I have isolated these two species from the coastal region
the cultivated conditions: BG11 media with nitrogen 1.5g/L and 45mg/L phosphorous, ph 7.4,temp.28 c , 16:8(light/dark) for 12-15 days with continuous aeration.
As I have to screen out for biodiesel application but they shows high amout of polyunsaturated fatty acid which is not suitable for the biodiesel application, but these two stain are good for biodiesel as many people have reported in there papers so i am bit confused what to do how the cultivation condition / stress condition could improve the fatty acid profile.
kindly help me out with your answers.
Dear Priti
You try to culture them in BBM (Bold, 1949) with reduced nitrogen. All species of Chlorella and Scenedesmus changes their fatty acid profile with different concentrations of culture medium. In BG11, nitrogen conc. (1.5 g/L) level should decreased. In low nitrogen, synthesis of MUFA will be enhanced. So, the ratio of SFA and MUFA will be higher than PUFA.
best wishes
Unlike higher plants, oils of some microalgae contain significant amount of polyunsaturated fatty acids (PUFAs) with four or more double bonds. This feature usually limits the use of microalgae as a source of biodiesel production. In order to obtain high biomass productivity and the desired lipid quality and quantity and also to make this microalgal system effective for biodiesel production one should modify the microalgal growth conditions. Chlorella and Scenedesmus are chlorophycean members and the growth medium BG-11 which you have used to grow them is well suited for the growth of blue greens and not for green algae. Moreover it also has high nitrogen content. You can obtain high lipid content if you grow these two microalgae in nitrogen-deficient conditions. This nitrogen stress will result a marked increase in saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) with concomitant decrease in PUFAs. I suggest you not to use BG-11 medium and find out some specific nitrogen deficient growth medium for these two algae.
thanks Satpati and I have also tried in BBM media but the things are same. I think nitrogen is more thats why feasible results are not there.
Thanks Surendra I am trying to find out the media besides BG-11.Can glucose as a source of carbon with nitrogen stress works.
Try to find out some alternative carbon source in place of glucose because it will make the production process economical and will also avoid bacterial contamination.
Maybe you could try with a culture system in two stages, where the first is the production of biomass and the second is the production of fatty acids of interest, by manipulating the nitrogen concentration in the second stage. It could also help to modify your photoperiod, since high amounts of light could direct the biosynthesis towards pigments production.
@surendra thanks for your answer. can you suggest me which carbon source will good enough.
I have seen production of Nanno that yields lots of PUFAs in cold conditions (Temp below 22C), but this same strain grows less unsaturated in favor of more saturated (palmitic like lipids) fatty acids if you grow them at higher temperatures without stressing them (about 27C). The other thing I have done is to saturate the unsaturated fats in algae by using a device I invented... But from my standpoint, I do not see why do you want to spoil 20:5 EPA that you can sell at 75 dollars per gallon into a 16-18:0 that you can sell at only 1 dollar per gallon... To produce Biofuels you need something very different... but that is something I will not share for the time being
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