JP2984749B2 - Algae cultivation method using silicon - Google Patents

Description

The present invention relates to a method for culturing algae using silicon,
More specifically, the present invention relates to a culture method that enables continuous algae culture using a silicon tube having excellent air permeability.

[Problems to be Solved by Conventional Techniques and Inventions] Algae contain various components useful as foods, and can be used for a wide variety of applications if the prices are reasonable. Although the components differ depending on the type of algae and the culture method, for example, spirulina and chlorella each have a protein, fat, carbohydrate, and nucleic acid content of 4
8, 6, 11, 4; 55, 18, 15, 4%. Generally, when the protein content is high and carbohydrates are to be increased, the culture may be carried out with the nitrogen source concentration in the medium lowered.

In addition, the useful value of vitamins, fats, pigments, plant hormones, and the like, which are contained as special components, is also high. For example, in one example, vitamin A precursors, B ₁ , B ₃ , B ₆ , B ₁₂ , and E are used in Spirujina platensis. , 1,700, 55, 118, respectively
It contains 3, 1.6 and 190 mg / kg dry matter. From such a thing, utilization of the whole algae body as health food, general food,
Polysaccharides such as agar, carrageenan, alginic acid, and fucoidan contained as carbohydrates can be used as food property improving agents.

However, the cost of producing algae is currently significantly higher,
Estimation of indoor pure culture is 160-200 USD / kg dry matter, and the ratio of cost is labor force 50-85, pump 4 ~
24, medium 4-20, mixed 5-8%.

Therefore, in the conventional method of cultivating algae, the obtained algae is expensive, so it is difficult to apply the algae to food materials, and at present it is applied to health foods with a slightly high added value. .

[Means for Solving the Problems] Accordingly, the present inventors have attempted to reduce the production cost of algal products by continuation of culture, and as a result of intensive studies, as a result of efficiently using a silicon tube, algae have been efficiently removed. They found out that they would produce them serially, and assembled the system.

In the conventional algae production method, especially in the case of microalgae, water is poured into a large flat pond, cultivation and harvesting is performed with gentle stirring, and a photosynthetic reactor (glass tubes and polyethylene tubes connected alternately) C. Guiden et al .: The World
biotech.Report 1984, Vol.1 Europe, pp541-59, Lond
on: Online Publications Ltd.).

The oxygen permeability of polyethylene, which was the highest so far,
Even at a thickness of 30 μm, the maximum is 6,000 cc / m ² · day · atm at 25 ° C., and the carbon dioxide permeability is 3 to 4 times this value. However, recently developed silicon has a permeability of 365,000 cc / m ² · day · atm for oxygen and 1,16 for carbon dioxide even at a thickness of 100 μm.
Also reached to ^{5,000cc / m 2 · day · atm} . Therefore, the present inventors have studied diligently about algae culture with this material, and using this material, the growth rate of algae does not decrease even if the algal culture solution is higher in concentration than before, and the concentration of algae is continuously increased. The inventors have found that a liquid can be obtained and completed the present invention.

 The present invention is described below.

The present invention relates to a method for culturing algae using silicon. More specifically, (1) cultivating algae by continuously supplying an algal inoculation medium and / or a fresh liquid medium to a tubular gas-permeable membrane made of silicon or a tubular gas-permeable membrane fixed to the outer surface of a substrate. And continuously drawing the cultured algal solution out of the system.

(2) The continuous culture method described above, wherein the algal culture is dialyzed or concentrated to remove the growth-inhibiting substances and cultured.

Silicon can change the air permeability to a desired degree depending on the processing method, and is easily used as a system because of its high mechanical strength. Further, it is a very useful material that can be processed into a sheet shape, a tubular shape, and other various shapes. Recently, there is an example of practical use of this material processed into a thin tube and used for an artificial lung, but this uses the breathability of this material. The method of the present invention uses this property for algae culture. There has been no example of using this material for algae culture, and there is no example of successful culture. In addition, the culture method of the present invention is not limited to silicon as a material, and any material having excellent air permeability, such as cellulose, ceramics and the like whose surface is waterproofed, can be used. is there.

Silicone material has a hydrophobic surface so that it can easily pass through algae, and it can pass through even high-concentration algal fluids.Moreover, growth is usually reduced when the algal concentration is 500-600 mg / min. Is extremely excellent,
The growth rate is fast even if it is twice or more.

The shape of silicon is not particularly limited as long as it is suitable for algae culture, but a flat plate for large algae and a tube for microalgae are convenient. The size of the tube is appropriately selected depending on the thickness of the tube.
For a thickness of 00 μm, about 3.6 × 4.0 mm is appropriate. In the case of a flat membrane, use a 300 x 300 mm square and reinforce the bottom with a mesh.

When a 200 μm tube is used, it is spiraled on a flat plate as shown in FIG. 1, wrapped around a cylinder, or placed horizontally and / or vertically. When the tubes are arranged on a flat plate, spaces can be provided little by little in consideration of light efficiency, and the tubes can be stacked in ten or more stages. Basically, the culture solution is circulated or passed through a long tube equipped as described above, but it is convenient to provide a storage tank at an appropriate place to keep the liquid level constant. The storage tank is preferably set so that the amount of liquid in the system is kept constant and a fresh medium can always be supplied.

In the culture method using the system according to the present invention,
If a long tube of 20 m or more is used, or the culture solution is extremely concentrated under dry conditions, it may be difficult to pass through the culture solution or the growth rate of algae may be reduced. A fresh medium (medium concentration may be selected arbitrarily) may be provided.

Furthermore, depending on the type of algae and the culture conditions, the growth inhibitory substance may accumulate with the elapse of the culture time, and the growth rate may decrease. In such a case, an ordinary filtration material and a dialysis membrane that allow other components to pass without passing through an ultrafiltration membrane or algae are set in an appropriate part of the system, and continuous culture is performed while removing growth inhibitors. According to this method, various substances produced by algae can be continuously taken out.

It is also a feature of the present system that the length of light and darkness can be arbitrarily changed, and it is only necessary to adjust the length flow rate of the tube to set it in the light or dark portion.

The concentration of the initial algal solution and the ratio of the amount of the cultured algal solution to be withdrawn may be arbitrarily selected depending on the culture speed and other conditions, but the highest concentration algal culture solution is used as a starting solution, for example, starting at 2 g /. If the solution is used, the concentration becomes twice in two days. Further, half of the amount may be returned to the starting tank, half of the fresh medium may be added, and the culture may be continued.

If the flow rate and the length of the tube are adjusted so that the algal concentration is doubled at the end of the tube, it is sufficient to simply pass through the tube. Draw out half, add fresh medium and continue culturing. The algae concentration is measured with a spectrophotometer 680 nm, and when the absorbance reaches twice the initial concentration, half of the algae can be automatically withdrawn and set so that half of the fresh medium is added.

The kind of algae is Chlorella (Chlorella) Sce
nedesmus, Spirulina, Por
phyridium, Nostoc, Chlam
Although there are many types such as ydomonas (Chlamydomonas), any culture method using the system of the present invention can be applied as long as it can pass through a tube. Further, two or more of these can be mixed and cultured. Similarly, the method of the present invention can be applied to large algae such as green algae, brown algae and red algae as long as the diameter of the tube is increased or the passage is enabled by using a flat plate.

Heterotrophic algae such as mutated chlorella can also be effectively applied to the system of the present invention, and the algae can be continuously produced by culturing using a sterile medium containing a carbon source.

EXAMPLES Next, the present invention will be described in more detail and specifically with reference to Examples, but it should not be construed that the invention is limited thereto.

Example 1 As algae, spirulina platensis (conservation strain No.39, Environmental Science Research Council) and SOT medium as medium, 2,50
The cells were cultured under a 0 Lux fluorescent lamp at 25 ° C. at a flow rate of 4 m / min. The system is circular as shown in FIG.
Set a 10-μm silicon tube with a diameter of 3.6 × 4.0 mm on an aluminum foil, and place the liquid level in a 200-m storage tank equipped with a medium supply device.
It is less than 1cm. As a result of filling the entire system with a 2 mg / m concentration algal solution (excluding the medium supply device) and circulating the culture using a peristaltic pump, as shown in Table 1,
The algal concentration doubled in a day.

Example 2 Culture was carried out in the same manner as in Example 1 except that a silicon tube 10 m having a thickness of 100 μm and a diameter of 3.0 × 3.2 mm was set on an aluminum foil (0.04 m ² ) and the algal concentration was set to 0.5 mg / m. However, the algal concentration tripled in one day.

Example 3 Algae concentration was set to 1 mg / m, and culturing was carried out in a water vapor saturation chamber in the same manner as in Example 1 in order to prevent excessive drying. As a result, the algal concentration was increased five times in 3 days.

Example 4 Circular culture was performed in the same manner as in Example 1 except that the concentration of algae was 0.5 mg / m, and a supply device for a 1/2 dilution medium was provided in the middle of a silicon tube. Concentration.

Example 5 As algae, Spirulina platensis (Environmental Research Council, stock strain No. 39), the algal concentration was 0.5 mg / m, and the thickness was 20
0 μm, a silicon tube with a pipe diameter of 3.6 × 4.0 mm, 230 m is set on an acrylic plate, and a space of 5 to 10 cm is taken to form 5 stages, and for each stage, 1/2 to 1/10 used for a normal algal culture solution The culture was performed at a flow rate of 2 m / min with a diluted medium supply device containing potassium phosphate and urea at a concentration of 5 mg / m.
m / min. When this algal solution was passed through the same silicon tube in a dry state at 35 ° C., it was concentrated to 1/4 at 10 m to obtain a milky algal solution.

Example 6 After culturing at an algal concentration of 1 mg / m in the same manner as in Example 1, doubling the concentration with an ultrafiltration membrane having an exclusion limit molecular weight of 200,000, adding a fresh medium, and continuing culturing for another day, 5 fold Concentration.

Example 7 1 mg / m of Chlorella regularis was prepared by using a system similar to that of Example 1 in a medium using acetic acid, sodium acetate, and urea as a nitrogen source at 35 ° C. As a result of circulating culture while adding acetic acid and sodium acetate, an algal solution of 10 mg / m was obtained in 24 hours.

[Effects of the Invention] According to the culture method using the system of the present invention, a high-concentration algal culture solution that has been difficult until now can be efficiently and continuously produced, and the algal solution is concentrated by various methods. , Algae concentration 1
It can be cooked and seasoned to make a tsukudani-style food by applying it to a liquid food by making it into a milky form at ~ 2% and further concentrating it into a creamy form with an algal concentration of 10 to 12%. It can also be mixed with cyclodextrin and / or dextrin, oligosaccharide, etc. and spray-dried into powder, or spread thinly on a gas-permeable membrane such as silicon and dried into a sheet to form glue. Applications are wide such as possible.

If concentrated to an algal concentration of 15 to 20%, it becomes cheese-like, and can be used as it is or after removing pigments as various food materials.

In addition, the cultured algae can be used as a raw material for extracting polysaccharides, carbohydrates, lipids, vitamins, physiologically active substances, and the like, and the extracted substance can be used as a functional, health food, or general food material.

[Brief description of the drawings]

FIG. 1 shows the entire system in which silicon tubes are set in a circular and square plate shape. This system mainly consists of a culture tube, a storage tank (reservoir tank), a medium or water supply device (auxiliary medium tank), a concentration or dialysis device (medium exchange, concentration system), and an automatic concentration sensor, which can be combined as necessary. Can be.

Continuation of the front page (72) Inventor Kazuya Fujisawa 7-36-5 Nakayamate-dori, Chuo-ku, Kobe-shi, Hyogo (56) References JP-A-51-110089 (JP, A) JP-A-56-61988 ( JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C12N 1/00-7/08 C12M 1/00-3/10

Claims (2)

(57) [Claims] An algal inoculation medium and / or a fresh liquid medium are continuously supplied to a tubular gas-permeable membrane made of silicon or a tubular gas-permeable membrane fixed on the outer surface of a substrate to culture algae. A method for continuously culturing algae, wherein the cultivated algal solution is sequentially drawn out of the system. 2. The method according to claim 1, wherein the algal culture is dialyzed or concentrated to remove the growth-inhibiting substance and cultured.