Modulation of fatty acids and hydrocarbons inAnabaena7120 and itsntcAmutant under calcium

Abstract

Calcium being a signaling molecule and mediator of cell response, we examined the modulation in fatty acid and hydrocarbon profiles of wild type cyanobacterium Anabaena sp. PCC 7120 and its ntcA mutant under the influence of different calcium chloride concentrations (0-10 mM). Dynamic modifications in fatty acid and hydrocarbon profile were evident through GC-FID analysis of extracted lipids. In the wild type, increase in CaCl (10 mM) resulted in unsaturation of fatty acids (observed in terms of high MUFA/PUFA ratio) while hydrocarbon production was distinctly high in the mutant strain compared to wild type at all tested concentrations. The synthesis of short chain hydrocarbons (C5-C8) were dominated at inhibitory concentration (10 mM CaCl) in mutant strain. Results suggest that the increase in MUFA/PUFA ratio at inhibitory concentration in wild type, and higher percentage of hydrocarbons in mutant strain, may be attributed to the survival and acclimation strategies under altered calcium environment. Our results also suggest the involvement of the ntcA gene (master regulator of N metabolism) in regulation of carbon metabolism; specifically fatty acid, hydrocarbon, and other metabolic compounds essential for maintenance and sustenance of growth under stress condition. Thus, our study outlines basic acclimation response along with possibilities of production of fatty acid and hydrocarbon derived biofuel and other bioactive compounds in Anabaena sp. PCC 7120 under altered calcium levels which could be of biotechnological interest.

The small Ca2+-binding protein CSE links Ca2+ signalling with nitrogen metabolism and filament integrity in Anabaena sp. PCC 7120

“…A transient increase in the intracellular Ca 2+ concentration ([Ca 2+ ] i ) from a resting level of about 0.2 μM up to 4 μM free Ca 2+ was observed upon light-to-dark transitions and during temperature, salt and osmotic stress [1][2][3]. The involvement of Ca 2+ has also been established in cyanobacterial growth [4], regulation of reactive oxygen species (ROS) [5], fine-tuning of the carbon (C) and nitrogen (N) balance [6,7], heat stress acclimation [8], exopolysaccharide production [9], and fatty acid and hydrocarbon composition [10].…”

Iron deficiency influences NtcA‐dependent regulation of fatty acid desaturation and heterocyte envelop formation in Anabaena sp. PCC 7120

“…In Anabaena cells, iron deficiency is related with symptoms such as elevated expression of isiA gene, various antioxidative enzymes and total reactive oxygen species (ROS) which suggested that iron deficiency leads to oxidative stress (Latifi et al , Kaushik et al , , ). In several microorganisms including cyanobacteria, lipids are considered as the most efficient source of storage energy and also provide insulation to delicate internal organs and hormones (Singh et al , ). In cyanobacteria, lipids constitute an essential structural part of most of the cellular membranes and exhibit tolerance to variety of stresses under different conditions (Singh et al , ).…”

“…In several microorganisms including cyanobacteria, lipids are considered as the most efficient source of storage energy and also provide insulation to delicate internal organs and hormones (Singh et al , ). In cyanobacteria, lipids constitute an essential structural part of most of the cellular membranes and exhibit tolerance to variety of stresses under different conditions (Singh et al , ). However, lipids are also a potential target of oxidative damages caused by ROS generated under oxidative stress.…”

Transcriptional regulation of acetyl CoA and lipid synthesis by PII protein in Synechococcus PCC 7942

“…Fatty acids are synthesized from the TCA cycle intermediate acetyl CoA and the esterification of fatty acids leads to the synthesis of lipids . In addition, lipids are also known to play protective roles under various stress conditions in cyanobacteria . The first and rate limiting step of fatty acid biosynthesis is known to be catalyzed by acetyl CoA carboxylase (ACCase) enzyme.…”