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Optimisation of Phaeodactylum tricornutum as a microalgal expression host for industrial biotechnology

Song, Zhongdi; (2020) Optimisation of Phaeodactylum tricornutum as a microalgal expression host for industrial biotechnology. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Phaeodactylum tricornutum is a polymorphic marine diatom and can undergo morphological conversions between cell morphotypes, mainly fusiform, triradiate and oval. However, limited information is available about the conditions that can be used for controlling cell morphology and maintaining a specific cell morphotype with high growth rate and biomass productivity. In this study, the effects of culture medium and culture age on morphological changes in P. tricornutum were first investigated. Mann and Myers’ medium was identified as eliciting significant morphotype conversion from fusiform to oval in P. tricornutum. Liquid cultures containing more than 90% oval cells were obtained and well-maintained in this medium under the constant shaking condition, allowing high dry biomass concentration (0.73 g L-1) to be achieved. The subsequent biochemical composition analyses of different cell morphotypes revealed that pigments, particularly fucoxanthin and chlorophyll a, were markedly accumulated and higher protein content (% dry weight) was obtained in oval cell cultures maintained in M & M medium compared to fusiform cell cultures maintained in f/2 medium, where lipid and carbohydrate were significantly accumulated over 21 days cultivation. The further investigation of downstream processing of different cell morphotypes using ultra scale-down approaches predicted that a high cell recovery efficiency (>93%) without evident cell damage could be obtained for both morphotypes when using either a hermetically or a non-hermetically sealed disc-stack centrifuge. Additionally, cell disruption analysis by focused acoustics demonstrated that oval cells were much more robust against mechanical forces, requiring a longer treatment time for complete cell rupture than fusiform cells. This study offered an effective and practical way to achieve high biomass production of oval cells in liquid cultures and provided significant implications for upstream cultivation strategies and downstream bioprocessing to optimise the manufacture of different classes of products in different morphotypes of P. tricornutum.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Optimisation of Phaeodactylum tricornutum as a microalgal expression host for industrial biotechnology
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Biochemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10109855
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