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      Complete Genome Sequence of Probiotic Strain Lactobacillus acidophilus La-14

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      Genome Announcements
      American Society for Microbiology

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          Abstract

          We present the 1,991,830-bp complete genome sequence of Lactobacillus acidophilus strain La-14 (SD-5212). Comparative genomic analysis revealed 99.98% similarity overall to the L. acidophilus NCFM genome. Globally, 111 single nucleotide polymorphisms (SNPs) (95 SNPs, 16 indels) were observed throughout the genome. Also, a 416-bp deletion in the LA14_1146 sugar ABC transporter was identified.

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          S layer protein A of Lactobacillus acidophilus NCFM regulates immature dendritic cell and T cell functions.

          Dendritic cells (DCs) are antigen-presenting cells that play an essential role in mucosal tolerance. They regularly encounter beneficial intestinal bacteria, but the nature of these cellular contacts and the immune responses elicited by the bacteria are not entirely elucidated. Here, we examined the interactions of Lactobacillus acidophilus NCFM and its cell surface compounds with DCs. L. acidophilus NCFM attached to DCs and induced a concentration-dependent production of IL-10, and low IL-12p70. We further demonstrated that the bacterium binds to DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), a DC- specific receptor. To identify the DC-SIGN ligand present on the bacterium, we took advantage of a generated array of L. acidophilus NCFM mutants. A knockout mutant of L. acidophilus NCFM lacking the surface (S) layer A protein (SlpA) was significantly reduced in binding to DC-SIGN. This mutant incurred a chromosomal inversion leading to dominant expression of a second S layer protein, SlpB. In the SlpB-dominant strain, the nature of the interaction of this bacterium with DCs changed dramatically. Higher concentrations of proinflammatory cytokines such as IL-12p70, TNFalpha, and IL-1beta were produced by DCs interacting with the SlpB-dominant strain compared with the parent NCFM strain. Unlike the SlpA-knockout mutant, T cells primed with L. acidophilus NCFM stimulated DCs produced more IL-4. The SlpA-DC-SIGN interaction was further confirmed as purified SlpA protein ligated directly to the DC-SIGN. In conclusion, the major S layer protein, SlpA, of L. acidophilus NCFM is the first probiotic bacterial DC-SIGN ligand identified that is functionally involved in the modulation of DCs and T cells functions.
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            Complete genome sequence of the probiotic lactic acid bacterium Lactobacillus acidophilus NCFM.

            Lactobacillus acidophilus NCFM is a probiotic bacterium that has been produced commercially since 1972. The complete genome is 1,993,564 nt and devoid of plasmids. The average GC content is 34.71% with 1,864 predicted ORFs, of which 72.5% were functionally classified. Nine phage-related integrases were predicted, but no complete prophages were found. However, three unique regions designated as potential autonomous units (PAUs) were identified. These units resemble a unique structure and bear characteristics of both plasmids and phages. Analysis of the three PAUs revealed the presence of two R/M systems and a prophage maintenance system killer protein. A spacers interspersed direct repeat locus containing 32 nearly perfect 29-bp repeats was discovered and may provide a unique molecular signature for this organism. In silico analyses predicted 17 transposase genes and a chromosomal locus for lactacin B, a class II bacteriocin. Several mucus- and fibronectin-binding proteins, implicated in adhesion to human intestinal cells, were also identified. Gene clusters for transport of a diverse group of carbohydrates, including fructooligosaccharides and raffinose, were present and often accompanied by transcriptional regulators of the lacI family. For protein degradation and peptide utilization, the organism encoded 20 putative peptidases, homologs for PrtP and PrtM, and two complete oligopeptide transport systems. Nine two-component regulatory systems were predicted, some associated with determinants implicated in bacteriocin production and acid tolerance. Collectively, these features within the genome sequence of L. acidophilus are likely to contribute to the organisms' gastric survival and promote interactions with the intestinal mucosa and microbiota.
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              Effects of seven potential probiotic strains on specific immune responses in healthy adults: a double-blind, randomized, controlled trial.

              This pilot study investigated the immunomodulatory properties of seven probiotic strains. Eighty-three healthy volunteers aged 18-62 years consumed 2 x 10(10) CFU of bacteria or a placebo (maltodextrin) over 3 weeks (D0-D21). Subjects received an oral cholera vaccine at D7 and at D14; blood and saliva samples were collected at D0, D21 and D28. Serum samples were analyzed for specific IgA, IgG and IgM, and saliva samples were analyzed for specific IgA only, by ELISA. Statistical analyses were based on Wilcoxon's signed-rank test (intragroup analyses) and exact median t-test (intergroup analyses). Salivary analysis showed no difference in specific IgA concentrations between groups. Serum analysis indicated an effect of some of the tested strains on specific humoral responses. Between D0 and D21, IgG increased in two probiotic groups, for example, Bifidobacterium lactis Bl-04 and Lactobacillus acidophilus La-14, compared with controls (P=0.01). Trends toward significant changes in immunoglobulin serum concentrations compared with controls (P<0.1) were found for six out of the seven probiotic strains. In conclusion, some strains of probiotics demonstrated a faster immune response measured with serum immunoglobulin indicators, especially IgG, although overall vaccination was not influenced. Specific strains of probiotics may thus act as adjuvants to the humoral immune response following oral vaccination.
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                Author and article information

                Journal
                Genome Announc
                Genome Announc
                ga
                ga
                GA
                Genome Announcements
                American Society for Microbiology (1752 N St., N.W., Washington, DC )
                2169-8287
                20 June 2013
                May-Jun 2013
                : 1
                : 3
                : e00376-13
                Affiliations
                DuPont Nutrition and Health, Madison, Wisconsin, USA [a ]
                Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina, USA [b ]
                Author notes
                Address correspondence to Rodolphe Barrangou, rbarran@ 123456ncsu.edu .
                Article
                genomeA00376-13
                10.1128/genomeA.00376-13
                3707595
                23788546
                7b695c7b-5b08-4ba5-9166-3d94a540aee4
                Copyright © 2013 Stahl and Barrangou.

                This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license.

                History
                : 2 May 2013
                : 13 May 2013
                Page count
                Pages: 2
                Categories
                Prokaryotes
                Custom metadata
                May/June 2013
                free

                Genetics
                Genetics

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