JP2006042699A - Method for producing lactic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing lactic acid, by solving such a problem that L-lactic acid is not produced directly from a raw material containing sucrose which is a natural resource of a sweet taste, so far as conventional molds are used, while a production cost of the lactic acid is reduced, when the molds are used, and a production ratio of the L-lactic acid which is necessary as a raw material for a biodegradable plastic is increased. <P>SOLUTION: In this method, the L-lactic acid is produced from a raw material containing the sucrose by using mold Amylomyces rouxii. The Amylomyces rouxii preferably comprises CBS438.76 which is a standard strain of the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing L-lactic acid from a raw material containing sucrose, which is a natural sweetening resource, by using the filamentous fungus Amyromyces luxeii.

  Lactic acid is an organic acid indispensable for the healthy growth and growth promotion of sake yeast and the adjustment of acidity in sake brewing, in addition to food additives for imparting food acidity, harmony of quality and taste, and improving storage stability. It is also used as a raw material for biodegradable plastic "polylactic acid". Usually, anaerobic lactic acid bacteria are used, but since the growth requires amino acids and vitamins, the medium used tends to be expensive. Thus, filamentous fungi have attracted attention as a substitute for lactic acid bacteria. Unlike lactic acid bacteria, it is necessary to ventilate air for the cultivation of filamentous fungi, and the yield of lactic acid against sugar is 70-80%, which is lower than that of lactic acid bacteria. However, since filamentous fungi grow vigorously only with sugar and inorganic salts, the production cost of lactic acid can be reduced. Moreover, since filamentous fungi secrete polysaccharide-degrading enzymes such as amylase, lactic acid is produced directly from starch without saccharification treatment. Furthermore, the lactic acid produced is L-type with high optical purity essential for polylactic acid synthesis.

As recent prior arts for producing lactic acid by filamentous fungi, there are Patent Documents 1 to 5, all of which use Rhizopus spp., Particularly Rhizopus oryzae, as filamentous fungi.
JP 2002-238590 JP 2000-37196 A JP-A-11-137286 JP 07-155191 A JP 06-253871

  A commonly used filamentous fungus in the production of lactic acid is Rhizopus oryzae, among which NRRL395 strain is said to be superior. Rhizopus oryzae vigorously grows with starch and glucose to produce lactic acid, but cannot grow with sucrose as a sugar source and produce lactic acid. In recent years, the importance of sugar beet and sugarcane has increased as biomass resources, and fermentative production of lactic acid from these plants is also considered an effective utilization method. However, since the main sugar in sugar beet and sugarcane is sucrose, lactic acid cannot be produced directly from these crops by Rhizopus oryzae. The present invention provides a method for producing lactic acid from sucrose by using the filamentous fungus Amyromyces luxii.

  In order to produce lactic acid from sucrose, filamentous fungi that grow vigorously with sucrose and produce lactic acid may be used. Thus, as a result of intensive research, the present inventors have found that the filamentous fungus Amyromyces luxii that grows vigorously in a medium containing sucrose as a sugar source has the ability to produce L-lactic acid from sucrose. The present invention has been completed.

  That is, the first invention is a lactic acid production method for producing lactic acid from a raw material containing sucrose by the filamentous fungus Amyromyces luxeii. The second invention is a method for producing lactic acid, wherein L-lactic acid is produced from a raw material containing sucrose by the filamentous fungus Amyromyces luxii.

  A third invention is a method for producing lactic acid based on the first invention and the second invention, wherein the Amyromyces luxii is CBS 438.76 which is a standard strain thereof. Furthermore, the fourth invention is a lactic acid production medium containing the filamentous fungus Amyromyces luxeii for producing lactic acid from a raw material containing sucrose. 5th invention is the lactic acid production agent containing the filamentous fungus Amyromices luxeii for producing | generating lactic acid from the raw material containing sucrose. According to a sixth aspect of the invention, there is provided an L-lactic acid production step for producing L-lactic acid from a raw material containing sucrose by a filamentous fungus Amyromyces luxii, and synthesizing the L-lactic acid produced in the L-lactic acid production step, And a polylactic acid production step for producing lactic acid.

  The seventh invention includes an L-lactic acid production step for producing L-lactic acid from a raw material containing sucrose by the filamentous fungus Amyromyces luxii, and synthesizing L-lactic acid produced in the L-lactic acid production step to produce poly A method for producing a lactic acid-derived material, comprising: a polylactic acid production step for producing lactic acid; and a biodegradable plastic production step for producing a biodegradable plastic using the polylactic acid produced in the polylactic acid production step. is there.

  An eighth invention is a method for producing lactic acid based on the first to third inventions, characterized in that the raw material containing sucrose is an extract from sugar beet or / and sugarcane. A ninth invention is a method for producing a lactic acid-derived material based on the sixth or seventh invention, wherein the raw material containing sucrose is an extract from sugar beet or / and sugarcane .

  Furthermore, the tenth invention is a food additive containing lactic acid produced using any one of the first to third lactic acid production methods. The eleventh invention is a sake yeast growing agent containing lactic acid produced by the lactic acid production method using any one of the first to third inventions.

  According to the method for producing lactic acid of the present invention, there is provided a method for producing L-lactic acid from a raw material containing sucrose, which is a natural sweetening resource, by the filamentous fungus Amyromyces luxeii. The present invention can be expected to greatly contribute to the effective use of sugar beet produced in Hokkaido and sugar cane produced in the Kyushu / Okinawa region.

  Hereinafter, the present invention will be described in detail. As long as it is a filamentous fungus classified into Amyromyces luxii as used in the present invention, the strain is not particularly limited. Particularly preferred is CBS 438.76 (CBS = Centraalbureau voor Schimmelcultures, the Netherland), which is a standard strain of Amyromyces luxeii. Amyromyces luxeii strain CBS 438.76 degrades sucrose and produces lactic acid. Lactic acid has two optical isomers, L-lactic acid and D-lactic acid. Lactic acid produced from Amyromyces luxii CBS strain 438.76 is characterized by a high ratio of L-lactic acid (high optical purity) preferable as a raw material for biodegradable plastics.

  The raw material containing sucrose in the present invention is not particularly limited as long as it contains sucrose as a main sugar. A specific raw material is preferably an extract from sugar beet or / and sugarcane. The former contains 10-17% sucrose and the latter contains 15-20% sucrose.

  In the present invention, fermentation of lactic acid is performed in a lactic acid production medium containing sugar and Amyromyces luxeii. The culture temperature in the lactic acid production medium is preferably 25 to 40 ° C, more preferably 30 to 37 ° C. Growth is slow at temperatures below this, and growth is not possible above this temperature. The culture period is preferably 4-7 days, more preferably 5-6 days. Below this range, proliferation is insufficient, and above this range, the concentration of lactic acid produced decreases. In any case, conditions such as the growth temperature and the period may be appropriately determined in consideration of the substrate to be used.

  A method for obtaining a biodegradable plastic from lactic acid obtained by the present invention will be described. Polylactic acid can be produced by directly dehydrating and condensing lactic acid to obtain the desired product, synthesizing cyclic lactide (dimer) from lactic acid, purifying it by crystallization, and then ring-opening polymerization. There is a way to do. As the catalyst used for the polymerization, usually at least one metal or metal compound selected from the group consisting of Group IA, IVA, IVB and VA of the Periodic Table can be mentioned. Since usually obtained lactic acid has a low optical purity, it is necessary to carry out the polymerization after a treatment for increasing the optical purity. However, since the lactic acid obtained by the present invention has high optical purity, the cost can be reduced for the treatment for increasing the optical purity. The polylactic acid thus obtained is processed and molded into fibers, films, molded articles, etc. to obtain biodegradable plastics.

  The lactic acid obtained in the present invention can be used as a food additive. Lactic acid plays a role as a sour agent or preservative in addition to confectionery and beverages. In addition to adding fermented lactic acid to food, lactic acid may be fermented in food.

  In addition, lactic acid obtained using the lactic acid production method of the present invention can be added in sake brewing. By adding lactic acid to sake, various bacteria can be killed and the environment for yeast growth and growth promotion can be prepared. In addition, refreshing sourness can be given to sake by adding lactic acid. In addition to adding lactic acid produced outside the sake brewing process to the sake being brewed, it is also possible to produce lactic acid by mixing amylomises luxii during sake brewing. By doing so, it is possible to respond to the recent consumer orientation that they do not like additives, and the original flavor of sake is not impaired.

注）培養液のpHは6.5〜7.0に合わせ、寒天を投入してから加熱溶解させた。そのうちの2mlを12×120mm試験管入れ、120℃、20分間高圧滅菌後、直立させたまま冷却して固化させた。

注）炭酸カルシウムを除く上記培地50mlを300ml三角フラスコに入れ、120℃、20分間高圧滅菌した。冷却後、乾熱滅菌した炭酸カルシウムを添加した。 Example 1 of the present invention will be described. One platinum ear was scraped with the filamentous fungus Amylomyces rouxii CBS 438.76 and inoculated on a PDA agar plate medium (Table 1). After culturing at 25 ° C. for 4 days, the cells were peeled off and added to the production medium (Table 2), followed by shaking culture at 30 ° C. while rotating at 120 rpm. The sugar contained in the production medium is either glucose or sucrose, and tests were conducted using these two kinds of sugars. The amount of L-lactic acid produced when each saccharide is used is shown in FIG.

Note) The pH of the culture solution was adjusted to 6.5 to 7.0, and agar was added and dissolved by heating. 2 ml of the solution was placed in a 12 × 120 mm test tube, autoclaved at 120 ° C. for 20 minutes, and then cooled and solidified while standing upright.

Note) 50 ml of the above medium excluding calcium carbonate was placed in a 300 ml Erlenmeyer flask and autoclaved at 120 ° C for 20 minutes. After cooling, dry heat sterilized calcium carbonate was added.

  Rhizopus oryzae NRRL 395 was each scraped with one platinum ear and inoculated on a PDA agar plate (Table 1). Subsequent tests are the same as in Example 1. The amount of L-lactic acid produced for each of the two types of sugars is shown in FIG. In both Example 1 (FIG. 1) and Comparative Example 1 (FIG. 2), L-lactic acid was produced from glucose, but only Example 1 produced lactic acid from sucrose.

The sucrose concentration of sugar beet and sugarcane juice was measured to prepare a medium having the composition shown in Table 2 so that the final concentration was 10%. The fungus Amylomyces rouxii CBS 438.76 (Example 3-1) or Rhizopus oryzae NRRL 395 (Example 3-2) was added thereto as in Example 1 and cultured for 5 days. The subsequent L-lactic acid concentration is shown in Table 3. In both sugar beet and sugarcane, lactic acid was produced in Example 3-1 (Amyromyces luxeii), and only a small amount was detected in Example 3-2 (Rhizopus oryzae).

The figure which shows the time change of the L-lactic-acid production amount when fermenting lactic acid using filamentous fungus Amylomyces rouxii (Amylomyces rouxii) CBS 438.76. The figure which shows the time change of the L-lactic acid production amount when fermenting lactic acid using filamentous fungus Rhizopus oryzae NRRL 395.

Claims (11)

  A method for producing lactic acid, wherein lactic acid is produced from a raw material containing sucrose by the filamentous fungus Amyromyces luxeii.   A method for producing lactic acid, wherein L-lactic acid is produced from a raw material containing sucrose by the filamentous fungus Amyromyces luxeii.   The method for producing lactic acid according to claim 1 or 2, wherein the Amyromyces luxii is CBS 438.76 which is a standard strain thereof.   A lactic acid production medium containing the filamentous fungus Amyromyces lucii for producing lactic acid from raw materials containing sucrose.   A lactic acid production agent containing the filamentous fungus Amyromyces lucii for producing lactic acid from raw materials containing sucrose.   L-lactic acid production step for producing L-lactic acid from a raw material containing sucrose by the filamentous fungus Amyromyces luxeii, and polylactic acid for producing polylactic acid by synthesizing L-lactic acid produced in the L-lactic acid production step A method for producing a lactic acid-derived material.   L-lactic acid production step for producing L-lactic acid from a raw material containing sucrose by the filamentous fungus Amyromyces luxeii, and polylactic acid for producing polylactic acid by synthesizing L-lactic acid produced in the L-lactic acid production step A method for producing a lactic acid-derived material, comprising: a production step; and a biodegradable plastic production step for producing a biodegradable plastic using the polylactic acid produced in the polylactic acid production step.   The method for producing lactic acid according to any one of claims 1 to 3, wherein the raw material containing sucrose is an extract from sugar beet or / and sugarcane.   The method for producing a lactic acid-derived material according to claim 6 or 7, wherein the raw material containing sucrose is an extract from sugar beet or / and sugarcane.   The food additive containing the lactic acid manufactured by the lactic acid manufacturing method as described in any one of Claim 1 to 3.   A sake yeast growing agent containing lactic acid produced by the method for producing lactic acid according to any one of claims 1 to 3.

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