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Improving photosynthetic conversion efficiency in marine microalgae

Improving photosynthetic conversion efficiency in marine microalgae
Improving photosynthetic conversion efficiency in marine microalgae
Marine photosynthetic microalgae have great potential in biotechnology. They have huge genetic diversity and naturally make an array of metabolites that are precursors in high value products such as fuels and pharmaceuticals. They do not compete with agriculture for land or fresh water and can be used to reduce industrial carbon-emissions. In order to realize this potential however much work needs to be done to overcome the engineering challenges of growing microalgae on large scales and developing the genetic tools required to increase the yield and diversity of products synthesized by cells. Irrespective of the type of microalgal species selected for growth, the efficiency at which light energy is converted into product, the 'photosynthetic conversion efficiency' sets a fundamental limitation on the potential yield. In natural systems as much as 90% of absorbed light energy is re-emitted as heat or fluorescence, representing a major loss in overall efficiency. In this thesis a high-throughput pipeline using random mutagenesis and live single cell sorting has been used to isolate two cell-lines of the eukaryotic microalgae Dunaliella tertiolecta with reduced chlorophyll content (termed lca1 and lca2). As there is no published genome for D. tertiolecta and the species is difficult to transform, this approach represents a feasible method to develop improved cell-lines from any microalgal species. These cell lines are characterized physiologically and shown to increase the maximum rate of chlorophyll-normalized photosynthesis Pmax by 289 (lca1) and 131% (lca2) respectively. The molecular basis of these random mutations characterized by transcriptomics using next-generation sequencing approaches, helps define the differences in regulation in light-harvesting and photosynthesis between the lca1, lca2 and wild-type. The approaches applied in this thesis therefore show how microalgal strains with poor genetic characterization can rapidly be selected for biotechnological applications, and providing new gene targets and valuable insights into the fundamental mechanisms of photosynthesis.
Johansson, Staffan Andreas
1f6a5f61-24d1-4007-81c6-8596aaaa7241
Johansson, Staffan Andreas
1f6a5f61-24d1-4007-81c6-8596aaaa7241
Bibby, Thomas
e04ea079-dd90-4ead-9840-00882de27ebd

(2016) Improving photosynthetic conversion efficiency in marine microalgae. University of Southampton, Ocean & Earth Science, Doctoral Thesis, 206pp.

Record type: Thesis (Doctoral)

Abstract

Marine photosynthetic microalgae have great potential in biotechnology. They have huge genetic diversity and naturally make an array of metabolites that are precursors in high value products such as fuels and pharmaceuticals. They do not compete with agriculture for land or fresh water and can be used to reduce industrial carbon-emissions. In order to realize this potential however much work needs to be done to overcome the engineering challenges of growing microalgae on large scales and developing the genetic tools required to increase the yield and diversity of products synthesized by cells. Irrespective of the type of microalgal species selected for growth, the efficiency at which light energy is converted into product, the 'photosynthetic conversion efficiency' sets a fundamental limitation on the potential yield. In natural systems as much as 90% of absorbed light energy is re-emitted as heat or fluorescence, representing a major loss in overall efficiency. In this thesis a high-throughput pipeline using random mutagenesis and live single cell sorting has been used to isolate two cell-lines of the eukaryotic microalgae Dunaliella tertiolecta with reduced chlorophyll content (termed lca1 and lca2). As there is no published genome for D. tertiolecta and the species is difficult to transform, this approach represents a feasible method to develop improved cell-lines from any microalgal species. These cell lines are characterized physiologically and shown to increase the maximum rate of chlorophyll-normalized photosynthesis Pmax by 289 (lca1) and 131% (lca2) respectively. The molecular basis of these random mutations characterized by transcriptomics using next-generation sequencing approaches, helps define the differences in regulation in light-harvesting and photosynthesis between the lca1, lca2 and wild-type. The approaches applied in this thesis therefore show how microalgal strains with poor genetic characterization can rapidly be selected for biotechnological applications, and providing new gene targets and valuable insights into the fundamental mechanisms of photosynthesis.

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Published date: 29 July 2016
Organisations: University of Southampton, Ocean and Earth Science

Identifiers

Local EPrints ID: 400390
URI: http://eprints.soton.ac.uk/id/eprint/400390
PURE UUID: 4a790b23-b681-49e8-bb16-2830032681a6

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Date deposited: 15 Sep 2016 13:31
Last modified: 21 Apr 2018 04:02

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