Essential Role of Acyl-ACP Synthetase in Acclimation of the CyanobacteriumSynechococcus elongatusStrain PCC 7942 to High-Light Conditions (original) (raw)
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Applied microbiology and biotechnology, 2016
Cyanobacterial mutants defective in acyl-acyl carrier protein synthetase (Aas) secrete free fatty acids (FFAs) into the external medium and hence have been used for the studies aimed at photosynthetic production of biofuels. While the wild-type strain of Synechocystis sp. PCC 6803 is highly sensitive to exogenously added linolenic acid, mutants defective in the aas gene are known to be resistant to the externally provided fatty acid. In this study, the wild-type Synechocystis cells were shown to be sensitive to lauric, oleic, and linoleic acids as well, and the resistance to these fatty acids was shown to be enhanced by inactivation of the aas gene. On the basis of these observations, we developed an efficient method to isolate aas-deficient mutants from cultures of Synechocystis cells by counter selection using linoleic acid or linolenic acid as the selective agent. A variety of aas mutations were found in about 70 % of the FFA-resistant mutants thus selected. Various aas mutants w...
Cyanobacteria as a Platform for Biofuel Production
Frontiers in bioengineering and biotechnology, 2013
Cyanobacteria have great potential as a platform for biofuel production because of their fast growth, ability to fix carbon dioxide gas, and their genetic tractability. Furthermore they do not require fermentable sugars or arable land for growth and so competition with cropland would be greatly reduced. In this perspective we discuss the challenges and areas for improvement most pertinent for advancing cyanobacterial fuel production, including: improving genetic parts, carbon fixation, metabolic flux, nutrient requirements on a large scale, and photosynthetic efficiency using natural light.
Biotechnology for biofuels, 2016
Among the three model cyanobacterial species that have been used for engineering a system for photosynthetic production of free fatty acids (FFAs), Synechococcus elongatus PCC7942 has been the least successful; the FFA-excreting mutants constructed from this strain could attain lower rates of FFA excretion and lower final FFA concentrations than the mutants constructed from Synechocystis sp. PCC6803 and Synechococcus sp. PCC7002. It has been suggested that S. elongatus PCC7942 cells suffer from toxicity of FFA, but the cause of the low productivity has remained to be determined. By modulating the expression level of the acyl-acyl carrier protein thioesterase and raising the light intensity during cultivation, FFA secretion rates comparable to those obtained with the other cyanobacterial species were attained with an engineered Synechococcus elongatus mutant (dAS1T). The final FFA concentration in the external medium was also higher than previously reported for other S. elongatus mut...
Photoautotrophic Polyhydroxyalkanoate Production in Cyanobacteria
Cyanobacteria: Omics and Manipulation, 2017
In this era of the 'Green Planet', cyanobacteria are ideally placed for exploitation as microbial cell factories, both for carbon capture and storage and for the sustainable production of secondary metabolites and biofuels. The application of omics technologies to cyanobacterial research has yielded a wealth of new information. However for today's busy researchers, trawling through the literature to stay abreast of current developments can be extremely time-consuming. By compiling and summarising the most important topics on cyanobacterial omics and manipulation, the authors of this book provide the reader with a timely overview of the field. Topics covered: The cyanobacterial core-genome with a focus on secondary metabolites; cyanobacterial evolution; genomics of NRPS/PKS biosynthetic gene clusters; RNA-seq based transcriptomic analysis of single cyanobacterial cells; transcriptomics of the responses: genes, sensors, and molecular triggers; transcriptomic and proteomic analysis of diurnal cycles in nitrogen-fixing cyanobacteria; proteomic analysis of post translational modifications; metabolic engineering and systems biology for free fatty acid production; isoprene production; ethanol production: impact of omics of the model organism Synechocystis on yield enhancement; engineering of alkane production; photoautotrophic polyhydroxyalkanoate production. This cutting-edge text will serve as a valuable resource for all those working in this field and is recommended for all microbiology libraries. Chapter 1. The Cyanobacterial Core-genome: Global and Specific Features with a Focus on Secondary Metabolites (Stefan Simm, Enrico Schleiff and Rafael Pernil) Chapter 2. Genome-wide Analysis of Cyanobacterial Evolution: The Example of Synechococcus (Petr Dvorák) Chapter 3. Genomics of NRPS/PKS Biosynthetic Gene Clusters in Cyanobacteria (Claire Pancrace, Muriel Gugger and Alexandra Calteau) Chapter 4. RNA-seq Based Transcriptomic Analysis of Single Cyanobacterial Cells
Indian journal of biochemistry & biophysics, 2000
Acyl-lipid desaturation introduces double bonds (unsaturated bonds) at specifically defined positions of fatty acids that are esterified to the glycerol backbone of membrane glycerolipids. Desaturation pattern of the glycerolipids of Cylindrospermopsis raciborskii (C. raciborskii), a filamentous cyanobacterial strain, was determined in cells grown at 35 degrees C and 25 degrees C. The lowering of the growth temperature from 35 degrees C to 25 degrees C resulted in a considerable accumulation of polyunsaturated octadecanoic fatty acids in all lipid classes. Lipid unsaturation of C. raciborskii was also compared to Synechocystis PCC6803. In C. raciborskii cells, a shift in growth temperature induced a much more pronounced alteration in the desaturation pattern of all lipid classes than in Synechocystis PCC6803. The tolerance to low-temperature photoinhibition of the C. raciborskii cells grown at 25 degrees C and 35 degrees C was also compared to the tolerance of Synechocystis cells gr...
Cyanobacterial Biofuel: A Platform for Green Energy
Advances in environmental and engineering research, 2023
Cyanobacteria have great potential as a platform for biofuel production because of their fast growth, ability to fix CO 2 gas, and genetic tractability. They also preserve the sustainability of an ecosystem without harming the environment. High-performance biofuels made from cyanobacteria can be utilized as a base for the production of green energy. Although a lot of studies have been conducted where plants and crops are used as the source of energy, cyanobacteria have been reported to have a more efficient photosynthetic process strongly responsible for increased production with limited land input along with affordable cost. The production of cyanobacteria-based biofuels can be accelerated through genetic engineering or genomics research, which may help to meet the global demand for these fuels on a large scale. Cyanobacterial strains that have undergone genetic modifications have been developed as part of a green recovery approach to transform membrane lipids into fatty acids to produce cheap and eco-friendly green energy. Cyanobacteria also produce different biofuels such as butanol, ethanol and isoprene. The four different generations of biofuel production to meet the energy requirement have been discussed in this review. This review presents a
Recent advances and challenges of the use of cyanobacteria towards the production of biofuels
Renewable and Sustainable Energy Reviews, 2016
Higher oil prices and the necessity for long-term energy security have increased the public and scientific attention on the production of biofuels. Bioenergy is much cleaner, safer, and more economical source of energy than fossil-based fuels. Of several organisms, cyanobacteria are attractive source of biofuels because of their genetic tractability, photosynthetic capability and lack of dependency on fertile land. Synthetic biology and metabolic engineering approaches have been successfully used towards the production of biofuels including ethanol, butanol, biodiesel and hydrogen. This review highlights the recent advances of pathway engineering and uses of synthetic biology tools in cyanobacteria for the production of economical and ecologically biofuels.
Incorporation, fate and turnover of free fatty acids in cyanobacteria
FEMS Microbiology Reviews
Fatty acids are important molecules in bioenergetics and also in industry. The phylum Cyanobacteria consists of a group of prokaryotes that typically carry out oxygenic photosynthesis with water as an electron donor and use carbon dioxide as a carbon source to generate a range of biomolecules, including fatty acids. They are also able to import exogenous free fatty acids and direct them to biosynthetic pathways. Here, we review current knowledge on mechanisms and regulation of free fatty acid transport into cyanobacterial cells, their subsequent activation and use in the synthesis of fatty acid-containing biomolecules such as glycolipids and alka(e)nes, as well as recycling of free fatty acids derived from such molecules. This review also covers efforts in the engineering of such cyanobacterial fatty acid-associated pathways en route to optimized biofuel production.
PLoS ONE, 2013
We describe how pathway engineering can be used to convert a single intermediate derived from lipid biosynthesis, fatty aldehydes, into a variety of biofuel precursors including alkanes, free fatty acids and wax esters. In cyanobacteria, long-chain acyl-ACPs can be reduced to fatty aldehydes, and then decarbonylated to alkanes. We discovered a cyanobacteria class-3 aldehyde-dehydrogenase, AldE, that was necessary and sufficient to instead oxidize fatty aldehyde precursors into fatty acids. Overexpression of enzymes in this pathway resulted in production of 50 to 100 fold more fatty acids than alkanes, and the fatty acids were secreted from the cell. Co-expression of acyl-ACP reductase, an alcohol-dehydrogenase and a wax-estersynthase resulted in a third fate for fatty aldehydes: conversion to wax esters, which accumulated as intracellular lipid bodies. Conversion of acyl-ACP to fatty acids using endogenous cyanobacterial enzymes may allow biofuel production without transgenesis.