Lactic acid fermentation - New fermentation

Lactic acid fermentation is a phenomenon in which carbohydrates are acted upon by microorganisms to produce mainly lactic acid. Along with alcoholic fermentation, it is one of the major forms of fermentation in living organisms. Lactic acid fermentation is typically performed by lactic acid bacteria. The conversion of sugars to lactic acid has been known for a long time, and in 1857 Pasteur demonstrated that this is based on the action of lactic acid bacteria. The glycolysis seen widely in animal tissues is very similar to this, but the pathway is different, and the product is L-lactic acid. Lactic acid fermentation by lactic acid bacteria produces either L-lactic acid, D-lactic acid, or DL-lactic acid, depending on the type of bacteria. These bacteria often have racemase (an enzyme that catalyzes racemization, a microbial enzyme). In addition to lactic acid bacteria, filamentous fungi are known to be used for industrial lactic acid production, but in this case only L-lactic acid is produced. It can also be divided into normal fermentation (homolactic fermentation), which produces only lactic acid, and mixed fermentation (heterolactic fermentation), which produces lactic acid as the main product but also produces significant amounts of other products (ethanol, acetic acid, carbon dioxide, etc.). All of these fermentation processes play important roles in the brewing of sake, soy sauce, and miso, as well as in the production of various pickles, lactic acid beverages, and cheese, and are therefore the process most closely related to our diet. They are also used for the long-term preservation of livestock feed crops and pasture grass.

[Michiko Iijima]

"Basic Experiments on Microorganisms in Everyday Life Using Flowcharts," edited by Tanimura Kazuhachiro (1988, Chijin Shokan)" ▽ "Applied Microbiology," revised edition, edited by Murao Sawao and Arata Motoo (1993, Baifukan)" ▽ "Cultural Guide to Lactic Acid Fermentation," edited by Snow Brand Dairy Healthy Living Research Institute and Ozaki Michio (1996, Chuohoki Publishing)" ▽ "The Story of Bacteria," written by Ikuta Satoshi (1999, Nihon Jitsugyo Publishing)" ▽ "Fermentation Handbook," edited by Tochikura Tatsurokuro et al. (2001, Kyoritsu Publishing)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

糖質が微生物の作用を受けて、主として乳酸を生成する現象で、アルコール発酵と並んで生物の主要な発酵形式である。乳酸発酵を営む微生物の代表的なものが乳酸菌である。糖の乳酸への転換は古くから知られ、1857年パスツールはこれが乳酸菌の作用に基づくことを明らかにした。広く動物組織でみられる解糖作用はこれによく似ているが、経路は異なり、生成物はL-乳酸である。乳酸菌によるものでは、菌の種類によってL-乳酸、D-乳酸あるいはDL-乳酸のいずれかが生成される。これらの菌はラセマーゼ（ラセミ化を触媒する酵素、微生物酵素）をもっていることが多い。工業的乳酸生産に利用しうるものとしては、乳酸菌のほかに糸状菌が知られているが、この場合生成されるのはL-乳酸のみである。また、乳酸だけを生成する正常発酵（ホモ乳酸発酵）と、乳酸をおもな生成物とするが同時に他の種々の生成物（エタノール、酢酸、炭酸ガスなど）を相当量生成する混合発酵（ヘテロ乳酸発酵）の型式に分けられる。これらはいずれも、清酒、しょうゆ、みその醸造、種々の漬物、乳酸飲料やチーズの製造などに重要な役割を果たしており、食生活にもっとも密接な関係をもつ発酵といえる。また、家畜の飼料作物や牧草の長期保存にも利用される。

［飯島道子］

『谷村和八郎監修『フローチャートによる生活微生物基礎実験』（1988・地人書館）』▽『村尾澤夫・荒田基夫編『応用微生物学』改訂版（1993・培風館）』▽『雪印乳業健康生活研究所編、小崎道雄編著『乳酸発酵の文化譜』（1996・中央法規出版）』▽『生田哲著『バクテリアのはなし』（1999・日本実業出版社）』▽『栃倉辰六郎他監修『発酵ハンドブック』（2001・共立出版）』

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