【Reading】にゅうさんきん

【English Name】Lactic Acid Bacteria

Lactic acid bacteria is a collective term for a group of bacteria that produce lactic acid by breaking down sugar. It is not a strict taxonomic concept but is so called for convenience based on the functional feature of producing large amounts of lactic acid.

Lactic acid bacteria are classified into two types by fermentation pattern. The two poles are homofermentative lactic acid bacteria, whose final product is lactic acid only, and heterofermentative lactic acid bacteria, which produce acetic acid and alcohol in addition to lactic acid. The genera Lactobacillus and Bifidobacterium are cited as representative genera, and morphologically two forms exist: cocci and bacilli.

In the history of sushi, they have played an indispensable role in the production process of narezushi such as funa-zushi. By lactic acid fermentation creating an acidic environment, the growth of spoilage bacteria is suppressed and long-term preservation is achieved. This principle works in common across Japan's traditional fermented foods such as pickles and miso.

Classification systems based on habitat have also been proposed by researchers. In addition to the conventional division into the intestinal type living in the gut, the animal type derived from dairy products, and the plant type derived from miso, pickles and the like, in 2009 a report of marine lactic acid bacteria collected and isolated from the ocean drew worldwide attention. Research is also actively progressing on them as probiotic materials expected to benefit the gut flora.