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A cryptic plasmid, pJY33, from Weissella cibaria 33 was characterized. pJY33 was 2365 bp in size with a GC content of 41.27% and contained two putative open reading frames (ORFs). orf1 encoded a putative hypothetical protein of 134 amino acids. orf2 was 849 bp in size, and its putative translation product exhibited 87% identity with a replication initiation factor from a plasmid from W. cibaria KLC140. A Weissella-Escherichia coli shuttle vector, pJY33E (6.5 kb, Em(r)), was constructed by ligation of pJY33 with pBluescript II SK(-) and an erythromycin resistance gene (Em(r)). pJY33E replicated in Lactococcus lactis, Leuconostoc citreum, Lactobacillus brevis, Lactobacillus plantarum, and Weissella confusa. A single-stranded DNA intermediate was detected from Lb. brevis 2.14 harbouring pJY33E, providing evidence for rolling-circle replication of pJY33. Most Lb. brevis 2.14 cells (85.9%) retained pJY33E after one week of daily culturing in MRS broth without Em. An aga gene encoding α-galactosidase (α-Gal) from Leuconostoc mesenteroides was successfully expressed in Lb. brevis 2.14 using pJY33E, and the highest level of α-Gal activity (36.13 U/mg protein) was observed when cells were grown on melibiose., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Three Pediococcus pentosaceus strains were isolated from jeotgals, salted and fermented Korean sea-foods, and their probiotic potentials were examined. After 2 h exposure to pH 3.0, P. pentosaceus F66 survived with the survival ratio of 32.6% followed by P. pentosaceus D56 (17.2%) and P. pentosaceus A24 (7.5%). P. pentosaceus F66 also survived better (26.6%) than P. pentosaceus A24 (13.7%) and P. pentosaceus D56 (5.8%) after 2 h exposure to 0.3% bile salts. Three strains grew slowly on MRS broth with 15% NaCl (w/v), reaching the OD600 values of 0.4-0.8 in 36 h. They adhered to Caco-2 cells (10.9-13.9 CFU/cell) with similar degree of adherence of a positive control, Lactobacillus rhamnosus GG (12.8 ± 0.5 CFU/cell). Three strains possess some desirable enzyme activities such as β-galactosidase, α-glucosidase, β-glucosidase, and N-acetyl-β-glucosidase. From these results, P. pentosaceus F66 seems qualified as a probiotic and can be utilized for fermented foods including jeotgals., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Three Weissella confusa and five Weissella cibaria strains were previously isolated from human faeces and their potential as probiotics was examined in this work. Resistance to low pHs (pH 2.0 and 3.0) and 0.3% bile salt were examined. Enzyme activities, susceptibilities to heat treatment and various antibiotics, and adhesion capacities to Caco-2 cells were also examined. All Weissella strains were killed when exposed to pH 2.0 for 2 h but survived at pH 3.0 with different survival ratios. W. confusa 31 survived best (20.2%) and W. confusa 31 was also quite resistant against 0.3% bile salt (128.8%). All strains except one grew well at temperature between 15 and 45 °C and all strains grew in the presence of 6.5% NaCl. W. confusa 20 showed the highest β-galactosidase activity (527.3 ± 23.66 unit/mg protein) and W. cibaria 31 had the highest β-glucosidase activity (115.12 ± 5.3 unit/mg protein) in MRS broth. All strains adhered to Caco-2 cells better than Lactobacillus rhamnosus GG and W. confusa 20 was the best adhesive strain (85 CFU/cell). These results show that some strains such as W. confusa 31 and W. confusa 20 are fully qualified as probiotics and deserve further application studies., (Copyright © 2011 Elsevier Ltd. All rights reserved.)