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Title: Modulation of medium-chain fatty acid synthesis in Synechococcus sp. PCC 7002 by replacing FabH with a Chaetoceros Ketoacyl-ACP synthase

The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs) is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis in photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%), with the majority of C14 fatty acids allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novo assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes putatively lacking bacterial evolutionary control mechanisms could be used to improve MCFA production in this promising production strain. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase Ill increased MCFA synthesis up to fivefold. In conclusion, the level of increase is dependent on promoter strength and culturing conditions.
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Colorado School of Mines, Golden, CO, (United States). Dept. of Chemistry and Geochemistry
  2. Carnegie Institution for Science, Stanford, CA, (United States). Dept. of Plant Biology
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 1664-462X
Frontiers Research Foundation
Research Org:
Colorado School of Mines, Golden, CO, (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Chemical Sciences, Geosciences and Biosciences Division
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; medium chain fatty acids; Chaetoceros; type III ketoacyl-ACP synthase; Synechococcus sp PCC 7002; lauric acid production; RNAseq; chlamydomonas-reinhardtii; biofuel production; lipid-composition; triacylglycerol accumulation; phaeodactylum-tricornutum; nitrogen starvation; escherichia-coli; fuel properties; life-cycle; microalgae
OSTI Identifier: