Kimchi lactic acid bacteria have antimicrobial, antifungal properties.

Kimchi, a traditional Korean food, is a well-known lactic acid-fermented vegetable product, and is a good source of industrially useful lactic acid bacteria (LAB). The microorganisms involved in the fermentation of kimchi include approximately 200 species of bacteria and several yeasts. The LAB involved in this fermentation continuously produce organic acids after an optimum ripening time, and cause changes in the composition of the product, referred to as the over-ripening or acid deterioration of kimchi.

The over-ripening of kimchi is the most serious concern when it is in storage. Since the over-ripening is mainly due to acid-forming LAB, the best way to overcome this issue is to control the growth of LAB without destroying the quality of the end product. The LAB play an important role in the taste of kimchi, and many LAB from kimchi have antimicrobial activity in addition to other useful properties.

Recently, scientists at Chosun University investigated LAB from kimchi as molecular sources for various end products, including antimicrobial compounds. Antimicrobial compounds are relatively abundant in traditionally fermented foods, in which they may play an important role as competitors with natural microflora during fermentation. Antimicrobial compound-producing LAB may be useful in preserving kimchi. This can be done by either directly applying the LAB to the culture or by adding LAB-produced antimicrobial compounds as natural bio-preservatives.

Toward this end, the researchers isolated two interesting antimicrobial compound-producing LAB from kimchi: Leuconostoc citreum GJ7 and Lactobacillus planatrum AF1. The Lb. citreum GJ7 produces a heat- and pH-stable bacteriocin. This compound has antagonistic activity against a broad spectrum of microorganisms including LAB, and Gram-positive and -negative bacteria.

The investigators also isolated from kimchi an antifungal isolate identified as Lb. plantarum. They designated it as Lb. plantarum AF1. It has antifungal activity against various fungus genera. The antifungal compound is stable from 4 C to 121 C in a pH range of 2.0 to 5.0.

Further information. Hae Choon Chang, Department of Food and Nutrition, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759, Korea; phone: +82-62-230-7345; fax: +82-62-222-8086; email: hcchang@mail.chosun.ac.kr.

Print Get the Mag Weekly Updates