Isolation of lactic acid bacteria from kimchi and screening of Lactobacillus sakei ADM14 with anti-adipogenic effect and potential probiotic properties
Introduction
Kimchi is one of the traditional fermented foods in Korea and is made with various vegetables and spices. Kimchi is known to contain various lactic acid bacteria as well as active components such as vitamins and minerals (Cheigh & Park, 1994). Kimchi fermentation is started by endogenous LAB which is present in various raw materials such as vegetables and joet-gal (Lee et al., 2014). Acid production increases simultaneously with increase of LAB during the fermentation process, and LAB remains a dominant microorganism in fermented kimchi. Kimchi is dominated by various LAB strains, such as Leuconostoc spp., Lactobacillus spp., and Weissella spp. (Jung et al., 2011). The abundant LAB and environmental characteristics of kimchi also have value as potential sources of probiotics. Probiotics is a generic term for live microorganisms that provide the host with a health beneficial effect when administered in proper quantities (FAO & WHO, 2002). The beneficial effects of probiotics on the host include treatment and prevention of allergies, reduction in total serum cholesterol and inflammation, anticancer effects, and management of intestinal inflammatory diseases (Roller, Rechkemmer, & Watzl, 2004; Yoo & Kim, 2016).
To assess the potential use and value as probiotics, LAB has been continuously investigated in terms of safety and functional characteristics. As potential probiotics, LAB can improve the quality of fermented food and subsequently be beneficial to health (Lee et al., 2016). Some studies have shown that some probiotics were effective in regulating adipocytes both in human and in animal subjects (Kadooka et al., 2010; Sato et al., 2008). In addition, research results related to anti-obesity were reported as functional properties of kimchi (Cui et al., 2015). The anti-obesity properties of kimchi may be attributed to the lactic acid bacteria and various bioactive components in kimchi (Kim et al., 2011; Park et al., 2012). Therefore, the screening of kimchi LAB with ability to regulate adipocytes can secure functional LAB and bring competitiveness to the fermented food industry.
To screen potential novel LAB probiotic strains for adipocyte regulation, the following properties of LAB should be considered. First, the LAB components should regulate the amount of lipid accumulation in adipocytes and be associated with amount of intracellular triglyceride. Second, expression of adipocyte-related genes should be controlled to affect lipid metabolism. Third, the components of the LAB strain should not have a toxic effect on the cells. Fourth, the fundamental probiotic properties should be examined and consider survival, maintenance and safety in vivo.
The aims of this study were to isolate LAB strains from various kimchi and to screen useful LAB strains with effective adipocyte regulation and useful properties thereby to find probiotic candidates with potential as functional food.
Section snippets
Isolation of LAB strains and growth conditions
Eleven different kimchi samples were collected from local markets and homes in four regions (Andong, Ganneung, Gwangju and Suncheon) in Korea. Kimchi samples (10 g) were mixed with 40 ml of 0.85% sterile saline and homogenized sufficiently by vortexing. Samples were performed by serial dilution and plated on De Man-Rogosa-Sharpe (MRS; BD Difco, Sparks, MD, USA) agar. Culture plates were incubated at 30 °C or 37 °C for 48h. The LAB colonies were selected from the plates and cultured at 30 °C or
Isolation and identification of LAB strains from kimchi
LAB strains were isolated from various kinds of kimchi collected in various regions of Korea. A total of 225 LAB strains identified by 16S rRNA gene sequence analysis was isolated from 11 different types of kimchi. Among them, 122 strains had 16S rRNA gene sequence similarities closest to Lactobacillus sakei, 5 strains had similarities closest to Lactobacillus plantarum, and 98 strains had similarities closest to Leuconostoc pseudomesenteroides. Lactobacillus sakei, Lactobacillus plantarum and
Conclusion
This study showed that L. sakei ADM14, one of several LAB isolated from kimchi, has the potential to be used as probiotic candidate through the analyses of specific properties. L. sakei ADM14 inhibits adipogenesis through inhibition of lipid-related transcription factors and gene expression and reduces triglyceride content. In addition, L. sakei ADM14 did not produce β-glucuronidase and showed good tolerance against acid and bile salts, excellent intestinal cell adhesion and susceptibility to
CRediT authorship contribution statement
Sung-Min Won: Writing - original draft, Writing - review & editing. Siyu Chen: Data curation, Investigation. Kye Won Park: Conceptualization, Supervision. Jung-Hoon Yoon: Writing - original draft, Writing - review & editing.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was supported by BK21 plus project of the Ministry of Education, Republic of Korea and “Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ013743)" of Rural Development Administration, Republic of Korea.
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