Photoinhibition 13
The intensity of light for efficient microalgal growth ,for many species, lies in range of 200 to 400 umol photons m^-2 s^-1, but photosynthetically active radiation intensities from sunlight can exceed 2,000 umol photons m^-2 s^-1, during midday which reducesthe growth rate, a phenomenon known as photoinhibition.
Many attempts have been made to reduce the effects of photoinhibition on microalgal growth and much of this work has been focused on reducing the size of the chlorophyll antenna or lowering the number of light-harvesting complexes to minimize the absorption of sunlight by individual chloroplasts.. This approach may seem counterintuitive, but this strategy may have two positive effects; first, it permits higher light penetration in high-density cultures, and second, it can allow a higher maximum rate of photosynthesis due to the fact that the cells are less likely to be subjected to photoinhibition since their light-harvesting complexes absorb less light.
It is done by lowering the activity or silencing genes like LHCI and LHCII in C. reinhardtii or homologs in other algae or selecting desired mutant strains from random mutagenesis.
Wed August 04 2010 12:06:25 PM by Aayush
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Interesting.
very interesting.....
Thank you very much for these interesting information. I think that this is one of the defects of open bond cultures. Alga in open bond are subjected to photoinhibition than in photobioreactors. This because in photobioreactors algae take some time away from light (in the tubes) and then go out to light (flash light)which stimulate the photosynthesis. So we can use photobioreactors to overcome this problem.
Please find this paper:
http://www.springerlink.com/content/6q7132q0g8532620/fulltext.pdf
Best Regards,
Abomohra
It?s a good idea, but if photoinhibition is caused by oxidative stress (which it may be), via photosynthetic electron transport and the oxygen radicals thus produced, I don?t see how decreasing the photosystem array would decrease photoinhitition without decreasing biomass production? Assuming energy entering a cell is proportional to the reactive oxygen species generated. Care to comment?
suppose we decrease the no of lhc's,wouldn't it directly lead to a decrease in productiviy...lowering the antenna size looks fine....
Would it be easier to do some of the research somewhere there's less light, like Scotland or Ireland?
Is it possible to measure photoinhibition ?
Does it vary with light intensity r heat intensity or does it vary with the species too ?
photoinhibtion does vary with light intensity. it occurs when the intensity increases beyond the photoinhibition threshold. the threshold intensity depends upon several other environmental factors like supply of co2 and other nutrients and also it varies with species used
You could use transparent solar cells as a solar screen at mid day. Place the screen between the algae and the sun. This will lower the amount of solar radiation on the algae and at the same time provides some energy for your electronic equipment (pumps, aeration, harvesting equipment). Some transparent solar cells are also flexible. This could ease placing and removing the screen. Just like roller blinds.
@ Arnoldboer
So, u mean to say that we can grow alage and generate solar power as well. Is it ?
This helps answer someb of my problems. High desert sun is strong & I have been loosing algae in the afternoon that was grown in the morning. I chalked it up to heat but mayge a combination.
@Krupali
This is correct! It's a more efficient way of using a simple sun shade. I do not know if this method is being used in the algae growing community.
in a word,this difficult can be solved by screen microalgae of thermal resistance! also have a better adaptation to vary of temperature!