JPH0529435B2 - - Google Patents

Description

[Detailed description of the invention]

It is known that a microbial fermentation liquid containing amino acids or the like is directly subjected to ultrafiltration to remove microorganisms. However, in addition to target substances and microorganisms, the fermentation liquid contains polymeric substances such as proteins and sugars that are byproducts of microbial reactions. These polymeric substances cause clogging of the ultrafiltration membrane during ultrafiltration, resulting in a problem in that the amount of permeated liquid per unit time and per unit membrane area, that is, the flux, decreases. Therefore, the present inventors focused on the property that polymeric substances such as proteins denature and aggregate when heated, and solved the above problems by preheating the solution during ultrafiltration of fermentation liquid. The present invention was completed by discovering that the problem can be solved. That is, as mentioned above, heating can denature and coagulate polymeric substances such as proteins, prevent clogging of the ultrafiltration membrane, and increase the flux of the solution, that is, the permeation performance. The detailed conditions for the heat treatment vary depending on the type of liquid to be treated, but are usually 50 to 100°C for several seconds to several tens of minutes. In addition, the supply to the ultrafiltration after heating may be carried out while it is heated, or whether it should be supplied after cooling or after cooling should be determined depending on the performance of the ultrafiltration membrane and the properties of the target substance. It is. Incidentally, ultrafiltration itself is a known technique as described above, and the liquid to be treated that has undergone the pretreatment according to the present invention may be subjected to such known ultrafiltration treatment. The ultrafiltration membrane used in the present invention may be any ordinary semipermeable membrane material and is not particularly limited. Possible materials include polyamide, polyacronitrile, polysulfone, and cellulose acetate. The membrane format is tube-shaped,
There are flat membranes, spirals, hollow fibers, etc., but these are not particularly limited. The filtration limit molecular weight of the membrane is 5000 to 5000, taking into account the filtration rate, removal rate of proteins, etc.
About 100,000 is convenient. In this way, the concentration time can be shortened in the operation of concentrating an amino acid fermentation liquid containing a large amount of bacterial cells to a high concentration, which was conventionally considered difficult. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Glutamic acid fermentation liquid 48 was heated to 60 to 70°C for 10 minutes and subjected to ultrafiltration. As a control, the same fermented liquid 48 was subjected to ultrafiltration under the same conditions without being heated. The conditions for ultrafiltration are as follows. In other words, the membrane is a polysulfone membrane with a filtration limit molecular weight of 6000, the membrane structure is hollow fiber, and the membrane area is
The area was 0.2 m ² , the pressure was 1 to 2 Kg/cm ² , and the filtration temperature was 35 to 45°C. In both cases, filtration was carried out until the amount of filtrate reached 38. In other words, both are 4.8 times in terms of concentration factor. The results are shown in Table 1.

[Table] As clearly shown in Table 1, in the case without heat treatment (control), a rapid decrease in flux is observed immediately after the start of filtration, but in the case of heat treatment (invention), the flux decreases. The decrease is extremely small. As a result, the filtration time required 5 hours in the case of no treatment, but was completed in 3 hours, about 60% of the time, in the case of heat treatment. Example 2 Lysine fermentation liquid 36 was heat-treated at 90 to 100°C for 5 minutes and subjected to ultrafiltration. As a control, the same fermentation solution 36 was subjected to ultrafiltration under the same conditions without being heated. The conditions for ultrafiltration are as follows. That is, the membrane is a polyacrylonitrile membrane with a molecular weight cut-off of 13,000, the membrane structure is hollow fiber, the membrane area is 0.2 ^m2 , the pressure is 1Kg/ ^cm2 , and the temperature is It was 40℃. In both cases, until the concentration factor reaches 10 times,
That is, filtration was performed until the liquid volume reached 3.6. The time required for filtration is 3.8 hours without heating.
The heating time was 2.8 hours. The average filtration rates were 43/m ² H and 58/m ² H, respectively. As described above, according to the present invention, when microbial fermentation liquid of amino acids etc. is subjected to ultrafiltration treatment, by heating the solution in advance, the flux of the solution, that is, the membrane filtration property is significantly increased compared to the conventional method.
It will be appreciated that this can be done efficiently.

Claims (1)

[Claims] 1 Ultrafiltration flux improvement characterized by pre-heating the amino acid fermentation liquid to 50 to 100°C to denature and aggregate proteins, etc., to prevent membrane clogging during filtration. Law.