Characterization of long-chain acyl-CoA synthetases which stimulate secretion of fatty acids in green algae Chlamydomonas reinhardtii

Abstract

BackgroundMicroalgae biofuel has become the most promising renewable energy over the past few years. But limitations still exist because of its high cost. Although, efforts have been made in enhancement of lipid productivity, the major cost problem in harvesting and oil extraction is still intractable. Thus, the idea of fatty acids (FAs) secretion which can massively facilitate algae harvesting and oil extraction was investigated here.ResultsThe cDNAs of two long-chain acyl-CoA synthetases (LACSs) genes were cloned from Chlamydomonas reinhardtii and named as cracs1 and cracs2. They showed different substrate adaptation in the yeast complementation experiments. Cracs2 could utilize FAs C12:0, C14:0, C16:0, C18:0, C16:1 and C18:1, while crac1 could only utilize substrate C14:0, C16:1 and C18:1. Knockdown of cracs1 and cracs2 in C. reinhardtii resulted in accumulation of intracellular lipids. The total intracellular lipids contents of transgenic algae q-15 (knockdown of cracs1) and p-13 (knockdown of cracs2) were 45 and 55 %, respectively higher than that of cc849. Furthermore, FAs secretion was discovered in both transgenic algae. Secreted FAs can reach 8.19 and 9.66 mg/109 cells in q-15 and p-13, respectively.ConclusionThese results demonstrated the possibility of FAs secretion by microalgae and may give a new strategy of low-cost oil extraction. According to our findings, we proposed that FAs secretion may also be achieved in other species besides Chlamydomonas reinhardtii by knocking-down cracs genes, which may promote the future industrial application of microalgae biofuels.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0598-7) contains supplementary material, which is available to authorized users.

Transcriptional regulation of microalgae for concurrent lipid overproduction and secretion

“…However, there is no experimental evidence to determine the impact of NobZIP1 on the regulation of its key target genes, and hence, we carried out chromatin immunoprecipitation (ChIP) to investigate the regulatory role of NobZIP1 on the expression of other genes. ChIP analysis revealed that NobZIP1 regulates the expression of key genes involved in fatty acid, lipid, and carbohydrate metabolism, such as ACBP [acyl–coenzyme A (CoA)–binding protein] ( 24 ), KAS [3-ketoacyl-acyl carrier protein synthase] ( 25 ), LC-FACS (long-chain acyl-CoA synthetase) ( 26 ), LPAAT ( 26 ), and CPS (putative capsular polysaccharide synthesis gene) ( 11 ), and UGDH ( 27 ), the key genes involved in cell wall carbohydrate polymer metabolism (Fig. 3, A to F).…”

Regulation of fatty acid and flavonoid biosynthesis by miRNAs in Lonicera japonica

“…LACS could be activated during both the synthesis of cellular lipids and their degradation through boxidation and also participates in the cutin pathway. [27][28][29] ACP is involved in the pathway for fatty acid synthesis and export. 30,31 FAH could catalyse the synthesis of hydroxylated fatty acid moieties, absence of which could increase the salicylate levels and resistance towards obligate biotrophic fungal pathogens.…”

Over-expression of LPAAT gene in Phaeodactylum tricornutum enhances fatty acid accumulation and increases fatty acid chain length

“…The irreversible depletion of fossil fuels and fossil fuel burning-associated global warming have accelerated the search for biofuel production via renewable feedstock over the past few years [1,2] . Due to some obvious advantages which include higher photosynthetic efficiency and biomass production rate, microalgal lipid, especially triacylglycerols (TAGs), have broadly been researched as a hidden biodiesel raw material [3] .…”