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Here is the remarkable Weissella koreensis bacterium of Leuconostocaceae family which has the Anti-obesity Effects in food production and exhibit chemopreventive and anti-tumor effects.
Weissella koreensis is the predominant lactic acid bacteria isolated from kimchi, a traditional Korean fermented-vegetable food . Collins et al. first proposed this species in 1993 based on 16S rRNA gene phylogenetic analysis. Members of the genus Weissella are Gram-positive, facultative anaerobic, non-motile, heterofermentative, non-spore-forming and acid tolerant. The cells are either irregular, short rods with rounded to tapered ends or coccoid . As a psychrophilic bacterium, W. koreensis is the dominating species in fermenting kimchi at -1ºC, and it significantly contributes to kimchi’s taste and flavoring.
Studies have shown that the LAB isolated during kimchi fermentation exhibit antimicrobial activities by producing compounds such as organic acids, fatty acids and hydrogen peroxide. W. koreensis also shows anti-obesity effects by producing the non-protein amino acid ornithine. W. koreensis contributes to sourdough fermentation to improve the quality of bread by producing D (-)-lactic acid and metabolites from glucose. Acetic acid, being one of the products of fermentation, not only improves the flavor of the sourdough, but also increases the shelf life. It has also been found that W. koreensis inhibits spore germination of the target microorganism during food fermentation.
The genomic makeup and structure of this bacterium include the strain KCTC 3621 of W.koreensis possesses one chromosome with 1672 coding sequences, 61 tRNA genes and 5 rRNA loci. The chromosome has 1.7Mb and a low GC- content (Guanine-Cytosine content) ratio (35.5%), typical of a low GC Gram-positive phylum Firmicutes. A relatively small percentage of the open reading frames (23.4% ) matches with the potential protein sequence in a public database while 7.7% of the genes are specific in KCTC 3621 but not in other Weissella species’ gene sequences. The genome of strain KACC 15510 of W.koreensis is most closely related to strain KCTC 3621, sharing 98.76% and 99.48% similarity values which further confirms that both strains belong to the same species. Upon studying the genome of strain KCTC 3621, six genes related to ornithine metabolism, five genes related to arginine metabolism and six genes related to antibiotic resistance are found.
Several Weissella strains have been found to act as probiotics, mainly due to their antimicrobial activity, as is the case for certain bacteriocinogenic strains of W. paramesenteroides, W. hellenica, and W. cibaria. For example, W. hellenica DS-12 isolated from flounder intestine has been used as probiotic in fish, due to its antimicrobial activity against fish pathogens, such as Edwardsiella, Pasteurella, Aeromonas, and Vibrio. Also, strains of W. cibaria were proposed as probiotics for oral health, inhibiting Streptococcus mutans glucan biofilm formation. Recently, weissellas were also shown to exhibit chemopreventive and anti-tumor effects.
W. koreensis, found in kimchi, is associated with L-Ornithine production from arginine. L-Ornithine is a medicinal, non-protein amino acid which has the potential to combat obesity by promoting hormone release and accelerating basal metabolism rate. W. koreensis strain OK1-6 significantly reduces mRNA expression of C/EBP- α , a potential central regulator for adipocyte development, correlated to lipid accumulation. The decreased expression level of C/EBP- α down-regulates the expression of adipogenic specific genes and results in the reduced accumulation of lipid in cell lines.
