JPS6156070A - Method of culture using sintered metal element - Google Patents

Abstract

PURPOSE:To carry out efficient culture production, by feeding and dispersing air, air rich in oxygen or an oxygen gas as very fine bubbles into a culture tank by the use of a sintered metal element. CONSTITUTION:Air, air rich in oxygen, or an oxygen gas is fed and dispersed as very fine bubbles into a culture tank at <=500m/hr aerating line velocity. The sintered metal element is set in an ventilating pipe having a structure to discharge condensed water retaining in the ventilating pipe to the outside of the system. By the above-mentioned structure, effective culture production is made possible by with smaller energy. Loss of usable nutritive source which is scattered usually by excess aeration is reduced, and yield of product based on main and subsidiary raw materials is increased. Since a material with small thickness (about 3mm.) is used, pressure loss by aeration is reduced, this process is advantageous in terms of so-called aerating energy, washing and regeneration are easy, maintenance and control are simplified.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a method for introducing air, oxygen-enriched air, or oxygen through a sintered metal as a method of aerating a culture tank when performing 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 performing culture production under aerobic conditions, an important issue is how to increase the efficiency of oxygen supply to the liquid relative to the energy required. In particular, the production of microorganisms such as baker's yeast and single-cell proteins (Single Cell Prot, ein) consumes a large amount of energy for stirring and aeration for oxygen supply, and it is difficult to improve oxygen supply efficiency. It is recognized as an important issue.

For this reason, various attempts have been made to improve the shape of conventional fermentation tanks, improve stirrers, improve super jars and ventilation nozzles, and use porous ceramics (perforated tubes).

The present inventors focused on the method of using sintered metal elements as a method of aeration to the culture tank, and as a result of various studies, by performing aeration at a relatively low linear velocity,
The present invention was completed by discovering that extremely efficient culture production is possible.

(Means and Effects for Solving the Problems) That is, the present invention is characterized in that air, oxygen-enriched air, or oxygen gas is distributed and supplied to the culture tank in the form of fine bubbles using a sintered metal element. The contents include aerobic culture methods.

Sintered metal is an element with countless capillary tubes made 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 to absorb various materials. It is used for many purposes such as dehydration and foaming.

The possibility of application to air oxidation and activated sludge methods is also considered, but there are no reports yet on the use of sintered metal in culture production, and no efficient method for use in culture production is known. There have been examples of using porous ceramics as an aeration method in culture production, but ceramics have a large pressure loss, tend to clog the pores, break easily, and require a lot of effort to replace. It had drawbacks such as being expensive.

An advantage of the present invention is that it enables efficient culture production with less energy than conventional methods. A second advantage is that there is less loss of available nutrients, which are normally dispersed due to excessive aeration, and the yield of product relative to the primary raw material is improved. The fifth advantage is that the material has a thin wall thickness (compared to about 15 aam for unglazed ceramic tubes, 5 aam for sintered metal).
Since it uses a wall with a wall thickness of about 100 fl liters, there is little pressure loss due to ventilation, which is advantageous in terms of the required ventilation energy, and it is easy to clean and regenerate, and maintenance is simple.

Next, a method for implementing the present invention will be described in detail. Elements made of different materials such as bronze and stainless steel are known for the sintered metal, but it is preferable to use stainless steel from the viewpoint of strength and nitric acid cleaning. Although the shape is not particularly limited, as an example, one side of a sintered metal tube welded into a cylindrical shape may be sealed, and the other may be set in place of a ventilation pipe, ventilation nozzle, or aeration pipe. There are no particular restrictions on the length of the sintered metal part or the diameter of the tube, but the cylinder diameter is usually 40 to 45 mm.
am, length 400-160011x is convenient. It is also possible to increase the ventilation efficiency within the tank by selecting the direction and position of the pipes.

The pore size of the sintered metal element can be used in the range of 1 to 1100 μm depending on the purpose, but high ventilation efficiency can usually be obtained by using an element with a pore size of 1 to 20 μm.

As described above, the sintered metal element can be used in place of the aeration super jar, nozzle, aeration pipe, etc. normally used in aerobic culture.

Applicable culture tanks include aeration stirring type culture tanks, air lift type culture tanks, and culture tanks with aeration tubes used in the production of bread mash, etc.! It can be used for. It exhibits particularly high efficiency in flat culture tanks with low liquid depth. In the case of culture production using aerobic culture, oxygen supply efficiency is an important factor for economical production, but air is usually used as the oxygen source, and depending on the purpose, pure oxygen may be used instead of acid XXX-formed air. You can also do it. Sintered metal element (thickness 2-5
Air is dispersed into the liquid as extremely fine bubbles from the porous tube of z).

The present inventors investigated the relationship between the amount of air to be ventilated and the oxygen supply and absorption rate (efficiency), and found that increasing the air supply rate would increase the oxygen absorption rate. It was recognized that there are conditions for high efficiency in the area where The optimal air flow rate also differs depending on the pore size of the sintering element used, the shape of the culture tank, the stirring and fluid flow conditions, and the oxygen source such as oxygen-enriched air or pure oxygen.

As an example, when using a sintered metal element with a pore size of 2μ, the optimum oxygen transfer capacity coefficient (KLa) was obtained at an air linear velocity of +SO~401'1 m/Hr (
(See Example 26 below) When using the sintered metal element for culture production according to the present invention, before venting to the sintered metal ventilation pipe, a pre-filter (for example, a 5μ filter) is used to remove minute suspended matter in the air. It is preferable to remove it by. Additionally, it is necessary to devise a way to drain the condensed water that accumulates in the ventilation pipes out of the system. That is, since water droplets condensing inside the pipe block the pores of the sintered metal, resulting in a significant pressure loss, it is preferable to provide a structure for automatically discharging the condensed water.

The present invention is widely applicable to culture production under aerobic conditions. Examples include production of baker's yeast, production of single-cell proteins (SEP) such as yeast, bacteria, and filamentous fungi, production of amino acids or organic acids by fermentation, production of nucleic acid-related substances, and production of antibiotics.

In culture production, the air supply is usually stopped after completion, but when using sintered metal, a small amount of ventilation is continued to maintain positive pressure inside the sintered metal cylinder to prevent clogging due to backflow of culture solution. Consideration must be taken to prevent this.

(Example) This will be explained in detail below using examples.

Example 1! Using an airlift type fermenter with a volume of 3001 ft (height 1.5 m), a perforated tube (length 500 mm, inner diameter 42 mm) was used.
, su-/<-jar (length 2Q OmRs diameter 2 spans 0 deg diameter 5 aog), spray nozzle (Vee Jet
) (length 321 DI, inner diameter 4.5 m) (Figure 2 above)
) and sintered metal tube (A (length 500#I11, inner diameter 60
Oxygen transfer rate (K
d-Pp') IIC was measured by a conventional method using sodium sulfite.

That is, anhydrous sodium sulfite was dissolved in 14.77 g of water and placed in an air lift fermenter to make the liquid volume 244 g. A predetermined amount of air is supplied from the ventilation nozzle to ensure sufficient liquid mixing. Add 11 parts of copper sulfate solution (499/l) to start the reaction. Sample 5 ml of the solution in the tank at predetermined intervals,
It was placed in 01N iodine solution at 50 tn/ml, and titrated with Q, IN NIL*S*Ox solution using 1% soluble starch solution as an indicator.

The oxygen transfer rate was calculated using the following equation.

2×(θ1-01)S θ1. et al: sampling time (min) CI r c,
:θ1. θ! α1N Sodium Thiosulfate (Nax
Sx03) titration value (ml) f: 0. Factor S of I N N5LiSiCh
: Sample amount C”rzt) Kd, P tick oxygen absorption rate (f-mo102/x//m
1n) Kd: Oxygen absorption rate coefficient (y-molo, /mmin-atm) Py:
Oxygen partial pressure in gas phase (ATM) Table 1 K (1, Pp value of various aeration methods Example 2 Fermentation tank for bread yeast production (20 m' volume, diameter 2300 m)
Overall oxygen transfer capacity coefficient KLa when a sintered metal element is used as a ventilation nozzle in a cylindrical shape of aIφ
(S, Miyamoto: Buyu 1., Ch.
em.

Soc, (Japan), 1101.7.
P-8 (1932)) was compared with the case of using a normal J-tube by changing the ventilation linear velocity (m/hr). The sintered metal has a pore diameter of 2μ, a wall thickness of 5IIIlffI,
An inner diameter of 40 to 5mm and a length of 400 to 1,600ag were used by installing them in the air diffuser pipe/D section as shown in Fig. 50 minutes together). The obtained results are shown in FIG.

Example 5 In Example 2, the production of baker's yeast using molasses as the main raw material was studied when a sintered metal element was used as an aeration nozzle. Commercially available bread #Mother (Satsukalomyces Fist Cereviche) Used as tFnEk, original form 1. Oy/d
1. Ammonium sulfate 0.2! /dl.

Sterilized and clarified cane molasses was added to a basal medium containing 0.9 t/dl of 75% phosphoric acid at an ethanol concentration of 500 to 700.
Aerobic culture was performed by dividing the mixture into ppm. The pH was controlled to 4.7 with aqueous ammonia.

A phenomenon in which the aeration pressure loss suddenly increased 6 to 8 hours after the start of culture was observed, so when we inspected the aeration nozzle and air conduit, we found that condensed water had accumulated. When culturing was carried out by installing an i-structure (drain trap) to discharge condensate (condensed water) into the pipe, the air pressure loss was o.
, 15 kg/cm2G or less, and aerobic culture could be carried out. FIG. 5 shows the relationship between the linear ventilation velocity and the bread yield.

[Brief explanation of drawings]

FIG. 1 shows one of the ventilation nozzles of the sintered metal element of the present invention.
A perspective view showing the shape of an example (AC length 500 mm, diameter 60 mm,
Figure 2 shows the shape of the ventilation nozzle of husband 4 of the conventional porous pipe (1), super jar (2), and spray nozzle (Vee Jθt) (3). Perspective views (1, 2) and vertical cross-sectional views (3) showing
), Figure 5 is a plan view showing the %L of the sintered metal element installed in the fermenter, and Figure 4 is a graph showing the relationship between the ventilation linear velocity of the ventilation nozzle and the overall oxygen transfer capacity coefficient (KLa). Figure 5 is a graph showing the relationship between linear ventilation velocity and pan liquefaction rate (compared using the same ventilation nozzle as in Figure 4). , Figure 6 is a layout explanatory diagram showing the installation of a drain trap in the air main pipe of a fermenter; ]

Claims (3)

[Claims] (1) An aerobic culture method characterized by supplying air, oxygen-enriched air, or oxygen gas to a culture tank in the form of fine bubbles using a sintered metal element. (2) The method according to claim 1, characterized in that air is aerated at a linear velocity of 500 m/hr or less. (3) The method according to claim 1, wherein the sintered metal element is installed in a vent pipe having a structure for discharging condensate (condensed water) remaining in the vent pipe to the outside of the system.