phytoplankton culture help

[Jakegr]

Originally Posted by Myka

I always get best results 16 hours on, 8 hours off.

You are likely using too intense of light then. From a physiological standpoint there is no reason to give microalgae 8 hours of darkness. The dark reactions occur on the order of milliseconds and the light reactions occur pretty much instantaneously. The cells get their "dark" period on the inside of the reactor, when they are not illuminated. If you give the algae 8 hours of darkness, they are likely switching to respiration, which will lower growth rates. Try reducing light intensity to 30 umol on a 24/7 schedule, and then slowly ramping up the light intensity over time.

[mameroo2000]

As a plant to grow properly you need to provided the right habitat, which depends of the species they need usually a light intensity of 2500-5000 lux (250-500 footcandles) Conversion of foot candles to lux or lumens is: one ft. c = 10.8 lumens or lux, for nannochloropsis oculta (the mos common phyto to culture) you need 2,500-8,000 lux...You would get that intensity in a led warm white light on a 16 hours on that will allow the micro algae to breething co2 and you need 8 hours in full darkness for breething oxygene...like this system you will have a balance with your PH level inside the reactor chamber. Light shading by algae cells would become limiting as density increase, at high densities incoming light is shade from all but the cells currently at the outer surface of the reactor, that is mean is time to harvest the culture.

[Jakegr]

Originally Posted by mameroo2000

As a plant to grow properly you need to provided the right habitat, which depends of the species they need usually a light intensity of 2500-5000 lux (250-500 footcandles) Conversion of foot candles to lux or lumens is: one ft. c = 10.8 lumens or lux, for nannochloropsis oculta (the mos common phyto to culture) you need 2,500-8,000 lux...You would get that intensity in a led warm white light on a 16 hours on that will allow the micro algae to breething co2 and you need 8 hours in full darkness for breething oxygene...like this system you will have a balance with your PH level inside the reactor chamber. Light shading by algae cells would become limiting as density increase, at high densities incoming light is shade from all but the cells currently at the outer surface of the reactor, that is mean is time to harvest the culture.

Microalgae do not require a prolonged period of darkness to "breath oxygen". Microalgae require ATP to fix CO2. They produce ATP only when illuminated, and therefore will not fix CO2 in darkness. As soon as CO2 fixation ceases, growth will also cease. I'm not saying you can't grow microalgae if you give them a dark period, I'm saying growth is maximized if they are illuminated 24/7.

Here are a few references that explain the reasoning, which is firmly based on the well established physiology of plant cells and photosynthesis.

"..long dark periods (i.e., of the order of magnitude of several hours) generally result in biomass loss, as well as decline in growth rates, because microalgae switch to respiration processes; several authors have indeed suggested that a suitable dark period should be of the order of miliseconds (Kommareddy and Anderson 2004)—which would be more appropriately seen as an intermittent cycle"

From - Carvalho et al. 2011. Light requirements in microalgae photobioreactors: an overview of biophotonic aspects. Applied Microbiology and Biotechnology, 89, 1275 - 1288.

"This internal shading (clearly visible in that light does not pass through the culture’s optical path, being essentially fully absorbed in the outer surfaces), results in cells receiving light intermit- tently, a phenomenon augmented by the fact that light energy attenuates exponentially in passing through the culture column. The higher the cell density, the shorter the depth light penetrates into the culture. Two light zones are thereby established in the culture: the outer illuminated volume, in which light is sufficient to support photosynthesis (i.e. the photic zone); and the dark volume, in which net photosynthetic productivity cannot take place, since light intensity is below the compensation point (Fig. 8.1). The higher the population density (and the longer the optical path), the more complex it becomes to address the basic requirements for efficient utilization of strong light, i.e. an even distribution of the available light to all cells in the culture, at an optimal dose per cell (to be elucidated somewhat later).

Clearly then, when mutual shading prevails, cells are not exposed to continuous illumination but rather to cycles of light and darkness (L–D cycle), which may take scores of milliseconds to a few seconds to complete, depending on the optical path and the extent of turbulence in the culture. The endless combinations of light intermittency expressed in L–D cycles to which the individual cells are exposed at a given instant, relate to two basic para- meters: first, the ratio between the light and the dark period in the cycle and second, the frequency of the cycle. As shall be elucidated, the higher the frequency of the L–D cycle, the more efficient strong light may be used for photosynthesis."

From Richmond (2005) - page 127/128. "Handbook of Microalgae Culture".

[MitchM]

Jakegr,
Thanks for posting references.
It's helpful to see that.

[mameroo2000]

I am not say that you can't grow microalgae if they are illuminated 24/7. I just said that it would be unhealthy, the phyto required the most nature habitat you can provided. Lets start with a natural law "everything that is over used is bad from a carrot to exced of exercise" I am analizing what you said and the books part that you used, so if phytoplankton grow good and normally being under lights 24/7 of the 12 months of the year how is possibly that phytoplankton have declined in the world's oceans over the past century in response to ocean warming. When the phytoplankton have abundant sunlight, carbon dioxide and disolved nutrients an undergo explosive growth forming blooms, algal blooms, during these blooms most of the phyto die and sink to the bottom, where descomposes. This process deplets the dissolved oxygen at the water bottom which demaged the culture in no time, in the ocean time this occurs during the springtime.
For confirm what I just wrote you can check on wikipedia: algal bloom; earthobservatory.nasa.gov/NaturalHazards/
There is many reason you don't want to have a wrong amount of light for your phyto the cells will get dense and they would don't feed certains organism like tisbes or rotifers.
In bade the hyphotesis you used, you also can have a look at the following paragraphs on the same book, I just will writte a part!
Appl Microbiol Biotechnol (2011) page 1279; Kimmareddy and Anderson 2004:- In view of the relatives magnitude of aforementioned time scales, the turnover time of the photo-synthetic unit (PSU) or photosyntetic reaction center, is given by the dark reaction time for practical purposes. The light-dark cycle period, which is determined by the travel time of cells between the dark and lit portions along PBR, should accordingly be made AS SHORT AS POSSIBLE, this usually means an optical path of 0.5 to 1.0 cm (to make it clear if the dark time was not necessary then they would mentioned)

Appl Microbiol Biotechnol (2011) page 1279 "Effects of excessively low and high light supply"
"Althought light is required for photosynthesis, too low or high levels thereof will entertain serious disaventantages!! ..."
To who is interesting this pages could be read at http://www.hcmv.vn.refer.org/moodle/...ic-aspects.pdf

You can have more information on Plakton Culture Manual by Frank H. Hoff & Terry W. Snell.

http://en.m.wikipedia.org/wiki/Phytoplankton
Also you can read it all, but if you just want to be more secure about the light process, look on the last paragraph of Aquaculture.

Just to make it clear, it is always good to try or do different things, for some reason what you suggest didn't work for me on one of the Golden Brown Species of phyto which one required a strong illumination. I am just try to pass on all the information I learned and help any one who is interesting, I have six species of phyto and other live foods and I learn to don't expouse your culture to something that may don't work or you are not 100% sure, but I still respect all the opinion of other people. 16 hours on and 8 hours off it works for me since I start the cultired.

[donkey77]

thanks all for the input, iam learning as i go

[Myka]

Originally Posted by Jakegr

You are likely using too intense of light then. From a physiological standpoint there is no reason to give microalgae 8 hours of darkness.

My method works very well for me. I use less electricity and get the same results as 24 hour lighting. Phyto doesn't need a dark period, but it also doesn't need 24 hour lighting. Thanks for the advice though.

[Jakegr]

Originally Posted by mameroo2000

In bade the hyphotesis you used, you also can have a look at the following paragraphs on the same book, I just will writte a part!
Appl Microbiol Biotechnol (2011) page 1279; Kimmareddy and Anderson 2004:- In view of the relatives magnitude of aforementioned time scales, the turnover time of the photo-synthetic unit (PSU) or photosyntetic reaction center, is given by the dark reaction time for practical purposes. The light-dark cycle period, which is determined by the travel time of cells between the dark and lit portions along PBR, should accordingly be made AS SHORT AS POSSIBLE, this usually means an optical path of 0.5 to 1.0 cm (to make it clear if the dark time was not necessary then they would mentioned)

Appl Microbiol Biotechnol (2011) page 1279 "Effects of excessively low and high light supply"
"Althought light is required for photosynthesis, too low or high levels thereof will entertain serious disaventantages!! ..."
To who is interesting this pages could be read at http://www.hcmv.vn.refer.org/moodle/...ic-aspects.pdf

You can have more information on Plakton Culture Manual by Frank H. Hoff & Terry W. Snell.

http://en.m.wikipedia.org/wiki/Phytoplankton
Also you can read it all, but if you just want to be more secure about the light process, look on the last paragraph of Aquaculture.

Just to make it clear, it is always good to try or do different things, for some reason what you suggest didn't work for me on one of the Golden Brown Species of phyto which one required a strong illumination. I am just try to pass on all the information I learned and help any one who is interesting, I have six species of phyto and other live foods and I learn to don't expouse your culture to something that may don't work or you are not 100% sure, but I still respect all the opinion of other people. 16 hours on and 8 hours off it works for me since I start the cultired.

You are misinterpreting what that first reference is saying. It is saying that the light-dark cycle should be repeated all day by circulating the culture vigorously, not that a long dark period is helpful. I never did say the dark time is not necessary. I said it should be on very, very short and that they get ample dark periods in a dense culture by moving in and out of the "photic zone" of the culture.

I do not doubt you have been culturing phytoplankton for a long time with good results. So have I. You obviously have a solid practical knowledge about how to do it, but based on your explanations you do not understand the physiology. If I'm wrong, just answer this simple question:

As you said, from a physiological standpoint, why do you think microalgae need a prolonged dark period to "breath oxygen"?

That just doesn't make sense. Plant cells produce oxygen during photosynthesis by splitting water. Outside of the chloroplast, cellular respiration is occurring and uses up some of that oxygen (although there is a net production of O2 if light intensity is high enough). This is a major advantage of having a chloroplast - it provides oxygen to the rest of the cell. So why would they need a dark period to "breath oxygen" if they actually are able to obtain plenty of oxygen internally when illuminated?

We are not talking about multi-cellular plants here, which have many reasons to need a dark periods. Microalgae can be seen as the most basic photosynthetic unit and there is no physiological reason microalgae need a dark period. It is not "unhealthy" - I'm actually not sure what you mean by that, as it is a pretty vague statement. What process is being disrupted by illuminating with 24/7 light?

Again, I'm not saying you should switch methods as your method works for you. But I do feel if incorrect information is being spread, which is a problem in our hobby, that it should be corrected.

I do not think global warming has anything to do with our conversation.

[mameroo2000]

Jakegr I am not taking my information basing just on one book, you keep saying illumination should be 24/7, I don't understand on which time you get the dark time then! You don't explained the intensity of the illumination either...I understand all the reading, I just highlighter the point that you didn't mentioned where clear said "Effects of excessively low and high light suppy" Algal bloom, as I said read those pages plus Plankton Culture Manual and the last part of Aquaculture on Phytoplankton from wikipedia were it said "Light must be provided for the growth of phytoplankton. The colour temperature of illumination should be approximately 6,500 K, but values from 4,000 K to upwards of 20,000 K have been used successfully. ¡The duration of light exposure should be approximately 16 hours daily; this is the most efficient artificial day length!!"
I am sorry I put breath oxygene instead of consuming oxygene, I just see that know, I am going to fix it "Algae produce oxygen during the daylight hours and then consume it at night. During the day algae use energy from the sun to drive a chemical reaction between carbon dioxide (CO2) and water (H2O) to produce sugar and oxygen (O2). The second respiration process in plants is called dark phase respiration. It occurs primarily during the night and, to a much lesser extent, during daylight hours. During the dark phase process the plant consumes sugar and oxygen to produce energy, carbon dioxide, and water. The critical point is that at night, aquatic plants shut down the oxygen- producing photosynthetic reaction and initiate a process where they consume oxygen. I feel 24/7 is unhealthy because we try to provided for our aquarium a live food that have to be proper culture to give the right nutrition. My goal is to describe the technical aspects of culturing phytoplankton, I am try to have a simple description that should be comprehensible to those with minimal experience in aquaculture, how you can see I am not just have a succes experience with one type of algae, but to 6 and I am not just try to make points but also to promote more species and the proper care. If you feel the information what I provided have been incorrect, then you are free to contact Marine Biologyst in Chile and Argentina to correct them, also you can contct Florida Aquar Farms, Inc to they stop sell the Plankton Culture Manual, you can also leave a disagreed feedback on wikipedia on phytoplakton Aquaculture information. Just analized how the phyto works in the ocean.

[Mrs. Saltwater]

Donkey77 I year and a half ago in the city where I live, Edmonton, just 2 stores would provided phytoplankton one species "nannochloropsis" I have the pleasure to see mamero works he not just culture Nannochloropsis, he also culture other species, rotifers, brine shrimp and pods. He don't used the coca cola bottle system, he use a container and when you look at it you can see his deditation in the culture. This guy is a genius, beside any time I being on his home I saw how he take time to explained and listen to the people, I walked more then a time with extra free stuff and I do have wild corals that seems to love his phyto. The bad things in pages like this one is that every one can post copy texts and try to make points destroying the work of others. I will take any opinion or words from Mou as I used and see his live food culture system.

Jake I will like to know which specie or especies of phyto do you culture, I also will like to know if you have another type of life food culture. I will also like if you can post pictures of your system. I think actions talks more then words, I don't think any one in this Country have import and done the job that Mou did, when we try to help out comunity we don't need just talk we also action, I didn't see any store in the Country that provided many species of algaes as Mou that is why I keep saying he is a genius! He informed himself on how to proper care of the live stock and come up with something that not ones have in an entire country, now I don't think so he brought something and he wouldn't know how to take care of it.