ORIGINAL ARTICLE Probiotic characteristics of lactic acid bacteria isolated from kimchi J.-H. Chang 1,2 , Y.Y. Shim 3 , S.-K. Cha 2 and K.M. Chee 1 1 School of Life Sciences and Biotechnology, Korea University, Seoul, South Korea 2 Traditional Foods Research Center, Korea Food Research Institute, Kyunggi-do, South Korea 3 Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada Introduction The lactic acid bacteria (LAB) a component of several fermented foods including dairy products have long been consumed by people. LAB are the focus of intensive inter- national research for their essential role in most fermented foods. Their ability to produce various antimicrobial compounds, (Temmerman et al. 2002), antitumoural activity (Hilde et al. 2003), inhibition of pathogenic species (Salminen et al. 1998), protection against colon cancer (Al-Rwaily et al. 2005), stimulation of the immune system (Isolauri et al. 2001), stabilization of gut microflora (Gibson et al. 1997) and alleviation of lactose intolerance (de Vrese et al. 2001) is of high value. At present, exports of kimchi have been rising, and it has been developed as a global cultural product by its regis- tration with CODEX in 2001 (Kim et al. 2006). Further, one of the most important factors in human longevity is the control of tumours, and a variety of LAB originating from yogurt has been reported to possess antitumour effects as well as antimutagenic activities (Hirayama and Rafter 2000). In Korea, LAB are utilized as starter micro-organisms in Korean-fermented vegetable kimchi. Korean kimchi is Keywords cytotoxicity, ELISA, kimchi fermentation, lactic acid bacteria, Lactobacillus acidophilus KFRI342, probiotics. Correspondence Youn Young Shim, Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place Saskatoon, SK S7N 0X2, Canada. E-mail: ShimY@agr.gc.ca Kew M. Chee, School of Life Sciences and Technology, Korea University, Anam-dong, 21 Sungbuk-gu, Seoul 136-701, South Korea. E-mail: mahnchee@hotmail.com 2009 ⁄ 0936: received 28 May 2009, revised 18 November 2009 and accepted 30 November 2009 doi:10.1111/j.1365-2672.2009.04648.x Abstract Aims: The present work was aimed at identifying strains of lactic acid bacteria (LAB) from kimchi, with properties suitable for use as starter cultures in yogurt fermentation. Methods and Results: A total of 2344 LAB strains were obtained from two dif- ferent sources, one group consisted of commercial LAB strains from kimchi, and the second group consisted of those strains isolated from various types of kimchi. The LAB strains from both groups were screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that KFRI342 of the four selected strains displayed the greatest ability to reduce the growth of the cancer cells, SNU-C4. The in vivo efficacy of strains in quinone reductase induction assay was evaluated, and the extent of DNA strand breakage in individual cells was investigated using the comet assay. Strain KFRI342 was identified as Lactobacillus acidophilus by 16S rRNA sequence analysis, showed protection against tumour initiation and imparted immunostimulation as well as protection against DNA damage. Conclusions: Strain KFRI342, which showed probiotic characteristics reducing cancer cell growth, could be a suitable starter culture for yogurt fermentation because of its strong acid production and high acid tolerance. Significance and Impact of the Study: This is the first report to describe a bacterium, isolated from kimchi, Lact. acidophilus KFRI342 which has the probiotic characteristics and the acid tolerance needed for its use as a starter culture in yogurt fermentation. Journal of Applied Microbiology ISSN 1364-5072 220 Journal compilation ª 2010 The Society for Applied Microbiology, Journal of Applied Microbiology 109 (2010) 220–230 ª 2010 The Authors