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7 - photosynthesis -

Photosynthese Spirulina is a member of the Family Osciliatoriaceae - which means that they oscillate or move backward and forward. This is done by fimbria which are tubular filaments 5 to 7 nanometers in diameter and from 1 to 2 microns in length that protrude from extremely small pores situated around the circumference of the ends of the cells where the cells join to form a filament. These fimbria, like oarsmen in a galley slave ship, propel the filament to and fro. The "nerve" or protein apparatus that must run the length of the filament giving the command to row backward or forward has not been discovered.

Also Spirulina are able to make tiny gas cylinders (called gas vesicles) which are about 70 nanometers in diameter and constructed of woven protein chains. These gas cylinders are formed and filled with gas when the Spirulina filament wants to rise in the water column in order to receive sunlight and start photosynthesis. When (usuaIly toward the end of the day) the cells have manufactured large amounts of carbohydrate which overcrowds the cell and creates high osmotic pressure within the cell, then these gas cylinders can no longer support the osmotic pressure within the cell and they implode and the liberated gas is compressed and absorbed by the surrounding fluids. Now, the gas vesicles that had been acting like miniature cargo balloons or airships collapsed the filament sinks toward the bottom and darkness where a major part of the accumulated carbohydrate is converted into protein.
These two methods of locomotion enable Spirulina to protect itself against a killing overdose of sunlight while at the same time absorbing just the amount of sunshine it needs - by going up and down within the water column - and by being able to row itself out of any dangerous embrace in the coils of its companions alI floating in a mass at the water surface when the day begins. I am amazed at Spirulina's capability for solving life's problem.
Here in a natural alkaline lake situation Spirulina has its ups and downs at 1east once every 24 hours, and much more often if there is alight breeze stirring the lake - and it produces between 2 to 4 grams of biomass every day that the climate conditions are favorable.

Our artificial basins are not deep enough to allow the gas vesicle system to work effectively in protecting from photolysis (destruction especially of the chlorophyll by light).
But by stirring the culture with paddlewheels placed across one arm of the raceway basin, the filaments are tumbled up and down, into the light and down underneath the other filaments where (when the culture is dense enough) it is dark and respiration can take place. This includes the act of converting the carbohydrate photosynthate into proteins. Chemical reactions within a cell are extremely rapid, so that if the light-dark, photosynthesis-respiration cycle can be compressed into a matter of a few seconds by creating sufficient turbulence within the basin, our friend, Spirulina, can produce 40 or more grams of biomass per day per square meter of surface area. That means that one square meter of basin area could provide the supplemental nutrients for at least four children ! There are no commercial-size Spirulina basin systems that give 40 grams even though from an engineering standpoint it is possible.

Protein productions

Commercial farms produce from 8 to 10 grams. But even this extrapolates to 36.5 tons of biomass and MORE or 23.7 tons of protein per hectare per year. Beef cattle produce only 160 kilograms per hectare per year. Cereals, soybeans, and sugarcane produce less than 4 tons - nearly 6 times less than Spiru1ina.

Natural Alkaline Lakes
Rombou Lake
Rombou Lake
photo: R.D.Fox
Orovilca Lake
Orovilca Lake
photo: R.D.Fox
Lonar Lake
Lonar Lake
Getting back to the unstirred natural lake where incoming carbon dioxide from the atmosphere is sufficient to produce 4 grams of biomass/day, 47% of which is carbon: this is the case, too, in an unstirred artificial basin.

Stirred artificial basins
Wind stirred
Wind Stirred
photo: O. Barbaroux
Paddle-Wheel stirred
Paddlewheel stirred
photo: R.D.Fox
hand - stirred
Stirred by a bicycle
photo: R.D Fox
With stirring at a rate of about 10 centimeters per second with one paddlewheel, a 100 square meter artificial basin can produce around 8 grams per square meter a day. This is because the atmospheric carbon dioxide has a better chance to make contact with all the filaments in the water column - not just those lying on the surface. If you want higher production rates you have to add a source of carbon at regular intervals throughout the daylight period, and increase the turbulence in the culture flow path by installing turbulence-producing devices and increasing the flow rate up to 30 centimeters per second. Under these circumstances one can get production rates of 20 or more grams of dry biomass per square meter per day, even in 5000 square meter basins ...

- Introduction ] CD-ROM Spirulina for Reducing Malnutrition - Historic of the World ]
- SPIRULINA Composition  ]   [  - Texcoco Lake Story  ]
 [ -  
WHERE SPIRULINA is found ] [  - Basins  ]   [  - Photosynthesis ]  
- SPIRULINA Production  ]  [  - Laboratory ]  [  - Harvesting ]
- Mix-drying SPIRULINA ]   [  - Starting ]  [ Problems and Solutions  ] 
[  -
- Why should we grow SPIRULINA ? : for nutrition and health ]
- Public Information-paper on SPIRULINAuseful links ]


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