JP2512117B2 - Method for producing chlorella high in γ-aminobutyric acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing chlorella high in γ-aminobutyric acid.

[Prior Art] γ-aminobutyric acid is a kind of amino acid existing in the brain, and was found by Roberts et al. In 1950 to be present in large amounts in the brain of vertebrates. Has been attracting attention and has been actively studied. γ-Aminobutyric acid is contained in the cerebral cortex of normal people at a rate of 40 mg%, and it decreases norepinephrine in the brain as an amino acid neurotransmitter, increases serotonin, and increases acetylcholine, which is important for transmission of nerve stimulation. It is also known to have a convulsive suppressive action because it is involved in promoting the function of the brain, and that a decrease in the amount of γ-aminobutyric acid in the brain plays a triggering role in the process of transition from nerve cell excitation to convulsions. There is.
Thus, γ-aminobutyric acid has been treated as a drug because of its unique function.

By the way, it has been clarified that γ-aminobutyric acid is contained in various plants, and it has been attempted to produce the aminobutyric acid. Specifically, 1970 TRLane and Ma
rv.Stiller is a freshwater green alga Chlorella in late culture stage as a metabolic inhibitor sodium fluoride, acetic acid, lactic acid,
It has been reported that glutamic acid in chlorella is decarboxylated and converted to γ-aminobutyric acid by adding propionic acid or the like to a low pH and anaerobic conditions.

[Problems to be Solved by the Invention] However, it was difficult to produce chlorella having a high γ-aminobutyric acid content by the method reported above.

The present invention has been made in order to solve the above conventional problems, and an object thereof is to provide a method capable of producing chlorella having an extremely high content rate of γ-aminobutyric acid.

[Means for Solving the Problems] The present invention contains chlorella as an organic carbon source and has a pH of 6 or less.
~ 8 in dark culture in aerobic atmosphere, when the carbon source is deficient, the pH value, while maintaining the aerobic atmosphere, a nitrogen source is added and recultured, then pH 3 ~ A method for producing chlorella having a high content of γ-aminobutyric acid, which is characterized by performing low pH treatment under the condition of 5.

As a means for creating an aerobic atmosphere during the above dark culture and reculture, for example, an aeration treatment method of an oxygen-containing gas such as air or an aeration stirring method can be adopted.

The reason why the pH in the dark culture is limited to 6 to 8 is that the growth of Chlorella is inhibited if the pH is out of this range. Further, the reason for maintaining the pH at 6 to 8 during the above-mentioned reculturing is that if it deviates from this range, the accumulating ability of glutamic acid in the cultivated chlorella decreases. These pH
A pH adjusting agent such as NaOH can be used for the adjustment.

Examples of the nitrogen source added during the reculturing include ammonia, urea, nitric acid and the like. In particular,
Since organic acids are produced from Chlorella during reculturing,
To maintain the pH of 6 to 8, it is necessary to add an alkalinity adjusting agent, but by using ammonia as the nitrogen source, it becomes possible to also serve as the pH adjusting agent.

The reason for limiting the pH during the low pH treatment to 3 to 5 is that glutamic acid accumulated in chlorella cannot be efficiently converted into γ-aminobutyric acid if the pH is outside this range.

The atmosphere for the low pH treatment may be either aerobic or anaerobic, but it is desirable to carry out the anaerobic atmosphere from the viewpoint of efficiently converting glutamic acid accumulated in chlorella into γ-aminobutyric acid.

[Operation] According to the present invention, chlorella is dark-cultured in a predetermined culture medium, and when the carbon source is deficient, a nitrogen source is added while maintaining the pH value and aerobic atmosphere, and re-culture is performed. This can promote the accumulation of glutamate in Chlorella. As a result, when glutamic acid in chlorella is converted to γ-aminobutyric acid by a low pH treatment thereafter, the amount of accumulated glutamic acid is large, so that chlorella having a high γ-aminobutyric acid content can be produced. Therefore, the produced chlorella is washed with water and then heat-treated as it is to be spray-dried into powder, or by utilizing the heat-extracted extract, γ-aminobutyric acid, which could only be taken as a medicine until now, can be safely and continuously maintained. It becomes possible to ingest.

[Examples] Examples of the present invention will be described in detail below.

Example First, while containing 6 l of the culture solution having the composition shown below in a 10 l jar fermenter, chlorella algal cells were added as unicellular algae, pH was adjusted to 7 by addition of NaOH, and aeration was performed at a temperature of 25 ° C. Dark culture was performed with stirring. The amount of Chlorella algal cells after such dark culture was PCV 150. Then, while continuing aeration and stirring at a temperature of 25 ° C, ammonia, which is a nitrogen source, was added to maintain the pH around 7.
Reculture was performed for 2 hours. Then, aeration was stopped, and while continuing stirring, 0.01M acetic acid and phosphoric acid were added to adjust the pH to 4, and a low pH treatment was carried out at a temperature of 25 ° C. for 1 hour. Then, the Chlorella algal cells were taken out from the jar fermenter, separated by continuous centrifugation, washed with water and dried.

[Culture solution composition]

Glucose 100 g / l Calcium phosphate 2.5 g / l Magnesium sulfate 2.5 g / l Urea 7.5 g / l Fe-EDTA 75 mg / l A5solution (trace element) 15 ml / l Comparative example In a 10 l jar fermenter as in the previous example While holding 6 l of the culture solution having the above-mentioned composition, chlorella algal cells were added as single-celled algae, pH was adjusted to 7 by addition of NaOH, and dark culture was performed while performing aeration and stirring at a temperature of 25 ° C. The amount of Chlorella algal cells after such dark culture is
It was a PCV 150. Then, aeration was stopped, and while continuing stirring, 0.01 M acetic acid and phosphoric acid were added to adjust the pH to 4, and low pH treatment was carried out at a temperature of 25 ° C. for 1 hour. After this, take out the Chlorella algal cells from the jar fermenter, separate the Chlorella algal cells by continuous centrifugation, wash with water,
It was dried.

Then, the Chlorella algal cells before the low pH treatment of this example and the comparative example were subjected to heat extraction at 100 ° C. for 15 minutes, and amino acid analysis was performed on the supernatant after centrifugation. The results shown in the table were obtained.

As is clear from Table 1 above, the method of this example can produce Chlorella algal cells having a significantly higher L-glutamic acid content than the comparative example.

Next, after the above-mentioned Chlorella algal cells were subjected to pH treatment, amino acid analysis was performed under the same conditions, and the results shown in Table 2 below were obtained.

As is clear from Table 2 above, it can be seen that the method of this example can produce Chlorella algal cells having an extremely high content of γ-aminobutyric acid as compared with the comparative example.

[Effects of the Invention] As described in detail above, according to the present invention, chlorella having a high γ-aminobutyric acid content can be produced, and further, the chlorella is powdered by drying and the extract is subjected to heat extraction to obtain a conventional medicine. As a result, remarkable effects such as safe and continuous ingestion of γ-aminobutyric acid that could only be taken as an effect are exhibited.

Claims (1)

(57) [Claims] 1. A chlorella containing an organic carbon source and having a pH of 6
~ 8 in dark culture in aerobic atmosphere, when the carbon source is deficient, the pH value, while maintaining the aerobic atmosphere, a nitrogen source is added and recultured, then pH 3 ~ A method for producing a γ-aminobutyric acid-enriched chlorella, which comprises treating with low pH under the condition of 5.