JPH0665295B2 - Culture method using sintered metal element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention uses air, oxygen-enriched air, or oxygen through a sintered metal as a method for aerating a culture tank during culture production by aerobic culture. The present invention relates to a method for carrying out efficient culture production by supplying.

(Problems to be Solved by the Invention) When carrying out culture production under aerobic conditions, how to increase the efficiency of oxygen supply to the liquid with respect to the energy required for aeration becomes an important issue. In particular, in the production of microbial cells such as baker's yeast and single cell protein, the energy consumption required for agitation and aeration for oxygen supply is large, and it is important to improve the oxygen supply efficiency. Recognized as a challenge.

For this reason, various attempts have been made in the past, such as devising the shape of the fermenter, devising a stirrer, improving the super jar, aeration nozzle, and using a porous ceramic (perforated tube).

The inventors of the present invention focused on a method using a sintered metal element as a ventilation system for the culture tank, and as a result of various examinations, by performing ventilation at a relatively low linear velocity of air,
The present invention has been completed by discovering that extremely efficient culture production is possible. Vent linear velocity here means
It is a value obtained by the following equation and is a value that is often used in relation to the oxygen transfer rate in the culture tank.

(Means and Effects for Solving Problems) That is, the present invention uses air, oxygen-enriched air, or oxygen gas,
Using a sintered metal element having a pore size of 1 to 20 μm, fine air bubbles are dispersed and supplied to a culture tank, and aeration linear velocity is 5
The aerobic culture method is characterized by aeration at a rate of 00 m / hr or less.

Sintered metal is an element with innumerable capillaries obtained by sintering metals such as bronze and stainless steel, but it is a porous metal with high mechanical strength such as heat resistance and impact resistance, and it can be used for excess and dehydration of various substances. It is used for foaming. There is a possibility of application to air oxidation and activated sludge method, but there is no report about the method of using sintered metal in culture production, and the efficient usage method for culture production is not known. Although there are examples of using porous ceramics (porcelain) as an aeration method in culture production so far, in the case of ceramics, pressure loss is large, clogging of pores and easy cracking, and great labor and cost for replacement. There were drawbacks such as requiring.

An advantage of the present invention is that efficient culture production can be performed with less energy as compared with the conventional method.
A second advantage is that there is less loss of available nutrient source, which is normally scattered by excess aeration, and improved product yields with respect to the main and secondary raw materials. The third advantage is that the material with thin wall thickness (compared with the wall thickness of about 15 mm in the case of each ceramic unfired tube, 3 mm in the case of sintered metal)
Since it has a wall thickness of about a certain degree), there is little pressure loss due to ventilation, it is advantageous in terms of required ventilation energy, cleaning and regeneration are easy, and maintenance management is simple.

Next, a method for carrying out the present invention will be described in detail. As the sintered metal, elements made of different materials such as bronze and stainless are known, but it is preferable to use stainless steel in terms of strength and nitric acid cleaning. The shape is not particularly limited, but as an example, one of the sintered metal tubes welded in a cylindrical shape can be sealed, and the other can be set as a ventilation pipe or a ventilation nozzle or an air diffusing pipe. The length of the sintered metal portion and the diameter of the tube are not particularly limited, but usually the cylindrical diameter is 40 to 4
5mm and length of 400-1600mm are convenient. It is also possible to increase the ventilation efficiency in the tank depending on the direction and position of the pipe.

The pore diameter of the sintered metal element can be used according to the purpose in the range of 1 to 100 μm, but in the case of the present invention, it is 1 to 20 μm.
High ventilation efficiency can be obtained by using an element having a hole diameter of.

As described above, the sintered metal element can be used in place of the aeration super jar, nozzle, air diffuser and the like which are usually used for aerobic culture.

As the culture tank to be applied, various culture tanks such as an aeration-stirring culture tank, an air-lift culture tank, and a culture tank with an air diffuser used for the production of baker's yeast can be used. In particular, the flat type low-depth culture tank exhibits high efficiency. In the case of culture production by aerobic culture, oxygen supply efficiency is an important factor for economic production, but air is usually used as the oxygen source, and oxygen-enriched air or pure oxygen is used depending on the purpose. You can also Sintered metal element (wall thickness 2-3)
From the perforated tube of m / m), air is dispersed in the liquid as extremely fine bubbles.

The present inventors have examined the relationship between the amount of air to be aerated and the oxygen supply absorption rate (efficiency), and found that if the air supply rate were increased, the oxygen absorption rate would be increased. It was confirmed that there is a condition with high efficiency in the area. The optimum air flow rate is the pore size of the sintering element to be used, the shape of the culture tank, the agitation and fluid flow conditions,
Although it depends on the oxygen source such as oxygen-enriched air and pure oxygen, when the air is passed at a linear velocity of usually 500 m / hr or less, the objective can be achieved with high efficiency. If it exceeds 500 m / hr, the oxygen absorption rate (efficiency) tends to decrease. The circumstances during this time are as shown in the graphs of FIGS. As an example, when a sintered metal element having a pore size of 2 μ was used, an optimum oxygen transfer capacity coefficient (K _L a) was obtained at an air linear velocity of 150 to 400 m / Hr (see Example 2 described later). According to the present invention, when the sintered metal element is used for culture production, a microscopic suspended matter in the air is filtered by a prefilter (for example, a 5 μ filter) before being aerated by the sintered metal ventilation pipe. It is preferable to remove. Furthermore, it is necessary to devise a method of draining the condensed water accumulated in the ventilation pipe to the outside of the system. That is, it is preferable that a structure for automatically discharging the condensed water be provided because water droplets condensing in the tube block the pores of the sintered metal and the pressure loss becomes significantly large.

The present invention is widely applicable to culture production under aerobic conditions. For example, baker's yeast production, production of yeast, bacteria, single cell proteins (SCP) such as filamentous fungi, amino acid or organic acid production by fermentation, nucleic acid-related substance production, antibiotic production, etc. can be mentioned.

In culture production, the air supply is normally stopped after completion, but when using sintered metal, a small amount of aeration is continued to keep the pressure inside the sintered metal cylinder at a positive pressure to prevent clogging due to backflow of the culture solution. is necessary.

(Example) Hereinafter, it demonstrates in detail using an Example.

Example 1 Using an air-lift type fermenter having a total capacity of 300 (height: 1.5 m), a perforated tube (length: 500 mm, inner diameter: 42 mm), super jar (length: 200 mm, diameter: 20 mm, hole diameter: 3 mm), spray nozzle ( Vee Jet) (length 32mm, inner diameter 4.5mm)
(Figure 2 above) and sintered metal tube [A (length 500 mm, inner diameter 60 mm, hole diameter 2 μ), B (length 200 mm, hole diameter 5 μ)]
The oxygen transfer rate (Kd · Pg) when (Fig. 1) was used as a ventilation nozzle was measured by a conventional method using sodium sulfite.

That is, anhydrous sodium sulfite was dissolved in 14.7 g of water and put in an air lift fermenter to adjust the flow rate to 244. A predetermined amount of air is supplied from the ventilation nozzle to perform sufficient liquid mixing. Add 1 copper sulfate solution (49 g /) to start the reaction. 3 ml of liquid in the tank is sampled every 30 minutes
0.1 N iodine solution was added to the solution and titrated with 0.1 N Na ₂ S ₂ O ₃ solution using 1% soluble starch solution as an indicator. The oxygen transfer rate was calculated by the following formula.

θ _1, θ _2: Sampling Time _{(min) C 1, C 2} : θ 1, drops of 0.1N sodium thiosulfate in the _{θ 2 (Na 2 S 2 O} 3) value (ml): 0.1NNa ₂ S ₂ O ₃ factor S: Sample volume (3 ml) Kd.Pg: Oxygen absorption rate (g-molo ₂ / ml / min) Kd: Oxygen absorption rate coefficient (g-molo ₂ / ml ・ min ・ atm) Pg: Gas phase Oxygen partial pressure (atm) Example 2 Fermenter for baker's yeast production (20 m ³ capacity, diameter 2300 mmφ
Cylindrical shape), the overall oxygen transfer capacity coefficient K _L a [S. Miy
amoto: Bull.Chem.Soc., (Japan) .Vol.7, P-8 (1932)], comparing the difference with the case of using a normal air diffuser by changing the ventilation linear velocity (m / hr) did. As the sintered metal, a hole diameter of 2 μ, a wall thickness of 3 mm, an inner diameter of 40 to 45 mm, and a length of 400 to 1,600 mm were used instead of the air diffusing pipe as shown in FIG. And the distance between the fermenter walls is 50 mm). The obtained results are shown in FIG.

Example 3 In Example 2, the production of baker's yeast containing molasses as a main raw material was examined when a sintered metal element was used as a ventilation nozzle. Commercially available baker's yeast (Satsucaromyces cerevisiae) is used as a seed, urea 1.0 g / dl, ammonium sulfate 0.2 g /
Sterilized and clarified cane molasses was divided and fed to a basal medium containing dl and 75% phosphoric acid 0.9 g / dl so that the concentration of ethanol in the liquid was 500 to 700 ppm, and aerobically cultivated. The pH was adjusted to 4.7 with aqueous ammonia. A phenomenon in which the aeration pressure loss rapidly increased 6 to 8 hours after the start of the culture was observed. Therefore, when the aeration nozzle and the air conduit were inspected, the accumulation of condensed water was observed. When a mechanism (drain trap) for discharging drain (condensed water) was installed in the culture, the air pressure loss was stably maintained at 0.15 kg / cm ² G or less, and aerobic culture could be carried out. . FIG. 5 shows the relationship between the aeration linear velocity and the yield of baker's yeast.

[Brief description of drawings]

FIG. 1 shows one of the ventilation nozzles of the sintered metal element of the present invention.
FIG. 2 is a perspective view showing the shape of an example [A (length 500 mm, diameter 60 mm, pore diameter 2 μ), B (length 200 mm, pore diameter 5 μ)], FIG. 2 showing a conventional porous tube (1), super jar (2), A perspective view (1, 2) and a vertical cross-sectional view (3) showing the shape of each ventilation nozzle of the spray nozzle (Vee Jet) (3), and FIG. 3 is a plan view showing the installation of the sintered metal element in the fermentation tank. FIG. 4 is a graph showing the relationship between the ventilation linear velocity of the ventilation nozzle and the overall oxygen transfer capacity coefficient (K _L a) (comparison between a sintered metal element and an ordinary diffuser tube as the ventilation nozzle), Is a graph showing the relationship between aeration linear velocity and baker's yeast yield (comparison of the same aeration nozzle as in FIG. 4), and FIG. 6 is a layout explanatory diagram showing installation of a drain trap in an air main conduit of a fermenter. , (Vertical cross-sectional views (A) and (A), the cross-sectional view perpendicular to the length direction of the main air conduit (B))

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Kato, 2-70 Yamatedai, Okubo-cho, Akashi-shi, Hyogo (56) References JP 54-117379 (JP, A) Seki 56-47739 (JP, U) Actual development Sho 52-97948 (JP, U)

Claims (2)

[Claims] 1. Air, oxygen-enriched air, or oxygen gas is dispersed and supplied to a culture layer as fine bubbles using a sintered metal element having a pore size of 1 to 20 μm, and an aeration linear velocity is 500 m / hr or less. An aerobic culture method, which comprises aerating with aeration. 2. The method according to claim 1, wherein the sintered metal element is arranged in a ventilation pipe having a structure for discharging drain (condensed water) accumulated in the ventilation pipe to the outside of the system.