combination of sample preparation and imaging conditions for keeping the arrangement of the aerial hyphae and conidia morphology closer to the natural state. These combined methodologies can be applied in the SSF of fungal growth to characterize the formation of conidiophores over time, the conidia morphology and the spatial organization after their release from conidiophores. Mycelium colonization over the matrix, which is an important characteristic related to the production of different biotechnological products, could be observed and provide more knowledge about fungal physiology behavior during SSF.
authors.affiliation: Instituto de Microbiologia Paulo de Góes, CCS, Bloco I, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Centro Nacional de Biologia Estrutural e Bioimagem, CCS, Bloco M, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Fernando Pereira
authors.initials: FP
authors.lastname: de Almeida
authors.affiliation: Departamento de Bioquímica - Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil.
authors.forename: Denise Maria Guimarães
authors.initials: DMG
authors.lastname: Freire
authors.affiliation: Instituto de Microbiologia Paulo de Góes, CCS, Bloco I, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Ulysses
authors.initials: U
authors.lastname: Lins
authors.affiliation: Laboratório de Microbiologia Industrial - Escola de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-909, Brazil; Polo Xerém - Universidade Federal do Rio de Janeiro, RJ 25245-390, Brazil. Electronic address: gutarra@gmail.com.
authors.forename: Melissa Limoeiro Estrada
authors.initials: MLE
authors.lastname: Gutarra
mesh_terms: D005285:Fermentation; D005658:Fungi / Q000166:cytology / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure*; D025301:Hyphae / Q000648:ultrastructure; D008853:Microscopy / Q000295:instrumentation / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D025282:Mycelium / Q000648:ultrastructure; D010407:Penicillium / Q000166:cytology / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure*; D013172:Spores, Fungal / Q000648:ultrastructure; D013499:Surface Properties
keywords: Fungal morphology; Scanning electron microscopy; Solid-state fermentations; Stereomicroscopy; Variable pressure