JPH10313854A - Culture of microbial cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for culturing a microbial cell by which the culture can be carried out by a simple apparatus such as a culture vessel of an opened system and the objective aerobic microbial cell can efficiently be cultured. SOLUTION: This method is to culture the objective aerobic microbial cell in an opened system and comprises controlling the feed rate of dissolved oxygen fed to a culture solution of the aerobic microbial cell to that required to culture the aerobic microbial cell and within the range of the amount capable of preventing the growth of protozoans preying upon the aerobic microbial cell. When the microbial cell is a kind of Pseudomonas bacteria, the feed rate of the dissolved oxygen is preferably controlled within the range of 0.005-0.5 mg/L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an efficient method for culturing microbial cells which can be carried out with a simple apparatus.

[0002]

2. Description of the Related Art In recent years, various attempts have been made to remove contaminants such as organic substances such as trichlorethylene as a solution to the environmental problem of soil contamination. For example, suction of soil contaminants using a vacuum pump has been made. Then, a method of performing activated carbon treatment has been proposed. However, in the method of removing contaminants by adsorption with activated carbon, there has been a problem of reprocessing of the used activated carbon having adsorbed the contaminants, so that more efficient treatment has been required.

[0003] On the other hand, a method has been proposed in which a pollutant is decomposed by a bioreactor containing microorganisms that decompose the contaminant, and thereafter, a liquid component and air are discharged. Organic components can be efficiently extracted and processed. Furthermore, since the pollutants are treated by using the decomposition action of microorganisms, there is no problem of secondary pollution.

[0004] Pseudomonas fungi are known as microbial cells used here. Pseudomonas fungi are aerobic cells,
Toluene can be utilized and grown as the sole carbon source. When this microbial cell is cultured in an open system using toluene as a carbon source, it is known that the bacterial concentration decreases extremely with time. The decrease in the number of viable bacteria is considered to be due to an increase in protozoa that prey on microbial cells. In the open culture, the number of protozoa that prey on Pseudomonas fungi is considered An increase has been observed.

[0005] As a method of preventing this, a method of culturing microbial cells in a closed culture tank incorporating a device for preventing the incorporation of various bacteria can be considered. However, according to this method, the device becomes complicated and handling becomes complicated. There was a problem of becoming.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for culturing microbial cells which can be efficiently cultivated by a simple apparatus such as an open culture tank. To provide.

[0007]

Means for Solving the Problems Claim 1 according to the present application
The described invention is a method for culturing a target aerobic microbial cell in an open system, wherein the supply amount of dissolved oxygen supplied to a culture solution of the aerobic microbial cell is controlled by the aerobic microbial cell. The present invention relates to a method for culturing microbial cells characterized by controlling the amount of the microbial cells required for culturing of the aerobic microbial cells so as to prevent the growth of protozoa that feed on the aerobic microbial cells.

[0008] More specifically, the present application relates to a method wherein the aerobic microbial cells are a kind of Pseudomonas fungi,
The supply amount of the dissolved oxygen amount is 0.005 per liter.
The present invention relates to a method for culturing microbial cells, wherein the method is controlled to a range of 0.5 mg.

In the method for culturing microbial cells of the present invention, an open system culture tank is used for culturing aerobic microbial cells such as Pseudomonas, and the amount of dissolved oxygen supplied to the culture solution is determined. The required amount of the aerobic microbial cells is controlled to a range that can prevent the growth of protozoa that prey on the aerobic microbial cells. This control can be easily performed by a conventional method. Therefore, efficient continuous culture can be carried out without a decrease in the number of viable bacteria.

[0010]

The present invention will be described below in more detail with reference to specific examples, but the present invention is not limited thereto. (Example 1) The method for culturing microbial cells of the present invention will be described in detail.

The culture used here is Pseudomonas sp. The Pseudomonas sp. May be, for example, a cell belonging to the genus Pseudomonas described in JP-B-63-7752 and JP-B-5-88106. Ion-exchanged water 1000 as a culture solution
Toluene was added to the following medium tissue and sterilized by adding the following.Toluene was further added to the culture medium at 20 ° C. in an open system culture tank equipped with a dissolved oxygen electrode for measuring the amount of dissolved oxygen in the culture solution.
For 8 days.

Culture medium tissue: ammonium sulfate 2.5 g magnesium sulfate 0.2 g monopotassium phosphate 1.4 g disodium phosphate 3.6 g ferrous sulfate 2 mg calcium chloride 10 mg (based on 1000 ml of ion-exchanged water) : Culture temperature: 20 ° C Culture pH: 7.0 to 7.2

The data on the amount of dissolved oxygen in the culture solution measured by the dissolved oxygen electrode is sent to an oxygen supply device to control the amount of dissolved oxygen in the culture solution. A graph showing the relationship between the number of bacteria and the bacterial concentration of the fungi of Pseudomonas sp. Cultured at this time while changing the dissolved oxygen amount of the culture solution to be 0.005 to 3.0 mg / l and the dissolved oxygen amount. Is shown in FIG.

As is clear from FIG.
When the concentration is controlled in the range of 005 to 0.5 mg / l, the generation and growth of protozoa that prey on Pseudomonas sp. Can be suppressed, and the bacterial concentration can be maintained at a high concentration. Also,
The dissolved oxygen content exceeds 0.5 mg / l, especially 1.0 mg / l
At l or more, the number of protozoa was increased and the bacterial concentration tended to decrease. The bacterial concentration in this graph is represented by the optical density (absorbance) of light having a wavelength of 660 nm, and the higher the numerical value, the higher the bacterial concentration. The number of protozoa solids indicates the number per 1 ml.

The Pseudomonas sp. Cultured in this manner can be immobilized in a bioreactor and used for decomposing harmful substances such as trichlorethylene.

[0016] The immobilized material used in the bioreactor can be selected appropriately depending on the microorganism.
Organic porous materials such as peat moss and polyurethane resin can be used. The immobilization material preferably has a porous structure such as a filter in order to improve the contact area with the gas-liquid from which the contaminants have been extracted. The bioreactor using the microorganism immobilized on the immobilization material may be used as one stage, but it is preferable that the bioreactor be formed in multiple stages from the viewpoint of processing efficiency.

Microorganisms useful for the decomposition of organic chlorides such as trichloroethylene to which this culturing method can be applied include, for example, a kind of Pseudomonas,
Pseudomonas putida, Pseudomonas cepacia and the like. It is necessary to appropriately select the amount of dissolved oxygen in the culture solution suitable for cultivation according to the type of cells, but Pseudomonas fungi useful for decomposing harmful substances is 0 as described above. 0.005 to 0.5 mg / l
The degree is preferably used.

The Pseudomonas thus cultured (Pseu
domonas) If fungi are used to decompose and remove trichlorethylene, as with conventional physical adsorption such as activated carbon,
The treatment of the adsorbent itself does not become a problem, and
There is no problem of secondary pollution.

[0019]

According to the method for culturing microbial cells of the present invention, the desired aerobic microbial cells can be efficiently cultured using an open culture tank without using a complicated apparatus. It shows excellent effects that can be achieved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of dissolved oxygen when a Pseudomonas fungus is cultured, the number of protozoa that prey on the dissolved oxygen, and the bacterial concentration of the Pseudomonas fungus.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FIC12R 1:38) (72) Inventor Masayasu Kitagawa 3690-1 Sakuracho, Yokkaichi-shi, Mie Pref. International Environmental Technology Transfer Research Center

Claims (2)

[Claims] 1. A method for culturing a target aerobic microbial cell in an open system, wherein the amount of dissolved oxygen supplied to a culture solution of the aerobic microbial cell is:
Culturing of microbial cells which is an amount necessary for culturing the aerobic microbial cells and which is controlled in a range capable of preventing the growth of protozoa that prey on the aerobic microbial cells. Method. 2. The aerobic microbial cell is a kind of Pseudomonas fungus, and the amount of dissolved oxygen supplied to the culture solution is controlled in the range of 0.005 to 0.5 mg / l. The method for culturing a microbial cell according to claim 1.