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Title: Optimisation of Phaeodactylum tricornutum as a microalgal expression host for industrial biotechnology
Author: Song, Zhongdi
ISNI:       0000 0004 9359 6973
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available