KR0122436B1 - Method of lactic acid with yeast hydrolyzed material as nitrogen source - Google Patents

Abstract

A lactic acid was prepared by using waste yeast fungi as a culture medium compound for lactobacillus fermentation. The waste yeast fungi were suspended in 4N hydrochloric acid solution and hydrolyzed for 1-6 hrs at 40-80 deg.C to give microorganism culture medium which was suitable for preparing lactic acid. The other waste yeast fungi were suspended in aqueous solution or buffer solution at 38-50 deg.C, pH 5.5-7.5 and hydrolyzed with stirring for 0.5-24hrs by using the enzyme such as chitinase and protease to give the same culture medium.

Description

Process for producing lactic acid using yeast hydrolyzate as nitrogen source

1 is a graph showing the results of lactic fermentation using the novel medium of the present invention.

The present invention relates to a method for producing lactic acid using yeast hydrolyzate as a nitrogen source. More specifically, the present invention is a lactobacillus casei subspis rhamnosus in a fermentation medium containing a yeast hydrolyzate obtained by treating yeast cells with a hydrolyzate, acid or alkali, glucose or hydrochloride, salts and the like ( Lactobacillus caseisubsp.rhamnosus, KCTC 0084BP) and relates to a method for producing a lactic acid to ferment.

Lactic acid is an organic acid consisting of 3 carbon atoms, 3 oxygen atoms, and 6 hydrogen atoms. It is a compound that has a hydroxyl group and a carboxyl group in its molecule and is used in various fields. When it is decomposed, it is also produced as a biological compound.

Lactic acid has a unique flavor compared to other organic acids because of its mild acidity in foods, and is also used as an emulsifier by making various esters based on its chemical structure. In addition, biodegradable materials have been of interest as recent environmental issues, and lactic acid is also used as a main raw material to produce polylactide, a biodegradable material.

The production method of such lactic acid is generally a chemical method and a fermentative method, the fermentation method is increasingly prevalent as a new method is developed in succession in the purification method which is a disadvantage of fermentation production.

On the other hand, the most significant effect on the overall yield or economics in the fermentation method is the raw material used in fermentation, that is, the microbial medium, lactic acid bacteria such as Lactobacillus (Lactobacillus) generally used for lactic fermentation is its nutrients The demands are very demanding and require very complex organic nutrients and vitamins. In order to satisfy these complex nutritional components, it is necessary to add all of these various ingredients or to add nutrients containing these ingredients evenly. However, the addition of all these ingredients is quite disadvantageous in terms of cost and efficiency, so it is advantageous to choose a method of adding nutrients evenly contained in these ingredients. For this reason, the existing lactic acid fermentation uses yeast extract or whey as the nitrogen source.

However, since the yeast extract has to recover only the soluble portion finally through chemical and physical treatment in its manufacturing method, its use in industrial production has been limited because it is known as a very expensive nutrient. In addition, whey is difficult to store or transport, and there is a disadvantage in that a large cost is required because it is difficult to dry a lot of available sinter when manufacturing a dry matter to improve it. Therefore, there is a constant need for developing an economical and efficient medium suitable for lactic acid bacteria fermentation.

The inventors of the present invention, as a result of employing as a medium by pre-treatment or pre-treatment of a different material from the existing production medium, surprisingly found that yeast cells can be used as a nitrogen source in the medium and other nutrient medium for lactic production The present invention has been completed.

In addition, the inventors of the present invention have found that by using the yeast cells that are largely discharged as by-products in the beer industry and the like are mostly discarded as a microbial medium, the cost of conventional lactic fermentation can be significantly reduced.

After all, the main object of the present invention is to provide a novel medium using yeast hydrolyzate.

Still another object of the present invention is to provide a method for producing lactic acid economically and efficiently using the aforementioned medium.

Hereinafter, the present invention will be described in more detail.

In general, since the yeast cells are very large in structure, in order for the microorganisms for lactic acid production to efficiently use these nutrients, it is desirable to change these nitrogen sources into a form that is easy for microorganisms to use. In the present invention, a liquid or solid yeast cell widely used as a lactic acid bacteria fermentation medium component was processed through minimal hydrolysis treatment, and a method for producing lactic acid using the same as a medium component for lactic acid bacteria fermentation was developed. In addition, it has been found that the amount of the enzyme used can be minimized by controlling the hydrolysis conditions, thereby completing the present invention.

In order to use the yeast that can be used for lactic fermentation as a microbial medium suitable for lactic acid production, hydrolysis is required, and the hydrolysis method includes hydrolysis by acid, alkali and enzyme. In the hydrolysis method using an acid or an alkali, conventional acids or alkalis are used. The present inventors suspended the yeast cells in 4N hydrochloric acid solution and treated them at 40 to 80 ° C. for about 1 to 6 hours. In the enzyme hydrolysis method, the yeast cells are suspended in an aqueous solution or a buffer solution and hydrolyzed by the enzyme. That is, the solution containing the yeast cells is hydrolyzed using enzymes such as chitinase, zymolase, and protease, and the hydrolysis conditions are slightly different depending on the enzyme used, but pH 1.5 to 8.4, more preferably pH 5.5. To 7.5, the temperature is carried out at 33 to 62 ℃, more preferably 38 to 50 ℃. In addition, in order to efficiently hydrolyze, stirring is preferable, and the hydrolysis time is controlled according to the amount of enzyme used, but preferably 30 minutes to 24 hours. In the present invention, chitinase, zymolase, and protease were used as enzymes capable of hydrolyzing yeast cells, and hydrolysis was performed at optimum temperature and pH range of each enzyme for efficient hydrolysis. Digested. As described above, when fermentation is carried out using the newly prepared medium component, the batch culture can accumulate more than 120 g / L of lactic acid within 48 hours, and it is also possible to produce by continuous culture or fed-batch culture. .

Hereinafter, the present invention will be described in more detail with reference to Examples.

These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples according to the gist of the present invention. In particular, the fermentation medium using the yeast hydrolyzate of the present invention can be used as a nutrient source of a general nitrogen source or fermentation medium, as well as lactic fermentation mentioned in the examples, the present invention includes all the fermentation medium used for this purpose It should be seen as doing.

Example 1

Production of Yeast Hydrolysates by Enzymes

In order to use yeast which can be used for lactic fermentation as a microbial medium suitable for lactic acid production, hydrolysis by enzyme was adopted and hydrolyzed. That is, the yeast cells are suspended in an aqueous solution or a buffer solution, and enzyme chitinase, zymolase, and protease are added to the solution containing the yeast cells, and the pH is 1.5 to 8.4 and the temperature is 30 to 24 minutes under the conditions of 33 to 62 ° C. It was hydrolyzed about time.

Example 2

Preparation of Yeast Hydrolysates by Acids and Alkali

Hydrolysis by acid or alkali was performed using a conventional acid or alkali, and preferably, the yeast cells were suspended in 4N hydrochloric acid solution and treated at 40 to 80 ° C. for about 1 to 6 hours.

Example 3

Preparation of lactic acid medium

The production medium of the lactic acid-containing yeast hydrolyzate prepared in Examples 1 to 2 was first dissolved or suspended in water for each nutrient as shown in Table 1 below, and sterilized at 121 ° C. for about 15 minutes at a final pH of 4.3 to 7.3. It was.

In the above, the yeast hydrolyzate is hydrolyzed yeast cells by enzymes and acids or alkalis according to the present invention, and salts are selected from (NH ₄ ) ₂ PO ₄ , MgSO ₄ , CH ₃ COONa, FeSO ₄ and the like. However, (NH ₄ ) ₂ PO ₄ is most preferred.

Glucose and other components are preferably sterilized separately and mixed aseptically. At this time, all kinds of yeast cells such as brewer's yeast could be used as yeast hydrolysates which are the main nutrients.

Example 4

Fermentation of Lactic Acid Strains

First, MRS lactic acid culture medium prepared in advance by dissolving a 20% glycerol strain suspension of Lactobacillus casei subsp. Rhamnosus (KCTC 0084BP) for lactic acid production stored at a low temperature below -30 ° C. Was inoculated. When the spawn grows sufficiently, it is subcultured by 1 to 20%, and finally, 1 to 20% spawn is inoculated into the lactic acid production medium of the present invention. At this time, other than the primary spawn, the lactic acid production medium of the present invention may be used instead of the MRS medium.

Fermentation conditions of the lactic acid bacteria was a temperature of 29 to 58 ℃, pH 3.4 to 8.2, and shaken at 50 to 600rpm. In order to adjust the pH, a buffer such as CaCO ₃ which is commonly used, or an alkali such as Ca (OH) ₂ and NH ₄ OH was used. When the fermentation is carried out batchwise using CaCO ₃ , lactic acid is produced in the form of calcium lactate. According to the present invention, a saturated concentration of calcium lactate of 120 g / l (lactic acid basis) or more within 48 hours is achieved. Could get

FIG. 1 is a graph showing the results of lactic acid production in a batch culture using a 2 L fermentation tank. Since CaCO ₃ was used, lactic acid was accumulated in the form of calcium lactate. As shown in Figure 1, it can be seen that the initial 140g / L or more of the glucose is consumed within 48 hours to produce more than 125g / L lactic acid in more than 90% yield. The amount of lactic acid produced is very similar to lactic acid produced by culturing Lactobacillus casei subsp. Rhamnosus (KCTC 0084BP) in complex medium (hydrol + corn steep) or whey. (Reference: Novel lactic acid bacteria and the method of producing a high concentration lactic acid using the same).

As described and demonstrated in detail above, the present invention hydrolyzes a large amount of yeast cells that are mostly discarded as by-products in the beer industry, and then used as a microbial medium. It provides a manufacturing method. In particular, the present invention provides a method for producing lactic acid using a liquid or solid yeast cells widely used as a lactic acid bacteria fermentation medium through minimal hydrolysis treatment and using them as a medium component for lactic acid bacteria fermentation.

Claims (1)

Method of producing a lactic acid comprising the step of recovering the lactic acid by fermenting Lactobacillus casei subsp. Rhamnosus deposited with KCTC 0084BP using a fermentation medium as a nutrient medium as follows: