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It is well established that gluten-free diet reduces the incidence of type 1 diabetes mellitus (T1D) in non-obese diabetic (NOD) mice, though the mechanism is not known. However, regulatory T cells (Treg) are likely to play an important role. Also, it is known that dietary gluten induces an intestinal increase in the bacterium Lactococcus garvieae, but the importance of this phenomenon for T1D development is doubtful. Our hypothesis is that gluten is responsible for mediating its effect on T1D through the influence on Treg development independent of gluten-induced Lactococci. Four groups of female NOD and BALB/c mice of 3 week old were fed either a gluten-free diet or a standard diet. Lactococcus garvieae or saline water was administered per oral to one of each dietary group. Spleen and Peyer′s patches were sampled from BALB/c mice for flow cytometric monitoring of IL-10 and Treg. NOD mice were diagnosed diabetic with blood glucose level >12 mmol/l. Dietary gluten significantly decreased the occurrence of Tregs by 10–15% ( P < 0.05) in mice compared with those fed a standard diet. These results and the diabetes incidence were independent of the gluten-induced bacterial factor Lactococci. The prevalence of Treg was 5- to 10-fold more abundant in the Peyer′s patches than in the spleen ( P < 0.001). In conclusion, dietary gluten has a significant negative quantitative impact on the generation of Treg in mice, independent of gluten-induced Lactococcus garvieae, and Treg are far more abundant in Peyer′s patches than in the spleen. [ABSTRACT FROM AUTHOR]

Abstract Aims: To study the ability of the plasmid-encoded restriction and modification (R/M) system Lla AI to function as a bacteriophage resistance mechanism in Lactococcus lactis during milk fermentations. Methods and Results: Plasmid pAIcat4, carrying the R/M system Lla AI and a chloramphenicol resistance cassette, was introduced into the plasmid-free strain L. lactis MG1614 and the industrial strain L. lactis 964. By measuring changes in conductivity the influence of different phage on the growth was determined. Conclusions: The plasmid-encoded R/M system Lla AI significantly improves the bacteriophage resistance of L. lactis during milk fermentations. Significance and Impact of the Study: It is essential to determine the potential of a phage defence mechanism in L. lactis starter culture strains during growth in milk before steps are taken to improve starter cultures. This study shows that Lla AI is useful for improvement of starter cultures. [ABSTRACT FROM AUTHOR]

Aims: To investigate the potential of the plasmid-encoded restriction and modification (R/M) system Lla BIII to protect Lactococcua lactis against bacteriophages during milk fermentations. Methods and Results: The R/M system Lla BIII on plasmid pJW566 was cloned with a chloramphenicol cassette, resulting in plasmid pJK1. When introduced into L. lactis strains, pJK1 conferred increased phage resistance against the three most common lactococcal phage species 936, c2, and P335 and three unclassified industrial phages. The growth of the strains in RSM was not affected by the presence of plasmid pJK1. Conclusions: The plasmid-encoded R/M system Lla BIII has great ability to protect L. lactis strains against bacteriophages in milk fermentations. Significance and Impact of the Study: This study evaluates the ability of the Lla BIII R/M system to function as a phage defence mechanism which is an essential step prior to considering utilizing it for improving starter cultures. [ABSTRACT FROM AUTHOR]

k. dupont, f.k. vogensen and j. josephsen. 2005.To develop PCR assays able to distinguish between groups within lactococcal 936-species bacteriophages, as defined by their different receptor-binding protein (RBP) genes.DNA sequences of RBP genes from 17 lactococcal bacteriophages of the 936-species were compared, and six phage groups were identified. For each phage group a specific primer pair targeting a variable region of the RBP genes was designed. In nine of 20 whey samples, from dairies with recorded phage problems, between one and six phage groups were identified by conventional PCR. The sensitivity and specificity of the method was improved by magnetic capture hybridization (MCH)-PCR using a capture probe targeting an 80-bp highly conserved region just upstream from the RBP gene in all the investigated phages. The MCH-PCR was performed on 100 μl whey samples and the detection limit of the assay was 102–103 PFU ml−1 as opposed to the detection limit of 104 PFU ml−1 for conventional PCR performed on 1-μl whey samples.In this study, PCR assays have been developed to detect six different types of RBP genes in lactococcal 936-species bacteriophages.The PCR assays have practical applications at cheese plants for detection of 936-species phages with different RBP and thereby potentially with different host ranges. This knowledge will make it possible to improve starter culture rotation systems in the dairy industry. [ABSTRACT FROM AUTHOR]

j. chumchalová, j. stiles, j. josephsen and m. plocková. 2004. To characterize and to purify a bacteriocin produced by Lactobacillus acidophilus strain with its activity restricted to Gram-positive bacteria. Native acidocin CH5, a bacteriocin produced by L. acidophilus CH5 an isolate from a dairy starter culture forms in MRS (Oxoid, Basingstoke, UK) broth high-molecular weight aggregates which can dissociate into smaller units (retained by 5 kDa membrane) with higher activity. Acidocin CH5 was purified using combinations of chromatographic methods based on hydrophobic and cation exchange principles and the N-terminal region was sequenced. Based on our results it is evident that acidocin CH5 belongs, according to bacteriocin classification, to the class II bacteriocins with identical N-terminal amino acid sequence described in the literature previously. The study has provided further data on bacteriocin acidocin CH5 from class II with wide spectrum of antimicrobial activity atypical for bacteriocins produced by L. acidophilus sharing the same homology. [ABSTRACT FROM AUTHOR]

Aim: To screen five strains of lactic acid bacteria (LAB) isolated from rye sourdoughs for the potential production of antimicrobial substances. Methods and Results: Lactobacillus sakei KTU05-06, Pediococcus acidilactici KTU05-7, Pediococcus pentosaceus KTU05-8, KTU05-9 and KTU05-10 isolated from rye sourdoughs were investigated for the production of bacteriocin-like inhibitory substances (BLIS). The supernatants of analysed LAB inhibited growth of up to 15 out of 25 indicator bacteria strains as well as up to 25 out of 56 LAB strains isolated from rye sourdoughs. Moreover, these five LAB were active against ropes-producing Bacillus subtilis and the main bread mould spoilage causing fungi - Aspergillus, Fusarium, Mucor and Penicillium. Lactobacillus sakei KTU05-6 demonstrated the best antibacterial properties and is resistant towards heat treatment even at 100°C for 60 min. Conclusions: The use of LAB-producing antibacterial substances may be a good choice as a co-starter culture to ensure the stability of sourdoughs and to avoid the bacterial and fungi spoilage of the end product. Significance and Impact of the Study: The antimicrobial compounds designated as sakacin KTU05-6, pediocin KTU05-8 KTU05-9, KTU05-10 and AcKTU05-67 were not identical to any other known BLIS, and this finding leads up to the assumption that they might be the novel. [ABSTRACT FROM AUTHOR]