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Effects of dissolved oxygen on fungal morphology and process rheoleogy during fed-batch processing of Ganoderma lucidum

Fazenda, Mariana L. and Harvey, Linda M. and McNeil, Brian (2010) Effects of dissolved oxygen on fungal morphology and process rheoleogy during fed-batch processing of Ganoderma lucidum. Journal of Microbiology and Biotechnology, 20 (4). pp. 844-851. ISSN 1738-8872

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Abstract

Controlling the dissolved oxygen (DO) in the fed-batch culture of the medicinal mushroom Ganoderma lucidum led to a two-fold increase of the maximum biomass productivity compared to uncontrolled DO conditions. By contrast, extracellular polysaccharide (EPS) production was two times higher under oxygen limitation (uncontrolled DO) than under increased oxygen availability (controlled DO). Morphologically, dispersed mycelium was predominant under controlled DO conditions, with highly branched hyphae, consistent with the enhanced culture growth noted under these conditions. While in the uncontrolled DO processes mycelial clumps were the most common morphology throughout the culture. However, in both cultures clamp connections were found. This is an exciting new finding, which widens the applicability of this basidiomycete in submerged fermentation. In rheological terms, broths demonstrated shear-thinning behaviour with a yield stress under both DO conditions. The flow curves were best described by the Herschel-Bulkley model: flow index down to 0.6 and consistency coefficient up to 0.2 and 0.6 Pa sn in uncontrolled and controlled cultures DO, respectively. The pseudoplastic behaviour was entirely due to the fungal biomass, and not to the presence of EPS (rheological analysis of the filtered broth showed Newtonian behaviour). It is clear that dissolved oxygen tension is a critical process parameter that distinctly influences G. lucidum morphology and rheology, affecting the overall performance of the process. This study contributes to an improved understanding of the process physiology of submerged fermentation of G. lucidum.

Item type: Article
ID code: 26169
Keywords: dissolved oxygen, fungal morphology, process rheology, Ganoderma lucidum, Chemical technology, Microbiology, Applied Microbiology and Biotechnology, Biotechnology
Subjects: Technology > Chemical technology
Science > Microbiology
Department: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
Related URLs:
Depositing user: Strathprints Administrator
Date Deposited: 09 Sep 2010 11:56
Last modified: 05 Sep 2014 05:47
URI: http://strathprints.strath.ac.uk/id/eprint/26169

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