Detection and quantification of probiotic strain Lactobacillus gasseri K7 in faecal samples by targeting bacteriocin genes

Abstract

Lactobacillus gasseri K7 is a probiotic strain that produces bacteriocins gassericin K7 A and K7 B. In order to develop a real-time quantitative PCR assay for the detection of L. gasseri K7, 18 reference strains of the Lactobacillus acidophilus group and 45 faecal samples of adults who have never consumed strain K7 were tested with PCR using 14 pairs of primers specific for gassericin K7 A and K7 B gene determinants. Incomplete gassericin K7 A or K7 B gene clusters were found to be dispersed in different lactobacilli strains as well as in faecal microbiota. One pair of primers was found to be specific for the total gene cluster of gassericin K7A and one for gassericin K7B. The real-time PCR analysis of faecal samples spiked with K7 strain revealed that primers specific for the gene cluster of the gassericin K7 A were more suitable for quantitative determination than those for gassericin K7 B, due to the lower detection level. Targeting of the gassericin K7 A or K7 B gene cluster with specific primers could be used for detection and quantification of L. gasseri K7 in human faecal samples without prior cultivation. The results of this study also present new insights into the prevalence of bacteriocin-encoding genes in gastrointestinal tract.

Lactobacillus gasseriK7 modulates the blood cell transcriptome of conventional mice infected withEscherichia coliO157:H7

“…gasseri K7 has been previously shown to limit the severity of E. coli infection in vitro on Caco-2 cells and in vivo in gnotobiotic pigs (Matijasic et al 2006a,b;Rogelj and Matijasic 2006). This antimicrobial activity was attributed to the modulation of immune response, production of lactic acid and bacteriocins (Treven et al 2013), and the competitive exclusion of E. coli from intestinal mucosa (Rogelj and Matijasic 2006).…”

“…This anti‐microbial activity was attributed to the modulation of immune response, production of lactic acid and bacteriocins (Treven et al . ), and the competitive exclusion of E. coli from intestinal mucosa (Rogelj and Matijasic ).…”

Administration of probiotics Lactobacillus rhamnosus GG and Lactobacillus gasseri K7 during pregnancy and lactation changes mouse mesenteric lymph nodes and mammary gland microbiota

“…For detection of the LK7 R strain, the target of PCR was a total gene cluster of gassericin K7A, a specific bacteriocin produced by LK7 (Rogelj and Matijaši , 2006). A PCR with specific gassericin K7A primers, GasA_2F (5 -GGATCATGTG-GTAAAGGTGCAGTA-3 ) and GasA_2R (5 -TCCAC-TAGCAGTTTGTAGAACCAAT-3 ), was performed as described previously (Treven et al, 2013). For a template, 1 μL of DNA extracted from MRS R -rinsed bacterial suspension was used in a 20-μL reaction volume.…”

“…Quantification of LK7 was performed with specific gassericin K7A primers GasA_2F, applying the amplification program described by Treven et al (2013). Assays were performed on MX3000P instrument (Stratagene, Santa Clara, CA) in a 20-μL volume containing 1× KAPA SYBR FAST Universal 2× qPCR Master Mix (Kapa Biosystems, Wilmington, MA), 0.4 μM concentrations of each specific primer for LGG or 0.2 μM concentrations of each specific primer for LK7 and 1 μL of half-fold dilution of the extracted genomic DNA for LGG or 1 μL of 10-fold dilution of the extracted genomic DNA for LK7.…”

“…The LK7 strain is an isolate from a child's feces with established probiotic properties in vitro and in vivo (Rogelj and Matijaši , 2006). The gassericins K7A (GenBank: EF392861) and K7B (GenBank: AY307382) produced by this strain are among the first characterized bacteriocins of humanderived probiotic bacteria (Zori Peternel et al, 2010) and have been used as targets for detection and quantification of LK7 in complex samples (Treven et al, 2013).…”