JPS5840462B2 - How to culture microalgae - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a culture method for increasing the photosynthetic pigment content of microgreen algae such as Chlorella, Scenedesmus, and Coelastorum.

Chlorella and other green algae are easy to produce because their growth rate is faster than that of general green plants.They also contain proteins, carbohydrates, vitamins, pigments, special physiologically active substances, etc., and are therefore used in large quantities. Research has been carried out and it has also been commercialized.

The culture format can be divided into autotrophic, mixotrophic, and heterotrophic.

Traditionally, it has been produced in outdoor open culture ponds by autotrophic culture using carbon dioxide gas and sunlight irradiation, or by mixotrophic culture using acetic acid as a carbon source and sunlight irradiation.

However, this method requires a large amount of sunlight, so a vast amount of land is required for production, and the amount of sunlight varies depending on the weather and season, and because it is an open facility, it is not susceptible to microbial and other contamination. This method had the disadvantage that a product of stable quality could not be obtained.

In order to solve this problem, so-called tank culture has been carried out in recent years.

However, in heterotrophy that uses organic matter as a carbon and energy source, the chloroplast, which is a photosynthetic organ, does not fully develop and the content of photosynthetic pigments such as chlorophyll becomes low. A mixotrophic culture has been devised that provides light.

However, in this case as well, it is not practical because it is necessary to irradiate a large amount of light energy, which necessitates the installation of a device with a complicated structure, and also requires complicated operations.

The present inventors developed a heterotrophic culture using organic matter as a carbon and energy source without light irradiation, using a tank culture method that has high productivity and has little chance of contamination. As a result of research into a method for obtaining green algae with a high content of photosynthetic pigments, the present invention was arrived at.

That is, when culturing microgreen algae heterotrophically using organic matter as a carbon source and energy source, the present invention adjusts the dissolved oxygen concentration in the culture solution in the range of 0.5 ppm to 6 ppm, and adjusts the pH of the culture solution. This is a culture method that adjusts the temperature to a range of 5.5 to 7.5, but also by adding a trace amount of protein hydrolyzate or amino acid to the medium of 0.1 μ/1 medium or more, and continuously. The present invention relates to a method for cultivating microalgae that develops chloroplasts and has a high content of photosynthetic pigments by adjusting the amount of glucose in the culture solution to 10 to 40 μ/l of medium.

The present invention will be explained in detail below.

Microgreen algae are able to utilize organic matter and grow heterotrophically, and representative examples include Chlorella, Scenedesmus, Chlamydomonas, Selenastrum, and Coelastorum.

Glucose is used as an organic substance that is a carbon source and an energy source for microgreen algae.

The culture medium contains nitrogen sources such as nitrates, urea, and ammonium salts, phosphates, potassium salts, and magnesium salts as nutritional components, and trace elements such as iron, calcium, boron, manganese,
Salts of metals such as zinc, copper, molybdenum, cobalt, titanium, tungsten, chromium, vanadium, and nickel are added.

Also, to prevent the formation of insoluble salts, citric acid, E
A chelating agent such as DTA may also be added.

In the present invention, the dissolved oxygen concentration in the culture solution is set to 0.5 to 6.
Adjust the pH of the culture solution within the range of ppm and 5.5 to 7.
．． Adjustment within the range of 5 is necessary to develop chloroplasts of microgreen algae and increase the photosynthetic pigment content.

In order to obtain microgreen algae with a more stable photosynthetic pigment content, a mixture of amino acids obtained by hydrolysis of proteins such as yeast extract, casamino acids, peptone, tryptone, meat extract, and cornstarch liquor is added to the medium. and valine, leucine, inleucine, phenylalanine,
Tryptophan, glycine, serine, threonine, tyrosine, asparagine, glutamine, glutamic acid, aspartic acid, lysine, arginine, histine, or any other amino acid alone or in combination at 0.
It is preferable to add a trace amount of 1 ml/medium or more.

It is sufficient to add the amount of 0.1 mq/l, but in order to obtain more stable results, approximately 0.5 P/g is added.

Further, depending on the culture conditions, a larger amount may be added within an economically acceptable range.

Further, the addition method may be by adding temporarily or continuously into the culture solution.

Further, the amount of glucose in the continuous culture solution is adjusted to 10 to 40 μ/l of medium.

Example 1 A mini jar fermenter with a capacity of 2.51, a PH electrode,
A dissolved oxygen electrode was installed, medium 1.81 with the following composition was added, and Scenedesmus acutus was inoculated.
Pure culture was carried out at pH 6 and temperature of 33° C. with aeration and stirring.

Note that the pH was automatically adjusted with aqueous ammonia, and the dissolved oxygen concentration was adjusted to 1 to 2.5 ppm K.

During continuous cultivation, the following additives were temporarily added to the fermentor, and the amount of chlorophyll and protein in the algae and the content of glucose, ammonia nitrogen, and phosphoric acid in the culture solution were measured. The progress of the culture was observed.

The results are shown in Table-1. Medium composition Glucose ammonium monophosphate Potash magnesium sulfate heptahydrate Ferrous sulfate heptahydrate Trace metal solution (A,) Distilled water r O,825' 1.251 1.25y m9 m1 99.8ml Reference Example Using the same apparatus and culture medium as in Example 1, without adding any additives, the temperature was 33°C, the pH of the culture solution was 5.8, and the dissolved oxygen concentration was adjusted within the same range of 0.8 to 1.5 ppm. Culture was performed.

The chlorophyll content in the algae obtained at 50 hours was 2.
It was 0%.

Also, the pH is 6.5 and the dissolved oxygen concentration is 4.8 to 5.5 ppm.
After culturing for 50 hours, the chlorophyll content in the algal bodies was 2.2%.

Example 2 The same operation as in Example 1 was performed.

However, casein hydrolyzate 1 is added to the newly supplied medium.
00 my/l, and by aeration and stirring,
The amount of dissolved oxygen in the culture solution was adjusted, and the chlorophyll concentration in the algal bodies was measured 60 hours after adjusting the dissolved oxygen.

The results are shown in Table-2.

Example 4 The same procedure as in Example 3 was carried out, the pH was changed, and 4 seeds were sown after changing the pH settings.

Note that dissolved oxygen was set at 1 to 2 ppm.

Claims (1)

[Claims] 1. When culturing microalgae heterotrophically in a tank without light irradiation using organic matter as a carbon source and energy source, the dissolved oxygen concentration in the culture solution is adjusted in the range of 0.5 to 6 ppm, and the culture solution is adjusted to pH 5.5. to 7.5,
Protein hydrolyzate or amino acid from 0.1η to 0.5?
1. A method for cultivating microalgae to increase the content of photosynthetic pigments, which comprises adding glucose in the range of 1/l of medium and adjusting the amount of glucose in the continuous culture solution to 10 to 40 m/l of medium.