Sample records for bact lactis aerogenes

  1. Aerogen Bonding Interaction: A New Supramolecular Force?

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2015-06-15

    We report evidence of the favorable noncovalent interaction between a covalently bonded atom of Group?18 (known as noble gases or aerogens) and a negative site, for example, a lone pair of a Lewis base or an anion. It involves a region of positive electrostatic potential (?-hole), therefore it is a totally new and unexplored ?-hole-based interaction, namely aerogen bonding. We demonstrate for the first time the existence of ?-hole regions in aerogen derivatives by means of high-level ab?initio calculations. In addition, several crystal structures retrieved from the Cambridge Structural Database (CSD) give reliability to the calculations. Energetically, aerogen bonds are comparable to hydrogen bonds and other ?-hole-based interactions but less directional. They are expected to be important in xenon chemistry. PMID:25950423

  2. The function of ubiquinone in Klebsiella aerogenes

    Microsoft Academic Search

    Dick L. Knook; Rudi J. Planta

    1973-01-01

    1.Membranes fromKlebsiella aerogenes were used to study the reaction site and possible functional heterogeneity of ubiquinone participating in electron transport to both oxygen and nitrate.2.Ubiquinone-8 was found to be present in great molar excess as compared with the other electron transport carriers. Pentane extraction of ubiquinoe resulted in a decrease in the level of reduction of cytochromeb in the aerobic

  3. ?-Galactosidase of Streptococcus lactis

    PubMed Central

    Citti, J. E.; Sandine, W. E.; Elliker, P. R.

    1965-01-01

    Citti, J. E. (Oregon State University, Corvallis), W. E. Sandine, and P. R. Elliker. ?-Galactosidase of Streptococcus lactis. J. Bacteriol. 89:937–942. 1965.—Synthesis of ?-galactosidase by several strains of Streptococcus lactis was induced by lactose. The rate of hydrolysis of o-nitrophenyl-?-d-galactopyranoside was used to measure enzyme activity. The enzyme of all but one strain was unstable when whole cells were sonic-treated or treated with toluene; the enzyme of one strain of S. lactis was stable to these treatments, which resulted in at least a fivefold increase in activity over that found in whole cells. The optimal assay conditions for toluene-treated cells of this strain involved incubation at 37 C in pH 7.0 sodium phosphate buffer. Lactose was the most effective inducer of enzyme synthesis. Methyl-?-d-thiogalactopyranoside, isopropyl-?-d-thiogalactopyranoside, and galactose were also inducers of the enzyme, but were not as effective as lactose. Melibiose, maltose, and calcium lactobionate were poor inducers of enzyme synthesis. Exogenously supplied glucose repressed enzyme synthesis. The means of control of induced ?-galactosidase synthesis in S. lactis was similar to that in Escherichia coli. PMID:14276118

  4. Ribitol Catabolic Pathway in Klebsiella aerogenes

    PubMed Central

    Charnetzky, W. T.; Mortlock, R. P.

    1974-01-01

    In Klebsiella aerogenes W70, there is an inducible pathway for the catabolism of ribitol consisting of at least two enzymes, ribitol dehydrogenase (RDH) and d-ribulokinase (DRK). These two enzymes are coordinately controlled and induced in response to d-ribulose, an intermediate of the pathway. Whereas wild-type K. aerogenes W70 are unable to utilize xylitol as a carbon and energy source, mutants constitutive for the ribitol pathway are able to utilize RDH to oxidize the unusual pentitol, xylitol, to d-xylulose. These mutants are able to grow on xylitol, presumably by utilization of the d-xylulose produced. Mutants constitutive for l-fucose isomerase can utilize the isomerase to convert d-arabinose to d-ribulose. In the presence of d-ribulose, RDH and DRK are induced, and such mutants are thus able to phosphorylate the d-ribulose by using the DRK of the ribitol pathway. Derivatives of an l-fucose isomerase-constitutive mutant were plated on d-arabinose, ribitol, and xylitol to select and identify mutations in the ribitol pathway. Using the transducing phage PW52, we were able to demonstrate genetic linkage of the loci involved. Three-point crosses, using constitutive mutants as donors and RDH?, DRK? double mutants as recipients and selecting for DRK+ transductants on d-arabinose, resulted in DRK+RDH+-constitutive, DRK+RDH+-inducible, and DRK+RDH?-inducible transductants but no detectable DRK+RDH? constitutive transductants, data consistent with the order rbtC-rbtD-rbtK, where rbtC is a control site and rbtD and rbtK correspond to the sites for the sites for the enzymes RDH and DRK, respectively. PMID:4366025

  5. Amino acid utilization by Aerobacter aerogenes and Escherichia coli

    E-print Network

    Herrera, Rodolfo Eduardo

    1938-01-01

    A considerable amount of work has been done on the growth of A. aerogenes and E. coli in synthetic media, but little work has been undertaken on the utilization by these organisms of amino acids as comparative sources of ...

  6. Enterobacter aerogenes Needle Stick Leads to Improved Biological Management System

    Microsoft Academic Search

    Johanson; Richard E

    2004-01-01

    A laboratory worker who received a needle stick from a contaminated needle while working with a culture containing Enterobactor aerogenes developed a laboratory acquired infection. Although this organism has been shown to cause community and nosocomial infections, there have been no documented cases of a laboratory acquired infections. Lessons learned from the event led to corrective actions which included modification

  7. Energy Production During Nitrate Respiration by Aerobacter aerogenes

    Microsoft Academic Search

    LIGERI P. HADJIPETROU; A. H. STOUTHAMER

    1965-01-01

    SUMMARY The molar growth yield of Aerobacter aerogenes growing anaerobically with glucose in a mineral medium was almost doubled when NO3- was added as hydrogen acceptor. About half a mole of NO,- was reduced to NH,+ per mole of glucose. The amount of ATP produced from glucose fermentation calculated from the molar growth yield and the acetate production was about

  8. Draft Genome Sequence of Lactococcus lactis subsp. lactis Strain YF11

    PubMed Central

    Du, Yuhui; Song, Lifu; Feng, Wenjing; Pei, Guangsheng; Zheng, Ping; Yu, Zhichao; Sun, Jibin

    2013-01-01

    Lactococcus lactis subsp. lactis strain YF11 is a food preservative bacterium with a high capacity to produce nisin. Here, we announce the draft genome sequence of Lactococcus lactis subsp. lactis YF11 (2,527,433 bp with a G+C content of 34.81%). PMID:23929487

  9. Dissolution of Xylose Metabolism in Lactococcus lactis

    PubMed Central

    Erlandson, Karn A.; Park, Joo-Heon; Wissam; El Khal; Kao, Hsin-Hsin; Basaran, Pervin; Brydges, Susannah; Batt, Carl A.

    2000-01-01

    Xylose metabolism, a variable phenotype in strains of Lactococcus lactis, was studied and evidence was obtained for the accumulation of mutations that inactivate the xyl operon. The xylose metabolism operon (xylRAB) was sequenced from three strains of lactococci. Fragments of 4.2, 4.2, and 5.4 kb that included the xyl locus were sequenced from L. lactis subsp. lactis B-4449 (formerly Lactobacillus xylosus), L. lactis subsp. lactis IO-1, and L. lactis subsp. lactis 210, respectively. The two environmental isolates, L. lactis B-4449 and L. lactis IO-1, produce active xylose isomerases and xylulokinases and can metabolize xylose. L. lactis 210, a dairy starter culture strain, has neither xylose isomerase nor xylulokinase activity and is Xyl?. Xylose isomerase and xylulokinase activities are induced by xylose and repressed by glucose in the two Xyl+ strains. Sequence comparisons revealed a number of point mutations in the xylA, xylB, and xylR genes in L. lactis 210, IO-1, and B-4449. None of these mutations, with the exception of a premature stop codon in xylB, are obviously lethal, since they lie outside of regions recognized as critical for activity. Nevertheless, either cumulatively or because of indirect affects on the structures of catalytic sites, these mutations render some strains of L. lactis unable to metabolize xylose. PMID:10966417

  10. Characterization of purified human Bact spliceosomal complexes reveals compositional and morphological changes during spliceosome activation and first step catalysis

    PubMed Central

    Bessonov, Sergey; Anokhina, Maria; Krasauskas, Andrius; Golas, Monika M.; Sander, Bjoern; Will, Cindy L.; Urlaub, Henning; Stark, Holger; Lührmann, Reinhard

    2010-01-01

    To better understand the compositional and structural dynamics of the human spliceosome during its activation, we set out to isolate spliceosomal complexes formed after precatalytic B but prior to catalytically active C complexes. By shortening the polypyrimidine tract of the PM5 pre-mRNA, which lacks a 3? splice site and 3? exon, we stalled spliceosome assembly at the activation stage. We subsequently affinity purified human Bact complexes under the same conditions previously used to isolate B and C complexes, and analyzed their protein composition by mass spectrometry. A comparison of the protein composition of these complexes allowed a fine dissection of compositional changes during the B to Bact and Bact to C transitions, and comparisons with the Saccharomyces cerevisiae Bact complex revealed that the compositional dynamics of the spliceosome during activation are largely conserved between lower and higher eukaryotes. Human SF3b155 and CDC5L were shown to be phosphorylated specifically during the B to Bact and Bact to C transition, respectively, suggesting these modifications function at these stages of splicing. The two-dimensional structure of the human Bact complex was determined by electron microscopy, and a comparison with the B complex revealed that the morphology of the human spliceosome changes significantly during its activation. The overall architecture of the human and S. cerevisiae Bact complex is similar, suggesting that many of the higher order interactions among spliceosomal components, as well as their dynamics, are also largely conserved. PMID:20980672

  11. Natural immune systems protect animals from dangerous foreign pathogens, including bacte-

    E-print Network

    Garlan, David

    Natural immune systems protect animals from dangerous foreign pathogens, including bacte- ria computer immune systems with some of the important properties of natural immune systems, including are less well known. The immune system provides a persuasive example of how they might be implemented

  12. Industrial waste-water volatile organic compound emissions. Background information for BACT\\/LAER determinations

    Microsoft Academic Search

    J. Elliott; S. Watkins

    1990-01-01

    The purpose of the Control Technology Center (CTC) is to provide technical information to States on estimating and controlling volatile organic compounds (VOC) emissions from the collection and treatment of industrial wastewaters for Best Available Control Technology (BACT) and Lowest Achievable Emission Rate (LAER) determinations. Technical guidance projects, focus on topics of national or regional interest that are identified through

  13. Molecular Analysis of Tetracycline Resistance in Pasteurella aerogenes

    PubMed Central

    Kehrenberg, Corinna; Schwarz, Stefan

    2001-01-01

    Tetracycline-resistant Pasteurella aerogenes isolates obtained from the intestinal tract of swine were investigated for their tet genes by PCR analysis and hybridization experiments. In contrast to Pasteurella isolates from the respiratory tract, tet(H) genes were detected in the chromosomal DNA of only 2 of the 24 isolates, one of which also carried two copies of a tet(B) gene. All other P. aerogenes isolates carried tet(B) genes, which are the predominant tet genes among Enterobacteriaceae. A single isolate harbored a tet(B) gene as part of a truncated Tn10 element on the 4.8-kb plasmid pPAT2. Comparative analysis of the pPAT2 sequence suggested that the Tn10 relic on plasmid pPAT2 is the result of several illegitimate recombination events. The remaining 21 P. aerogenes isolates carried one or two copies of the tet(B) gene in their chromosomal DNA. In the majority of the cases, these tet(B) genes were associated with copies of Tn10 as confirmed by their SfuI and BamHI hybridization patterns. No correlation between the number of tet gene copies and the MICs of tetracycline, doxycyline and minocycline was observed. PMID:11557485

  14. Purification and properties of Klebsiella aerogenes D-arabitol dehydrogenase.

    PubMed Central

    Neuberger, M S; Patterson, R A; Hartley, B S

    1979-01-01

    An Escherichia coli K12 strain was constructed that synthesized elevated quantities of Klebsiella aerogenes D-arabitol dehydrogenase; the enzyme accounted for about 5% of the soluble protein in this strain. Some 280 mg of enzyme was purified from 180 g of cell paste. The purified enzyme was active as a monomer of 46,000 mol.wt. The amino acid composition and kinetic constants of the enzyme for D-arabitol and D-mannitol are reported. The apparent Km for D-mannitol was more than 3-fold that for D-arabitol, whereas the maximum velocities with both substrates were indistinguishable. The enzyme purified from the E. coli K12 construct was indistinguishable by the criteria of molecular weight, electrophoretic mobility in native polyacrylamide gel and D-mannitol/D-arabitol activity ratio from D-arabitol dehydrogenase synthesized in wild-type K. aerogenes. Purified D-arabitol dehydrogenase showed no immunological cross-reaction with K. aerogenes ribitol dehydrogenase. During electrophoresis in native polyacrylamide gels, oxidation by persulphate catalysed the formation of inactive polymeric forms of the enzyme. Dithiothreitol and pre-electrophoresis protected against this polymerization. Images Fig. 1. Fig. 2. PMID:393250

  15. RESEARCH ARTICLE Open Access Lactobacillus delbrueckii ssp. lactis and ssp.

    E-print Network

    Paris-Sud XI, Université de

    RESEARCH ARTICLE Open Access Lactobacillus delbrueckii ssp. lactis and ssp. bulgaricus: a chronicle: Lactobacillus delbrueckii ssp. lactis and ssp. bulgaricus are lactic acid producing bacteria that are largely. Keywords: Lactobacillus delbrueckii, Bulgaricus, Lactis, Genome, Comparative genomics, Adaptation

  16. Lactococcus lactis subsp. lactis infection in waterfowl: first confirmation in animals.

    PubMed Central

    Goyache, J.; Vela, A. I.; Gibello, A.; Blanco, M. M.; Briones, V.; González, S.; Téllez, S.; Ballesteros, C.; Domínguez, L.; Fernández-Garayzábal, J. F.

    2001-01-01

    We report the first description, confirmed by bacteriologic and molecular (polymerase chain reaction and pulsed-field gel electrophoresis) analysis, of an infection in animals caused by Lactococcus lactis subsp. lactis, affecting waterfowl. PMID:11747704

  17. Genome Sequence of Lactococcus lactis subsp. lactis NCDO 2118, a GABA-Producing Strain

    PubMed Central

    Oliveira, Letícia C.; Saraiva, Tessália D. L.; Soares, Siomar C.; Ramos, Rommel T. J.; Sá, Pablo H. C. G.; Carneiro, Adriana R.; Miranda, Fábio; Freire, Matheus; Renan, Wendel; Júnior, Alberto F. O.; Santos, Anderson R.; Pinto, Anne C.; Souza, Bianca M.; Castro, Camila P.; Diniz, Carlos A. A.; Rocha, Clarissa S.; Mariano, Diego C. B.; de Aguiar, Edgar L.; Folador, Edson L.; Barbosa, Eudes G. V.; Aburjaile, Flavia F.; Gonçalves, Lucas A.; Guimarães, Luís C.; Azevedo, Marcela; Agresti, Pamela C. M.; Silva, Renata F.; Tiwari, Sandeep; Almeida, Sintia S.; Hassan, Syed S.; Pereira, Vanessa B.; Abreu, Vinicius A. C.; Pereira, Ulisses P.; Dorella, Fernanda A.; Carvalho, Alex F.; Pereira, Felipe L.; Leal, Carlos A. G.; Figueiredo, Henrique C. P.; Silva, Artur; Miyoshi, Anderson

    2014-01-01

    Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity. PMID:25278529

  18. Comparison of the Cobas-Bact five-hour susceptibility testing system with the NCCLS agar diffusion and dilution methods

    Microsoft Academic Search

    J. Wrist I; W. Heizmann; U. Hardegger; B. Manncke

    1988-01-01

    The results of susceptibility tests performed by the Cobas-Bact system were compared with those of the NCCLS agar diffusion (Kirby-Bauer) and NCCLS agar dilution methods. A total of 998 clinical isolates were tested against 10 to 18 antimicrobial agents. Essential agreement (comprising full agreement and minor discrepancies) varied from 90.5 % to 99.2 % on comparison of Cobas-Bact with Kirby-Bauer

  19. Complete Genome Sequence of Lactococcus lactis subsp. cremoris A76

    PubMed Central

    Quinquis, Benoit; Ehrlich, Stanislas Dusko; Sorokin, Alexei

    2012-01-01

    We report the complete genome sequence of Lactococcus lactis subsp. cremoris A76, a dairy strain isolated from a cheese production outfit. Genome analysis detected two contiguous islands fitting to the L. lactis subsp. lactis rather than to the L. lactis subsp. cremoris lineage. This indicates the existence of genetic exchange between the diverse subspecies, presumably related to the technological process. PMID:22328746

  20. Complete genome sequence of Lactococcus lactis subsp. cremoris A76.

    PubMed

    Bolotin, Alexander; Quinquis, Benoit; Ehrlich, Stanislas Dusko; Sorokin, Alexei

    2012-03-01

    We report the complete genome sequence of Lactococcus lactis subsp. cremoris A76, a dairy strain isolated from a cheese production outfit. Genome analysis detected two contiguous islands fitting to the L. lactis subsp. lactis rather than to the L. lactis subsp. cremoris lineage. This indicates the existence of genetic exchange between the diverse subspecies, presumably related to the technological process. PMID:22328746

  1. 21 CFR 184.1985 - Aminopeptidase enzyme preparation derived from lactococcus lactis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...derived from lactococcus lactis. (a) Aminopeptidase enzyme preparation is derived from the nonpathogenic and nontoxicogenic bacterium Lactococcus lactis (previously named Streptococcus lactis ). The preparation contains the enzyme...

  2. Growth characteristics of Candida kefyr and two strains of Lactococcus lactis subsp. lactis isolated from Zimbabwean naturally fermented milk

    Microsoft Academic Search

    Tendekayi H Gadaga; Anthony N Mutukumira; Judith A Narvhus

    2001-01-01

    Lactic acid bacteria (LAB) and yeasts constitute part of the microflora in Zimbabwean traditional fermented cows' milk, amasi. The present study was carried out to investigate the growth characteristics of Candida kefyr 23, Lactococcus lactis subsp. lactis biovar. diacetylactis C1 and L. lactis subsp. lactis Lc261, previously isolated from amasi, in ultrahigh temperature (UHT)-treated cows' milk. The strains were inoculated

  3. Glutamate Biosynthesis in Lactococcus lactis subsp. lactis NCDO 2118

    PubMed

    Lapujade; Cocaign-Bousquet; Loubiere

    1998-07-01

    Unlike other lactic acid bacteria, Lactococcus lactis subsp. lactis NCDO 2118 was able to grow in a medium lacking glutamate and the amino acids of the glutamate family. Growth in such a medium proceeded after a lag phase of about 2 days and with a reduced growth rate (0.11 h-1) compared to that in the reference medium containing glutamate (0.16 h-1). The enzymatic studies showed that a phosphoenolpyruvate carboxylase activity was present, while the malic enzyme and the enzymes of the glyoxylic shunt were not detected. As in most anaerobic bacteria, no alpha-ketoglutarate dehydrogenase activity could be detected, and the citric acid cycle was restricted to a reductive pathway leading to succinate formation and an oxidative branch enabling the synthesis of alpha-ketoglutarate. The metabolic bottleneck responsible for the limited growth rate was located in this latter pathway. As regards the synthesis of glutamate from alpha-ketoglutarate, no glutamate dehydrogenase was detected. While the glutamate synthase-glutamine synthetase system was detected at a low level, high transaminase activity was measured. The conversion of alpha-ketoglutarate to glutamate by the transaminase, the reverse of the normal physiological direction, operated with different amino acids as nitrogen donor. All of the enzymes assayed were shown to be constitutive. PMID:9647819

  4. BACT analysis: Are there cost effective air quality benefits from trees?

    SciTech Connect

    McPherson, E.G.; Simpson, J.R.; Scott, K.I. [Forest Service, Davis, CA (United States). Pacific Southwest Research Station

    1996-12-31

    Trees absorb gaseous pollutants through leaf stomata and can bind or dissolve water soluble pollutants onto moist leaf surfaces. Tree canopies also intercept particulates and reduce local air temperatures. Urban trees may reduce ambient air ozone concentrations, either by direct absorption of ozone or other pollutants such as NO{sub 2}, or by reducing air temperatures, which reduces hydrocarbon emission and ozone formation rates. On the other hand, biogenic hydrocarbon emissions from trees may play a role in ozone formation. The role of trees in air quality has become coupled with concern over the costs and benefits of large-scale urban free planting programs. Air quality management districts provide pollution abatement credits to businesses and institutions by permitting the use of controls or processes, provided they are technically feasible and cost effective, based upon guidelines in Best Available Control Technology (BACT) manuals. Typically BACT analysis is applied to stationary sources, but the authors apply it here to determine if a large-scale urban tree planting can be a cost effective means to improve air quality.

  5. Draft Genome Sequence of the Putrescine-Producing Strain Lactococcus lactis subsp. lactis 1AA59.

    PubMed

    Ladero, Victor; Del Rio, Beatriz; Linares, Daniel M; Fernandez, María; Mayo, Baltasar; Martín, M Cruz; Alvarez, Miguel A

    2015-01-01

    We report here the 2,576,542-bp genome annotated draft assembly sequence of Lactococcus lactis subsp. lactis 1AA59. This strain-isolated from a traditional cheese-produces putrescine, one of the most frequently biogenic amines found in dairy products. PMID:26089428

  6. Draft Genome Sequence of the Putrescine-Producing Strain Lactococcus lactis subsp. lactis 1AA59

    PubMed Central

    Ladero, Victor; del Rio, Beatriz; Linares, Daniel M.; Fernandez, María; Mayo, Baltasar; Martín, M. Cruz

    2015-01-01

    We report here the 2,576,542-bp genome annotated draft assembly sequence of Lactococcus lactis subsp. lactis 1AA59. This strain—isolated from a traditional cheese—produces putrescine, one of the most frequently biogenic amines found in dairy products. PMID:26089428

  7. Insertion of Transposon Tn917 Derivatives into the Lactococcus lactis subsp. lactis Chromosome

    PubMed Central

    Israelsen, Hans; Hansen, Egon Bech

    1993-01-01

    Two transposition vectors, pTV32 and pLTV1, containing transposon Tn917 derivatives TV32 and LTV1, respectively, were introduced into Lactococcus lactis subsp. lactis MG1614. It was found that pTV32 and pLTV1 replicate and that TV32 and LTV1 transpose in this strain. A protocol for production of a collection of Tn917 insertions in L. lactis subsp. lactis was developed. The physical locations of TV32 on the chromosomal SmaI fragments of 62 independent transpositions were established by pulsed-field gel electrophoresis. These transpositions could be divided into at least 38 different groups that exhibited no Tn917-dominating hot spots on the L. lactis subsp. lactis chromosome. A total of 10 of the 62 transpositions resulted in strains that express ?-galactosidase. This indicates that there was fusion of the promoterless lacZ of the Tn917 derivatives to a chromosomal promoter. Thus, the Tn917-derived transposons should be powerful genetic tools for studying L. lactis subsp. lactis. Images PMID:16348845

  8. Genome Sequence of the Lactic Acid Bacterium Lactococcus lactis subsp. lactis TOMSC161, Isolated from a Nonscalded Curd Pressed Cheese.

    PubMed

    Velly, H; Renault, P; Abraham, A-L; Loux, V; Delacroix-Buchet, A; Fonseca, F; Bouix, M

    2014-01-01

    Lactococcus lactis is a lactic acid bacterium used in the production of many fermented foods, such as dairy products. Here, we report the genome sequence of L. lactis subsp. lactis TOMSC161, isolated from nonscalded curd pressed cheese. This genome sequence provides information in relation to dairy environment adaptation. PMID:25377704

  9. Genome Sequence of the Lactic Acid Bacterium Lactococcus lactis subsp. lactis TOMSC161, Isolated from a Nonscalded Curd Pressed Cheese

    PubMed Central

    Velly, H.; Abraham, A.-L.; Loux, V.; Delacroix-Buchet, A.; Fonseca, F.; Bouix, M.

    2014-01-01

    Lactococcus lactis is a lactic acid bacterium used in the production of many fermented foods, such as dairy products. Here, we report the genome sequence of L. lactis subsp. lactis TOMSC161, isolated from nonscalded curd pressed cheese. This genome sequence provides information in relation to dairy environment adaptation. PMID:25377704

  10. Regulation of Gene Expression and Cellular Localization of Cloned Klebsiella aerogenes (K. pneumoniae) Urease

    Microsoft Academic Search

    SCOTT B. MULROONEY; H. S. PANKRATZ; ROBERT P. HAUSINGER

    1989-01-01

    The genes for Klebsiella aerogenes (K. pneumoniae) urease were cloned and the protein was overexpressed (up to 18% of total protein consisted of this enzyme) in several hosts. The small size of the DNA encoding urease (3.5 kb), the restriction map, and the regulation of enzyme expression directed by the recombinant plasmid are distinct from other cloned ureases. Nickel concentration

  11. Environmental stress responses in Lactococcus lactis

    Microsoft Academic Search

    Jan Willem Sanders; Gerard Venema; Jan Kok

    1999-01-01

    Bacteria can encounter a variety of physical conditions during their life. Bacterial cells are able to survive these (often adverse) conditions by the induction of specific or general protection mechanisms. The lactic acid bacterium Lactococcus lactis is widely used for the production of cheese. Before and during this process as well as in its natural habitats, it is subjected to

  12. Bacteriocinogenic Lactococcus lactis subsp. lactis DF04Mi isolated from goat milk: Evaluation of the probiotic potential

    PubMed Central

    Furtado, Danielle N.; Todorov, Svetoslav D.; Landgraf, Mariza; Destro, Maria T.; Franco, Bernadette D.G.M.

    2014-01-01

    Lactic acid bacteria capable of producing bacteriocins and presenting probiotic potential open innovative technological applications in the dairy industry. In this study, a bacteriocinogenic strain (Lactococcus lactis subsp. lactis DF4Mi) was isolated from goat milk, and studied for its probiotic potential. Lc. lactis DF4Mi was resistant to acidic pH and oxbile, presented co-aggregation with Listeria monocytogenes, and was not affected by several drugs from different generic groups, being sensitive to most tested antibiotics. These properties indicate that this Lc. lactis strain can be used for enhancement of dairy foods safety and quality, in combination with potential probiotic properties. PMID:25477942

  13. Isolation and characterization of nisin-producing Lactococcus lactis subsp. lactis from bean-sprouts.

    PubMed

    Cai, Y; Ng, L K; Farber, J M

    1997-10-01

    Bacterial isolates from bean-sprouts were screened for anti-Listeria monocytogenes bacteriocins using a well diffusion method. Thirty-four of 72 isolates inhibited the growth of L. monocytogenes Scott A. One, HPB 1688, which had the biggest inhibition zone against L. monocytogenes Scott A, was selected for subsequent analysis. Both ribotyping and DNA sequencing of 16S ribosomal RNA gene demonstrated that the isolate was Lactococcus lactis subsp. lactis. Polymerase chain reaction and nucleotide sequencing revealed that the genomic DNA of the bean-sprout isolates contained a nisin Z structural gene. In MRS broth, bean-sprout isolate HPB 1688 survived at 3-4.5 degrees C for at least 20 d, grew at 4 degrees C and produced anti-listerial compounds at 5 degrees C. When co-cultured with L. monocytogenes in MRS broth, the isolate inhibited the growth of L. monocytogenes at 4 degrees C after 14 d and at 10 degrees C after 2 d. When co-inoculated with 10(2) cells g-1 of L. monocytogenes on fresh-cut ready-to-eat Caesar salad, L. lactis subsp. lactis (10(8) cells g-1) was able to reduce the number of L. monocytogenes by 1-1.4 logs after storage for 10 d at 7 zero and 10 degrees C. A bacteriocin-producing Enterococcus faecium was also able to reduce the numbers of L. monocytogenes on Caesar salad, but did not act synergistically when co-inoculated with L. lactis subsp. lactis. PMID:9351230

  14. Biodegradation of 2-methylquinoline by Enterobacter aerogenes TJ-D isolated from activated sludge.

    PubMed

    Wang, Lin; Li, Yongmei; Duan, Jingyuan

    2013-07-01

    Bacterial strain Enterobacter aerogenes TJ-D capable of utilizing 2-methylquinoline as the sole carbon and energy source was isolated from acclimated activated sludge under denitrifying conditions. The ability to degrade 2-methylquinoline by E. aerogenes TJ-D was investigated under denitrifying conditions. Under optimal conditions of temperature (35 degrees C) and initial pH 7, 2-methylquinoline of 100 mg/L was degraded within 176 hr. The degradation of 2-methylquinoline by E. aerogenes TJ-D could be well described by the Haldane model (R2 > 0.91). During the degradation period of 2-methylquinoline (initial concentration 100 mg/L), nitrate was almost completely consumed (the removal efficiency was 98.5%), while nitrite remained at low concentration (< 0.62 mg/L) during the whole denitrification period. 1,2,3,4-Tetrahydro-2-methylquinoline, 4-ethyl-benzenamine, N-butyl-benzenamine, N-ethyl-benzenamine and 2,6-diethyl-benzenamine were metabolites produced during the degradation. The degradation pathway of 2-methylquinoline by E. aerogenes TJ-D was proposed. 2-Methylquinoline is initially hydroxylated at C-4 to form 2-methyl-4-hydroxy-quinoline, and then forms 2-methyl-4-quinolinol as a result of tautomerism. Hydrogenation of the heterocyclic ring at positions 2 and 3 produces 2,3-dihydro-2-methyl-4-quinolinol. The carbon-carbon bond at position 2 and 3 in the heterocyclic ring may cleave and form 2-ethyl-N-ethyl-benzenamine. Tautomerism may result in the formation of 2,6-diethyl-benzenamine and N-butyl-benzenamine. 4-Ethyl-benzenamine and N-ethyl-benzenamine were produced as a result of losing one ethyl group from the above molecules. PMID:24218841

  15. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

    PubMed Central

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

  16. Production and secretion of heterologous proteins by Lactococcus lactis

    Microsoft Academic Search

    Asseldonk van M

    1994-01-01

    Lactococcus lactis strains have been used for centuries in food fermentation, now appreciated as traditional biotechnology. They have been applied in the cheesemaking process and for the manufacturing of other dairy products. Years of experience with these lactic acid bacteria have led to a profound understanding of the microbiological and technological aspects of L.lactis. Recent progress in the genetics of

  17. Influence of the carbon source on nisin production in Lactococcus lactis subsp. lactis batch fermentations

    Microsoft Academic Search

    LUC DE VUYST; ERICK J. VANDAMME

    1992-01-01

    Nisin production by Lactucmcus lrrctis subsp. lactis NIZO 22186 was studied in batch fermentation using a complex medium. Nisin production showed primary metabolite kinetics: nisin biosynthesis took place during the active growth phase and completely stopped when cells entered the stationary phase. A stringent correlation could be observed between the expression of the prenisin gene (nisA) and the synthesis of

  18. Detection and Viability of Lactococcus lactis throughout Cheese Ripening

    PubMed Central

    Cocolin, Luca

    2014-01-01

    Recent evidences highlighted the presence of Lactococcus lactis during late cheese ripening. For this reason, the role of this microorganism, well known as dairy starter, should be reconsidered throughout cheese manufacturing and ripening. Thus, the main objective of this study was to develop a RT-qPCR protocol for the detection, quantification and determination of the viability of L. lactis in ripened cheese samples by direct analysis of microbial nucleic acids. Standard curves were constructed for the specific quantification of L. lactis in cheese matrices and good results in terms of selectivity, correlation coefficient and efficiency were obtained. Thirty-three ripened cheeses were analyzed and, on the basis of RNA analysis, twelve samples showed 106 to 108 CFU of L. lactis per gram of product, thirteen from 103 to 105 CFU/g, and in eight cheeses, L. lactis was not detected. Traditional plating on M17 medium led to loads ranging from 105 to 109 CFU/g, including the cheese samples where no L. lactis was found by RT-qPCR. From these cheeses, none of the colonies isolated on M17 medium was identified as L. lactis species. These data could be interpreted as a lack of selectivity of M17 medium where colony growth is not always related to lactococcal species. At the same time, the absence or low abundance of L. lactis isolates on M17 medium from cheese where L. lactis was detected by RT-qPCR support the hypothesis that L. lactis starter populations are mainly present in viable but not culturable state during ripening and, for this reason, culture-dependent methods have to be supplemented with direct analysis of cheese. PMID:25503474

  19. Relationship between the presence of the citrate permease plasmid and high electron-donor surface properties of Lactococcus lactis ssp. lactis biovar. diacetylactis.

    PubMed

    Lý, Mai Hu'o'ng; Cavin, Jean-François; Cachon, Rémy; Lê, Thanh Mai; Belin, Jean-Marc; Waché, Yves

    2007-03-01

    Some strains of Lactococcus lactis subspecies possess a citrate permease that enables them to utilize citrate and to produce diacetyl. Such strains are classified as diacetylactis biovariants (L. lactis ssp. lactis biovar. diacetylactis). We investigated the electron-donor surface properties of L. lactis strains and observed that the diacetylactis biovariants presented increased adhesion to electron-acceptor solvents (microbial adhesion to solvents electron-donor characteristics of cells of <27% for L. lactis and about 50% for L. lactis ssp. lactis biovar diacetylactis). We investigated the properties of a pCitP- derivative and observed for a diacetylactis biovariant strain a loss of the electron-donor characteristics falling from 47% for a pCitP+ strain to 8% for its pCitP- derivative. This suggests that the presence of high electron-donor characteristics on the surface of L. lactis results to a large extent from the presence of the citrate permease plasmid. PMID:17250762

  20. Cutaneous abscess caused by Corynebacterium lactis in a companion dog.

    PubMed

    Antunes, João Marcelo Azevedo de Paula; Ribeiro, Márcio Garcia; Demoner, Larissa de Castro; Ramos, Juliana Nunes; Baio, Paulo Victor Pereira; Simpson-Louredo, Liliane; Santos, Cíntia Silva; Hirata, Raphael; Ferioli, Raquel Beneton; Romera, Adriana Resmond Cruz; Vieira, Verônica Viana; Mattos-Guaraldi, Ana Luíza

    2015-07-01

    Many new, emerging and re-emerging diseases of humans are caused by pathogens which originate from animals or products of animal origin. Corynebacterium lactis, a recently described species of the genus Corynebacterium, was first isolated from milk of asymptomatic cows. In the present study a cutaneous abscess caused by C. lactis in a dog was recognized by cytologic and histologic examination in addition to 16S rRNA gene analysis of the microorganism. Therefore, C. lactis should be included among other bacterial species recognized as emerging pathogens for companion animals. PMID:25937144

  1. DNA Macroarray Profiling of Lactococcus lactis subsp. lactis IL1403 Gene Expression during Environmental Stresses†

    PubMed Central

    Xie, Yi; Chou, Lan-szu; Cutler, Adele; Weimer, Bart

    2004-01-01

    This report describes the use of an oligonucleotide macroarray to profile the expression of 375 genes in Lactococcus lactis subsp. lactis IL1403 during heat, acid, and osmotic stress. A set of known stress-associated genes in IL1403 was used as the internal control on the array. Every stress response was accurately detected using the macroarray, compared to data from previous reports. As a group, the expression patterns of the investigated metabolic genes were significantly altered by heat, acid, and osmotic stresses. Specifically, 13 to 18% of the investigated genes were differentially expressed in each of the environmental stress treatments. Interestingly, the methionine biosynthesis pathway genes (metA-metB1 and metB2-cysK) were induced during heat shock, but methionine utilization genes, such as metK, were induced during acid stress. These data provide a possible explanation for the differences between acid tolerance mechanisms of L. lactis strains IL1403 and MG1363 reported previously. Several groups of transcriptional responses were common among the stress treatments, such as repression of peptide transporter genes, including the opt operon (also known as dpp) and dtpT. Reduction of peptide transport due to environmental stress will have important implications in the cheese ripening process. Although stress responses in lactococci were extensively studied during the last decade, additional information about this bacterium was gained from the use of this metabolic array. PMID:15528540

  2. Characterization of two nisin-producing Lactococcus lactis subsp. lactis strains isolated from a commercial sauerkraut fermentation.

    PubMed Central

    Harris, L J; Fleming, H P; Klaenhammer, T R

    1992-01-01

    Two Lactococcus lactis subsp. lactis strains, NCK400 and LJH80, isolated from a commercial sauerkraut fermentation were shown to produce nisin. LJH80 was morphologically unstable and gave rise to two stable, nisin-producing (Nip+) derivatives, NCK318-2 and NCK318-3. NCK400 and derivatives of LJH80 exhibited identical morphological and metabolic characteristics, but could be distinguished on the basis of plasmid profiles and genomic hybridization patterns to a DNA probe specific for the iso-ISS1 element, IS946. NCK318-2 and NCK318-3 harbored two and three plasmids, respectively, which hybridized with IS946. Plasmid DNA was not detected in NCK400, and DNA from this strain failed to hybridize with IS946. Despite the absence of detectable plasmid DNA in NCK400, nisin-negative derivatives (NCK402 and NCK403) were isolated after repeated transfer in broth at 37 degrees C. Nisin-negative derivatives concurrently lost the ability to ferment sucrose and became sensitive to nisin. A 4-kbp HindIII fragment containing the structural gene for nisin (spaN), cloned from L. lactis subsp. lactis ATCC 11454, was used to probe genomic DNA of NCK318-2, NCK318-3, NCK400, and NCK402 digested with EcoRI or HindIII. The spaN probe hybridized to an 8.8-kbp EcoRI fragment and a 10-kbp HindIII fragment in the Nip+ sauerkraut isolates, but did not hybridize to the Nip- derivative, NCK402. A different hybridization pattern was observed when the same probe was used against Nip+ L. lactis subsp. lactis ATCC 11454 and ATCC 7962. These phenotypic and genetic data confirmed that unique Nip+ L. lactis subsp. lactis strains were isolated from fermenting sauerkraut. Images PMID:1622214

  3. Characterization of two nisin-producing Lactococcus lactis subsp. lactis strains isolated from a commercial sauerkraut fermentation.

    PubMed

    Harris, L J; Fleming, H P; Klaenhammer, T R

    1992-05-01

    Two Lactococcus lactis subsp. lactis strains, NCK400 and LJH80, isolated from a commercial sauerkraut fermentation were shown to produce nisin. LJH80 was morphologically unstable and gave rise to two stable, nisin-producing (Nip+) derivatives, NCK318-2 and NCK318-3. NCK400 and derivatives of LJH80 exhibited identical morphological and metabolic characteristics, but could be distinguished on the basis of plasmid profiles and genomic hybridization patterns to a DNA probe specific for the iso-ISS1 element, IS946. NCK318-2 and NCK318-3 harbored two and three plasmids, respectively, which hybridized with IS946. Plasmid DNA was not detected in NCK400, and DNA from this strain failed to hybridize with IS946. Despite the absence of detectable plasmid DNA in NCK400, nisin-negative derivatives (NCK402 and NCK403) were isolated after repeated transfer in broth at 37 degrees C. Nisin-negative derivatives concurrently lost the ability to ferment sucrose and became sensitive to nisin. A 4-kbp HindIII fragment containing the structural gene for nisin (spaN), cloned from L. lactis subsp. lactis ATCC 11454, was used to probe genomic DNA of NCK318-2, NCK318-3, NCK400, and NCK402 digested with EcoRI or HindIII. The spaN probe hybridized to an 8.8-kbp EcoRI fragment and a 10-kbp HindIII fragment in the Nip+ sauerkraut isolates, but did not hybridize to the Nip- derivative, NCK402. A different hybridization pattern was observed when the same probe was used against Nip+ L. lactis subsp. lactis ATCC 11454 and ATCC 7962. These phenotypic and genetic data confirmed that unique Nip+ L. lactis subsp. lactis strains were isolated from fermenting sauerkraut. PMID:1622214

  4. Influence of pH on growth and bacteriocin production by Lactococcus lactis subsp. lactis 14ONWC during batch fermentation

    Microsoft Academic Search

    E. Parente; A. Ricciardi; G. Addario

    1994-01-01

    The influence of pH on growth, and lactic acid and bacteriocin production byLactococcus lactis subsp.lactis 140 NWC was studied during batch fermentation in a lactose-based complex medium. Growth and lactic acid production were modelled using a simple logistic equation while substrate consumption was found to be a function growth and lactic acid production rate. The optimal pH for growth and

  5. 21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Lactase enzyme preparation from Kluyveromyces lactis...Affirmed as GRAS § 184.1388 Lactase enzyme preparation from Kluyveromyces lactis. (a) This enzyme preparation is derived from the...

  6. 21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Lactase enzyme preparation from Kluyveromyces lactis...Affirmed as GRAS § 184.1388 Lactase enzyme preparation from Kluyveromyces lactis. (a) This enzyme preparation is derived from the...

  7. 21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Lactase enzyme preparation from Kluyveromyces lactis...Affirmed as GRAS § 184.1388 Lactase enzyme preparation from Kluyveromyces lactis. (a) This enzyme preparation is derived from the...

  8. 21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Lactase enzyme preparation from Kluyveromyces lactis...Affirmed as GRAS § 184.1388 Lactase enzyme preparation from Kluyveromyces lactis. (a) This enzyme preparation is derived from the...

  9. Transcriptome Analysis Reveals Mechanisms by Which Lactococcus lactis Acquires Nisin Resistance

    Microsoft Academic Search

    Naomi E. Kramer; Jan Knol; Jan Kok; Oscar P. Kuipers

    2006-01-01

    Nisin, a posttranslationally modified antimicrobial peptide produced by Lactococcus lactis, is widely used as a food preservative. Yet, the mechanisms leading to the development of nisin resistance in bacteria are poorly understood. We used whole-genome DNA microarrays of L. lactis IL1403 to identify the factors underlying acquired nisin resistance mechanisms. The transcriptomes of L. lactis IL1403 and L. lactis IL1403

  10. Low-redundancy sequencing of the entire Lactococcus lactis IL1403 genome

    Microsoft Academic Search

    Alexander Bolotin; Stéphane Mauger; Karine Malarme; S. Dusko Ehrlich; Alexei Sorokin

    1999-01-01

    Lactococcus lactis is an AT-rich gram positive bacterium phylogenetically close to the genus Streptococcus. Various strains of L. lactis are used in dairy industry as starters for cheese making. L. lactis is also one of the well characterized laboratory microorganisms, widely used for studies on physiology of lactic acid bacteria. We describe here a low redundancy sequence of the genome

  11. Enhanced Secretion of Biologically Active Murine Interleukin12 by Lactococcus lactis

    Microsoft Academic Search

    Antonio Fernandez; Nikki Horn; Udo Wegmann; Claudio Nicoletti; Michael J. Gasson; Arjan Narbad

    2009-01-01

    Many heterologous proteins and peptides have been suc- cessfully expressed in Lactococcus lactis for different biotech- nological applications. Despite its lack of invasiveness, L. lactis is able to deliver heterologous antigens and cytokines to the systemic and mucosal immune system (11). Cytokine mucosal delivery is dependent upon its release into the mucosa when L. lactis cells are in contact with

  12. Irreproducible and uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes.

    PubMed

    Landman, David; Salamera, Julius; Quale, John

    2013-12-01

    Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ?2 ?g/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution. PMID:24088860

  13. Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes

    PubMed Central

    Landman, David; Salamera, Julius

    2013-01-01

    Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of ?2 ?g/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution. PMID:24088860

  14. Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2.

    PubMed

    Panda, Jigisha; Sarkar, Priyabrata

    2014-01-01

    Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 ?g L(-1) Cr(VI) and the limit of detection was found to be 6.6 ?g L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity. PMID:24410691

  15. Probiotic characterization of potential hydrolases producing Lactococcus lactis subsp. lactis isolated from pickled yam.

    PubMed

    Bhanwar, Seema; Singh, Arashdeep; Ganguli, Abhijit

    2014-02-01

    The aim of this study was to characterize potential probiotic strain co-producing ?-amylase and ?-galactosidase. Sixty-three strains, isolated from pickle samples were screened for their hydrolase producing capacity by utilizing different starches as carbon source. One out of 63 strains, isolated from traditionally fermented pickled yam showing maximum hydrolase activity (?-amylase (36.9?U/ml) and ?-galactosidase (42.6?U/ml)) within a period of 48 hours was identified as Lactococcus lactis subsp. lactis. Further, it was assessed for the probiotic characteristics under gastrointestinal conditions like acidic, alkaline, proteolytic enzymes, bile stress and found to exhibit tolerance to these stresses. The therapeutic potential of the isolate is implicated because of its antagonistic effect against enteric foodborne pathogens (Salmonella typhimurium, Escherichia coli 0157:H7, Staphylococcus aureus, Yersinia enterocolitica and Aeromonas hydrophila). The results of this study entail a potential applicability of the isolate in developing future probiotic foods besides the production of industrially significant hydrolases. PMID:24020495

  16. Selection during Cefepime Treatment of a New Cephalosporinase Variant with Extended-Spectrum Resistance to Cefepime in an Enterobacter aerogenes Clinical Isolate

    PubMed Central

    Barnaud, G.; Benzerara, Y.; Gravisse, J.; Raskine, L.; Sanson-Le Pors, M. J.; Labia, R.; Arlet, G.

    2004-01-01

    Enterobacter aerogenes resistant to cefepime (MIC, 32 ?g/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC ?-lactamase (MIC of cefepime, 0.5 ?g/ml). The AmpC ?-lactamase of the resistant strain had an L-293-P amino acid substitution and a high kcat/Km ratio for cefepime. Both of these modifications were necessary for resistance to cefepime. PMID:14982805

  17. Isolation of Lactococcus lactis subsp. cremoris from nature by colony hybridization with rRNA probes.

    PubMed Central

    Salama, M S; Sandine, W E; Giovannoni, S J

    1993-01-01

    Lactococcus lactis subsp. cremoris is widely used in the manufacture of fermented milk products. Despite numerous attempts, efforts to isolate new strains by traditional plating and identification methods have not been successful. Previously, we described oligonucleotide probes for 16S rRNAs which could be used to discriminate L. lactis subsp. cremoris from related strains. These probes were used in colony hybridization experiments to screen large numbers of colonies obtained from enrichment cultures. A total of 170 strains of L. lactis were isolated from six milk samples, two colostrum samples, and one corn sample by using oligonucleotide probe 212RLa specific for the species L. lactis. Fifty-nine of these isolates also hybridized to L. lactis subsp. cremoris-specific probe 68RCa, and 26 of the strains which hybridized to the L. lactis subsp. cremoris-specific probe had the L. lactis subsp. cremoris phenotype. Images PMID:7506898

  18. Draft Genome Sequence of Enterobacter aerogenes, a DDE-Degrading and Plant Growth-Promoting Strain Isolated from Cucurbita pepo

    PubMed Central

    Eevers, Nele; Van Hamme, Jonathan D.; Bottos, Eric M.; Weyens, Nele

    2015-01-01

    We report here the draft genome of Enterobacter aerogenes, a Gram-negative bacterium of the Enterobacteriaceae isolated from Cucurbita pepo root tissue. This bacterium shows 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (DDE)-degrading potential and plant growth-promoting capacity. An analysis of its 4.5-Mb draft genome will enhance the understanding of DDE degradation pathways and phytoremediation applications for DDE-contaminated soils. PMID:25883299

  19. The nitrogen assimilation control protein, NAC, is a DNA binding transcription activator in Klebsiella aerogenes.

    PubMed Central

    Goss, T J; Bender, R A

    1995-01-01

    A 32-kDa polypeptide corresponding to NAC, the product of the Klebsiella aerogenes nac gene, was overexpressed from a plasmid carrying a tac'-'nac operon fusion and purified to near homogeneity by taking advantage of its unusual solubility properties. NAC was able to shift the electrophoretic migration of DNA fragments carrying the NAC-sensitive promoters hutUp, putPp1, and ureDp. The interaction between NAC and hutUp was localized to a 26-bp region centered approximately 64 bp upstream of the hutUp transcription initiation site. Moreover, NAC protected this region from DNase I digestion. Mobility shift and DNase I protection studies utilizing the putP and ureD promoter regions identified NAC-binding regions of sizes and locations similar to those found in hutUp. Comparison of the DNA sequences which were protected from DNase I digestion by NAC suggests a minimal NAC-binding consensus sequence: 5'-ATA-N9-TAT-3'. In vitro transcription assays demonstrated that NAC was capable of activating the transcription of hutUp by sigma 70-RNA polymerase holoenzyme when this promoter was presented as either a linear or supercoiled DNA molecule. Thus, NAC displays the in vitro DNA-binding and transcription activation properties which have been predicted for the product of the nac gene. PMID:7768865

  20. Evolution of aminobenzoate synthases: nucleotide sequences of Salmonella typhimurium and Klebsiella aerogenes pabB.

    PubMed

    Goncharoff, P; Nichols, B P

    1988-09-01

    p-Aminobenzoate synthase (PS) and anthranilate synthase (AS) are structurally related enzymes that catalyze similar reactions and produce similar products, para- and ortho-aminobenzoate (anthranilate). Each enzyme is composed of two non-identical subunits: a glutamine amidotransferase subunit (CoII) and a subunit that produces an aminobenzoate product (CoI). Nucleotide sequence comparisons of the Escherichia coli genes encoding each of the subunits suggest a common evolutionary origin for both subunits of the enzyme complexes. We report here the nucleotide sequences of the pabB genes that encode Salmonella typhimurium and Klebsiella aerogenes PS CoI. Comparative sequence information suggests that pabB is encoded as the first gene in a multicistronic transcript. Comparison of deduced amino acid sequences of PS CoI genes indicates that the majority of sequence identity occurs in the C-terminal two-thirds of the proteins. Similarly, identities in an alignment of eight PS and AS CoI sequences are confined to the C-terminal segments of the proteins. Secondary-structure predictions for the nine sequences suggest considerable similarity in the folding of the C-terminal portions of the aminobenzoate synthases. PMID:3057324

  1. Generation of Dipeptidyl Peptidase-IV-Inhibiting Peptides from ?-Lactoglobulin Secreted by Lactococcus lactis

    PubMed Central

    Shigemori, Suguru; Oshiro, Kazushi; Wang, Pengfei; Yamamoto, Yoshinari; Wang, Yeqin; Sato, Takashi; Uyeno, Yutaka; Shimosato, Takeshi

    2014-01-01

    Previous studies showed that hydrolysates of ?-lactoglobulin (BLG) prepared using gastrointestinal proteases strongly inhibit dipeptidyl peptidase-IV (DPP-IV) activity in vitro. In this study, we developed a BLG-secreting Lactococcus lactis strain as a delivery vehicle and in situ expression system. Interestingly, trypsin-digested recombinant BLG from L. lactis inhibited DPP-IV activity, suggesting that BLG-secreting L. lactis may be useful in the treatment of type 2 diabetes mellitus. PMID:25157356

  2. Characterization of a Wild, Novel Nisin A-Producing Lactococcus Strain with an L. lactis subsp. cremoris Genotype and an L. lactis subsp. lactis Phenotype, Isolated from Greek Raw Milk

    PubMed Central

    Parapouli, Maria; Delbès-Paus, Céline; Kakouri, Athanasia; Koukkou, Anna-Irini; Montel, Marie-Christine

    2013-01-01

    Several molecular taxonomic studies have revealed that many natural (wild) Lactococcus lactis strains of dairy origin which are phenotypically representative of the L. lactis subspecies lactis cluster genotypically within subspecies cremoris and vice versa. Recently, we isolated two wild nisin-producing (Nis+) L. lactis strains, M78 and M104, of the lactis phenotype from Greek raw milk (J. Samelis, A. Lianou, A. Kakouri, C. Delbès, I. Rogelj, B. B. Matijašic, and M. C. Montel, J. Food Prot. 72:783–790, 2009); strain M78 possess a novel nisin A sequence (GenBank accession number HM219853). In this study, the actual subspecies identity of M78 and M104 isolates was elucidated, using 16S rRNA and acmA (encoding lactococcal N-acetylmuramidase) gene and histidine biosynthesis operon polymorphisms and 16S rRNA and ldh (encoding lactate dehydrogenase) gene phylogenies. Except the acmA gene analysis, molecular tools revealed that isolates M78 and M104 clustered with strains of the cremoris genotype, including the LMG 6897T strain, while they were distant from strains of the lactis genotype, including the LMG 6890T strain. The two wild isolates had identical repetitive sequence-based PCR (rep-PCR), randomly amplified polymorphic DNA (RAPD), plasmid, and whole-cell protein profiles and shared high 16S rRNA (99.9%) and ldh (100%) gene sequence homologies. In contrast, they exhibited identical sugar fermentation and enzymatic patterns which were similar to those of the subspecies lactis LMG 6890T strain. To our knowledge, this is the first complete identification report on a wild L. lactis subsp. cremoris genotype of the lactis phenotype which is capable of nisin A production and, thus, has strong potential for use as a novel dairy starter and/or protective culture. PMID:23542625

  3. Genetic Basis of Tetracycline Resistance in Bifidobacterium animalis subsp. lactis?

    PubMed Central

    Gueimonde, Miguel; Flórez, Ana Belén; van Hoek, Angela H. A. M.; Stuer-Lauridsen, Birgitte; Strøman, Per; de los Reyes-Gavilán, Clara G.; Margolles, Abelardo

    2010-01-01

    All strains of Bifidobacterium animalis subsp. lactis described to date show medium level resistance to tetracycline. Screening of 26 strains from a variety of sources revealed the presence of tet(W) in all isolates. A transposase gene upstream of tet(W) was found in all strains, and both genes were cotranscribed in strain IPLAIC4. Mutants with increased tetracycline resistance as well as tetracycline-sensitive mutants of IPLAIC4 were isolated and genetically characterized. The native tet(W) gene was able to restore the resistance phenotype to a mutant with an alteration in tet(W) by functional complementation, indicating that tet(W) is necessary and sufficient for the tetracycline resistance seen in B. animalis subsp. lactis. PMID:20348299

  4. Metabolic profiling of Lactococcus lactis under different culture conditions.

    PubMed

    Azizan, Kamalrul Azlan; Baharum, Syarul Nataqain; Mohd Noor, Normah

    2012-01-01

    Gas chromatography mass spectrometry (GC-MS) and headspace gas chromatography mass spectrometry (HS/GC-MS) were used to study metabolites produced by Lactococcus lactis subsp. cremoris MG1363 grown at a temperature of 30 °C with and without agitation at 150 rpm, and at 37 °C without agitation. It was observed that L. lactis produced more organic acids under agitation. Primary alcohols, aldehydes, ketones and polyols were identified as the corresponding trimethylsilyl (TMS) derivatives, whereas amino acids and organic acids, including fatty acids, were detected through methyl chloroformate derivatization. HS analysis indicated that branched-chain methyl aldehydes, including 2-methylbutanal, 3-methylbutanal, and 2-methylpropanal are degdradation products of isoleucine, leucine or valine. Multivariate analysis (MVA) using partial least squares discriminant analysis (PLS-DA) revealed the major differences between treatments were due to changes of amino acids and fermentation products. PMID:22759915

  5. Proteomic signature of Lactococcus lactis NCDO763 cultivated in milk.

    PubMed

    Gitton, Christophe; Meyrand, Mickael; Wang, Juhui; Caron, Christophe; Trubuil, Alain; Guillot, Alain; Mistou, Michel-Yves

    2005-11-01

    We have compared the proteomic profiles of L. lactis subsp. cremoris NCDO763 growing in the synthetic medium M17Lac, skim milk microfiltrate (SMM), and skim milk. SMM was used as a simple model medium to reproduce the initial phase of growth of L. lactis in milk. To widen the analysis of the cytoplasmic proteome, we used two different gel systems (pH ranges of 4 to 7 and 4.5 to 5.5), and the proteins associated with the cell envelopes were also studied by two-dimensional electrophoresis. In the course of the study, we analyzed about 800 spots and identified 330 proteins by mass spectrometry. We observed that the levels of more than 50 and 30 proteins were significantly increased upon growth in SMM and milk, respectively. The large redeployment of protein synthesis was essentially associated with an activation of pathways involved in the metabolism of nitrogenous compounds: peptidolytic and peptide transport systems, amino acid biosynthesis and interconversion, and de novo biosynthesis of purines. We also showed that enzymes involved in reactions feeding the purine biosynthetic pathway in one-carbon units and amino acids have an increased level in SMM and milk. The analysis of the proteomic data suggested that the glutamine synthetase (GS) would play a pivotal role in the adaptation to SMM and milk. The analysis of glnA expression during growth in milk and the construction of a glnA-defective mutant confirmed that GS is an essential enzyme for the development of L. lactis in dairy media. This analysis thus provides a proteomic signature of L. lactis, a model lactic acid bacterium, growing in its technological environment. PMID:16269754

  6. Proteomic Signature of Lactococcus lactis NCDO763 Cultivated in Milk†

    PubMed Central

    Gitton, Christophe; Meyrand, Mickael; Wang, Juhui; Caron, Christophe; Trubuil, Alain; Guillot, Alain; Mistou, Michel-Yves

    2005-01-01

    We have compared the proteomic profiles of L. lactis subsp. cremoris NCDO763 growing in the synthetic medium M17Lac, skim milk microfiltrate (SMM), and skim milk. SMM was used as a simple model medium to reproduce the initial phase of growth of L. lactis in milk. To widen the analysis of the cytoplasmic proteome, we used two different gel systems (pH ranges of 4 to 7 and 4.5 to 5.5), and the proteins associated with the cell envelopes were also studied by two-dimensional electrophoresis. In the course of the study, we analyzed about 800 spots and identified 330 proteins by mass spectrometry. We observed that the levels of more than 50 and 30 proteins were significantly increased upon growth in SMM and milk, respectively. The large redeployment of protein synthesis was essentially associated with an activation of pathways involved in the metabolism of nitrogenous compounds: peptidolytic and peptide transport systems, amino acid biosynthesis and interconversion, and de novo biosynthesis of purines. We also showed that enzymes involved in reactions feeding the purine biosynthetic pathway in one-carbon units and amino acids have an increased level in SMM and milk. The analysis of the proteomic data suggested that the glutamine synthetase (GS) would play a pivotal role in the adaptation to SMM and milk. The analysis of glnA expression during growth in milk and the construction of a glnA-defective mutant confirmed that GS is an essential enzyme for the development of L. lactis in dairy media. This analysis thus provides a proteomic signature of L. lactis, a model lactic acid bacterium, growing in its technological environment. PMID:16269754

  7. Genomic Exploration of the Hemiascomycetous Yeasts: 11. Kluyveromyces lactis

    Microsoft Academic Search

    Monique Bolotin-Fukuhara; Claire Toffano-Nioche; François Artiguenave; Guillemette Duchateau-Nguyen; Marc Lemaire; Roland Marmeisse; Robert Montrocher; Catherine Robert; Michel Termier; Patrick Wincker; Micheline Wésolowski-Louvel

    2000-01-01

    Random sequencing of the Kluyveromyces lactis genome allowed the identification of 2235–2601 open reading frames (ORFs) homologous to S. cerevisiae ORFs, 51 ORFs which were homologous to genes from other species, 64 tRNAs, the complete rDNA repeat, and a few Ty1- and Ty2-like sequences. In addition, the complete sequence of plasmid pKD1 and a large coverage of the mitochondrial genome

  8. Modeling Lactococcus lactis using a genome-scale flux model

    Microsoft Academic Search

    Ana Paula Oliveira; Jens Nielsen; Jochen Förster

    2005-01-01

    BACKGROUND: Genome-scale flux models are useful tools to represent and analyze microbial metabolism. In this work we reconstructed the metabolic network of the lactic acid bacteria Lactococcus lactis and developed a genome-scale flux model able to simulate and analyze network capabilities and whole-cell function under aerobic and anaerobic continuous cultures. Flux balance analysis (FBA) and minimization of metabolic adjustment (MOMA)

  9. Selection during cefepime treatment of a new cephalosporinase variant with extended-spectrum resistance to cefepime in an Enterobacter aerogenes clinical isolate.

    PubMed

    Barnaud, G; Benzerara, Y; Gravisse, J; Raskine, L; Sanson-Le Pors, M J; Labia, R; Arlet, G

    2004-03-01

    Enterobacter aerogenes resistant to cefepime (MIC, 32 microg/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC beta-lactamase (MIC of cefepime, 0.5 microg/ml). The AmpC beta-lactamase of the resistant strain had an L-293-P amino acid substitution and a high k(cat)/K(m) ratio for cefepime. Both of these modifications were necessary for resistance to cefepime. PMID:14982805

  10. Growth Enhancement of Bifidobacterium lactis Bo and Lactobacillus acidophilus Ki by Milk Hydrolyzates

    Microsoft Academic Search

    Ana M. P. Gomes; F. Xavier Malcata; Frank A. M. Klaver

    1998-01-01

    The determination of the best conditions of prepa- ration of a (tentatively) probiotic starter culture that might be suitable for cheese making composed solely of Bifidobacterium lactis Bo and Lactobacillus acidophilus Ki is critical if a consistently reliable acid production is to be achieved, especially because bifidobacteria have stringent requirements for growth. Therefore, we determined whether B. lactis Bo and

  11. Identity of Additional Aroma Constituents in Milk Cultures of Streptococcus lactis var. Maltigenes1

    Microsoft Academic Search

    M. E. Morgan; R. C. Lindsay; L. M. Libbey; R. L. Pereira

    1966-01-01

    Gas chromatographic analyses of the headspace vapor over a series of milk cul- tures of malty and nomnalty strains of Streptococcus lactis revealed components in the malty strains tentatively identified as 2-methylpropanol and 3-methylbutanol. In a more detailed study the volatiles from milk cultures of a typical strain of S. lactis var. maltigenes were entrained and col- lected by an

  12. Antihypertensive and hypolipidemic effect of milk fermented by specific Lactococcus lactis strains.

    PubMed

    Rodríguez-Figueroa, J C; González-Córdova, A F; Astiazaran-García, H; Hernández-Mendoza, A; Vallejo-Cordoba, B

    2013-07-01

    The antihypertensive and hypolipidemic effects of milk fermented by specific Lactococcus lactis strains in spontaneously hypertensive rats (SHR) were investigated. The SHR were fed ad libitum milk fermented by Lc. lactis NRRL B-50571, Lc. lactis NRRL B-50572, Captopril (40mg/kg of body weight, Sigma-Aldrich Co., St. Louis, MO) or purified water for 4 wk. Results suggested that Lc. lactis fermented milks presented a significant blood pressure-lowering effect. No significant difference was noted among milk fermented by Lc. lactis NRRL B-50571 and Captopril by the second and third week of treatment. Additionally, milk fermented by Lc. lactis strains modified SHR lipid profiles. Milk fermented by Lc. lactis NRRL B-50571 and B-50572 were able to reduce plasma low-density lipoprotein cholesterol and triglyceride contents. Thus, milk fermented by Lc. lactis strains may be a coadjuvant in the reduction of hypertension and hyperlipidemia and may be used as a functional food for better cardiovascular health. PMID:23628247

  13. Behavior of Listeria monocytogenes in Mozzarella cheese in presence of Lactococcus lactis

    Microsoft Academic Search

    Mara Lucia Stecchini; Valeria Aquili; Ileana Sarais

    1995-01-01

    The behavior of Listeria monocytogenes (Scott A) on fully processed Italian Mozzarella cheese was examined in presence and in absence of bacteriocins produced by Lactococcus lactis ssp. lactis strains (DIP 15 and DIP 16). These strains, isolated from raw milk, produced heat stable bacteriocins that were inactivated by pronase, alpha- chymotrypsin and proteinase K, but not by pepsin, trypsin and

  14. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor

    PubMed Central

    Jitrwung, Rujira; Yargeau, Viviane

    2015-01-01

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol. PMID:25970750

  15. Physiological characterisation of the efflux pump system of antibiotic-susceptible and multidrug-resistant Enterobacter aerogenes.

    PubMed

    Martins, A; Spengler, G; Martins, M; Rodrigues, L; Viveiros, M; Davin-Regli, A; Chevalier, J; Couto, I; Pagès, J M; Amaral, L

    2010-10-01

    Enterobacter aerogenes predominates amongst Enterobacteriaceae species that are increasingly reported as producers of extended-spectrum beta-lactamases. Although this mechanism of resistance to beta-lactams is important, other mechanisms bestowing a multidrug-resistant (MDR) phenotype in this species are now well documented. Amongst these mechanisms is the overexpression of efflux pumps that extrude structurally unrelated antibiotics prior to their reaching their targets. Interestingly, although knowledge of the genetic background behind efflux pumps is rapidly advancing, few studies assess the physiological nature of the overall efflux pump system of this, or for that matter any other, bacterium. The study reported here evaluates physiologically the efflux pump system of an E. aerogenes ATCC reference as well as two strains whose MDR phenotypes are mediated by overexpressed efflux pumps. The activities of the efflux pumps in these strains are modulated by pH and glucose, although the effects of the latter are essentially restricted to pH 8, suggesting the presence of two general efflux pump systems, i.e. proton-motive force-dependent and ABC transporter types, respectively. PMID:20688487

  16. Effects of carbon source and Vitreoscilla hemoglobin (VHb) on the production of beta-galactosidase in Enterobacter aerogenes.

    PubMed

    Khleifat, Khaled M; Abboud, Muayad M; Al-Mustafa, Ahmed H; Al-Sharafa, Khalid Y

    2006-10-01

    At fixed concentration (0.5%), lactose and galactose acted as inducers while glucose and other tested carbon sugars showed repression effects on beta-galactosidase production in Enterobacter aerogenes strain. The expression of Vitreoscilla hemoglobin gene (vgb) in this bacterial strain managed to overcome the repression effects as well as improving the induction of beta-galactosidase formation by carbon sources. In parallel, the bacterial O(2) consumption was increased correspondingly to the vgb induction of beta-galactosidase synthesis. When Enterobacter aerogenes strains were grown at the incubation temperature 42 degrees C, about 5-fold higher enzyme productivity was obtained than with a similar incubation at 37 degrees C. The bacterial growth expressed as biomass yield had a different optimum temperature and was not influenced to the same extent by variations in the carbon sources. These data are discussed in terms of proposed enhancement in beta-galactosidase productivity by vgb expression as well as its significance to improve the technology of whey processing. PMID:16972134

  17. Reduced Lysis upon Growth of Lactococcus lactis on Galactose Is a Consequence of Decreased Binding of the Autolysin AcmA

    Microsoft Academic Search

    Anton Steen; Girbe Buist; Naomi E. Kramer; Ruud Jalving; Germaine F. J. D. Benus; Gerard Venema; Oscar P. Kuipers; Jan Kok

    2008-01-01

    When Lactococcus lactis subsp. lactis IL1403 or L. lactis subsp. cremoris MG1363 is grown in a medium with galactose as the carbon source, the culture lyses to a lesser extent in stationary phase than when the bacteria are grown in a medium containing glucose. Expression of AcmA, the major autolysin of L. lactis, is not influenced by the carbon source.

  18. Assessment of the Diversity of Dairy Lactococcus lactis subsp. lactis Isolates by an Integrated Approach Combining Phenotypic, Genomic, and Transcriptomic Analyses ? †

    PubMed Central

    Tan-a-ram, Punthip; Cardoso, Tamara; Daveran-Mingot, Marie-Line; Kanchanatawee, Sunthorn; Loubière, Pascal; Girbal, Laurence; Cocaign-Bousquet, Muriel

    2011-01-01

    The intrasubspecies diversity of six strains of Lactococcus lactis subsp. lactis was investigated at the genomic level and in terms of phenotypic and transcriptomic profiles in an ultrafiltration cheese model. The six strains were isolated from various sources, but all exhibited a dairy phenotype (growth in ultrafiltration cheese model and high acidification rate). The six strains exhibited similar behaviors in terms of growth during cheese ripening, while different acidification capabilities were detected. Even if all strains displayed large genomic similarities, sharing a large core genome of almost 2,000 genes, the expression of this core genome directly in the cheese matrix revealed major strain-specific differences that potentially could account for the observed different acidification capabilities. This work demonstrated that significant transcriptomic polymorphisms exist even among Lactococcus lactis subsp. lactis strains with the same dairy origin. PMID:21131529

  19. Kentucky Department for Natural Resources and Environmental Protection permit application for air contaminant source: SRC-I Demonstruation Plant, Newman, Kentucky. Appendix B. Best available control technology (BACT) proposals. [Demonstration plant at Newman, KY

    SciTech Connect

    Not Available

    1980-11-21

    The best available control technology (BACT) proposals for the following areas of the SRC-I demonstration plant are described: coal preparation and handling, SRC process and deashing, coke and liquid fuels (control of particles and hydrocarbon vapors), cryogenic systems and fuel gas purification (including sulfur recovery system and venting of gaseous wastes). (LTN)

  20. Short communication: Genotypic and phenotypic identification of environmental streptococci and association of Lactococcus lactis ssp. lactis with intramammary infections among different dairy farms.

    PubMed

    Werner, B; Moroni, P; Gioia, G; Lavín-Alconero, L; Yousaf, A; Charter, M E; Carter, B Moslock; Bennett, J; Nydam, D V; Welcome, F; Schukken, Y H

    2014-11-01

    Lactococcus species are counted among a large and closely related group of environmental streptococci and streptococci-like bacteria that include bovine mastitis pathogenic Streptococcus, Enterococcus, and Aerococcus species. Phenotypic and biochemical identification methods can be inaccurate and unreliable for species within this group, particularly for Lactococcus spp. As a result, the incidence of Lactococcus spp. on the farm may have been historically underreported and consequently little is known about the clinical importance of this genus as a mastitis pathogen. We used molecular genetic identification methods to accurately differentiate 60 environmental streptococci and streptococci-like bacteria isolated from cows with high somatic cell count and chronic intramammary infection (IMI; >2 somatic cell scores above 4) among 5 geographically distinct farms in New York and Minnesota that exhibited an observed increase in IMI. These isolates were phenotypically identified as Streptococcus uberis and Streptococcus spp. Genetic methods identified 42 isolates (70%) as Lactococcus lactis ssp. lactis, including all 10 isolates originally phenotypically identified as Streptococcus uberis. Antibiotic inhibition testing of all Lc. lactis ssp. lactis showed that 7 isolates were resistant to tetracycline. In the present study, a predominance of Lc. lactis ssp. lactis was identified in association with chronic, clinical bovine IMI among all 5 farms and characterized antimicrobial resistance for treatment therapies. Routine use by mastitis testing labs of molecular identification methods for environmental streptococci and streptococci-like bacteria can further define the role and prevalence of Lc. lactis ssp. lactis in association with bovine IMI and may lead to more targeted therapies. PMID:25242419

  1. Metabolic and Transcriptomic Adaptation of Lactococcus lactis subsp. lactis Biovar diacetylactis in Response to Autoacidification and Temperature Downshift in Skim Milk

    Microsoft Academic Search

    Sandy Raynaud; Remi Perrin; Muriel Cocaign-Bousquet; Pascal Loubiere

    2005-01-01

    For the first time, a combined genome-wide transcriptome and metabolic analysis was performed with a dairy Lactococcus lactis subsp. lactis biovar diacetylactis strain under dynamic conditions similar to the conditions encountered during the cheese-making process. A culture was grown in skim milk in an anaerobic environment without pH regulation and with a controlled temperature downshift. Fermentation kinetics, as well as

  2. Regulation of cytokinesis in the milk yeast Kluyveromyces lactis.

    PubMed

    Rippert, Dorthe; Heppeler, Nele; Albermann, Sabine; Schmitz, Hans-Peter; Heinisch, Jürgen J

    2014-11-01

    Cytokinesis in yeast and mammalian cells is a highly coordinated process mediated by the constriction of an actomyosin ring. In yeasts, it is accompanied by the formation of a chitinous primary septum. Although much is known about the regulation of cytokinesis in budding yeast, overlapping functions of redundant genes complicates genetic analyses. Here, we investigated the effects of various deletion mutants on cytokinesis in the milk yeast Kluyveromyces lactis. To determine the spatiotemporal parameters of cytokinesis components, live-cell imaging of fluorophor-tagged KlMyo1 and a new Lifeact probe for KlAct1 was employed. In contrast to Saccharomyces cerevisiae, where deletion of ScMYO1 is lethal, Klmyo1 deletion was temperature-sensitive. Transmission and scanning electron microscopy demonstrated that the Klmyo1 deletion cells had a defect in the formation of the primary septum and in cell separation; this result was confirmed by FACS analyses. Deletion of KlCYK3 was lethal, whereas in S. cerevisiae a cyk3 deletion is synthetically lethal with hof1 deletion. Growth of Klhof1 mutants was osmoremedial at 25°C, as it is in S. cerevisiae. CYK3 and HOF1 genes cross-complemented in both species, suggesting that they are functional homologs. Inn1, a common interactor for these two regulators, was essential in both yeasts and the encoding genes did not cross-complement. The C2 domain of the Inn1 homologs conferred species specificity. Thus, our work establishes K. lactis as a model yeast to study cytokinesis with less genetic redundancy than S. cerevisiae. The viability of Klmyo1 deletions provides an advantage over budding yeast to study actomyosin-independent cytokinesis. Moreover, the lethality of Klcyk3 null mutants suggests that there are fewer functional redundancies with KlHof1 in K. lactis. PMID:25110348

  3. Plasmid linkage of a bacteriocin-like substance in Streptococcus lactis subsp. diacetylactis strain WM4: transferability to Streptococcus lactis.

    PubMed Central

    Scherwitz, K M; Baldwin, K A; McKay, L L

    1983-01-01

    Streptococcus lactis subsp. diacetylactis strain WM4 transferred lactose-fermenting and bacteriocin-producing (Bac+) abilities to S. lactis LM2301, a lactose-negative, streptomycin-resistant (Lac- Strr), plasmid-cured derivative of S. lactis C2. Three types of transconjugants were obtained: Lac+ Bac+, Lac+ Bac-, and Lac-Bac+.S. diacetylactis WM4 possessed plasmids of 88, 33, 30, 5.5, 4.8, and 3.8 megadaltons (Mdal). In Lac+ Bac+ transconjugants, lactose-fermenting ability was linked to the 33-Mdal plasmid and bacteriocin-producing ability to the 88-Mdal plasmid. Curing the 33-Mdal plasmid from Lac+ Bac+ transconjugants resulted in loss of lactose-fermenting ability but not bacteriocin-producing ability (Lac- Bac+). These strains retained the 88-Mdal plasmid. Curing of both plasmids resulted in a Lac- Bac- phenotype. The Lac+ Bac- transconjugant phenotype was associated with a recombinant plasmid of 55 or 65 Mdal. When these transconjugants were used as donors in subsequent matings, the frequency of Lac transfer was about 2.0 X 10(-2) per recipient plated, whereas when Lac+ Bac+ transconjugants served as donors, the frequency of Lac transfer was about 2.0 X 10(-5) per recipient plated. Also, Lac- Bac+ transconjugants were found to contain the 88-Mdal plasmid. The data indicate that the ability of WM4 to produce bacteriocin is linked to an 88-Mdal conjugative plasmid and that lactose-fermenting ability resides on a 33-Mdal plasmid. Images PMID:6408984

  4. Characterization of Lactococcus lactis isolates from bovine mastitis.

    PubMed

    Plumed-Ferrer, Carme; Uusikylä, Kaisa; Korhonen, Jenni; von Wright, Atte

    2013-12-27

    Lactococcus lactis is a widely used mesophilic dairy starter and has been included in the Qualified Presumption of Safety (QPS) list of the European Food Safety Authority. However, it is increasingly found as the cause of human or animal infections, such as bovine mastitis, probably due to the improvement of the identification of the infective microorganisms. Since there are some grounds to suspect that at least certain variants of L. lactis may cause animal or human diseases, it is important to properly identify the differences between the strains associated with infections and the safe starter strains. Bovine mastitis isolates and dairy starter strains were genotypically characterized and clustered by the 16S rRNA gene sequence and RAPD-PCR fingerprint patterns, and phenotypically characterized by their tolerance to different stress conditions typically found in the intestinal tract of mammals, the carbohydrate- and antibiotic resistance profile, as well as the in vitro adhesion capacity to udder epithelial cells. Genotypically, there were no differences between the mastitis isolates and the dairy starter strains. However, there were clear phenotypic distinctions between mastitis isolates and typical starter strains, the former showing an increased tolerance to temperature, lysozyme, bile salts, pH and antibiotics, as well as improved carbohydrate fermentation capacity, and in vitro adhesion to udder epithelial cells. Although these differences might not be considered as actual virulence factors, they improve the ability of the strain to survive in the body of homeothermic animals and, interestingly, are also typical properties associated with potential probiotic strains. PMID:24080351

  5. Cholate-Stimulated Biofilm Formation by Lactococcus lactis Cells ? †

    PubMed Central

    Zaidi, Arsalan Haseeb; Bakkes, Patrick J.; Krom, Bastiaan P.; van der Mei, Henny C.; Driessen, Arnold J. M.

    2011-01-01

    Bile acid resistance by Lactococcus lactis depends on the ABC-type multidrug transporter LmrCD. Upon deletion of the lmrCD genes, cells can reacquire bile acid resistance upon prolonged exposure to cholate, yielding the ?lmrCDr strain. The resistance mechanism in this strain is non-transporter based. Instead, cells show a high tendency to flocculate, suggesting cell surface alterations. Contact angle measurements demonstrate that the ?lmrCDr cells are equipped with an increased cell surface hydrophilicity compared to those of the parental and wild-type strains, while the surface hydrophilicity is reduced in the presence of cholate. ?lmrCDr cells are poor in biofilm formation on a hydrophobic polystyrene surface, but in the presence of subinhibitory concentrations of cholate, biofilm formation is strongly stimulated. Biofilm cells show an enhanced extracellular polymeric substance production and are highly resistant to bile acids. These data suggest that non-transporter-based cholate resistance in L. lactis is due to alterations in the cell surface that stimulate cells to form resistant biofilms. PMID:21335382

  6. Expression of Helicobacter pylori hspA Gene in Lactococcus lactis NICE System and Experimental Study on Its Immunoreactivity

    PubMed Central

    Zhang, Xiao-Juan; Feng, Shu-Ying; Li, Zhi-Tao; Feng, Yan-Ming

    2015-01-01

    Aim. The aim of this study was to develop an oral Lactococcus lactis (L. lactis) vaccine against Helicobacter pylori (H. pylori). Methods. After L. lactis NZ3900/pNZ8110-hspA was constructed, growth curves were plotted to study whether the growth of recombinant L. lactis was affected after hspA was cloned into L. lactis and whether the growth of empty bacteria, empty plasmid bacteria, and recombinant L. lactis was affected by different concentrations of Nisin; SDS-PAGE and Western blot were adopted, respectively, to detect the HspA expressed by recombinant L. lactis and its immunoreactivity. Results. There was no effect observed from the growth curve after exogenous gene hspA was cloned into L. lactis NZ3900; different concentrations of Nisin did not affect the growth of NZ3900 and NZ3900/pNZ8110, while different concentrations of Nisin inhibited the growth of NZ3900/pNZ8110-hspA except 10?ng/mL Nisin. No HspA strip was observed from SDS-PAGE. Western blot analysis showed that HspA expressed by recombinant bacteria had favorable immunoreactivity. Conclusion. The growth of recombinant L. lactis was suppressed even though a small amount of HspA had been induced to express. Therefore recombinant L. lactis only express HspA which was not suitable to be oral vaccine against Helicobacter pylori. PMID:25977689

  7. Expression of Helicobacter pylori hspA Gene in Lactococcus lactis NICE System and Experimental Study on Its Immunoreactivity.

    PubMed

    Zhang, Xiao-Juan; Feng, Shu-Ying; Li, Zhi-Tao; Feng, Yan-Ming

    2015-01-01

    Aim. The aim of this study was to develop an oral Lactococcus lactis (L. lactis) vaccine against Helicobacter pylori (H. pylori). Methods. After L. lactis NZ3900/pNZ8110-hspA was constructed, growth curves were plotted to study whether the growth of recombinant L. lactis was affected after hspA was cloned into L. lactis and whether the growth of empty bacteria, empty plasmid bacteria, and recombinant L. lactis was affected by different concentrations of Nisin; SDS-PAGE and Western blot were adopted, respectively, to detect the HspA expressed by recombinant L. lactis and its immunoreactivity. Results. There was no effect observed from the growth curve after exogenous gene hspA was cloned into L. lactis NZ3900; different concentrations of Nisin did not affect the growth of NZ3900 and NZ3900/pNZ8110, while different concentrations of Nisin inhibited the growth of NZ3900/pNZ8110-hspA except 10?ng/mL Nisin. No HspA strip was observed from SDS-PAGE. Western blot analysis showed that HspA expressed by recombinant bacteria had favorable immunoreactivity. Conclusion. The growth of recombinant L. lactis was suppressed even though a small amount of HspA had been induced to express. Therefore recombinant L. lactis only express HspA which was not suitable to be oral vaccine against Helicobacter pylori. PMID:25977689

  8. Anaerobic sugar catabolism in Lactococcus lactis: genetic regulation and enzyme control over pathway flux.

    PubMed

    Cocaign-Bousquet, Muriel; Even, Sergine; Lindley, Nicolas D; Loubière, Pascal

    2002-10-01

    Lactic acid bacteria and particularly Lactococcus lactis are widely used for the production of lactic acid in fermented foods. Control of the catabolic rate in L. lactis, i.e., the rate of lactic acid production, appears to be determinant for dairy product quality. While the mechanisms involved in control have not been totally elucidated, they seem to depend upon the strain and the growth conditions. Furthermore, it remains unclear whether the catabolic rate is controlled at the level of transcription, translation or enzyme activity. The recent sequencing of the L. lactis genome has brought novel insights to physiologic studies of the bacteria. This review discusses both genetic information and metabolic studies concerning anaerobic sugar catabolism in L. lactis. PMID:12382039

  9. 21 CFR 184.1985 - Aminopeptidase enzyme preparation derived from lactococcus lactis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Aminopeptidase enzyme preparation derived from lactococcus...GRAS § 184.1985 Aminopeptidase enzyme preparation derived from lactococcus lactis. (a) Aminopeptidase enzyme preparation is derived from the...

  10. 21 CFR 184.1985 - Aminopeptidase enzyme preparation derived from lactococcus lactis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Aminopeptidase enzyme preparation derived from lactococcus...GRAS § 184.1985 Aminopeptidase enzyme preparation derived from lactococcus lactis. (a) Aminopeptidase enzyme preparation is derived from the...

  11. 21 CFR 184.1985 - Aminopeptidase enzyme preparation derived from lactococcus lactis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Aminopeptidase enzyme preparation derived from lactococcus...GRAS § 184.1985 Aminopeptidase enzyme preparation derived from lactococcus lactis. (a) Aminopeptidase enzyme preparation is derived from the...

  12. 21 CFR 184.1985 - Aminopeptidase enzyme preparation derived from lactococcus lactis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Aminopeptidase enzyme preparation derived from lactococcus...GRAS § 184.1985 Aminopeptidase enzyme preparation derived from lactococcus lactis. (a) Aminopeptidase enzyme preparation is derived from the...

  13. Comparative Genomics of Bifidobacterium animalis subsp. lactis Reveals a Strict Monophyletic Bifidobacterial Taxon

    PubMed Central

    Milani, Christian; Duranti, Sabrina; Lugli, Gabriele Andrea; Bottacini, Francesca; Strati, Francesco; Arioli, Stefania; Foroni, Elena; Turroni, Francesca; van Sinderen, Douwe

    2013-01-01

    Strains of Bifidobacterium animalis subsp. lactis are extensively exploited by the food industry as health-promoting bacteria, although the genetic variability of members belonging to this taxon has so far not received much scientific attention. In this article, we describe the complete genetic makeup of the B. animalis subsp. lactis Bl12 genome and discuss the genetic relatedness of this strain with other sequenced strains belonging to this taxon. Moreover, a detailed comparative genomic analysis of B. animalis subsp. lactis genomes was performed, which revealed a closely related and isogenic nature of all currently available B. animalis subsp. lactis strains, thus strongly suggesting a closed pan-genome structure of this bacterial group. PMID:23645200

  14. Lactococcus lactis Metabolism and Gene Expression during Growth on Plant Tissues

    PubMed Central

    Golomb, Benjamin L.

    2014-01-01

    Lactic acid bacteria have been isolated from living, harvested, and fermented plant materials; however, the adaptations these bacteria possess for growth on plant tissues are largely unknown. In this study, we investigated plant habitat-specific traits of Lactococcus lactis during growth in an Arabidopsis thaliana leaf tissue lysate (ATL). L. lactis KF147, a strain originally isolated from plants, exhibited a higher growth rate and reached 7.9-fold-greater cell densities during growth in ATL than the dairy-associated strain L. lactis IL1403. Transcriptome profiling (RNA-seq) of KF147 identified 853 induced and 264 repressed genes during growth in ATL compared to that in GM17 laboratory culture medium. Genes induced in ATL included those involved in the arginine deiminase pathway and a total of 140 carbohydrate transport and metabolism genes, many of which are involved in xylose, arabinose, cellobiose, and hemicellulose metabolism. The induction of those genes corresponded with L. lactis KF147 nutrient consumption and production of metabolic end products in ATL as measured by gas chromatography-time of flight mass spectrometry (GC-TOF/MS) untargeted metabolomic profiling. To assess the importance of specific plant-inducible genes for L. lactis growth in ATL, xylose metabolism was targeted for gene knockout mutagenesis. Wild-type L. lactis strain KF147 but not an xylA deletion mutant was able to grow using xylose as the sole carbon source. However, both strains grew to similarly high levels in ATL, indicating redundancy in L. lactis carbohydrate metabolism on plant tissues. These findings show that certain strains of L. lactis are well adapted for growth on plants and possess specific traits relevant for plant-based food, fuel, and feed fermentations. PMID:25384484

  15. Induction of Sucrose Utilization Genes from Bifidobacterium lactis by Sucrose and Raffinose

    Microsoft Academic Search

    Marla I. Trindade; Valerie R. Abratt; Sharon J. Reid

    2003-01-01

    The probiotic organism Bifidobacterium lactis was isolated from a yoghurt starter culture with the aim of analyzing its use of carbohydrates for the development of prebiotics. A sucrose utilization gene cluster of B. lactis was identified by complementation of a gene library in Escherichia coli. Three genes, encoding a sucrose phosphorylase (ScrP), a GalR-LacI-type transcriptional regulator (ScrR), and a sucrose

  16. Lactococcus lactis metabolism and gene expression during growth on plant tissues.

    PubMed

    Golomb, Benjamin L; Marco, Maria L

    2015-01-01

    Lactic acid bacteria have been isolated from living, harvested, and fermented plant materials; however, the adaptations these bacteria possess for growth on plant tissues are largely unknown. In this study, we investigated plant habitat-specific traits of Lactococcus lactis during growth in an Arabidopsis thaliana leaf tissue lysate (ATL). L. lactis KF147, a strain originally isolated from plants, exhibited a higher growth rate and reached 7.9-fold-greater cell densities during growth in ATL than the dairy-associated strain L. lactis IL1403. Transcriptome profiling (RNA-seq) of KF147 identified 853 induced and 264 repressed genes during growth in ATL compared to that in GM17 laboratory culture medium. Genes induced in ATL included those involved in the arginine deiminase pathway and a total of 140 carbohydrate transport and metabolism genes, many of which are involved in xylose, arabinose, cellobiose, and hemicellulose metabolism. The induction of those genes corresponded with L. lactis KF147 nutrient consumption and production of metabolic end products in ATL as measured by gas chromatography-time of flight mass spectrometry (GC-TOF/MS) untargeted metabolomic profiling. To assess the importance of specific plant-inducible genes for L. lactis growth in ATL, xylose metabolism was targeted for gene knockout mutagenesis. Wild-type L. lactis strain KF147 but not an xylA deletion mutant was able to grow using xylose as the sole carbon source. However, both strains grew to similarly high levels in ATL, indicating redundancy in L. lactis carbohydrate metabolism on plant tissues. These findings show that certain strains of L. lactis are well adapted for growth on plants and possess specific traits relevant for plant-based food, fuel, and feed fermentations. PMID:25384484

  17. Dietary Bifidobacterium lactis (HN019) enhances resistance to oral Salmonella typhimurium infection in mice.

    PubMed

    Shu, Q; Lin, H; Rutherfurd, K J; Fenwick, S G; Prasad, J; Gopal, P K; Gill, H S

    2000-01-01

    The ability of a newly identified probiotic lactic acid bacterial strain, Bifidobacterium lactis (HN019), to confer protection against Salmonella typhimurium was investigated in BALB/c mice. Feeding mice with B. lactis conferred a significant degree of protection against single or multiple oral challenge with virulent S. typhimurium, in comparison to control mice that did not receive B. lactis. Protection included a ten-fold increase in survival rate, significantly higher post-challenge food intake and weight gain, and reduced pathogen translocation to visceral tissues (spleen and liver). Furthermore, the degree of pathogen translocation showed a significant inverse correlation with splenic lymphocyte proliferative responses to mitogens, blood and peritoneal cell phagocytic activity and intestinal mucosal anti-S. typhimurium antibody titers in infected mice; all of these immune parameters were enhanced in mice fed B. lactis. Together, these results suggest that dietary B. lactis can provide a significant degree of protection against Salmonella infection by enhancing various parameters of immune function that are relevant to the immunological control of salmonellosis. Thus dietary supplementation with B. lactis provides a unique opportunity for developing immune-enhancing probiotic dairy food products with proven health benefits. PMID:10832963

  18. Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis

    Microsoft Academic Search

    Manilduth Ramnath; Safia Arous; Anne Gravesen; John W. Hastings; Yann Hechard

    2004-01-01

    Lactococcus lactis, using the NICE double plasmid system. Upon induction of the cloned operon, the recombinant Lc. lactis became sensitive to leucocin A. Pediocin PA-1 and enterocin A also showed inhibitory activity against Lc. lactis cultures expressing mptACD. Furthermore, the role of the three genes of the mptACD operon was investigated. Derivative plasmids containing various combinations of these three genes

  19. Evaluation of Lactococcus lactis Isolates from Nondairy Sources with Potential Dairy Applications Reveals Extensive Phenotype-Genotype Disparity and Implications for a Revised Species.

    PubMed

    Cavanagh, Daniel; Casey, Aidan; Altermann, Eric; Cotter, Paul D; Fitzgerald, Gerald F; McAuliffe, Olivia

    2015-06-15

    Lactococcus lactis is predominantly associated with dairy fermentations, but evidence suggests that the domesticated organism originated from a plant niche. L. lactis possesses an unusual taxonomic structure whereby strain phenotypes and genotypes often do not correlate, which in turn has led to confusion in L. lactis classification. A bank of L. lactis strains was isolated from various nondairy niches (grass, vegetables, and bovine rumen) and was further characterized on the basis of key technological traits, including growth in milk and key enzyme activities. Phenotypic analysis revealed all strains from nondairy sources to possess an L. lactis subsp. lactis phenotype (lactis phenotype); however, seven of these strains possessed an L. lactis subsp. cremoris genotype (cremoris genotype), determined by two separate PCR assays. Multilocus sequence typing (MLST) showed that strains with lactis and cremoris genotypes clustered together regardless of habitat, but it highlighted the increased diversity that exists among "wild" strains. Calculation of average nucleotide identity (ANI) and tetranucleotide frequency correlation coefficients (TETRA), using the JSpecies software tool, revealed that L. lactis subsp. cremoris and L. lactis subsp. lactis differ in ANI values by ?14%, below the threshold set for species circumscription. Further analysis of strain TIFN3 and strains from nonindustrial backgrounds revealed TETRA values of <0.99 in addition to ANI values of <95%, implicating that these two groups are separate species. These findings suggest the requirement for a revision of L. lactis taxonomy. PMID:25841018

  20. Characterization of a bacteriocin produced by Lactococcus lactis subsp. lactis CRL 1584 isolated from a Lithobates catesbeianus hatchery.

    PubMed

    Pasteris, Sergio E; Vera Pingitore, Esteban; Ale, Cesar E; Nader-Macías, María E Fatima

    2014-03-01

    Lactococcus lactis CRL 1584 isolated from a Lithobates catesbeianus hatchery inhibits the growth of Citrobacter freundii (a bullfrog pathogen) and Listeria monocytogenes by a synergistic effect between lactic acid, hydrogen peroxide and a bacteriocin-like molecule. The chemical characterization of the bacteriocin in cell-free supernatants indicates that it has a proteinaceous nature. Hexadecane and ethyl acetate did not modify the bacteriocin activity, while 10 and 20 % (v/v) chloroform decreased the activity by 29 and 43 %, respectively. The antimicrobial peptide was heat stable since 85 % of residual activity was detected when neutralized supernatants were heated at 80 °C for 30 min. Moreover, no bacteriocin inactivation was observed when supernatants were kept at -20 °C for 3 months. The synthesis of the bacteriocin was associated with bacterial growth, highest production (2,100 AU/ml) being detected at the end of the exponential growth phase. At pH ranges of 5-6.5 and 5.0-5.5 the inhibitory molecule was stable when stored for 2 days at 4 and 25 °C, respectively. Moreover, it had a bactericidal effect on L. monocytogenes and the ultrastructural studies of pathogenic cells revealed clumping of the cytoplasmic material, increased periplasmic space and cell wall modifications. The deduced amino acid sequence of the bacteriocin was identical to nisin Z and the genetic determinants for its production are harbored in the chromosome. These results, described for the first time in L. lactis from a bullfrog hatchery, will increase knowledge of the bacteriocin under study with a view to its potential inclusion in probiotics for raniculture or biopreservatives. PMID:24150985

  1. Interaction between the genomes of Lactococcus lactis and phages of the P335 species

    PubMed Central

    Kelly, William J.; Altermann, Eric; Lambie, Suzanne C.; Leahy, Sinead C.

    2013-01-01

    Phages of the P335 species infect Lactococcus lactis and have been particularly studied because of their association with strains of L. lactis subsp. cremoris used as dairy starter cultures. Unlike other lactococcal phages, those of the P335 species may have a temperate or lytic lifestyle, and are believed to originate from the starter cultures themselves. We have sequenced the genome of L. lactis subsp. cremoris KW2 isolated from fermented corn and found that it contains an integrated P335 species prophage. This 41 kb prophage (? KW2) has a mosaic structure with functional modules that are highly similar to several other phages of the P335 species associated with dairy starter cultures. Comparison of the genomes of 26 phages of the P335 species, with either a lytic or temperate lifestyle, shows that they can be divided into three groups and that the morphogenesis gene region is the most conserved. Analysis of these phage genomes in conjunction with the genomes of several L. lactis strains shows that prophage insertion is site specific and occurs at seven different chromosomal locations. Exactly how induced or lytic phages of the P335 species interact with carbohydrate cell surface receptors in the host cell envelope remains to be determined. Genes for the biosynthesis of a variable cell surface polysaccharide and for lipoteichoic acids (LTAs) are found in L. lactis and are the main candidates for phage receptors, as the genes for other cell surface carbohydrates have been lost from dairy starter strains. Overall, phages of the P335 species appear to have had only a minor role in the adaptation of L. lactis subsp. cremoris strains to the dairy environment, and instead they appear to be an integral part of the L. lactis chromosome. There remains a great deal to be discovered about their role, and their contribution to the evolution of the bacterial genome. PMID:24009606

  2. Lactose metabolism in Streptococcus lactis: studies with a mutant lacking glucokinase and mannose-phosphotransferase activities

    SciTech Connect

    Thompson, J.; Chassy, B.M.; Egan, W.

    1985-04-01

    A mutant of Streptococcus lactis 133 has been isolated that lacks both glucokinase and phosphoenolpyruvate-dependent mannose- phosphotransferase (mannose-PTS) activities. The double mutant S. lactis 133 mannose-PTSd GK- is unable to utilize either exogenously supplied or intracellularly generated glucose for growth. Fluorographic analyses of metabolites formed during the metabolism of (/sup 14/C)lactose labeled specifically in the glucose or galactosyl moiety established that the cells were unable to phosphorylate intracellular glucose. However, cells of S. lactis 133 mannose-PTSd GK- readily metabolized intracellular glucose 6-phosphate, and the growth rates and cell yield of the mutant and parental strains on sucrose were the same. During growth on lactose, S. lactis 133 mannose-PTSd GK- fermented only the galactose moiety of the disaccharide, and 1 mol of glucose was generated per mol of lactose consumed. For an equivalent concentration of lactose, the cell yield of the mutant was 50% that of the wild type. The specific rate of lactose utilization by growing cells of S. lactis 133 mannose-PTSd GK- was ca. 50% greater than that of the wild type, but the cell doubling times were 70 and 47 min, respectively. High-resolution /sup 31/P nuclear magnetic resonance studies of lactose transport by starved cells of S. lactis 133 and S. lactis 133 mannose-PTSd GK- showed that the latter cells contained elevated lactose-PTS activity. Throughout exponential growth on lactose, the mutant maintained an intracellular steady-state glucose concentration of 100 mM.

  3. Vaccination against Staphylococcus aureus experimental endocarditis using recombinant Lactococcus lactis expressing ClfA or FnbpA.

    PubMed

    Veloso, Tiago Rafael; Mancini, Stefano; Giddey, Marlyse; Vouillamoz, Jacques; Que, Yok-Ai; Moreillon, Philippe; Entenza, José Manuel

    2015-07-01

    Staphylococcus aureus is a major cause of serious infections in humans and animals and a vaccine is becoming a necessity. Lactococcus lactis is a non-pathogenic bacterium that can be used as a vector for the delivery of antigens. We investigated the ability of non-living L. lactis heterologously expressing S. aureus clumping factor A (ClfA) and fibronectin-binding protein A (FnbpA), alone or together, to elicit an immune response in rats and protect them from S. aureus experimental infective endocarditis (IE). L. lactis ClfA was used for immunization against S. aureus Newman (expressing ClfA but not FnbpA), while L. lactis ClfA, L. lactis FnbpA, as well as L. lactis ClfA/FnbpA, were used against S. aureus P8 (expressing ClfA and FnbpA). Vaccination of rats with L. lactis ClfA elicited antibodies that inhibited binding of S. aureus Newman to fibrinogen, triggered the production of IL-17A and conferred protection to 13/19 (68%) of the animals from IE (P<0.05). Immunization with L. lactis ClfA, L. lactis FnbpA or L. lactis ClfA/FnbpA also produced antibodies against the target proteins, but these did not prevent binding of S. aureus P8 to fibrinogen or fibronectin and did not protect animals against S. aureus P8 IE. Moreover, immunization with constructs containing FnbpA did not increase IL-17A production. These results indicate that L. lactis is a valuable antigen delivery system able to elicit efficient humoral and cellular responses. However, the most appropriate antigens affording protection against S. aureus IE are yet to be elucidated. PMID:26048778

  4. An X-Prolyl Dipeptidyl Aminopeptidase from Lactococcus lactis: Cloning, Expression in Escherichia coli, and Application for Removal of N-Terminal Pro-Pro from Recombinant Proteins

    Microsoft Academic Search

    Ming Xin; Yang Li; Lin Jie; Ding Min; Jingjing Liu

    2002-01-01

    A novel pepX gene was cloned from isolated DNA of Lactococcus lactis by PCR. The deduced amino acid sequence of the 89-kDa protein showed 94, 93, 65, and 44% identity with the pepX protein from Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Lactobacillus delbruecki subsp. bulgaricus, and Lactobacillus helveticus, respectively, and contained a serine protease G-K-S-Y-L-G consensus motif. The

  5. Characterization of the structural gene encoding nisin F, a new lantibiotic produced by a Lactococcus lactis subsp. lactis isolate from freshwater catfish (Clarias gariepinus).

    PubMed

    de Kwaadsteniet, M; Ten Doeschate, K; Dicks, L M T

    2008-01-01

    Lactococcus lactis F10, isolated from freshwater catfish, produces a bacteriocin (BacF) active against Staphylococcus aureus, Staphylococcus carnosus, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus reuteri. The operon encoding BacF is located on a plasmid. Sequencing of the structural gene revealed no homology to other nisin genes. Nisin F is described. PMID:18039827

  6. Host-pathogen interactions in specific pathogen-free chickens following aerogenous infection with Chlamydia psittaci and Chlamydia abortus.

    PubMed

    Kalmar, Isabelle; Berndt, Angela; Yin, Lizi; Chiers, Koen; Sachse, Konrad; Vanrompay, Daisy

    2015-03-15

    Although Chlamydia (C.) psittaci infections are recognized as an important factor causing economic losses and impairing animal welfare in poultry production, the specific mechanisms leading to severe clinical outcomes are poorly understood. In the present study, we comparatively investigated pathology and host immune response, as well as systemic dissemination and expression of essential chlamydial genes in the course of experimental aerogeneous infection with C. psittaci and the closely related C. abortus, respectively, in specific pathogen-free chicks. Clinical signs appeared sooner and were more severe in the C. psittaci-infected group. Compared to C. abortus infection, more intense systemic dissemination of C. psittaci correlated with higher and faster infiltration of immune cells, as well as more macroscopic lesions and epithelial pathology, such as hyperplasia and erosion. In thoracic air sac tissue, mRNA expression of immunologically relevant factors, such as IFN-?, IL-1?, IL-6, IL-17, IL-22, LITAF and iNOS was significantly stronger up-regulated in C. psittaci- than in C. abortus-infected birds between 3 and 14 days post-infection. Likewise, transcription rates of the chlamydial genes groEL, cpaf and ftsW were consistently higher in C. psittaci during the acute phase. These findings illustrate that the stronger replication of C. psittaci in its natural host also evoked a more intense immune response than in the case of C. abortus infection. PMID:25638671

  7. Staphylococcus aureus Virulence Expression Is Impaired by Lactococcus lactis in Mixed Cultures? †

    PubMed Central

    Even, Sergine; Charlier, Cathy; Nouaille, Sébastien; Ben Zakour, Nouri L.; Cretenet, Marina; Cousin, Fabien J.; Gautier, Michel; Cocaign-Bousquet, Muriel; Loubière, Pascal; Le Loir, Yves

    2009-01-01

    Staphylococcus aureus is responsible for numerous food poisonings due to the production of enterotoxins by strains contaminating foodstuffs, especially dairy products. Several parameters, including interaction with antagonistic flora such as Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, can modulate S. aureus proliferation and virulence expression. We developed a dedicated S. aureus microarray to investigate the effect of L. lactis on staphylococcal gene expression in mixed cultures. This microarray was used to establish the transcriptomic profile of S. aureus in mixed cultures with L. lactis in a chemically defined medium held at a constant pH (6.6). Under these conditions, L. lactis hardly affected S. aureus growth. The expression of most genes involved in the cellular machinery, carbohydrate and nitrogen metabolism, and stress responses was only slightly modulated: a short time lag in mixed compared to pure cultures was observed. Interestingly, the induction of several virulence factors and regulators, including the agr locus, sarA, and some enterotoxins, was strongly affected. This work clearly underlines the complexity of L. lactis antagonistic potential for S. aureus and yields promising leads for investigations into nonantibiotic biocontrol of this major pathogen. PMID:19429556

  8. Immunomodulatory effect of Lactococcus lactis JCM5805 on human plasmacytoid dendritic cells.

    PubMed

    Sugimura, Tetsu; Jounai, Kenta; Ohshio, Konomi; Tanaka, Takaaki; Suwa, Masahiro; Fujiwara, Daisuke

    2013-12-01

    Plasmacytoid dendritic cells (pDCs) play a crucial role in anti-viral immunity through production of large amounts of interferons (IFNs). A previous study revealed the existence of lactic acid bacteria that directly stimulate pDCs in mice. In this study, we demonstrated that Lactococcus lactis JCM5805 activates human pDCs and induces IFN production in vitro. In addition, our randomized, placebo-controlled, double blind test showed that yogurt fermented with L. lactis JCM5805 activated pDC activity in vivo. This effect was greater in low pDC subjects, and their ability to produce IFNs was increased from the beginning. Furthermore, the risk of morbidity from the common cold was suppressed in the L. lactis JCM5805 group compared with the placebo group. In conclusion, intake of L. lactis JCM5805 can directly activate pDCs and increase the ability to produce IFNs in vivo. Therefore, L. lactis JCM5805 may be a beneficial tool to enhance anti-viral immunity in humans. PMID:24239838

  9. Cooperation between Lactococcus lactis and Nonstarter Lactobacilli in the Formation of Cheese Aroma from Amino Acids

    PubMed Central

    Kieronczyk, Agnieszka; Skeie, Siv; Langsrud, Thor; Yvon, Mireille

    2003-01-01

    In Gouda and Cheddar type cheeses the amino acid conversion to aroma compounds, which is a major process for aroma formation, is essentially due to lactic acid bacteria (LAB). In order to evaluate the respective role of starter and nonstarter LAB and their interactions in cheese flavor formation, we compared the catabolism of phenylalanine, leucine, and methionine by single strains and strain mixtures of Lactococcus lactis subsp. cremoris NCDO763 and three mesophilic lactobacilli. Amino acid catabolism was studied in vitro at pH 5.5, by using radiolabeled amino acids as tracers. In the presence of ?-ketoglutarate, which is essential for amino acid transamination, the lactobacillus strains degraded less amino acids than L. lactis subsp. cremoris NCDO763, and produced mainly nonaromatic metabolites. L. lactis subsp. cremoris NCDO763 produced mainly the carboxylic acids, which are important compounds for cheese aroma. However, in the reaction mixture containing glutamate, only two lactobacillus strains degraded amino acids significantly. This was due to their glutamate dehydrogenase (GDH) activity, which produced ?-ketoglutarate from glutamate. The combination of each of the GDH-positive lactobacilli with L. lactis subsp. cremoris NCDO763 had a beneficial effect on the aroma formation. Lactobacilli initiated the conversion of amino acids by transforming them mainly to keto and hydroxy acids, which subsequently were converted to carboxylic acids by the Lactococcus strain. Therefore, we think that such cooperation between starter L. lactis and GDH-positive lactobacilli can stimulate flavor development in cheese. PMID:12570989

  10. Metabolic engineering of Lactococcus lactis influence of the overproduction of lipase enzyme.

    PubMed

    Raftari, Mohammad; Ghafourian, Sobhan; Bakar, Fatimah Abu

    2013-11-01

    The dairy industry uses lipase extensively for hydrolysis of milk fat. Lipase is used in the modification of the fatty acid chain length, to enhance the flavours of various chesses. Therefore finding the unlimited source of lipase is a concern of dairy industry. Due to the importance of lipase, this study was an attempt to express the lipase from Burkholderia cepacia in Lactococcus lactis. To achieve this, a gene associated with lipase transport was amplified and subcloned in inducible pNZ8148 vector, and subsequently transformed into Lc. lactis NZ9000. The enzyme assay as well as SDS-PAGE and western blotting were carried out to analysis the recombinant lipase expression. Nucleotide sequencing of the DNA insert from the clone revealed that the lipase activity corresponded to an open reading frame consisting of 1092 bp coding for a 37·5-kDa size protein. Blue colour colonies on nile blue sulphate agar and sharp band on 37·5-kD size on SDS-PAGE and western blotting results confirm the successful expression of lipase by Lc. lactis. The protein assay also showed high expression, approximately 152·2 ?g/ml.h, of lipase by recombinant Lc. lactis. The results indicate that Lc. lactis has high potential to overproduce the recombinant lipase which can be used commercially for industrially purposes. PMID:24063299

  11. Molecular Physiology of Sugar Catabolism in Lactococcus lactis IL1403

    PubMed Central

    Even, Sergine; Lindley, Nic D.; Cocaign-Bousquet, Muriel

    2001-01-01

    The metabolic characteristics of Lactococcus lactis IL1403 were examined on two different growth media with respect to the physiological response to two sugars, glucose and galactose. Analysis of specific metabolic rates indicated that despite significant variations in the rates of both growth and sugar consumption, homolactic fermentation was maintained for all cultures due to the low concentration of either pyruvate-formate lyase or alcohol dehydrogenase. When the ionophore monensin was added to the medium, flux through glycolysis was not increased, suggesting a catabolic flux limitation, which, with the low intracellular concentrations of glycolytic intermediates and high in vivo glycolytic enzyme capacities, may be at the level of sugar transport. To assess transcription, a novel DNA macroarray technology employed RNA labeled in vitro with digoxigenin and detection of hybrids with an alkaline phosphatase-antidigoxigenin conjugate. This method showed that several genes of glycolysis were expressed to higher levels on glucose and that the genes of the mixed-acid pathway were expressed to higher levels on galactose. When rates of enzyme synthesis are compared to transcript concentrations, it can be deduced that some translational regulation occurs with threefold-higher translational efficiency in cells grown on glucose. PMID:11395443

  12. Molecular physiology of sugar catabolism in Lactococcus lactis IL1403.

    PubMed

    Even, S; Lindley, N D; Cocaign-Bousquet, M

    2001-07-01

    The metabolic characteristics of Lactococcus lactis IL1403 were examined on two different growth media with respect to the physiological response to two sugars, glucose and galactose. Analysis of specific metabolic rates indicated that despite significant variations in the rates of both growth and sugar consumption, homolactic fermentation was maintained for all cultures due to the low concentration of either pyruvate-formate lyase or alcohol dehydrogenase. When the ionophore monensin was added to the medium, flux through glycolysis was not increased, suggesting a catabolic flux limitation, which, with the low intracellular concentrations of glycolytic intermediates and high in vivo glycolytic enzyme capacities, may be at the level of sugar transport. To assess transcription, a novel DNA macroarray technology employed RNA labeled in vitro with digoxigenin and detection of hybrids with an alkaline phosphatase-antidigoxigenin conjugate. This method showed that several genes of glycolysis were expressed to higher levels on glucose and that the genes of the mixed-acid pathway were expressed to higher levels on galactose. When rates of enzyme synthesis are compared to transcript concentrations, it can be deduced that some translational regulation occurs with threefold-higher translational efficiency in cells grown on glucose. PMID:11395443

  13. Heterologous expression of Brucella abortus GroEL heat-shock protein in Lactococcus lactis

    PubMed Central

    Miyoshi, Anderson; Bermúdez-Humarán, Luis G; Ribeiro, Luciana A; Le Loir, Yves; Oliveira, Sérgio C; Langella, Philippe; Azevedo, Vasco

    2006-01-01

    Background Brucella abortus is a facultative intracellular pathogen that mainly infects cattle and humans. Current vaccines rely on live attenuated strains of B. abortus, which can revert to their pathogenic status and thus are not totally safe for use in humans. Therefore, the development of mucosal live vaccines using the food-grade lactic acid bacterium, Lactococcus lactis, as an antigen delivery vector, is an attractive alternative and a safer vaccination strategy against B. abortus. Here, we report the construction of L. lactis strains genetically modified to produce B. abortus GroEL heat-shock protein, a candidate antigen, in two cellular locations, intracellular or secreted. Results Only the secreted form of GroEL was stably produced in L. lactis, suggesting a detrimental effect of GroEL protein when intracellularly produced in this bacterium. Only trace amounts of mature GroEL were detected in the supernatant fraction of induced lactococcal cultures, and the GroEL precursor remained stacked in the cell fraction. Attempts to raise the secretion yields were made, but even when GroEL was fused to a synthetic propeptide, secretion of this antigen was not improved. Conclusion We found that L. lactis is able to produce, and to secrete, a stable form of GroEL into the extracellular medium. Despite the low secretion efficiency of GroEL, which suggest that this antigen interacts with the cell envelope of L. lactis, secretion seems to be the best way to achieve both production and protein yields, regardless of cellular location. The L. lactis strain secreting GroEL has potential for in vivo immunization. PMID:16556312

  14. Bifidobacterium animalis subsp. lactis ATCC 27673 Is a Genomically Unique Strain within Its Conserved Subspecies

    PubMed Central

    Loquasto, Joseph R.; Barrangou, Rodolphe; Dudley, Edward G.; Stahl, Buffy; Chen, Chun

    2013-01-01

    Many strains of Bifidobacterium animalis subsp. lactis are considered health-promoting probiotic microorganisms and are commonly formulated into fermented dairy foods. Analyses of previously sequenced genomes of B. animalis subsp. lactis have revealed little genetic diversity, suggesting that it is a monomorphic subspecies. However, during a multilocus sequence typing survey of Bifidobacterium, it was revealed that B. animalis subsp. lactis ATCC 27673 gave a profile distinct from that of the other strains of the subspecies. As part of an ongoing study designed to understand the genetic diversity of this subspecies, the genome of this strain was sequenced and compared to other sequenced genomes of B. animalis subsp. lactis and B. animalis subsp. animalis. The complete genome of ATCC 27673 was 1,963,012 bp, contained 1,616 genes and 4 rRNA operons, and had a G+C content of 61.55%. Comparative analyses revealed that the genome of ATCC 27673 contained six distinct genomic islands encoding 83 open reading frames not found in other strains of the same subspecies. In four islands, either phage or mobile genetic elements were identified. In island 6, a novel clustered regularly interspaced short palindromic repeat (CRISPR) locus which contained 81 unique spacers was identified. This type I-E CRISPR-cas system differs from the type I-C systems previously identified in this subspecies, representing the first identification of a different system in B. animalis subsp. lactis. This study revealed that ATCC 27673 is a strain of B. animalis subsp. lactis with novel genetic content and suggests that the lack of genetic variability observed is likely due to the repeated sequencing of a limited number of widely distributed commercial strains. PMID:23995933

  15. Effects of eliminating pyruvate node pathways and of coexpression of heterogeneous carboxylation enzymes on succinate production by Enterobacter aerogenes.

    PubMed

    Tajima, Yoshinori; Yamamoto, Yoko; Fukui, Keita; Nishio, Yousuke; Hashiguchi, Kenichi; Usuda, Yoshihiro; Sode, Koji

    2015-02-01

    Lowering the pH in bacterium-based succinate fermentation is considered a feasible approach to reduce total production costs. Newly isolated Enterobacter aerogenes strain AJ110637, a rapid carbon source assimilator under weakly acidic (pH 5.0) conditions, was selected as a platform for succinate production. Our previous work showed that the ?adhE/PCK strain, developed from AJ110637 with inactivated ethanol dehydrogenase and introduced Actinobacillus succinogenes phosphoenolpyruvate carboxykinase (PCK), generated succinate as a major product of anaerobic mixed-acid fermentation from glucose under weakly acidic conditions (pH <6.2). To further improve the production of succinate by the ?adhE/PCK strain, metabolically engineered strains were designed based on the elimination of pathways that produced undesirable products and the introduction of two carboxylation pathways from phosphoenolpyruvate and pyruvate to oxaloacetate. The highest production of succinate was observed with strain ES04/PCK+PYC, which had inactivated ethanol, lactate, acetate, and 2,3-butanediol pathways and coexpressed PCK and Corynebacterium glutamicum pyruvate carboxylase (PYC). This strain produced succinate from glucose with over 70% yield (gram per gram) without any measurable formation of ethanol, lactate, or 2,3-butanediol under weakly acidic conditions. The impact of lowering the pH from 7.0 to 5.5 on succinate production in this strain was evaluated under pH-controlled batch culture conditions and showed that the lower pH decreased the succinate titer but increased its yield. These findings can be applied to identify additional engineering targets to increase succinate production. PMID:25416770

  16. Respiration Capacity of the Fermenting Bacterium Lactococcus lactis and Its Positive Effects on Growth and Survival†

    PubMed Central

    Duwat, Patrick; Sourice, Sophie; Cesselin, Bénédicte; Lamberet, Gilles; Vido, Karin; Gaudu, Philippe; Le Loir, Yves; Violet, Florent; Loubière, Pascal; Gruss, Alexandra

    2001-01-01

    Oxygen is a major determinant of both survival and mortality of aerobic organisms. For the facultative anaerobe Lactococcus lactis, oxygen has negative effects on both growth and survival. We show here that oxygen can be beneficial to L. lactis if heme is present during aerated growth. The growth period is extended and long-term survival is markedly improved compared to results obtained under the usual fermentation conditions. We considered that improved growth and survival could be due to the capacity of L. lactis to undergo respiration. To test this idea, we confirmed that the metabolic behavior of lactococci in the presence of oxygen and hemin is consistent with respiration and is most pronounced late in growth. We then used a genetic approach to show the following. (i) The cydA gene, encoding cytochrome d oxidase, is required for respiration and plays a direct role in oxygen utilization. cydA expression is induced late in growth under respiration conditions. (ii) The hemZ gene, encoding ferrochelatase, which converts protoporphyrin IX to heme, is needed for respiration if the precursor, rather than the final heme product, is present in the medium. Surprisingly, survival improved by respiration is observed in a superoxide dismutase-deficient strain, a result which emphasizes the physiological differences between fermenting and respiring lactococci. These studies confirm respiratory metabolism in L. lactis and suggest that this organism may be better adapted to respiration than to traditional fermentative metabolism. PMID:11443085

  17. Lactococcus lactis, an Alternative System for Functional Expression of Peripheral and Intrinsic Arabidopsis Membrane Proteins

    Microsoft Academic Search

    Annie Frelet-Barrand; Sylvain Boutigny; Lucas Moyet; Aurélien Deniaud; Daphné Seigneurin-Berny; Daniel Salvi; Florent Bernaudat; Pierre Richaud; Eva Pebay-Peyroula; Jacques Joyard; Norbert Rolland; Paulo Lee Ho

    2010-01-01

    BackgroundDespite their functional and biotechnological importance, the study of membrane proteins remains difficult due to their hydrophobicity and their low natural abundance in cells. Furthermore, into established heterologous systems, these proteins are frequently only produced at very low levels, toxic and mis- or unfolded. Lactococcus lactis, a Gram-positive lactic bacterium, has been traditionally used in food fermentations. This expression system

  18. Heterologous expression of the Bacillus subtilis (natto) alanine dehydrogenase in Escherichia coli and Lactococcus lactis.

    PubMed

    Ye, Wei; Huo, Guicheng; Chen, Junliang; Liu, Fei; Yin, Jingyuan; Yang, Lijie; Ma, Xiaolong

    2010-05-30

    The major objective of the present study is to change the alanine production of Lactic acid bacteria by expression of Bacillus subtilis (natto) alanine dehydrogenase (AlaDH), the gene that is not present in Lactic acid. B. subtilis AlaDH gene (ald) was cloned into a pGEX6p-1 and expressed in E. coli JM109. Its enzyme activity was 48.3U/mg at 30 degrees C and 45.2U/mg at 42 degrees C. This ald gene was then cloned into a vector pNZ8148 to generate a vector pNZ8148/ald. The same ald gene was placed downstream of the ldh promoter from Streptococcus thermophilus to generate pNZ273/ldhp/ald. The pNZ8148/ald and pNZ273/ldhp/ald were introduced separately in Lactococcus lactis NZ9000. As a result of over-expressed ald, the production of alanine detected by HPLC in L. lactis NZ9000 carrying pNZ273/ldhp/ald reached 52mug/ml, an approximately 26-fold increase compared to the parent strain L. lactis NZ9000, but not in L. lactis NZ9000 carrying pNZ8148/ald. This study would help strain improvement to be used in dairy fermentation for developing healthy yogurts with sweet taste or other fermented dairy foods. PMID:19720515

  19. Allergy Therapy by Intranasal Administration with Recombinant Lactococcus lactis Producing Bovine ?-Lactoglobulin

    Microsoft Academic Search

    Naima G. Cortes-Perez; Sandrine Ah-Leung; Luis G. Bermúdez-Humarán; Gérard Corthier; Philippe Langella; Jean-Michel Wal; Karine Adel-Patient

    2009-01-01

    Background: In the last years, the use of probiotics such as lactic acid bacteria (LAB) has been proposed as an attractive alternative for the management of allergic diseases. A partial prevention from sensitization to bovine ?-lactoglobulin (BLG), one of the major cows’ milk allergens, could be achieved in mice after intranasal administration with a recombinant LAB strain, Lactococcus lactis, producing

  20. The las Enzymes Control Pyruvate Metabolism in Lactococcus lactis during Growth on Maltose?

    PubMed Central

    Solem, Christian; Koebmann, Brian; Yang, Fen; Jensen, Peter R.

    2007-01-01

    The fermentation pattern of Lactococcus lactis with altered activities of the las enzymes was examined on maltose. The wild type converted 65% of the maltose to mixed acids. An increase in phosphofructokinase or lactate dehydrogenase expression shifted the fermentation towards homolactic fermentation, and with a high level of expression of the las operon the fermentation was homolactic. PMID:17616595

  1. Genome Sequence of Lactococcus lactis subsp. cremoris Mast36, a Strain Isolated from Bovine Mastitis

    PubMed Central

    Gazzola, Simona; Fontana, Cecilia; Bassi, Daniela; Cocconcelli, Pier-Sandro; von Wright, Atte

    2015-01-01

    The genome sequence of Lactococcus lactis subsp. cremoris Mast36, isolated from bovine mastitis, is reported here. This strain was shown to be able to grow in milk and still possess genes of vegetable origin. The genome also contains a cluster of genes associated with pathogenicity. PMID:25999570

  2. The Plasmid Complement of Lactococcus lactis UC509.9 Encodes Multiple Bacteriophage Resistance Systems

    PubMed Central

    Ainsworth, Stuart; Mahony, Jennifer

    2014-01-01

    Lactococcus lactis subsp. cremoris strains are used globally for the production of fermented dairy products, particularly hard cheeses. Believed to be of plant origin, L. lactis strains that are used as starter cultures have undergone extensive adaptation to the dairy environment, partially through the acquisition of extrachromosomal DNA in the form of plasmids that specify technologically important phenotypic traits. Here, we present a detailed analysis of the eight plasmids of L. lactis UC509.9, an Irish dairy starter strain. Key industrial phenotypes were mapped, and genes that are typically associated with lactococcal plasmids were identified. Four distinct, plasmid-borne bacteriophage resistance systems were identified, including two abortive infection systems, AbiB and AbiD1, thereby supporting the observed phage resistance of L. lactis UC509.9. AbiB escape mutants were generated for phage sk1, which were found to carry mutations in orf6, which encodes the major capsid protein of this phage. PMID:24814781

  3. Genome Sequence of the Probiotic Strain Bifidobacterium animalis subsp. lactis CNCM I-2494

    PubMed Central

    Chervaux, Christian; Grimaldi, Christine; Bolotin, Alexander; Quinquis, Benoit; Legrain-Raspaud, Sophie; van Hylckama Vlieg, Johan E. T.; Denariaz, Gerard; Smokvina, Tamara

    2011-01-01

    Bifidobacterium animalis subsp. lactis CNCM I-2494 is part of a commercialized fermented dairy product with documented health benefits revealed by multiple randomized placebo-controlled clinical trials. Here we report the complete genome sequence of this strain, which has a circular genome of 1,943,113 bp with 1,660 open reading frames and 4 ribosomal operons. PMID:21914878

  4. Diversity in Robustness of Lactococcus lactis Strains during Heat Stress, Oxidative Stress, and Spray Drying Stress

    PubMed Central

    Dijkstra, Annereinou R.; Setyawati, Meily C.; Bayjanov, Jumamurat R.; Alkema, Wynand; van Hijum, Sacha A. F. T.; Hugenholtz, Jeroen

    2014-01-01

    In this study we tested 39 Lactococcus lactis strains isolated from diverse habitats for their robustness under heat and oxidative stress, demonstrating high diversity in survival (up to 4 log units). Strains with an L. lactis subsp. lactis phenotype generally displayed more-robust phenotypes than strains with an L. lactis subsp. cremoris phenotype, whereas the habitat from which the strains had been isolated did not appear to influence stress survival. Comparison of the stress survival phenotypes with already available comparative genomic data sets revealed that the absence or presence of specific genes, including genes encoding a GntR family transcriptional regulator, a manganese ABC transporter permease, a cellobiose phosphotransferase system (PTS) component, the FtsY protein, and hypothetical proteins, was associated with heat or oxidative stress survival. Finally, 14 selected strains also displayed diversity in survival after spray drying, ranging from 20% survival for the most robust strains, which appears acceptable for industrial application, to 0.1% survival for the least-tolerant strains. The high and low levels of survival upon spray drying correlated clearly with the combined robustness under heat and oxidative stress. These results demonstrate the relevance of screening culture collections for robustness under heat and oxidative stress on top of the typical screening for acidifying and flavor-forming properties. PMID:24212574

  5. Complete Genome Sequence of Lactococcus lactis Strain AI06, an Endophyte of the Amazonian Açaí Palm.

    PubMed

    McCulloch, John Anthony; de Oliveira, Viviane Matoso; de Almeida Pina, André Vicioli; Pérez-Chaparro, Paula Juliana; de Almeida, Lara Mendes; de Vasconcelos, Janaina Mota; de Oliveira, Layanna Freitas; da Silva, Daisy Elaine Andrade; Rogez, Hervé Louis Ghislain; Cretenet, Marina; Mamizuka, Elsa Masae; Nunes, Marcio Roberto Teixeira

    2014-01-01

    We report the genome, in a single chromosome, of Lactococcus lactis strain AI06, isolated from the mesocarp of the açaí fruit (Euterpe oleracea) in eastern Amazonia, Brazil. This strain is an endophyte of the açaí palm and also a component of the microbiota of the edible food product. PMID:25414513

  6. Sugar metabolism, redox balance and oxidative stress response in the respiratory yeast Kluyveromyces lactis

    Microsoft Academic Search

    M. Isabel Gonzalez-Siso; Ana García-Leiro; Nuria Tarrío; M. Esperanza Cerdan

    2009-01-01

    A lot of studies have been carried out on Saccharomyces cerevisiae, an yeast with a predominant fermentative metabolism under aerobic conditions, which allows exploring the complex response induced by oxidative stress. S. cerevisiae is considered a eukaryote model for these studies. We propose Kluyveromyces lactis as a good alternative model to analyse variants in the oxidative stress response, since the

  7. Regulation of Exopolysaccharide Production by Lactococcus lactis subsp. cremoris by the Sugar Source

    Microsoft Academic Search

    PETRONELLA J. LOOIJESTEIJN; INGEBORG C. BOELS; MICHIEL KLEEREBEZEM; JEROEN HUGENHOLTZ

    1999-01-01

    Lactococcus lactis produced more exopolysaccharide (EPS) on glucose than on fructose as the sugar sub- strate, although the transcription level of the eps gene cluster was independent of the sugar source. A major difference between cells grown on the two substrates was the capacity to produce sugar nucleotides, the EPS precursors. However, the activities of the enzymes required for the

  8. Gene regulation in Lactococcus lactis : the gap between predicted and characterized regulators

    Microsoft Academic Search

    Eric Guédon; Emmanuel Jamet; Pierre Renault

    2002-01-01

    The genome sequence of Lactococcus lactis IL1403 was previously determined with high quality, allowing a reliable determination of the potential ORFs present in the genome. It encodes 2310 proteins, and 138 of them were assigned as potential regulators, half of which being further classified by their similarity to known protein families. Among these regulators, most could have a direct role

  9. Conservation of key elements of natural competence in Lactococcus lactis ssp

    Microsoft Academic Search

    Sandra Wydau; Rozenn Dervyn; Jamila Anba; S. Dusko Ehrlich; Emmanuelle Maguin

    2006-01-01

    Natural competence is active in very diverse species of the bacterial kingdom and probably participates in horizontal gene transfer. Recently, the genome sequence of various species, including Lactococcus lactis, revealed the presence of homologues of competence genes in bacteria, which were not previously identified as naturally transformable. We investigated the conservation among lactococcal strains of key components of the natural

  10. Production of Pediocin PA-1 by Lactococcus lactis Using the Lactococcin A Secretory Apparatus

    PubMed Central

    Horn, Nikki; Martínez, María I.; Martínez, José M.; Hernández, Pablo E.; Gasson, Michael J.; Rodríguez, Juan M.; Dodd, Helen M.

    1998-01-01

    The class II bacteriocins pediocin PA-1, from Pediococcus acidilactici, and lactococcin A, from Lactococcus lactis subsp. lactis bv. diacetylactis WM4 have a number of features in common. They are produced as precursor peptides containing similar amino-terminal leader sequences with a conserved processing site (Gly-Gly at positions ?1 and ?2). Translocation of both bacteriocins occurs via a dedicated secretory system. Because of the strong antilisterial activity of pediocin PA-1, its production by lactic acid bacteria strains adapted to dairy environments would considerably extend its application in the dairy industry. In this study, the lactococcin A secretory system was adapted for the expression and secretion of pediocin PA-1. A vector containing an in-frame fusion of sequences encoding the lcnA promoter, the lactococcin A leader, and the mature pediocin PA-1, was introduced into L. lactis IL1403. This strain is resistant to pediocin PA-1 and encodes a lactococcin translocation apparatus. The resulting L. lactis strains secreted a bacteriocin with an antimicrobial activity of approximately 25% of that displayed by the parental pediocin-producing P. acidilactici 347. A noncompetitive indirect enzyme-linked immunosorbent assay with pediocin PA-1-specific antibodies and amino-terminal amino acid sequencing confirmed that pediocin PA-1 was being produced by the heterologous host. PMID:9501421

  11. Novel paired starter culture system for sauerkraut, consisting of a nisin-resistant Leuconostoc mesenteroides strain and a nisin-producing Lactococcus lactis strain.

    PubMed Central

    Harris, L J; Fleming, H P; Klaenhammer, T R

    1992-01-01

    Nisin-resistant Leuconostoc mesenteroides NCK293 and nisin-producing Lactococcus lactis subsp. lactis NCK401 were evaluated separately and in combination for growth and nisin production in a model sauerkraut fermentation. Strains were genetically marked and selectively enumerated by using antibiotic-containing media. The growth and survival of L. mesenteroides were similar in the presence and absence of Lactococcus lactis subsp. lactis. The growth of Lactococcus lactis subsp. lactis was not inhibited, although the maximum cell density was reduced and the population decline was more pronounced in the presence of L. mesenteroides. Nisin was detected within 24 h, and levels were relatively constant over the 12-day test period. The maximum cell populations and nisin level achieved could be altered by changing the initial cell ratios of L. mesenteroides and lactococcus lactis subsp. lactis. Isogenic nisin-producing and nisin-negative Lactococcus lactis subsp. lactis derivatives were used in combination with nisin-resistant L. mesenteroides to demonstrate that nisin levels produced in mixed culture were sufficient to retard the onset of the growth of nisin-sensitive, homofermentative Lactobacillus plantarum ATCC 14917. PMID:1622215

  12. Novel paired starter culture system for sauerkraut, consisting of a nisin-resistant Leuconostoc mesenteroides strain and a nisin-producing Lactococcus lactis strain.

    PubMed

    Harris, L J; Fleming, H P; Klaenhammer, T R

    1992-05-01

    Nisin-resistant Leuconostoc mesenteroides NCK293 and nisin-producing Lactococcus lactis subsp. lactis NCK401 were evaluated separately and in combination for growth and nisin production in a model sauerkraut fermentation. Strains were genetically marked and selectively enumerated by using antibiotic-containing media. The growth and survival of L. mesenteroides were similar in the presence and absence of Lactococcus lactis subsp. lactis. The growth of Lactococcus lactis subsp. lactis was not inhibited, although the maximum cell density was reduced and the population decline was more pronounced in the presence of L. mesenteroides. Nisin was detected within 24 h, and levels were relatively constant over the 12-day test period. The maximum cell populations and nisin level achieved could be altered by changing the initial cell ratios of L. mesenteroides and lactococcus lactis subsp. lactis. Isogenic nisin-producing and nisin-negative Lactococcus lactis subsp. lactis derivatives were used in combination with nisin-resistant L. mesenteroides to demonstrate that nisin levels produced in mixed culture were sufficient to retard the onset of the growth of nisin-sensitive, homofermentative Lactobacillus plantarum ATCC 14917. PMID:1622215

  13. Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis.

    PubMed

    Ramnath, Manilduth; Arous, Safia; Gravesen, Anne; Hastings, John W; Héchard, Yann

    2004-08-01

    Sensitivity to class IIa bacteriocins from lactic acid bacteria was recently associated with the mannose phosphotransferase system (PTS) permease, in Listeria monocytogenes. To assess the involvement of this protein complex in class IIa bacteriocin activity, the mptACD operon, encoding, was heterologously expressed in an insensitive species, namely Lactococcus lactis, using the NICE double plasmid system. Upon induction of the cloned operon, the recombinant Lc. lactis became sensitive to leucocin A. Pediocin PA-1 and enterocin A also showed inhibitory activity against Lc. lactis cultures expressing mptACD. Furthermore, the role of the three genes of the mptACD operon was investigated. Derivative plasmids containing various combinations of these three genes were made from the parental mptACD plasmid by divergent PCR. The results showed that expression of mptC alone is sufficient to confer sensitivity to class IIa bacteriocins in Lc. lactis. PMID:15289562

  14. Plasmid Complements ofStreptococcus lactis NCDO 712and Other Lactic Streptococci After Protoplast-Induced Curing

    Microsoft Academic Search

    MICHAELJ. GASSON

    traits inStreptococcus lactis subsp. diacetylactis strains. Theloss offive different plasmids, including small multicopy molecules, wasreadily detected inStreptococcus lactis 712byscreening lysates ofrandom protoplast regenerants onagarose gels. Inthisstrain sequential rounds of protoplast regeneration wereused toproduce aplasmid-free strain andderivatives carrying onlysingle molecules fromtheplasmid complement. During these experiments a33-megadalton plasmid, pLP712, wasfound toencode genesfor lactose andprotein utilization. Onlythis plasmid wasrequired fornormal growth andacid production

  15. Characterization of Plasmid-Encoded Citrate Permease (citP) Genes fromLeuconostocSpecies Reveals High Sequence Conservation with theLactococcus lactis citPGene

    Microsoft Academic Search

    ELAINE E. VAUGHAN; SILKE DAVID; AIDAN HARRINGTON; CHARLES DALY; GERALD F. FITZGERALD; M. DE VOS

    1995-01-01

    The citrate permease determinant (citP) in several Leuconostoc strains was demonstrated to be plasmid encoded by curing experiments and hybridization studies with a DNA fragment containing thecitPgene from Lactococcus lactis subsp. lactis biovar diacetylactis NCDO176. Cloning and nucleotide sequence analysis of Leuconostoc lactisNZ6070citPrevealed almost complete identity to lactococcalcitP. StrainsbelongingtothegenusLeuconostocformanessential component of mesophilic starter cultures used in the manufac- ture of

  16. Direct Identification of Staphylococcus aureus and Determination of Methicillin Susceptibility From Positive Blood-Culture Bottles in a Bact/ALERT System Using Binax Now S. aureus and PBP2a Tests.

    PubMed

    Heraud, Sandrine; Freydiere, Anne-Marie; Doleans-Jordheim, Anne; Bes, Michèle; Tristan, Anne; Vandenesch, François; Laurent, Frederic; Dauwalder, Olivier

    2015-07-01

    Staphylococcus aureus bacteremia is associated with high mortality and morbidity, requiring prompt and appropriate antimicrobial treatment. Therefore, it is important to detect methicillin-resistant S. aureus (MRSA) rapidly from blood cultures. Two immunochromatographic tests, BinaxNow S. aureus and BinaxNow PBP2a, were directly applied to 79 Bact/Alert bottles that were positive for Gram positive cocci in cluster aggregations. Sensitivity and specificity for the identification of S. aureus and determination of methicillin resistance were 94% and 87%, and 100% and 100%, respectively, with less than 30 min of performance time. These tests are efficient and rapid; these tests are valuable alternatives to more sophisticated and expensive methods used in the diagnosis of MRSA bacteremia. PMID:26131419

  17. Direct Identification of Staphylococcus aureus and Determination of Methicillin Susceptibility From Positive Blood-Culture Bottles in a Bact/ALERT System Using Binax Now S. aureus and PBP2a Tests

    PubMed Central

    Heraud, Sandrine; Freydiere, Anne-Marie; Doleans-Jordheim, Anne; Bes, Michèle; Tristan, Anne; Vandenesch, François; Laurent, Frederic

    2015-01-01

    Staphylococcus aureus bacteremia is associated with high mortality and morbidity, requiring prompt and appropriate antimicrobial treatment. Therefore, it is important to detect methicillin-resistant S. aureus (MRSA) rapidly from blood cultures. Two immunochromatographic tests, BinaxNow S. aureus and BinaxNow PBP2a, were directly applied to 79 Bact/Alert bottles that were positive for Gram positive cocci in cluster aggregations. Sensitivity and specificity for the identification of S. aureus and determination of methicillin resistance were 94% and 87%, and 100% and 100%, respectively, with less than 30 min of performance time. These tests are efficient and rapid; these tests are valuable alternatives to more sophisticated and expensive methods used in the diagnosis of MRSA bacteremia.

  18. Safety of Bifidobacterium animalis subsp. lactis (B. lactis) strain BB-12-supplemented yogurt in healthy adults on antibiotics: a phase I safety study.

    PubMed

    Merenstein, Daniel J; Tan, Tina P; Molokin, Aleksey; Smith, Keisha Herbin; Roberts, Robert F; Shara, Nawar M; Mete, Mihriye; Sanders, Mary Ellen; Solano-Aguilar, Gloria

    2015-01-01

    Probiotics are live microorganisms that, when administered in sufficient doses, provide health benefits on the host. The United States Food and Drug Administration (FDA) requires phase I safety studies for probiotics when the intended use of the product is as a drug. The purpose of the study was to determine the safety of Bifidobacterium animalis subsp lactis (B. lactis) strain BB-12 (BB-12)-supplemented yogurt when consumed by a generally healthy group of adults who were prescribed a 10-day course of antibiotics for a respiratory infection. Secondary aims were to assess the ability of BB-12 to affect the expression of whole blood immune markers associated with cell activation and inflammatory response. A phase I, double-blinded, randomized controlled study was conducted in compliance with FDA guidelines for an Investigational New Drug (IND). Forty participants were randomly assigned to consume 4 ounces of either BB-12 -supplemented yogurt or non-supplemented control yogurt daily for 10 d. The primary outcome was to assess safety and tolerability, assessed by the number of reported adverse events. A total of 165 non-serious adverse events were reported, with no differences between the control and BB-12 groups. When compared to the control group, B lactis fecal levels were modestly higher in the BB-12-supplemented group. In a small subset of patients, changes in whole blood expression of genes associated with regulation and activation of immune cells were detected in the BB-12-supplemented group. BB-12-supplemented yogurt is safe and well tolerated when consumed by healthy adults concurrently taking antibiotics. This study will form the basis for future randomized clinical trials investigating the potential immunomodulatory effects of BB-12-supplemented yogurt in a variety of disease states. PMID:25569274

  19. Plasmids of Raw Milk Cheese Isolate Lactococcus lactis subsp. lactis Biovar diacetylactis DPC3901 Suggest a Plant-Based Origin for the Strain ? †

    PubMed Central

    Fallico, Vincenzo; McAuliffe, Olivia; Fitzgerald, Gerald F.; Ross, R. Paul

    2011-01-01

    The four-plasmid complement of the raw milk cheese isolate Lactococcus lactis subsp. lactis biovar diacetylactis DPC3901 was sequenced, and some genetic features were functionally analyzed. The complete sequences of pVF18 (18,977 bp), pVF21 (21,739 bp), pVF22 (22,166 bp), and pVF50 (53,876 bp) were obtained. Each plasmid contained genes not previously described for Lactococcus, in addition to genes associated with plant-derived lactococcal strains. Most of the novel genes were found on pVF18 and encoded functions typical of bacteria associated with plants, such as activities of plant cell wall modification (orf11 and orf25). In addition, a predicted high-affinity regulated system for the uptake of cobalt was identified (orf19 to orf21 [orf19-21]), which has a single database homolog on a plant-derived Leuconostoc plasmid and whose functionality was demonstrated following curing of pVF18. pVF21 and pVF22 encode additional metal transporters, which, along with orf19-21 of pVF18, could enhance host ability to uptake growth-limiting amounts of biologically essential ions within the soil. In addition, vast regions from pVF50 and pVF21 share significant homology with the plant-derived lactococcal plasmid pGdh442, which is indicative of extensive horizontal gene transfer and recombination between these plasmids and suggests a common plant niche for their hosts. Phenotypes associated with these regions include glutamate dehydrogenase activity and Na+ and K+ transport. The presence of numerous plant-associated markers in L. lactis DPC3901 suggests a plant origin for the raw milk cheese isolate and provides for the first time the genetic basis to support the concept of the plant-milk transition for Lactococcus strains. PMID:21803914

  20. Intranasal immunization with live recombinant Lactococcus lactis combined with heat-labile toxin B subunit protects chickens from highly pathogenic avian influenza H5N1 virus.

    PubMed

    Lei, Han; Peng, Xiaojue; Shu, Handing; Zhao, Daxian

    2015-01-01

    Development of safe and effective vaccines to prevent highly pathogenic avian influenza H5N1 virus infection is a challenging goal. Lactococcus lactis (L. lactis) is an ideal delivery vector for vaccine development, and it has been shown previously that oral immunization of encapsulated secretory L. lactis-hemagglutinin (HA) could provide complete protection against homologous H5N1 virus challenge in the mice model. While intranasal immunization is an appealing approach, it is now reported that secretory L. lactis-HA combined with mucosal adjuvant heat-labile toxin B subunit (LTB) could provide protective immunity in the chicken model. As compared to intranasal immunization with L. lactis-HA alone, L. lactis-HA combined with LTB (L. lactis-HA?+?LTB) could elicit robust neutralizing antibody responses and mucosal IgA responses, as well as strong cellular immune responses in the vaccinated chickens. Importantly, intranasal immunization with L. lactis-HA?+?LTB could provide 100% protection against H5N1 virus challenge. Taken together, these results suggest that intranasal immunization with L. lactis-HA?+?LTB can be considered as an effective approach for preventing and controlling infection of H5N1 virus in poultry during an avian influenza A/H5N1 pandemic. PMID:24861477

  1. A dynamic, genome-scale flux model of Lactococcus lactis to increase specific recombinant protein expression.

    PubMed

    Oddone, Gian M; Mills, David A; Block, David E

    2009-11-01

    Recently, lactic acid bacteria (LAB) have attracted a great deal of interest because of their potential to serve as oral delivery vehicles for recombinant protein vaccines. An important limitation to their use is the typically low level of heterologous expression obtained in LAB. To address this, a dynamic flux balance analysis (DFBA) model was used to identify gene targets for increasing specific expression of Green Fluorescent Protein (GFP), a model heterologous protein, in Lactococcus lactis IL1403. Two strains, each targeting one of the top model-identified genes, were constructed and tested in vivo. Data show that both strains, by a conservative estimate, achieved 15% higher GFP per cell than the control strain, a qualitative confirmation of the model predictions. A genome-scale DFBA model for L. lactis growing on M17 medium is presented along with the procedure for screening gene targets and a powerful method for visualizing fluxes in genome-scale metabolic networks. PMID:19666133

  2. Survival of Lactobacillus acidophilus and Bifidobacterium animalis ssp. lactis in stirred fruit yogurts

    Microsoft Academic Search

    K. Kailasapathy; I. Harmstorf; M. Phillips

    2008-01-01

    The effect of commercial fruit preparations (mango, mixed berry, passion fruit and strawberry) on the viability of probiotic bacteria, Lactobacillus acidophilus LAFTI® L10 and Bifidobacterium animalis ssp. lactis LAFTI® B94 in stirred yogurts during storage (35 days) at refrigerated temperature (4°C) was evaluated. The results showed that addition of either 5 or 10g\\/100g fruit preparations had no significant (p>0.05) effect

  3. Enhancement of natural immune function by dietary consumption of Bifidobacterium lactis (HN019)

    Microsoft Academic Search

    K Arunachalam; HS Gill; RK Chandra

    2000-01-01

    Objective: To determine the effects of dietary consumption of Bifidobacterium lactis (strain HN019, DR10TM) on natural immunity.Design: A randomized, double blind, placebo-controlled clinical trial.Setting:: Janeway Medical Centre, Memorial University, St Johns, Newfoundland.Subjects: Twenty-five healthy elderly volunteers (median age 69 y; range 60–83 y).Interventions: Twelve control subjects consumed 180 ml low-fat\\/low-lactose milk twice daily for a period of 6 weeks; 13

  4. Isolation and characterization of the gene encoding xylose reductase from Kluyveromyces lactis

    Microsoft Academic Search

    Patrick Billard; Sandrine Ménart; Reinhard Fleer; Monique Bolotin-Fukuhara

    1995-01-01

    The identification of a xylose reductase (XR)-encoding gene (XYL1) from the xylose-assimilating yeast Kluyveromyces lactis (Kl) is described. XYL1 was isolated as a highly expressed fusion clone from a 'lacZ translational fusion library. DNA sequence analysis revealed an open reading frame (ORF) of 987 bp capable of encoding a polypeptide of 329 amino acids (aa). The deduced aa sequence displays

  5. The respiratory system of Kluyveromyces lactis escapes from HAP2 control

    Microsoft Academic Search

    C. Nguyen; M. Bolotin-Fukuhara; M. Wésolowski-Louvel; H. Fukuhara

    1995-01-01

    A functional homolog of the Saccharomyces cerevisiae HAP2 gene, coding for one element of a transcriptional activator complex, was cloned from the yeast Kluyveromyces lactis and its nucleotide sequence was determined. Inactivation of the gene had no significant effect on respiration-dependent growth, suggesting that the HAP2\\/3\\/4 complex has no major control over the formation of the mitochondrial respiratory system in

  6. Expression and Secretion of a Thermostable Bacterial Xylanase in Kluyveromyces lactis

    Microsoft Academic Search

    DAVID J. WALSH; PETER L. BERGQUIST

    1997-01-01

    The xynA structural gene from the extremely thermophilic anaerobe Dictyoglomus thermophilum Rt46B.1 was fused in frame with the secretion signal of the Kluyveromyces lactis killer toxin in episomal expression vectors based on the Kluyveromyces plasmid pKD1. XynA was secreted predominantly as an unglycosylated 35-kDa protein which comprised up to 90% of the total extracellular proteins and reached a concentration of

  7. Six putative two-component regulatory systems isolated from Lactococcus lactis subsp. cremoris MG1363

    Microsoft Academic Search

    Mary O'Connell-Motherway; Douwe van Sinderen; Gerald F. Fitzgerald; S. Dusko Ehrlich; Patrice Morel

    2000-01-01

    The genetic elements specifying six putative two-component regulatory systems (2CSs) were identified on the chromosome of Lactococcus lactis MG1363. These 2CSs appear to represent distinct loci, each containing a histidine kinase and response-regulator-encoding gene pair. Transcriptional analysis of the six 2CSs was performed either by generating transcriptional fusions to a reporter gene or by primer extension. Two of the systems

  8. Optimization of lactic acid production by immobilized Lactococcus lactis IO1

    Microsoft Academic Search

    Sarote Sirisansaneeyakul; Tiyaporn Luangpipat; Wirat Vanichsriratana; Thongchai Srinophakun; Henry Ho-Hsien Chen; Yusuf Chisti

    2007-01-01

    Production of lactic acid from glucose by immobilized cells of Lactococcus lactis IO-1 was investigated using cells that had been immobilized by either entrapment in beads of alginate or encapsulation in\\u000a microcapsules of alginate membrane. The fermentation process was optimized in shake flasks using the Taguchi method and then\\u000a further assessed in a production bioreactor. The bioreactor consisted of a

  9. VOLATILE PROFILE OF NON-FERMENTED MILK AND MILK FERMENTED BY BIFIDOBACTERIUM ANIMALIS SUBSP. LACTIS

    Microsoft Academic Search

    Dorota Zareba; Malgorzata Ziarno; Mieczyslaw Obiedzinski

    2011-01-01

    The aim of this work was to determine low-molecular volatile compounds in milk supplemented with the strain Bifidobacterium animalis subsp. lactis Bb-12 with or without fermentation process, stored at 6 ºC for 4 weeks. The chromatographic analysis of probiotic-supplemented non-fermented milk and milk fermented by strain Bb-12 revealed the presence of volatile compounds such as ketones, organic acid, and alcohols.

  10. An ABC-type multidrug transporter of Lactococcus lactis possesses an exceptionally broad substrate specificity

    Microsoft Academic Search

    Gerrit J. Poelarends; Piotr Mazurkiewicz; Monique Putman; Robbert H. Cool; Hendrik W. van Veen; Wil N. Konings

    2000-01-01

    LmrA is a 590-amino acid membrane protein which confers multidrug resistance on Lactococcus lactis cells by extruding amphiphilic compounds from the inner leaflet of the cytoplasmic membrane at the expense of ATP hydrolysis. Its structural and functional characteristics place it in the P-glycoprotein cluster of the ATP-binding cassette transporter superfamily, making it the first prokaryotic multidrug transporter of this cluster.

  11. Glycolic acid production in the engineered yeasts Saccharomyces cerevisiae and Kluyveromyces lactis

    PubMed Central

    2013-01-01

    Background Glycolic acid is a C2 hydroxy acid that is a widely used chemical compound. It can be polymerised to produce biodegradable polymers with excellent gas barrier properties. Currently, glycolic acid is produced in a chemical process using fossil resources and toxic chemicals. Biotechnological production of glycolic acid using renewable resources is a desirable alternative. Results The yeasts Saccharomyces cerevisiae and Kluyveromyces lactis are suitable organisms for glycolic acid production since they are acid tolerant and can grow in the presence of up to 50 g l-1 glycolic acid. We engineered S. cerevisiae and K. lactis for glycolic acid production using the reactions of the glyoxylate cycle to produce glyoxylic acid and then reducing it to glycolic acid. The expression of a high affinity glyoxylate reductase alone already led to glycolic acid production. The production was further improved by deleting genes encoding malate synthase and the cytosolic form of isocitrate dehydrogenase. The engineered S. cerevisiae strain produced up to about 1 g l-1 of glycolic acid in a medium containing d-xylose and ethanol. Similar modifications in K. lactis resulted in a much higher glycolic acid titer. In a bioreactor cultivation with d-xylose and ethanol up to 15 g l-1 of glycolic acid was obtained. Conclusions This is the first demonstration of engineering yeast to produce glycolic acid. Prior to this work glycolic acid production through the glyoxylate cycle has only been reported in bacteria. The benefit of a yeast host is the possibility for glycolic acid production also at low pH, which was demonstrated in flask cultivations. Production of glycolic acid was first shown in S. cerevisiae. To test whether a Crabtree negative yeast would be better suited for glycolic acid production we engineered K. lactis in the same way and demonstrated it to be a better host for glycolic acid production. PMID:24053654

  12. A chloride-inducible acid resistance mechanism in Lactococcus lactis and its regulation

    Microsoft Academic Search

    Jan Willem Sanders; Kees Leenhouts; Jan Roel Brands; Gerard Venema; Jan Kok

    1998-01-01

    Previously, a promoter was identified in Lactococcus lactis that is specifically induced by chloride. Here, we describe the nucleotide sequence and functional analysis of two genes transcribed from this promoter, gadC and gadB. GadC is homologous to putative glutamate-?-aminobutyrate antiporters of Escherichia coli and Shigella flexneri and contains 12 putative membrane-spanning domains. GadB shows similarity to glutamate decarboxylases. A L.

  13. A Chloride-Inducible Gene Expression Cassette and Its Use in Induced Lysis of Lactococcus lactis

    Microsoft Academic Search

    Gerard Venema; Jan Willem Sanders; Jan Kok

    1997-01-01

    A chloride-inducible promoter previously isolated from the chromosome of Lactococcus lactis was exploited for the inducible expression of homologous and heterologous genes. An expression cassette consisting of the positive-regulator gene gadR, the chloride-inducible promoter Pgad, and the translation initiation signals of gadC was amplified by PCR. The cassette was cloned upstream of Escherichia coli lacZ, the holin-lysin cassette (lytPR) of

  14. A chloride-inducible acid resistance mechanism in Lactococcus lactis and its regulation.

    PubMed

    Sanders, J W; Leenhouts, K; Burghoorn, J; Brands, J R; Venema, G; Kok, J

    1998-01-01

    Previously, a promoter was identified in Lactococcus lactis that is specifically induced by chloride. Here, we describe the nucleotide sequence and functional analysis of two genes transcribed from this promoter, gadC and gadB. GadC is homologous to putative glutamate-gamma-aminobutyrate antiporters of Escherichia coli and Shigella flexneri and contains 12 putative membrane-spanning domains. GadB shows similarity to glutamate decarboxylases. A L. lactis gadB mutant and a strain that is unable to express both gadB and gadC was more sensitive to low pH than the wild type when NaCl and glutamate were present. Expression of gadCB in L. lactis in the presence of chloride was increased when the culture pH was allowed to decrease to low levels by omitting buffer from the medium, while glutamate also stimulated gadCB expression. Apparently, these genes encode a glutamate-dependent acid resistance mechanism of L. lactis that is optimally active under conditions in which it is needed to maintain viability. Immediately upstream of the chloride-dependent gadCB promoter Pgad, a third gene encodes a protein (GadR) that is homologous to the activator Rgg from Streptococcus gordonii. gadR expression is chloride and glutamate independent. A gadR mutant did not produce the 3kb gadCB mRNA that is found in wild-type cells in the presence of NaCl, indicating that GadR is an activator of the gadCB operon. PMID:9484886

  15. Microwave-assisted synthesis of galacto-oligosaccharides from lactose with immobilized ?-galactosidase from Kluyveromyces lactis

    Microsoft Academic Search

    Thierry Maugard; Damian Gaunt; Marie Dominique Legoy; Thierry Besson

    2003-01-01

    Galacto-oligosaccharides (GOS) were synthesized from lactose by immobilized and free ß-galactosidase from Kluyveromyces lactis (Lactozym 3000 L HP-G) using either focused microwave irradiation or conventional heating. Immobilization of the ß-galactosidase on to Duolite A-568 increased the synthesis of GOS. GOS selectivity (GOS synthesis\\/lactose hydrolysis ratio) increased when the water activity of the media was reduced, notably with a high initial

  16. PpiA, a Surface PPIase of the Cyclophilin Family in Lactococcus lactis

    PubMed Central

    Trémillon, Nicolas; Morello, Eric; Llull, Daniel; Mazmouz, Rabia; Gratadoux, Jean-Jacques; Guillot, Alain; Chapot-Chartier, Marie-Pierre; Monlezun, Laura; Solé, Véronique; Ginisty, Hervé; Poquet, Isabelle

    2012-01-01

    Background Protein folding in the envelope is a crucial limiting step of protein export and secretion. In order to better understand this process in Lactococcus lactis, a lactic acid bacterium, genes encoding putative exported folding factors like Peptidyl Prolyl Isomerases (PPIases) were searched for in lactococcal genomes. Results In L. lactis, a new putative membrane PPIase of the cyclophilin subfamily, PpiA, was identified and characterized. ppiA gene was found to be constitutively expressed under normal and stress (heat shock, H2O2) conditions. Under normal conditions, PpiA protein was synthesized and released from intact cells by an exogenously added protease, showing that it was exposed at the cell surface. No obvious phenotype could be associated to a ppiA mutant strain under several laboratory conditions including stress conditions, except a very low sensitivity to H2O2. Induction of a ppiA copy provided in trans had no effect i) on the thermosensitivity of an mutant strain deficient for the lactococcal surface protease HtrA and ii) on the secretion and stability on four exported proteins (a highly degraded hybrid protein and three heterologous secreted proteins) in an otherwise wild-type strain background. However, a recombinant soluble form of PpiA that had been produced and secreted in L. lactis and purified from a culture supernatant displayed both PPIase and chaperone activities. Conclusions Although L. lactis PpiA, a protein produced and exposed at the cell surface under normal conditions, displayed a very moderate role in vivo, it was found, as a recombinant soluble form, to be endowed with folding activities in vitro. PMID:22442694

  17. Natural sweetening of food products by engineering Lactococcus lactis for glucose production

    Microsoft Academic Search

    Wietske A. Pool; Ana Rute Neves; Jan Kok; Helena Santos; Oscar P. Kuipers

    2006-01-01

    We show that sweetening of food products by natural fermentation can be achieved by a combined metabolic engineering and transcriptome analysis approach. A Lactococcus lactis ssp. cremoris strain was constructed in which glucose metabolism was completely disrupted by deletion of the genes coding for glucokinase (glk), EIIman\\/glc (ptnABCD), and the newly discovered glucose-PTS EIIcel (ptcBAC). After introducing the lactose metabolic

  18. Regulation of pyruvate metabolism in Lactococcus lactis depends on the imbalance between catabolism and anabolism.

    PubMed

    Garrigues, C; Mercade, M; Cocaign-Bousquet, M; Lindley, N D; Loubiere, P

    2001-07-20

    Two strains of Lactococcus lactis ssp. cremoris, MG 1820 and MG 1363, which differed by the presence or absence of the lactose plasmid, respectively, were cultivated in batch-mode fermentation on lactose as carbon substrate. A correlation between the rate of sugar consumption, the growth rate, and the type of metabolism was observed. The MG 1820 strain grew rapidly on lactose and homolactic fermentation occurred. The major regulating factor was the NADH/NAD(+) ratio proportional to the catabolic flux, which inhibited glyceraldehyde-3-phosphate dehydrogenase activity. This control led to an increase in metabolite concentration upstream of this enzyme, glyceraldehyde-3-phosphate and dihydroxyacetone-phosphate, and inhibition of pyruvate formate lyase activity, while lactate dehydrogenase was strongly activated by the high coenzyme ratio. The contrary was observed during growth of the MG 1363 strain. Further investigation during growth of L. lactis ssp. lactis NCDO 2118 on galactose as carbon substrate and on various culture media enabling the growth rate to proceed at various rates demonstrated that the relative flux between catabolism and anabolism was the critical regulating parameter rather than the rate of glycolysis itself. In a minimal medium, where anabolism was strongly limited, the rate of sugar consumption was reduced to a low value to avoid carbon and energy waste. Despite this low sugar consumption rate, the catabolic flux was in excess relative to the anabolic capability and the NADH/NAD+ ratio was high, typical of a situation of nonlimiting catabolism leading to a homolactic metabolism. PMID:11369999

  19. Glucose metabolism and regulation of glycolysis in Lactococcus lactis strains with decreased lactate dehydrogenase activity.

    PubMed

    Garrigues, C; Goupil-Feuillerat, N; Cocaign-Bousquet, M; Renault, P; Lindley, N D; Loubiere, P

    2001-07-01

    The distribution of carbon flux at the pyruvate node was investigated in Lactococcus lactis under anaerobic conditions with mutant strains having decreased lactate dehydrogenase activity. Strains previously selected by random mutagenesis by H. Boumerdassi, C. Monnet, M. Desmazeaud, and G. Corrieu (Appl. Environ. Microbiol. 63, 2293-2299, 1997) were found to have single punctual mutations in the ldh gene and presented a high degree of instability. The strain L. lactis JIM 5711 in which lactate dehydrogenase activity was diminished to less than 30% of the wild type maintained homolactic metabolism. This was due to an increase in the intracellular pyruvate concentration, which ensures the maintained flux through the lactate dehydrogenase. Pyruvate metabolism was linked to the flux limitation at the level of glyceraldehyde-3-phosphate dehydrogenase, as previously postulated for the parent strain (C. Garrigues, P. Loubière, N. D. Lindley, and M. Cocaign-Bousquet (1997) J. Bacteriol. 179, 5282-5287, 1997). However, a strain (L. lactis JIM 5954) in which the ldh gene was interrupted reoriented pyruvate metabolism toward mixed metabolism (production of formate, acetate, and ethanol), though the glycolytic flux was not strongly diminished. Only limited production of acetoin occurred despite significant overflow of pyruvate. Intracellular metabolite profiles indicated that the in vivo glyceraldehyde-3-phosphate dehydrogenase activity was no longer flux limiting in the Deltaldh strain. The shift toward mixed acid fermentation was correlated with the lower intracellular trioses phosphate concentration and diminished allosteric inhibition of pyruvate formate lyase. PMID:11461143

  20. Genome-wide transcriptional responses to carbon starvation in nongrowing Lactococcus lactis.

    PubMed

    Ercan, Onur; Wels, Michiel; Smid, Eddy J; Kleerebezem, Michiel

    2015-04-01

    This paper describes the transcriptional adaptations of nongrowing, retentostat cultures of Lactococcus lactis to starvation. Near-zero-growth cultures (? = 0.0001 h(-1)) obtained by extended retentostat cultivation were exposed to starvation by termination of the medium supply for 24 h, followed by a recovery period of another 24 h by reinitiating the medium supply to the retentostat culture. During starvation, the viability of the culture was largely retained, and the expression of genes involved in transcription and translational machineries, cell division, and cell membrane energy metabolism was strongly repressed. Expression of these genes was largely recovered following the reinitiation of the medium supply. Starvation triggered the elevated expression of genes associated with synthesis of branched-chain amino acids, histidine, purine, and riboflavin. The expression of these biosynthesis genes was found to remain at an elevated level after reinitiation of the medium supply. In addition, starvation induced the complete gene set predicted to be involved in natural competence in L. lactis KF147, and the elevated expression of these genes was sustained during the subsequent recovery period, but our attempts to experimentally demonstrate natural transformation in these cells failed. Mining the starvation response gene set identified a conserved cis-acting element that resembles the lactococcal CodY motif in the upstream regions of genes associated with transcription and translational machineries, purine biosynthesis, and natural transformation in L. lactis, suggesting a role for CodY in the observed transcriptome adaptations to starvation in nongrowing cells. PMID:25636846

  1. Regulation of Acetate Kinase Isozymes and Its Importance for Mixed-Acid Fermentation in Lactococcus lactis

    PubMed Central

    Puri, Pranav; Goel, Anisha; Bochynska, Agnieszka

    2014-01-01

    Acetate kinase (ACK) converts acetyl phosphate to acetate along with the generation of ATP in the pathway for mixed-acid fermentation in Lactococcus lactis. The reverse reaction yields acetyl phosphate for assimilation purposes. Remarkably, L. lactis has two ACK isozymes, and the corresponding genes are present in an operon. We purified both enzymes (AckA1 and AckA2) from L. lactis MG1363 and determined their oligomeric state, specific activities, and allosteric regulation. Both proteins form homodimeric complexes, as shown by size exclusion chromatography and static light-scattering measurements. The turnover number of AckA1 is about an order of magnitude higher than that of AckA2 for the reaction in either direction. The Km values for acetyl phosphate, ATP, and ADP are similar for both enzymes. However, AckA2 has a higher affinity for acetate than does AckA1, suggesting an important role under acetate-limiting conditions despite the lower activity. Fructose-1,6-bisphosphate, glyceraldehyde-3-phosphate, and phospho-enol-pyruvate inhibit the activities of AckA1 and AckA2 to different extents. The allosteric regulation of AckA1 and AckA2 and the pool sizes of the glycolytic intermediates are consistent with a switch from homolactic to mixed-acid fermentation upon slowing of the growth rate. PMID:24464460

  2. Molecular and Metabolic Adaptations of Lactococcus lactis at Near-Zero Growth Rates

    PubMed Central

    Ercan, Onur; Wels, Michiel; Smid, Eddy J.

    2014-01-01

    This paper describes the molecular and metabolic adaptations of Lactococcus lactis during the transition from a growing to a near-zero growth state by using carbon-limited retentostat cultivation. Transcriptomic analyses revealed that metabolic patterns shifted between lactic- and mixed-acid fermentations during retentostat cultivation, which appeared to be controlled at the level of transcription of the corresponding pyruvate dissipation-encoding genes. During retentostat cultivation, cells continued to consume several amino acids but also produced specific amino acids, which may derive from the conversion of glycolytic intermediates. We identify a novel motif containing CTGTCAG in the upstream regions of several genes related to amino acid conversion, which we propose to be the target site for CodY in L. lactis KF147. Finally, under extremely low carbon availability, carbon catabolite repression was progressively relieved and alternative catabolic functions were found to be highly expressed, which was confirmed by enhanced initial acidification rates on various sugars in cells obtained from near-zero-growth cultures. The present integrated transcriptome and metabolite (amino acids and previously reported fermentation end products) study provides molecular understanding of the adaptation of L. lactis to conditions supporting low growth rates and expands our earlier analysis of the quantitative physiology of this bacterium at near-zero growth rates toward gene regulation patterns involved in zero-growth adaptation. PMID:25344239

  3. Microencapsulation of Bifidobacterium animalis subsp. lactis and Lactobacillus acidophilus in cocoa butter using spray chilling technology

    PubMed Central

    Pedroso, D.L.; Dogenski, M.; Thomazini, M.; Heinemann, R.J.B.; Favaro-Trindade, C.S.

    2013-01-01

    In the present study, the cells of Bifidobacterium animalis subsp. lactis (BI-01) and Lactobacillus acidophilus (LAC-04) were encapsulated in cocoa butter using spray-chilling technology. Survival assays were conducted to evaluate the resistance of the probiotics to the spray-chilling process, their resistance to the simulated gastric and intestinal fluids (SGF and SIF), and their stability during 90 days of storage. The viability of the cells was not affected by microencapsulation. The free and encapsulated cells of B. animalis subsp. lactis were resistant to both SGF and SIF. The micro-encapsulated cells of L. acidophilus were more resistant to SGF and SIF than the free cells; the viability of the encapsulated cells was enhanced by 67%, while the free cells reached the detection limit of the method (103 CFU/g). The encapsulated probiotics were unstable when they were stored at 20 °C. The population of encapsulated L. acidophilus decreased drastically when they were stored at 7 °C; only 20% of cells were viable after 90 days of storage. The percentage of viable cells of the encapsulated B. animalis subsp.lactis, however, was 72% after the same period of storage. Promising results were obtained when the microparticles were stored at ?18 °C; the freeze granted 90 days of shelf life to the encapsulated cells. These results suggest that the spray-chilling process using cocoa butter as carrier protects L. acidophilus from gastrointestinal fluids. However, the viability of the cells during storage must be improved. PMID:24516445

  4. Sec-Mediated Transport of Posttranslationally Dehydrated Peptides in Lactococcus lactis? †

    PubMed Central

    Kuipers, Anneke; Wierenga, Jenny; Rink, Rick; Kluskens, Leon D.; Driessen, Arnold J. M.; Kuipers, Oscar P.; Moll, Gert N.

    2006-01-01

    Nisin is a lanthionine-containing antimicrobial peptide produced by Lactococcus lactis. Its (methyl)lanthionines are introduced by two posttranslational enzymatic steps involving the dehydratase NisB, which dehydrates serine and threonine residues, and the cyclase NisC, which couples these dehydrated residues to cysteines, yielding thioether-bridged amino acids called lanthionines. The prenisin is subsequently exported by the ABC transporter NisT and extracellularly processed by the peptidase NisP. L. lactis expressing the nisBTC genes can modify and secrete a wide range of nonlantibiotic peptides. Here we demonstrate that in the absence of NisT and NisC, the Sec pathway of L. lactis can be exploited for the secretion of dehydrated variants of therapeutic peptides. Furthermore, posttranslational modifications by NisB and NisC still occur even when the nisin leader is preceded by a Sec signal peptide or a Tat signal peptide 27 or 44 amino acids long, respectively. However, transport of fully modified prenisin via the Sec pathway is impaired. The extent of NisB-mediated dehydration could be improved by raising the intracellular concentration NisB or by modulating the export efficiency through altering the signal sequence. These data demonstrate that besides the traditional lantibiotic transporter NisT, the Sec pathway with an established broad substrate range can be utilized for the improved export of lantibiotic enzyme-modified (poly)peptides. PMID:17041158

  5. HrtBA and menaquinones control haem homeostasis in Lactococcus lactis.

    PubMed

    Joubert, Laetitia; Derré-Bobillot, Aurélie; Gaudu, Philippe; Gruss, Alexandra; Lechardeur, Delphine

    2014-08-01

    Lactococcus lactis is a fermenting Gram-positive bacterium widely used for production of dairy products. Lacking haem biosynthesis genes, L. lactis can still shift to an energetically favourable respiratory metabolism by activating a terminal cytochrome bd oxidase when haem is added to an aerated culture. Haem intracellular homeostasis is mediated by the hrtRBA operon encoding the conserved membrane HrtBA haem efflux permease and the unique intracellular haem sensor and regulator, HrtR. Here we report that membrane-associated menaquinones (MK) favour the accumulation of reduced haem in membranes. An oxidative environment, provided by oxygen, prevents and reverses haemin reduction by MK and thus limits haem accumulation in membranes. HrtBA counteracts MK-dependent membrane retention of excess haem in membrane, suggesting direct efflux from this compartment. Moreover, both HrtBA and MK-mediated reduction have a strong impact on haem intracellular pools, as determined via HrtR haem sensor induction, suggesting that intracellular haem acquisition is controlled at the membrane level without the need for dedicated import systems. Our conclusions lead to a new hypothesis of haem acquisition and regulation in which HrtBA and the bacterial membrane have central roles in L. lactis. PMID:25040434

  6. Genome sequence analysis of potential probiotic strain Leuconostoc lactis EFEL005 isolated from kimchi.

    PubMed

    Moon, Jin Seok; Choi, Hye Sun; Shin, So Yeon; Noh, Sol Ji; Jeon, Che Ok; Han, Nam Soo

    2015-05-01

    Leuconostoc lactis EFEL005 (KACC 91922) isolated from kimchi showed promising probiotic attributes; resistance against acid and bile salts, absence of transferable genes for antibiotic resistance, broad utilization of prebiotics, and no hemolytic activity. To expand our understanding of the species, we generated a draft genome sequence of the strain and analyzed its genomic features related to the aforementioned probiotic properties. Genome assembly resulted in 35 contigs, and the draft genome has 1,688,202 base pairs (bp) with a G+C content of 43.43%, containing 1,644 protein-coding genes and 50 RNA genes. The average nucleotide identity analysis showed high homology (? 96%) to the type strain L. lactis KCTC3528, but low homology (? 95%) to L. lactis KCTC3773 (formerly L. argentinum). Genomic analysis revealed the presence of various genes for sucrose metabolism (glucansucrases, invertases, sucrose phosphorylases, and mannitol dehydrogenase), acid tolerance (F1F0 ATPases, cation transport ATPase, branched-chain amino acid permease, and lysine decarboxylase), vancomycin response regulator, and antibacterial peptide (Lactacin F). No gene for production of biogenic amines (histamine and tyramine) was found. This report will facilitate the understanding of probiotic properties of this strain as a starter for fermented foods. PMID:25935305

  7. Recombinant porcine epidermal growth factor-secreting Lactococcus lactis promotes the growth performance of early-weaned piglets

    PubMed Central

    2014-01-01

    Background Epidermal growth factor (EGF) is an important growth factor in regulation of cell proliferation, differentiation, survival and apoptosis. Studies showed that food-grade Lactococcus lactis (L. lactis) and NICE expression system have superior performance in exogenous protein expression. This study aimed to construct and express porcine EGF (pEGF), and use L. lactis as vehicle for producing and delivering pEGF. Furthermore, investigating biological activity of pEGF and exploring applications feasibility of combination effects of L. lactis and pEGF on early weaned piglets’ production. Results A recombinant Lactococcus lactis which produced and secreted pEGF at 1000 ng/ml in culture supernatant was generated. Secreted pEGF was a fully biologically active protein, as demonstrated by its capacity to stimulate L929 mouse fibroblast cell line proliferation in vitro. For in vivo study, forty piglets were randomly allocated to control, antibiotic control, empty vector-expressing L. lactis (LL-EV) and pEGF-secreting L. lactis (LL-pEGF). After 14 d of rearing, final body weight and average daily gain in LL-pEGF were greater (P < 0.05, 8.95 vs. 8.37 kg, 206.1 vs. 157.7 g/day, respectively) than those in control, but no significant differences between LL-pEGF, LL-EV and antibiotic control. Overall period average daily feed intake was higher in LL-pEGF, LL-EV and antibiotic control than in control (P < 0.05, 252.9, 255.6, 250.0, 207.3 g/day, respectively). No significant difference was observed on ADFI/ADG. LL-pEGF increased villous height in the duodenum, jejunum and ileum than in control and LL-EV (P < 0.05). Sucrase in the 3 intestinal segments, aminopeptidase A in the duodenum and Jejunum, aminopeptidase N and dipeptidase IV in the duodenum in LL-pEGF were higher than those in control (P < 0.05). Furthermore, Escherichia coli and Enterococcus counts decreased in the ileum and Lactobacillus increased in the ileum and cecum digesta in LL-pEGF compare with the control (P < 0.05). Lactobacillus increased in the cecum in LL-EV compared with control and antibiotic control (P < 0.05). Conclusion We have generated a recombinant Lactococcus lactis which produced and secreted fully biologically active porcine EGF. Oral administration of pEGF-secreting L. lactis had beneficial effects on intestinal health and performance of early-weaned piglets. PMID:25142032

  8. Protective Vaccination against Infectious Bursal Disease Virus with Whole Recombinant Kluyveromyces lactis Yeast Expressing the Viral VP2 Subunit

    PubMed Central

    Arnold, Marina; Durairaj, Vijay; Mundt, Egbert; Schulze, Katja; Breunig, Karin D.; Behrens, Sven-Erik

    2012-01-01

    Here we report on vaccination approaches against infectious bursal disease (IBD) of poultry that were performed with complete yeast of the species Kluyveromyces lactis (K. lactis). Employing a genetic system that enables the rapid production of stably transfected recombinant K. lactis, we generated yeast strains that expressed defined quantities of the virus capsid forming protein VP2 of infectious bursal disease virus (IBDV). Both, subcutaneous as well as oral vaccination regiments with the heat-inactivated but otherwise untreated yeast induced IBDV-neutralizing antibodies in mice and chickens. A full protection against a subsequent IBDV infection was achieved by subcutaneous inoculation of only milligram amounts of yeast per chicken. Oral vaccination also generated protection: while mortality was observed in control animals after virus challenge, none of the vaccinees died and ca. one-tenth were protected as indicated by the absence of lesions in the bursa of Fabricius. Recombinant K. lactis was thus indicated as a potent tool for the induction of a protective immune response by different applications. Subcutaneously applied K. lactis that expresses the IBDV VP2 was shown to function as an efficacious anti-IBD subunit vaccine. PMID:23024743

  9. Experimental study on the growth of Salmonella and coli-aerogenes bacteria in pure and mixed cultures, in a fermentor, in two different enrichment media: Sodium selenite and tetrathionate broth

    Microsoft Academic Search

    B. Hugues; M. Plissier; A. Pagliardini; J. L. Plantat; J. Gaissa

    1978-01-01

    Different serotypes of Salmonella and coli-aerogenes bacteria were grown in a fermentor at +43°C. The Culture media used were composed of two different nutrient broths, one supplemented with sodium selenite, the other with potassium tetrathionate. The growth of both bacteria and the following types of mixed bacteria was studied: Escherichia coli-Salmonella brancaster and Klebsiella pneumoniae-Salmonella brancaster. During the first 10

  10. Enhancement of natural and acquired immunity by Lactobacillus rhamnosus (HN001), Lactobacillus acidophilus (HN017) and Bifidobacterium lactis (HN019).

    PubMed

    Gill, H S; Rutherfurd, K J; Prasad, J; Gopal, P K

    2000-02-01

    Consumption of lactic acid bacteria (LAB) has been suggested to confer a range of health benefits including stimulation of the immune system and increased resistance to malignancy and infectious illness. In the present study, the effects of feeding Lactobacillus rhamnosus (HN001, DR20), Lactobacillus acidophilus (HN017) and Bifidobacterium lactis (HN019, DR10) on in vivo and in vitro indices of natural and acquired immunity in healthy mice were examined. Mice were fed daily with L. rhamnosus, L. acidophilus or B. lactis (10(9) colony forming units) and their immune function was assessed on day 10 or day 28. Supplementation with L. rhamnosus, L. acidophilus or B. lactis resulted in a significant increase in the phagocytic activity of peripheral blood leucocytes and peritoneal macrophages compared with the control mice. The proliferative responses of spleen cells to concanavalin A (a T-cell mitogen) and lipopolysaccharide (a B-cell mitogen) were also significantly enhanced in mice given different LAB. Spleen cells from mice given L. rhamnosus, L. acidophilus or B. lactis also produced significantly higher amounts of interferon-gamma in response to stimulation with concanavalin A than cells from the control mice. LAB feeding had no significant effect on interleukin-4 production by spleen cells or on the percentages of CD4+, CD8+ and CD40+ cells in the blood. The serum antibody responses to orally and systemically administered antigens were also significantly enhanced by supplementation with L. rhamnosus, L. acidophilus or B. lactis. Together, these results suggest that supplementation of the diet with L. rhamnosus (HN001), L. acidophilus (HN017) or B. lactis (HN019) is able to enhance several indices of natural and acquired immunity in healthy mice. PMID:10743496

  11. Anti-inflammatory effects of Lactococcus lactis NCDO 2118 during the remission period of chemically induced colitis

    PubMed Central

    2014-01-01

    Background Many probiotic bacteria have been described as promising tools for the treatment and prevention of inflammatory bowel diseases (IBDs). Most of these bacteria are lactic acid bacteria, which are part of the healthy human microbiota. However, little is known about the effects of transient bacteria present in normal diets, including Lactococcus lactis. Methods In the present study, we analysed the immunomodulatory effects of three L. lactis strains in vitro using intestinal epithelial cells. L. lactis NCDO 2118 was administered for 4 days to C57BL/6 mice during the remission period of colitis induced by dextran sodium sulphate (DSS). Results Only one strain, L. lactis NCDO 2118, was able to reduce IL-1?-induced IL-8 secretion in Caco-2 cells, suggesting a potential anti-inflammatory effect. Oral treatment using L. lactis NCDO 2118 resulted in a milder form of recurrent colitis than that observed in control diseased mice. This protective effect was not attributable to changes in secretory IgA (sIgA); however, NCDO 2118 administration was associated with an early increase in IL-6 production and sustained IL-10 production in colonic tissue. Mice fed L. lactis NCDO 2118 had an increased number of regulatory CD4+ T cells (Tregs) bearing surface TGF-? in its latent form (Latency-associated peptide-LAP) in the mesenteric lymph nodes and spleen. Conclusions Here, we identified a new probiotic strain with a potential role in the treatment of IBD, and we elucidated some of the mechanisms underlying its anti-inflammatory effect. PMID:25110521

  12. Altered superoxide dismutase activity by carbohydrate utilization in a Lactococcus lactis strain.

    PubMed

    Kimoto-Nira, H; Moriya, N; Ohmori, H; Suzuki, C

    2014-07-01

    Reactive oxygen species, such as superoxide, can damage cellular components, such as proteins, lipids, and DNA. Superoxide dismutase (SOD) enzymes catalyze the conversion of superoxide anions to hydrogen peroxide and dioxygen. SOD is present in most lactococcal bacteria, which are commonly used as starters for manufacturing fermented dairy products and may have health benefits when taken orally. We assessed the effects of carbohydrate use on SOD activity in lactococci. In Lactococcus lactis ssp. lactis G50, the SOD activity of cells grown on lactose and galactose was higher than that on glucose; in Lactococcus lactis ssp. cremoris H61, SOD activity was independent of the type of carbohydrate used. We also investigated the activity of NADH oxidase, which is related to the production of superoxide in strains G50 and H61. Activity was highest in G50 cells grown on lactose, lower on galactose, and lowest on glucose, whereas activity in H61 cells did not differ with the carbohydrate source used. The SOD and NADH oxidase activities of strain G50 in three carbohydrates were linked. Strain G50 fermented lactose and galactose to lactate, acetate, formate, and ethanol (mixed-acid fermentation) and fermented glucose to mainly lactate (homolactic fermentation). Strain H61 fermented glucose, lactose, and galactose to mainly lactate (homolactic fermentation). In strain G50, when growth efficiency was reduced by adding a metabolic inhibitor to the growth medium, SOD activity was higher than in the control; however, the metabolism was homofermentative. Aerobic conditions, but not glucose-limited conditions, increased SOD activity, and mixed-acid fermentation occurred. We conclude that the effect of carbohydrate on SOD activity in lactococci is strain dependent and that the activity of commercial lactococci can be enhanced through carbohydrate selection for mixed-acid fermentation or by changing the energy distribution, thus enhancing the value of the starter and the resulting dairy products. PMID:24988023

  13. Evolution of glutamine amidotransferase genes. Nucleotide sequences of the pabA genes from Salmonella typhimurium, Klebsiella aerogenes and Serratia marcescens.

    PubMed

    Kaplan, J B; Merkel, W K; Nichols, B P

    1985-06-01

    The amide group of glutamine is a source of nitrogen in the biosynthesis of a variety of compounds. These reactions are catalyzed by a group of enzymes known as glutamine amidotransferases; two of these, the glutamine amidotransferase subunits of p-aminobenzoate synthase and anthranilate synthase have been studied in detail and have been shown to be structurally and functionally related. In some micro-organisms, p-aminobenzoate synthase and anthranilate synthase share a common glutamine amidotransferase subunit. We report here the primary DNA and deduced amino acid sequences of the p-aminobenzoate synthase glutamine amidotransferase subunits from Salmonella typhimurium, Klebsiella aerogenes and Serratia marcescens. A comparison of these glutamine amidotransferase sequences to the sequences of ten others, including some that function specifically in either the p-aminobenzoate synthase or anthranilate synthase complexes and some that are shared by both synthase complexes, has revealed several interesting features of the structure and organization of these genes, and has allowed us to speculate as to the evolutionary history of this family of enzymes. We propose a model for the evolution of the p-aminobenzoate synthase and anthranilate synthase glutamine amidotransferase subunits in which the duplication and subsequent divergence of the genetic information encoding a shared glutamine amidotransferase subunit led to the evolution of two new pathway-specific enzymes. PMID:3894673

  14. Dynamic Analysis of the Lactococcus lactis Transcriptome in Cheeses Made from Milk Concentrated by Ultrafiltration Reveals Multiple Strategies of Adaptation to Stresses ?

    PubMed Central

    Cretenet, Marina; Laroute, Valérie; Ulvé, Vincent; Jeanson, Sophie; Nouaille, Sébastien; Even, Sergine; Piot, Michel; Girbal, Laurence; Le Loir, Yves; Loubière, Pascal; Lortal, Sylvie; Cocaign-Bousquet, Muriel

    2011-01-01

    Lactococcus lactis is used extensively for the production of various cheeses. At every stage of cheese fabrication, L. lactis has to face several stress-generating conditions that result from its own modification of the environment as well as externally imposed conditions. We present here the first in situ global gene expression profile of L. lactis in cheeses made from milk concentrated by ultrafiltration (UF-cheeses), a key economical cheese model. The transcriptomic response of L. lactis was analyzed directly in a cheese matrix, starting from as early as 2 h and continuing for 7 days. The growth of L. lactis stopped after 24 h, but metabolic activity was maintained for 7 days. Conservation of its viability relied on an efficient proteolytic activity measured by an increasing, quantified number of free amino acids in the absence of cell lysis. Extensive downregulation of genes under CodY repression was found at day 7. L. lactis developed multiple strategies of adaptation to stressful modifications of the cheese matrix. In particular, expression of genes involved in acidic- and oxidative-stress responses was induced. L. lactis underwent unexpected carbon limitation characterized by an upregulation of genes involved in carbon starvation, principally due to the release of the CcpA control. We report for the first time that in spite of only moderately stressful conditions, lactococci phage is repressed under UF-cheese conditions. PMID:21075879

  15. Exploring optimization parameters to increase ssDNA recombineering in Lactococcus lactis and Lactobacillus reuteri

    PubMed Central

    van Pijkeren, Jan-Peter; Neoh, Kar Mun; Sirias, Denise; Findley, Anthony S.; Britton, Robert A.

    2012-01-01

    Single-stranded DNA (ssDNA) recombineering is a technology which is used to make subtle changes in the chromosome of several bacterial genera. Cells which express a single-stranded DNA binding protein (RecT or Bet) are transformed with an oligonucleotide which is incorporated via an annealing and replication-dependent mechanism. By in silico analysis we identified ssDNA binding protein homologs in the genus Lactobacillus and Lactococcus lactis. To assess whether we could further improve the recombineering efficiency in Lactobacillus reuteri ATCC PTA 6475 we expressed several RecT homologs in this strain. RecT derived from Enterococcus faecalis CRMEN 19 yielded comparable efficiencies compared with a native RecT protein, but none of the other proteins further increased the recombineering efficiency. We successfully improved recombineering efficiency 10-fold in L. lactis by increasing oligonucleotide concentration combined with the use of oligonucleotides containing phosphorothioate-linkages (PTOs). Surprisingly, neither increased oligonucleotide concentration nor PTO linkages enhanced recombineering in L. reuteri 6475. To emphasize the utility of this technology in improving probiotic features we modified six bases in a transcriptional regulatory element region of the pdu-operon of L. reuteri 6475, yielding a 3-fold increase in the production of the antimicrobial compound reuterin. Directed genetic modification of lactic acid bacteria through ssDNA recombineering will simplify strain improvement in a way that, when mutating a single base, is genetically indistinguishable from strains obtained through directed evolution. PMID:22750793

  16. Identification of Four Phage Resistance Plasmids from Lactococcus lactis subsp. cremoris HO2

    PubMed Central

    Forde, Amanda; Daly, Charles; Fitzgerald, Gerald F.

    1999-01-01

    The bacteriophage-host sensitivity patterns of 16 strains of Lactococcus lactis originally isolated from a mixed strain Cheddar cheese starter culture were determined. Using phages obtained from cheese factory whey, four of the strains were found to be highly phage resistant. One of these isolates, Lactococcus lactis subsp. cremoris HO2, was studied in detail to determine the mechanisms responsible for the phage insensitivity phenotypes. Conjugal transfer of plasmid DNA from strain HO2 allowed a function to be assigned to four of its six plasmids. A 46-kb molecule, designated pCI646, was found to harbor the lactose utilization genes, while this and plasmids of 58 kb (pCI658), 42 kb (pCI642), and 4.5 kb (pCI605) were shown to be responsible for the phage resistance phenotypes observed against the small isometric-headed phage ?712 (936 phage species) and the prolate-headed phage ?c2 (c2 species). pCI658 was found to mediate an adsorption-blocking mechanism and was also responsible for the fluffy pellet phenotype of cells containing the molecule. pCI642 and pCI605 were both shown to be required for the operation of a restriction-modification system. PMID:10103248

  17. Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology.

    PubMed

    de Faria, Janaína T; Rocha, Pollyana F; Converti, Attilio; Passos, Flávia M L; Minim, Luis A; Sampaio, Fábio C

    2013-12-01

    The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as ?-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the ?-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L(-1) oNP min(-1) g(-1) was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry. PMID:24688494

  18. Exploring optimization parameters to increase ssDNA recombineering in Lactococcus lactis and Lactobacillus reuteri.

    PubMed

    Van Pijkeren, Jan-Peter; Neoh, Kar Mun; Sirias, Denise; Findley, Anthony S; Britton, Robert A

    2012-01-01

    Single-stranded DNA (ssDNA) recombineering is a technology which is used to make subtle changes in the chromosome of several bacterial genera. Cells which express a single-stranded DNA binding protein (RecT or Bet) are transformed with an oligonucleotide which is incorporated via an annealing and replication-dependent mechanism. By in silico analysis we identified ssDNA binding protein homologs in the genus Lactobacillus and Lactococcus lactis. To assess whether we could further improve the recombineering efficiency in Lactobacillus reuteri ATCC PTA 6475 we expressed several RecT homologs in this strain. RecT derived from Enterococcus faecalis CRMEN 19 yielded comparable efficiencies compared with a native RecT protein, but none of the other proteins further increased the recombineering efficiency. We successfully improved recombineering efficiency 10-fold in L. lactis by increasing oligonucleotide concentration combined with the use of oligonucleotides containing phosphorothioate-linkages (PTOs). Surprisingly, neither increased oligonucleotide concentration nor PTO linkages enhanced recombineering in L. reuteri 6475. To emphasize the utility of this technology in improving probiotic features we modified six bases in a transcriptional regulatory element region of the pdu-operon of L. reuteri 6475, yielding a 3-fold increase in the production of the antimicrobial compound reuterin. Directed genetic modification of lactic acid bacteria through ssDNA recombineering will simplify strain improvement in a way that, when mutating a single base, is genetically indistinguishable from strains obtained through directed evolution. PMID:22750793

  19. [Stability of Lactococcus lactis phages treated with sodium hypochlorite and during storage].

    PubMed

    Parada, J L; de Fabrizio, S V

    2001-01-01

    Survival of lytic bacteriophages active against Lactococcus lactis ssp. lactis and ssp. cremoris was determined after treatment with sodium hypochlorite and during storage at 4 degrees C. Three phages were isolated from dairy plants in Argentina (ARG) and the other phages were isolated in the United States of America (US). All of them represent phages that infected cheese manufacture industries and belong to different morphological or serological groups. These phages showed higher survival in M17 broth, buffered with sodium glycerophosphate, than in trypteine soy broth (TSB). Phage populations did not decrease significantly during 14 weeks in M17 broth, whereas in TSB the titers of phage suspensions began to decline around 9 days. In addition, the effect of sodium hypochlorite was more marked in broth than in milk. A higher surviving fraction was obtained in milk, even when tenfold higher concentrations of chlorine were used. The effect of hypochlorite on phages of the same serological group was quite similar and independent of phage morphology. However, phage 137-1, which belongs to other serological group, showed lower resistance to sodium hypochlorite. Comparing the hypochlorite inactivation for ARG and US phages, it was observed that they have their own inactivation values, independently of their origin and morphological group. Long periods of time and high concentrations of chlorine were necessary to reduce the surviving fraction in milk. This indicates that hypochlorite concentrations and times of contact can be critical for the efficiency of the operative sanitization processes. PMID:11494761

  20. Bifidobacterium animalis subsp. lactis fermented milk product reduces inflammation by altering a niche for colitogenic microbes

    PubMed Central

    Veiga, Patrick; Gallini, Carey Ann; Beal, Chloé; Michaud, Monia; Delaney, Mary L.; DuBois, Andrea; Khlebnikov, Artem; van Hylckama Vlieg, Johan E.T.; Punit, Shivesh; Glickman, Jonathan N.; Onderdonk, Andrew; Glimcher, Laurie H.; Garrett, Wendy S.

    2010-01-01

    Intestinal health requires the coexistence of eukaryotic self with the gut microbiota and dysregulated host-microbial interactions can result in intestinal inflammation. Here, we show that colitis improved in T-bet?/?Rag2?/? mice that consumed a fermented milk product containing Bifidobacterium animalis subsp. lactis DN-173 010 strain. A decrease in cecal pH and alterations in short chain fatty acid profiles occurred with consumption, and there were concomitant increases in the abundance of select lactate-consuming and butyrate-producing bacteria. These metabolic shifts created a nonpermissive environment for the Enterobacteriaceae recently identified as colitogenic in a T-bet?/?Rag2?/? ulcerative colitis mouse model. In addition, 16S rRNA-based analysis of the T-bet?/?Rag2?/?fecal microbiota suggest that the structure of the endogenous gut microbiota played a key role in shaping the host response to the bacterial strains studied herein. We have identified features of the gut microbiota, at the membership and functional level, associated with response to this B. lactis-containing fermented milk product, and therefore this model provides a framework for evaluating and optimizing probiotic-based functional foods. PMID:20921388

  1. Modeling of the Competitive Growth of Listeria monocytogenes and Lactococcus lactis in Vegetable Broth

    PubMed Central

    Breidt, Frederick; Fleming, Henry P.

    1998-01-01

    Current mathematical models used by food microbiologists do not address the issue of competitive growth in mixed cultures of bacteria. We developed a mathematical model which consists of a system of nonlinear differential equations describing the growth of competing bacterial cell cultures. In this model, bacterial cell growth is limited by the accumulation of protonated lactic acid and decreasing pH. In our experimental system, pure and mixed cultures of Lactococcus lactis and Listeria monocytogenes were grown in a vegetable broth medium. Predictions of the model indicate that pH is the primary factor that limits the growth of L. monocytogenes in competition with a strain of L. lactis which does not produce the bacteriocin nisin. The model also predicts the values of parameters that affect the growth and death of the competing populations. Further development of this model will incorporate the effects of additional inhibitors, such as bacteriocins, and may aid in the selection of lactic acid bacterium cultures for use in competitive inhibition of pathogens in minimally processed foods. PMID:9726854

  2. The Carbohydrate Metabolism Signature of Lactococcus lactis Strain A12 Reveals Its Sourdough Ecosystem Origin

    PubMed Central

    Passerini, Delphine; Coddeville, Michèle; Le Bourgeois, Pascal; Loubière, Pascal; Ritzenthaler, Paul; Fontagné-Faucher, Catherine; Cocaign-Bousquet, Muriel

    2013-01-01

    Lactococcus lactis subsp. lactis strain A12 was isolated from sourdough. Combined genomic, transcriptomic, and phenotypic analyses were performed to understand its survival capacity in the complex sourdough ecosystem and its role in the microbial community. The genome sequence comparison of strain A12 with strain IL1403 (a derivative of an industrial dairy strain) revealed 78 strain-specific regions representing 23% of the total genome size. Most of the strain-specific genes were involved in carbohydrate metabolism and are potentially required for its persistence in sourdough. Phenotype microarray, growth tests, and analysis of glycoside hydrolase content showed that strain A12 fermented plant-derived carbohydrates, such as arabinose and ?-galactosides. Strain A12 exhibited specific growth rates on raffinose that were as high as they were on glucose and was able to release sucrose and galactose outside the cell, providing soluble carbohydrates for sourdough microflora. Transcriptomic analysis identified genes specifically induced during growth on raffinose and arabinose and reveals an alternative pathway for raffinose assimilation to that used by other lactococci. PMID:23872564

  3. Functional and Morphological Adaptation to Peptidoglycan Precursor Alteration in Lactococcus lactis*

    PubMed Central

    Deghorain, Marie; Fontaine, Laetitia; David, Blandine; Mainardi, Jean-Luc; Courtin, Pascal; Daniel, Richard; Errington, Jeff; Sorokin, Alexei; Bolotin, Alexander; Chapot-Chartier, Marie-Pierre; Hallet, Bernard; Hols, Pascal

    2010-01-01

    Cell wall peptidoglycan assembly is a tightly regulated process requiring the combined action of multienzyme complexes. In this study we provide direct evidence showing that substrate transformations occurring at the different stages of this process play a crucial role in the spatial and temporal coordination of the cell wall synthesis machinery. Peptidoglycan substrate alteration was investigated in the Gram-positive bacterium Lactococcus lactis by substituting the peptidoglycan precursor biosynthesis genes of this bacterium for those of the vancomycin-resistant bacterium Lactobacillus plantarum. A set of L. lactis mutant strains in which the normal d-Ala-ended precursors were partially or totally replaced by d-Lac-ended precursors was generated. Incorporation of the altered precursor into the cell wall induced morphological changes arising from a defect in cell elongation and cell separation. Structural analysis of the muropeptides confirmed that the activity of multiple enzymes involved in peptidoglycan synthesis was altered. Optimization of this altered pathway was necessary to increase the level of vancomycin resistance conferred by the utilization of d-Lac-ended peptidoglycan precursors in the mutant strains. The implications of these findings on the control of bacterial cell morphogenesis and the mechanisms of vancomycin resistance are discussed. PMID:20525686

  4. Heterofermentative Carbohydrate Metabolism of Lactose-Impaired Mutants of Streptococcus lactis

    PubMed Central

    Demko, G. M.; Blanton, S. J. B.; Benoit, R. E.

    1972-01-01

    Two mutants of Streptococcus lactis ATCC 11454 have been isolated which possess an impaired lactose-fermenting capacity; galactose utilization is also affected, but to a lesser extent. Although the Embden-Meyerhof-Parnas pathway is the major, if not the sole, pathway of carbohydrate metabolism in the three strains, the fermentation end products of the mutants are dramatically different from the typical homolactic pattern of the wild type. Under conditions of low oxygen tension and growth-limiting lactose concentrations, mutant strain T-1 produces largely formic acid, acetic acid (2:1), and ethanol rather than lactic acid. Aerated cultures produce acetic acid, CO2 (1:1), acetyl-methylcarbinol, and diacetyl. When the mutants use galactose as an energy source, lactic acid is the major end product, but significant heterofermentative activity is observed. The aberrations responsible for the mutant phenotypes reside in the proteins which catalyze the transport and hydrolysis of galactosides. It is hypothesized that the impaired transport system of the mutants reduces the intracellular pool of glycolytic intermediates below that of the wild type. Since fructose-1, 6-diphosphate is an activator of lactic dehydrogenase in S. lactis, lactic acid production is reduced, and pathways leading to the formation of other products are expressed. PMID:4629656

  5. Microbial domestication signatures of Lactococcus lactis can be reproduced by experimental evolution

    PubMed Central

    Bachmann, Herwig; Starrenburg, Marjo J.C.; Molenaar, Douwe; Kleerebezem, Michiel; van Hylckama Vlieg, Johan E.T.

    2012-01-01

    Experimental evolution is a powerful approach to unravel how selective forces shape microbial genotypes and phenotypes. To this date, the available examples focus on the adaptation to conditions specific to the laboratory. The lactic acid bacterium Lactococcus lactis naturally occurs on plants and in dairy environments, and it is proposed that dairy strains originate from the plant niche. Here we investigate the adaptation of a L. lactis strain isolated from a plant to a dairy niche by propagating it for 1000 generations in milk. Two out of three independently evolved strains displayed significantly increased acidification rates and biomass yields in milk. Genome resequencing, revealed six, seven, and 28 mutations in the three strains, including point mutations in loci related to amino acid biosynthesis and transport and in the gene encoding MutL, which is involved in DNA mismatch repair. Two strains lost a conjugative transposon containing genes important in the plant niche but dispensable in milk. A plasmid carrying an extracellular protease was introduced by transformation. Although improving growth rate and growth yield significantly, the plasmid was rapidly lost. Comparative transcriptome and phenotypic analyses confirmed that major physiological changes associated with improved growth in milk relate to nitrogen metabolism and the loss or down-regulation of several pathways involved in the utilization of complex plant polymers. Reproducing the transition from the plant to the dairy niche through experimental evolution revealed several genome, transcriptome, and phenotype signatures that resemble those seen in strains isolated from either niche. PMID:22080491

  6. Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology

    PubMed Central

    de Faria, Janaína T.; Rocha, Pollyana F.; Converti, Attilio; Passos, Flávia M.L.; Minim, Luis A.; Sampaio, Fábio C.

    2013-01-01

    The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as ?-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the ?-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L?1 oNP min?1 g?1 was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry. PMID:24688494

  7. The targeted recognition of Lactococcus lactis phages to their polysaccharide receptors.

    PubMed

    McCabe, Orla; Spinelli, Silvia; Farenc, Carine; Labbé, Myriam; Tremblay, Denise; Blangy, Stéphanie; Oscarson, Stefan; Moineau, Sylvain; Cambillau, Christian

    2015-05-01

    Each phage infects a limited number of bacterial strains through highly specific interactions of the receptor-binding protein (RBP) at the tip of phage tail and the receptor at the bacterial surface. Lactococcus lactis is covered with a thin polysaccharide pellicle (hexasaccharide repeating units), which is used by a subgroup of phages as a receptor. Using L.?lactis and phage 1358 as a model, we investigated the interaction between the phage RBP and the pellicle hexasaccharide of the host strain. A core trisaccharide (TriS), derived from the pellicle hexasaccharide repeating unit, was chemically synthesised, and the crystal structure of the RBP/TriS complex was determined. This provided unprecedented structural details of RBP/receptor site-specific binding. The complete hexasaccharide repeating unit was modelled and found to aptly fit the extended binding site. The specificity observed in in vivo phage adhesion assays could be interpreted in view of the reported structure. Therefore, by combining synthetic carbohydrate chemistry, X-ray crystallography and phage plaquing assays, we suggest that phage adsorption results from distinct recognition of the RBP towards the core TriS or the remaining residues of the hexasacchride receptor. This study provides a novel insight into the adsorption process of phages targeting saccharides as their receptors. PMID:25708888

  8. Interaction of Bifidobacterium animalis subspecies lactis (Bb 12) and Salmonella typhimurium in continuous-flow chemostatic culture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A commercially available probiotic, Bifidobacterium animalis subspecies lactis (Bb12) was adapted to and maintained in a continuous-flow chemostat culture. We evaluated the growth characteristics and interactive effects of Bb12 and a porcine-derived Salmonella typhimurium (St) when cultivated singly...

  9. An alternative, arginase-independent pathway for arginine metabolism in Kluyveromyces lactis involves guanidinobutyrase as a key enzyme

    PubMed Central

    Romagnoli, G; Verhoeven, M D; Mans, R; Fleury Rey, Y; Bel-Rhlid, R; van den Broek, M; Maleki Seifar, R; Ten Pierick, A; Thompson, M; Müller, V; Wahl, S A; Pronk, J T; Daran, J M

    2014-01-01

    Most available knowledge on fungal arginine metabolism is derived from studies on Saccharomyces cerevisiae, in which arginine catabolism is initiated by releasing urea via the arginase reaction. Orthologues of the S. cerevisiae genes encoding the first three enzymes in the arginase pathway were cloned from Kluyveromyces lactis and shown to functionally complement the corresponding deletion in S. cerevisiae. Surprisingly, deletion of the single K. lactis arginase gene KlCAR1 did not completely abolish growth on arginine as nitrogen source. Growth rate of the deletion mutant strongly increased during serial transfer in shake-flask cultures. A combination of RNAseq-based transcriptome analysis and 13C-15N-based flux analysis was used to elucidate the arginase-independent pathway. Isotopic 13C15N-enrichment in ?-aminobutyrate revealed succinate as the entry point in the TCA cycle of the alternative pathway. Transcript analysis combined with enzyme activity measurements indicated increased expression in the Klcar1? mutant of a guanidinobutyrase (EC.3.5.3.7), a key enzyme in a new pathway for arginine degradation. Expression of the K. lactis KLLA0F27995g (renamed KlGBU1) encoding guanidinobutyrase enabled S. cerevisiae to use guanidinobutyrate as sole nitrogen source and its deletion in K. lactis almost completely abolish growth on this nitrogen source. Phylogenetic analysis suggests that this enzyme activity is widespread in fungi. PMID:24912400

  10. Characterization and Role of the BranchedChain Aminotransferase (BcaT) Isolated from Lactococcus lactis subsp. cremoris NCDO 763

    Microsoft Academic Search

    MIREILLE YVON; EMILIE CHAMBELLON; ALEXANDER BOLOTIN; FLORENCE ROUDOT-ALGARON

    2000-01-01

    In Lactococcus lactis, which is widely used as a starter in the cheese industry, the first step of aromatic and branched-chain amino acid degradation is a transamination which is catalyzed by two major aminotrans- ferases. We have previously purified and characterized biochemically and genetically the aromatic amino- transferase, AraT. In the present study, we purified and studied the second enzyme,

  11. Genotypic and Phenotypic Analysis of Dairy Lactococcus lactis Biodiversity in Milk: Volatile Organic Compounds as Discriminating Markers

    PubMed Central

    Dhaisne, Amandine; Guellerin, Maeva; Laroute, Valérie; Laguerre, Sandrine; Le Bourgeois, Pascal; Loubiere, Pascal

    2013-01-01

    The diversity of nine dairy strains of Lactococcus lactis subsp. lactis in fermented milk was investigated by both genotypic and phenotypic analyses. Pulsed-field gel electrophoresis and multilocus sequence typing were used to establish an integrated genotypic classification. This classification was coherent with discrimination of the L. lactis subsp. lactis bv. diacetylactis lineage and reflected clonal complex phylogeny and the uniqueness of the genomes of these strains. To assess phenotypic diversity, 82 variables were selected as important dairy features; they included physiological descriptors and the production of metabolites and volatile organic compounds (VOCs). Principal-component analysis (PCA) demonstrated the phenotypic uniqueness of each of these genetically closely related strains, allowing strain discrimination. A method of variable selection was developed to reduce the time-consuming experimentation. We therefore identified 20 variables, all associated with VOCs, as phenotypic markers allowing discrimination between strain groups. These markers are representative of the three metabolic pathways involved in flavor: lipolysis, proteolysis, and glycolysis. Despite great phenotypic diversity, the strains could be divided into four robust phenotypic clusters based on their metabolic orientations. Inclusion of genotypic diversity in addition to phenotypic characters in the classification led to five clusters rather than four being defined. However, genotypic characters make a smaller contribution than phenotypic variables (no genetic distances selected among the most contributory variables). This work proposes an original method for the phenotypic differentiation of closely related strains in milk and may be the first step toward a predictive classification for the manufacture of starters. PMID:23709512

  12. Contribution of Lactococcus lactis Reducing Properties to the Downregulation of a Major Virulence Regulator in Staphylococcus aureus, the agr System

    PubMed Central

    Nouaille, Sébastien; Rault, Lucie; Jeanson, Sophie; Loubière, Pascal; Le Loir, Yves

    2014-01-01

    Staphylococcus aureus is a major cause of food poisoning outbreaks associated with dairy products, because of the ingestion of preformed enterotoxins. The biocontrol of S. aureus using lactic acid bacteria (LAB) offers a promising opportunity to fight this pathogen while respecting the product ecosystem. We had previously established the ability of Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, to downregulate a major staphylococcal virulence regulator, the accessory gene regulator (agr) system, and, as a consequence, agr-controlled enterotoxins. In the present paper, we have shown that the oxygen-independent reducing properties of L. lactis contribute to agr downregulation. Neutralizing lactococcal reduction by adding potassium ferricyanide or maintaining the oxygen pressure constant at 50% released agr downregulation in the presence of L. lactis. This downregulation still occurred in an S. aureus srrA mutant, indicating that the staphylococcal respiratory response regulator SrrAB was not the only component in the signaling pathway. Therefore, this study clearly demonstrates the ability of L. lactis reducing properties to interfere with the expression of S. aureus virulence, thus highlighting this general property of LAB as a lever to control the virulence expression of this major pathogen in a food context and beyond. PMID:25192992

  13. Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

    PubMed

    Rezende, Rafael M; Oliveira, Rafael P; Medeiros, Samara R; Gomes-Santos, Ana C; Alves, Andrea C; Loli, Flávia G; Guimarães, Mauro A F; Amaral, Sylvia S; da Cunha, André P; Weiner, Howard L; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M C

    2013-02-01

    Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-? - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. PMID:22939403

  14. Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells

    PubMed Central

    Rezende, Rafael M.; Oliveira, Rafael P.; Medeiros, Samara R.; Gomes-Santos, Ana C.; Alves, Andrea C.; Loli, Flávia G.; Guimarães, Mauro A.F.; Amaral, Sylvia S.; da Cunha, André P.; Weiner, Howard L.; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M.C.

    2013-01-01

    Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-? - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. PMID:22939403

  15. Multilocus sequence typing of Lactococcus lactis from naturally fermented milk foods in ethnic minority areas of China.

    PubMed

    Xu, Haiyan; Sun, Zhihong; Liu, Wenjun; Yu, Jie; Song, Yuqin; Lv, Qiang; Zhang, Jiachao; Shao, Yuyu; Menghe, Bilige; Zhang, Heping

    2014-05-01

    To determine the genetic diversity and phylogenetic relationships among Lactococcus lactis isolates, 197 strains isolated from naturally homemade yogurt in 9 ethnic minority areas of 6 provinces of China were subjected to multilocus sequence typing (MLST). The MLST analysis was performed using internal fragment sequences of 12 housekeeping genes (carB, clpX, dnaA, groEL, murC, murE, pepN, pepX, pyrG, recA, rpoB, and pheS). Six (dnaA) to 8 (murC) different alleles were detected for these genes, which ranged from 33.62 (clpX) to 41.95% (recA) GC (guanine-cytosine) content. The nucleotide diversity (?) ranged from 0.00362 (murE) to 0.08439 (carB). Despite this limited allelic diversity, the allele combinations of each strain revealed 72 different sequence types, which denoted significant genotypic diversity. The dN/dS ratios (where dS is the number of synonymous substitutions per synonymous site, and dN is the number of nonsynonymous substitutions per nonsynonymous site) were lower than 1, suggesting potential negative selection for these genes. The standardized index of association of the alleles IA(S)=0.3038 supported the clonality of Lc. lactis, but the presence of network structure revealed by the split decomposition analysis of the concatenated sequence was strong evidence for intraspecies recombination. Therefore, this suggests that recombination contributed to the evolution of Lc. lactis. A minimum spanning tree analysis of the 197 isolates identified 14 clonal complexes and 23 singletons. Phylogenetic trees were constructed based on the sequence types, using the minimum evolution algorithm, and on the concatenated sequence (6,192 bp), using the unweighted pair-group method with arithmetic mean, and these trees indicated that the evolution of our Lc. lactis population was correlated with geographic origin. Taken together, our results demonstrated that MLST could provide a better understanding of Lc. lactis genome evolution, as well as useful information for future studies on global Lc. lactis structure and genetic evolution, which will lay the foundation for screening Lc. lactis as starter cultures in fermented dairy products. PMID:24612812

  16. Host lysozyme-mediated lysis of Lactococcus lactis facilitates delivery of colitis-attenuating superoxide dismutase to inflamed colons

    PubMed Central

    Ballal, Sonia A.; Veiga, Patrick; Fenn, Kathrin; Michaud, Monia; Kim, Jason H.; Gallini, Carey Ann; Glickman, Jonathan N.; Quéré, Gaëlle; Garault, Peggy; Béal, Chloé; Derrien, Muriel; Courtin, Pascal; Kulakauskas, Saulius; Chapot-Chartier, Marie-Pierre; van Hylckama Vlieg, Johan; Garrett, Wendy S.

    2015-01-01

    Beneficial microbes that target molecules and pathways, such as oxidative stress, which can negatively affect both host and microbiota, may hold promise as an inflammatory bowel disease therapy. Prior work showed that a five-strain fermented milk product (FMP) improved colitis in T-bet?/? Rag2?/? mice. By varying the number of strains used in the FMP, we found that Lactococcus lactis I-1631 was sufficient to ameliorate colitis. Using comparative genomic analyses, we identified genes unique to L. lactis I-1631 involved in oxygen respiration. Respiration of oxygen results in reactive oxygen species (ROS) generation. Also, ROS are produced at high levels during intestinal inflammation and cause tissue damage. L. lactis I-1631 possesses genes encoding enzymes that detoxify ROS, such as superoxide dismutase (SodA). Thus, we hypothesized that lactococcal SodA played a role in attenuating colitis. Inactivation of the sodA gene abolished L. lactis I-1631’s beneficial effect in the T-bet?/? Rag2?/? model. Similar effects were obtained in two additional colonic inflammation models, Il10?/? mice and dextran sulfate sodium-treated mice. Efforts to understand how a lipophobic superoxide anion (O2?) can be detoxified by cytoplasmic lactoccocal SodA led to the finding that host antimicrobial-mediated lysis is a prerequisite for SodA release and SodA’s extracytoplasmic O2? scavenging. L. lactis I-1631 may represent a promising vehicle to deliver antioxidant, colitis-attenuating SodA to the inflamed intestinal mucosa, and host antimicrobials may play a critical role in mediating SodA’s bioaccessibility. PMID:26056274

  17. Host lysozyme-mediated lysis of Lactococcus lactis facilitates delivery of colitis-attenuating superoxide dismutase to inflamed colons.

    PubMed

    Ballal, Sonia A; Veiga, Patrick; Fenn, Kathrin; Michaud, Monia; Kim, Jason H; Gallini, Carey Ann; Glickman, Jonathan N; Quéré, Gaëlle; Garault, Peggy; Béal, Chloé; Derrien, Muriel; Courtin, Pascal; Kulakauskas, Saulius; Chapot-Chartier, Marie-Pierre; van Hylckama Vlieg, Johan; Garrett, Wendy S

    2015-06-23

    Beneficial microbes that target molecules and pathways, such as oxidative stress, which can negatively affect both host and microbiota, may hold promise as an inflammatory bowel disease therapy. Prior work showed that a five-strain fermented milk product (FMP) improved colitis in T-bet(-/-) Rag2(-/-) mice. By varying the number of strains used in the FMP, we found that Lactococcus lactis I-1631 was sufficient to ameliorate colitis. Using comparative genomic analyses, we identified genes unique to L. lactis I-1631 involved in oxygen respiration. Respiration of oxygen results in reactive oxygen species (ROS) generation. Also, ROS are produced at high levels during intestinal inflammation and cause tissue damage. L. lactis I-1631 possesses genes encoding enzymes that detoxify ROS, such as superoxide dismutase (SodA). Thus, we hypothesized that lactococcal SodA played a role in attenuating colitis. Inactivation of the sodA gene abolished L. lactis I-1631's beneficial effect in the T-bet(-/-) Rag2(-/-) model. Similar effects were obtained in two additional colonic inflammation models, Il10(-/-) mice and dextran sulfate sodium-treated mice. Efforts to understand how a lipophobic superoxide anion (O2 (-)) can be detoxified by cytoplasmic lactoccocal SodA led to the finding that host antimicrobial-mediated lysis is a prerequisite for SodA release and SodA's extracytoplasmic O2 (-) scavenging. L. lactis I-1631 may represent a promising vehicle to deliver antioxidant, colitis-attenuating SodA to the inflamed intestinal mucosa, and host antimicrobials may play a critical role in mediating SodA's bioaccessibility. PMID:26056274

  18. Metabolic engineering of Lactococcus lactis: Influence of overproduction of ß-acetolactate synthase in strains deficient in lactate dehydrogenase as a function of culture conditions

    Microsoft Academic Search

    CHRIST PLATTEEUW; JEROEN HUGENHOLTZ; MARJO STARRENBURG; Alen-Boerrigter van I; Vos de W. M

    1995-01-01

    under the control of the inducible L. lactis lacA promoter. More than a hundredfold overproduction of a-acetolactate synthase was obtained inL. lactisunder inducing conditions as compared with that of the host strain, which contained a single chromosomal copy of the als gene. The effect of a-acetolactate synthase overproduction on the formation of end products in various L. lactis strains was

  19. Genetic and Biochemical Characterization of a High-Affinity Betaine Uptake System (BusA) in Lactococcus lactis Reveals a New Functional Organization within Bacterial ABC Transporters

    Microsoft Academic Search

    DAVID OBIS; ALAIN GUILLOT; JEAN-CLAUDE GRIPON; PIERRE RENAULT; ALEXANDER BOLOTIN; MICHEL-YVES MISTOU

    1999-01-01

    The cytoplasmic accumulation of exogenous betaine stimulates the growth of Lactococcus lactis cultivated under hyperosmotic conditions. We report that L. lactis possesses a single betaine transport system that be- longs to the ATP-binding cassette (ABC) superfamily of transporters. Through transposon mutagenesis, a mu- tant deficient in betaine transport was isolated. We identified two genes, busAA and busAB, grouped in an

  20. Utilisation of galacto-oligosaccharides as selective substrates for growth by lactic acid bacteria including Bifidobacterium lactis DR10 and Lactobacillus rhamnosus DR20

    Microsoft Academic Search

    Pramod K Gopal; Patrick A Sullivan; John B Smart

    2001-01-01

    Two probiotic strains of bacteria Bifidobacterium lactis DR10 and Lactobacillus rhamnosus DR20 were tested for their ability to utilise and grow on galacto-oligosaccharides present in a commercial hydrolysed lactose milk powder. The results clearly demonstrated that B. lactis DR10 preferentially utilises tri- and tetra-saccharides whereas Lb. rhamnosus DR20 prefers sugars with a lower degree of polymerisation, i.e., disaccharides and monosaccharides.

  1. Effect of galacto-oligosaccharide supplementation on human faecal microflora and on survival and persistence of Bifidobacterium lactis Bb12 in the gastrointestinal tract

    Microsoft Academic Search

    M. Alander; J. Mättö; W. Kneifel; M. Johansson; B. Kögler; R. Crittenden; T. Mattila-Sandholm; M. Saarela

    2001-01-01

    Galacto-oligosaccharides (GOS) are considered to have bifidogenic properties in humans. To study the effect of GOS-containing syrup (60% GOS) alone or together with the probiotic strain Bifidobacterium lactis Bb-12 on selected components of the faecal flora, and the effect of GOS supplementation on colonisation of B. lactis Bb-12, a feeding trial on 30 healthy volunteers was performed. Mean numbers of

  2. RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. lactis in whole soybean solid-state co-fermentation.

    PubMed

    Wang, Hai Kuan; Ng, Yi Kai; Koh, Eileen; Yao, Lina; Chien, Ang Sze; Lin, Hui Xin; Lee, Yuan Kun

    2015-10-01

    Bifidobacteria are anaerobes and are difficult to culture in conventional fermentation system. It was observed that Bacillus subtilis natto enhanced growth of Bifidobacterium animalis subsp. lactis v9 by about 3-fold in a whole soybean solid-state co-fermentation, in a non-anaerobic condition. For the purpose of understanding the metabolic interactions between Bif. animalis subsp. lactis v9 and Ba. subtilis natto, the transcriptome of Bif. animalis subsp. lactis v9 and Ba. subtilis natto was analyzed in single and mixed cultures using RNA-Seq. Compared with the single culture, 459 genes of Bif. animalis subsp. lactis v9 were up regulated and 21 were down regulated in the mixed culture with Ba. subtilis natto, with more than 2-fold difference. Predictive metagenomic analyses suggested that Ba. subtilis natto up regulated transport functions, complex carbohydrates and amino acid metabolism, DNA repair, oxydative stress-related functions, and cell growth of Bif. animalis subsp. lactis v9. In the mixed culture with Bif. animalis subsp. lactis v9, only 3 transcripts of Ba. subtilis natto were over-expressed and 3115 were under-expressed with more than 2-fold difference. The highest down-regulated genes were those involved in carbohydrate and amino acid metabolism. The data presented here demonstrated a parasitic-like interaction regulated at the transcription level, between Ba. subtilis natto and Bif. animalis subsp. lactis in the mixed culture. The over-expression of genes involved in substrate uptake and metabolism in Bif. animalis subsp. lactis in the mixed culture nevertheless, led to its higher cell concentration in the nutrient rich whole soybean medium. PMID:26187824

  3. Metabolism of Lactococcus lactis subsp. cremoris MG 1363 in acid stress conditions.

    PubMed

    Mercade, M; Lindley, N D; Loubière, P

    2000-04-10

    The metabolism of glucose by Lactococcus lactis subsp. cremoris MG 1363 remains homolactic whatever the pH of the culture medium. The growth rate decreased with the acidification of the medium until a limit pH value of 4.0 for which no growth was observed. In contrast, the specific rate of glucose consumption decreased only for very low pH values, i.e., below 4.5. The efficiency of biomass synthesis relative to the energy supply decreased when the medium pH diminished, as illustrated by Y(ATP) values. This observation was related to the increase in both components of the proton-motive force when the pH decreased. The growth stopped when the internal pH reached a limit value of 5.4 due to organic acid accumulation. PMID:10791737

  4. Selection of a Bifidobacterium animalis subsp. lactis strain with a decreased ability to produce acetic acid.

    PubMed

    Margolles, Abelardo; Sánchez, Borja

    2012-05-01

    We have characterized a new strain, Bifidobacterium animalis subsp. lactis CECT 7953, obtained by random UV mutagenesis, which produces less acetic acid than the wild type (CECT 7954) in three different experimental settings: De Man-Rogosa-Sharpe broth without sodium acetate, resting cells, and skim milk. Genome sequencing revealed a single Phe-Ser substitution in the acetate kinase gene product that seems to be responsible for the strain's reduced acid production. Accordingly, acetate kinase specific activity was lower in the low acetate producer. Strain CECT 7953 produced less acetate, less ethanol, and more yoghourt-related volatile compounds in skim milk than the wild type did. Thus, CECT 7953 shows promising potential for the development of dairy products fermented exclusively by a bifidobacterial strain. PMID:22389372

  5. A Food-Grade Approach for Functional Analysis and Modification of Native Plasmids in Lactococcus lactis

    PubMed Central

    Cotter, Paul D.; Hill, Colin; Ross, R. Paul

    2003-01-01

    While plasmids from lactic acid bacteria possess many traits that are of industrial value, their exploitation is often frustrated by an inability to conduct food-grade engineering of native plasmids or to readily screen for their transfer. Here we describe a system that uses a RepA+ temperature-sensitive helper plasmid and a RepA? cloning vector to overcome these problems while maintaining the food-grade status of the native plasmid. This strategy was used to precisely delete ltnA1 alone, or in conjunction with ltnA2 (encoding the structural proteins of the lantibiotic lacticin 3147), from the native 60.2-kb plasmid pMRC01 and to select for the transfer of pMRC01 between Lactococcus lactis strains. PMID:12514066

  6. Oral administration of Lactococcus lactis expressing Helicobacter pylori Cag7-ct383 protein induces systemic anti-Cag7 immune response in mice.

    PubMed

    Kim, Su-Jung; Lee, Ji Young; Jun, Do Youn; Song, Jae-Young; Lee, Woo-Kon; Cho, Myung-Je; Kim, Young Ho

    2009-12-01

    To express the 3'-region (1152 bp) of the cag7 gene of Helicobacter pylori 51 strain, encoding the C-terminal 383 amino acid (ct383 aa) region of Cag7 protein that is known to cover the needle region of T4SS, in a live delivery vehicle Lactococcus lactis, the cag7-ct383 gene was amplified by PCR. DNA sequence analysis revealed that the amino acid sequence of Cag7-ct383 of H. pylori 51 shared 98.4% and 97.4% identity with H. pylori 26695 and J99, respectively. Intramuscular injection of the GST-Cag7-ct383 fusion protein into a rat could raise the anti-Cag7 antibody, indicating the immunogenicity of the Cag7-ct383 protein. When the cag7-ct383 gene was cloned in Escherichia coli-L. lactis shuttle vector (pMG36e) and transformed into L. lactis, the transformant could produce the Cag7-ct383 protein, as evidenced by Western blot analysis. The Cag7-ct383 protein level in the L. lactis transformant reached a maximum at the early stationary phase without extracellular secretion. The oral administration of the L. lactis transformant into mice generated anti-Cag7 antibody in serum in five of five mice. These results suggest that L. lactis transformant expressing Cag7-ct383 protein may be applicable as an oral vaccine to induce mucosal and systemic immunity to H. pylori. PMID:19807786

  7. Reduced Lysis upon Growth of Lactococcus lactis on Galactose Is a Consequence of Decreased Binding of the Autolysin AcmA?

    PubMed Central

    Steen, Anton; Buist, Girbe; Kramer, Naomi E.; Jalving, Ruud; Benus, Germaine F. J. D.; Venema, Gerard; Kuipers, Oscar P.; Kok, Jan

    2008-01-01

    When Lactococcus lactis subsp. lactis IL1403 or L. lactis subsp. cremoris MG1363 is grown in a medium with galactose as the carbon source, the culture lyses to a lesser extent in stationary phase than when the bacteria are grown in a medium containing glucose. Expression of AcmA, the major autolysin of L. lactis, is not influenced by the carbon source. Binding studies with a fusion protein consisting of the MSA2 protein of Plasmodium falciparum and the C-terminal peptidoglycan-binding domain of AcmA revealed that cell walls of cells from both subspecies grown on galactose bind less AcmA than cell walls of cells grown on glucose. Cells grown on glucose or galactose and treated with trichloroacetic acid prior to AcmA binding bind similar amounts of AcmA. Analysis of the composition of the lipoteichoic acids (LTAs) of L. lactis IL1403 cells grown on glucose or galactose showed that the LTA composition is influenced by the carbon source: cells grown on galactose contain LTA with less galactose than cells grown on glucose. In conclusion, growth of L. lactis on galactose changes the LTA composition in the cell wall in such a way that less AcmA is able to bind to the peptidoglycan, resulting in a decrease in autolysis. PMID:18539791

  8. How recombinant swollenin from Kluyveromyces lactis affects cellulosic substrates and accelerates their hydrolysis

    PubMed Central

    2011-01-01

    Background In order to generate biofuels, insoluble cellulosic substrates are pretreated and subsequently hydrolyzed with cellulases. One way to pretreat cellulose in a safe and environmentally friendly manner is to apply, under mild conditions, non-hydrolyzing proteins such as swollenin - naturally produced in low yields by the fungus Trichoderma reesei. To yield sufficient swollenin for industrial applications, the first aim of this study is to present a new way of producing recombinant swollenin. The main objective is to show how swollenin quantitatively affects relevant physical properties of cellulosic substrates and how it affects subsequent hydrolysis. Results After expression in the yeast Kluyveromyces lactis, the resulting swollenin was purified. The adsorption parameters of the recombinant swollenin onto cellulose were quantified for the first time and were comparable to those of individual cellulases from T. reesei. Four different insoluble cellulosic substrates were then pretreated with swollenin. At first, it could be qualitatively shown by macroscopic evaluation and microscopy that swollenin caused deagglomeration of bigger cellulose agglomerates as well as dispersion of cellulose microfibrils (amorphogenesis). Afterwards, the effects of swollenin on cellulose particle size, maximum cellulase adsorption and cellulose crystallinity were quantified. The pretreatment with swollenin resulted in a significant decrease in particle size of the cellulosic substrates as well as in their crystallinity, thereby substantially increasing maximum cellulase adsorption onto these substrates. Subsequently, the pretreated cellulosic substrates were hydrolyzed with cellulases. Here, pretreatment of cellulosic substrates with swollenin, even in non-saturating concentrations, significantly accelerated the hydrolysis. By correlating particle size and crystallinity of the cellulosic substrates with initial hydrolysis rates, it could be shown that the swollenin-induced reduction in particle size and crystallinity resulted in high cellulose hydrolysis rates. Conclusions Recombinant swollenin can be easily produced with the robust yeast K. lactis. Moreover, swollenin induces deagglomeration of cellulose agglomerates as well as amorphogenesis (decrystallization). For the first time, this study quantifies and elucidates in detail how swollenin affects different cellulosic substrates and their hydrolysis. PMID:21943248

  9. Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

    PubMed Central

    Sperandio, Brice; Polard, Patrice; Ehrlich, Dusko S.; Renault, Pierre; Guédon, Eric

    2005-01-01

    Cysteine and methionine availability influences many processes in the cell. In bacteria, transcription of the specific genes involved in the synthesis of these two amino acids is usually regulated by different mechanisms or regulators. Pathways for the synthesis of cysteine and methionine and their interconversion were experimentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food. A new gene, yhcE, was shown to be involved in methionine recycling to cysteine. Surprisingly, 18 genes, representing almost all genes of these pathways, are under the control of a LysR-type activator, FhuR, also named CmbR. DNA microarray experiments showed that FhuR targets are restricted to this set of 18 genes clustered in seven transcriptional units, while cysteine starvation modifies the transcription level of several other genes potentially involved in oxidoreduction processes. Purified FhuR binds a 13-bp box centered 46 to 53 bp upstream of the transcriptional starts from the seven regulated promoters, while a second box with the same consensus is present upstream of the first binding box, separated by 8 to 10 bp. O-Acetyl serine increases FhuR binding affinity to its binding boxes. The overall view of sulfur amino acid metabolism and its regulation in L. lactis indicates that CysE could be a master enzyme controlling the activity of FhuR by providing its effector, while other controls at the enzymatic level appear to be necessary to compensate the absence of differential regulation of the genes involved in the interconversion of methionine and cysteine and other biosynthesis genes. PMID:15901700

  10. Pilus Biogenesis in Lactococcus lactis: Molecular Characterization and Role in Aggregation and Biofilm Formation

    PubMed Central

    Oxaran, Virginie; Ledue-Clier, Florence; Dieye, Yakhya; Herry, Jean-Marie; Péchoux, Christine; Meylheuc, Thierry; Briandet, Romain; Juillard, Vincent; Piard, Jean-Christophe

    2012-01-01

    The genome of Lactococcus lactis strain IL1403 harbors a putative pilus biogenesis cluster consisting of a sortase C gene flanked by 3 LPxTG protein encoding genes (yhgD, yhgE, and yhhB), called here pil. However, pili were not detected under standard growth conditions. Over-expression of the pil operon resulted in production and display of pili on the surface of lactococci. Functional analysis of the pilus biogenesis machinery indicated that the pilus shaft is formed by oligomers of the YhgE pilin, that the pilus cap is formed by the YhgD pilin and that YhhB is the basal pilin allowing the tethering of the pilus fibers to the cell wall. Oligomerization of pilin subunits was catalyzed by sortase C while anchoring of pili to the cell wall was mediated by sortase A. Piliated L. lactis cells exhibited an auto-aggregation phenotype in liquid cultures, which was attributed to the polymerization of major pilin, YhgE. The piliated lactococci formed thicker, more aerial biofilms compared to those produced by non-piliated bacteria. This phenotype was attributed to oligomers of YhgE. This study provides the first dissection of the pilus biogenesis machinery in a non-pathogenic Gram-positive bacterium. Analysis of natural lactococci isolates from clinical and vegetal environments showed pili production under standard growth conditions. The identification of functional pili in lactococci suggests that the changes they promote in aggregation and biofilm formation may be important for the natural lifestyle as well as for applications in which these bacteria are used. PMID:23236417

  11. A chloride-inducible gene expression cassette and its use in induced lysis of Lactococcus lactis.

    PubMed

    Sanders, J W; Venema, G; Kok, J

    1997-12-01

    A chloride-inducible promoter previously isolated from the chromosome of Lactococcus lactis (J. W. Sanders, G. Venema, J. Kok, and K. Leenhouts, Mol. Gen. Genet., in press) was exploited for the inducible expression of homologous and heterologous genes. An expression cassette consisting of the positive-regulator gene gadR, the chloride-inducible promoter Pgad, and the translation initiation signals of gadC was amplified by PCR. The cassette was cloned upstream of Escherichia coli lacZ, the holin-lysin cassette (lytPR) of the lactococcal bacteriophage r1t, and the autolysin gene of L. lactis, acmA. Basal activity of Pgad resulted in a low level of expression of all three proteins. Growth in the presence of 0.5 M NaCl of a strain containing the gadC::lacZ fusion resulted in a 1,500-fold increase of beta-galactosidase activity. The background activity levels of LytPR and AcmA had no deleterious effects on cell growth, but induction of lysin expression by addition of 0.5 M NaCl resulted in inhibition of growth. Lysis was monitored by following the release of the cytoplasmic marker enzyme PepX. Released PepX activity was maximal at 1 day after induction of lytPR expression with 0.1 M NaCl. Induction of acmA expression resulted in slower release of PepX from the cells. The presence of the inducing agent NaCl resulted in the stabilization of osmotically fragile cells. PMID:9406408

  12. Computational analysis of the interaction between transcription factors and the predicted secreted proteome of the yeast Kluyveromyces lactis

    PubMed Central

    Brustolini, Otávio JB; Fietto, Luciano G; Cruz, Cosme D; Passos, Flávia ML

    2009-01-01

    Background Protein secretion is a cell translocation process of major biological and technological significance. The secretion and downstream processing of proteins by recombinant cells is of great commercial interest. The yeast Kluyveromyces lactis is considered a promising host for heterologous protein production. Because yeasts naturally do not secrete as many proteins as filamentous fungi, they can produce secreted recombinant proteins with few contaminants in the medium. An ideal system to address the secretion of a desired protein could be exploited among the native proteins in certain physiological conditions. By applying algorithms to the completed K. lactis genome sequence, such a system could be selected. To this end, we predicted protein subcellular locations and correlated the resulting extracellular secretome with the transcription factors that modulate the cellular response to a particular environmental stimulus. Results To explore the potential Kluyveromyces lactis extracellular secretome, four computational prediction algorithms were applied to 5076 predicted K. lactis proteins from the genome database. SignalP v3 identified 418 proteins with N-terminal signal peptides. From these 418 proteins, the Phobius algorithm predicted that 176 proteins have no transmembrane domains, and the big-PI Predictor identified 150 proteins as having no glycosylphosphatidylinositol (GPI) modification sites. WoLF PSORT predicted that the K. lactis secretome consists of 109 putative proteins, excluding subcellular targeting. The transcription regulators of the putative extracellular proteins were investigated by searching for DNA binding sites in their putative promoters. The conditions to favor expression were obtained by searching Gene Ontology terms and using graph theory. Conclusion A public database of K. lactis secreted proteins and their transcription factors are presented. It consists of 109 ORFs and 23 transcription factors. A graph created from this database shows 134 nodes and 884 edges, suggesting a vast number of relationships to be validated experimentally. Most of the transcription factors are related to responses to stress such as drug, acid and heat resistance, as well as nitrogen limitation, and may be useful for inducing maximal expression of potential extracellular proteins. PMID:19555482

  13. Molecular Insights on the Recognition of a Lactococcus lactis Cell Wall Pellicle by the Phage 1358 Receptor Binding Protein

    PubMed Central

    Farenc, Carine; Spinelli, Silvia; Vinogradov, Evgeny; Tremblay, Denise; Blangy, Stéphanie; Sadovskaya, Irina

    2014-01-01

    ABSTRACT The Gram-positive bacterium Lactococcus lactis is used for the production of cheeses and other fermented dairy products. Accidental infection of L. lactis cells by virulent lactococcal tailed phages is one of the major risks of fermentation failures in industrial dairy factories. Lactococcal phage 1358 possesses a host range limited to a few L. lactis strains and strong genomic similarities to Listeria phages. We report here the X-ray structures of phage 1358 receptor binding protein (RBP) in complex with monosaccharides. Each monomer of its trimeric RBP is formed of two domains: a “shoulder” domain linking the RBP to the rest of the phage and a jelly roll fold “head/host recognition” domain. This domain harbors a saccharide binding crevice located in the middle of a monomer. Crystal structures identified two sites at the RBP surface, ?8 ? from each other, one accommodating a GlcNAc monosaccharide and the other accommodating a GlcNAc or a glucose 1-phosphate (Glc1P) monosaccharide. GlcNAc and GlcNAc1P are components of the polysaccharide pellicle that we identified at the cell surface of L. lactis SMQ-388, the host of phage 1358. We therefore modeled a galactofuranose (Galf) sugar bridging the two GlcNAc saccharides, suggesting that the trisaccharidic motif GlcNAc-Galf-GlcNAc (or Glc1P) might be common to receptors of genetically distinct lactococcal phages p2, TP091-1, and 1358. Strain specificity might therefore be elicited by steric clashes induced by the remaining components of the pellicle hexasaccharide. Taken together, these results provide a first insight into the molecular mechanism of host receptor recognition by lactococcal phages. IMPORTANCE Siphophages infecting the Gram-positive bacterium Lactococcus lactis are sources of milk fermentation failures in the dairy industry. We report here the structure of the pellicle polysaccharide from L. lactis SMQ-388, the specific host strain of phage 1358. We determined the X-ray structures of the lytic lactococcal phage 1358 receptor binding protein (RBP) in complex with monosaccharides. The positions and nature of monosaccharides bound to the RBP are in agreement with the pellicle structure and suggest a general binding mode of lactococcal phages to their pellicle saccharidic receptor. PMID:24719416

  14. Solid-state NMR spectroscopy reveals anomer specific transport of galactose in the milk yeast Kluyveromyces lactis.

    PubMed

    Fukasawa, Toshio; Abe, Akio; Nakamura, Atsusi; Horigome, Miyako; Naito, Akira

    2012-06-01

    Genetic evidence indicates that only the ?-anomer of galactose is transported to Kluyveromyces lactis cells by galactose/glucose transporter Hgt1p, and that aldose-1-epimerase encoded by GAL10 is a prerequisite for growth on galactose. Minor aldose-1-epimerases other than Gal10p also exist in K. lactis. Using a mutant defective in both aldose-1-epimerases, we show by solid-state nuclear magnetic resonance spectroscopy that only ?-anomer is transported in the cell and stays without or with a slow rate of conversion to ?-anomer. Signals due to intracellular ?-galactose appeared at two positions, both of which were shifted towards higher magnetic fields than that of ?-galactose in aqueous solution, suggesting that incorporated galactose binds to cellular components, probably proteins. PMID:22239854

  15. Consumption of Bifidobacterium lactis LKM512 yogurt reduces gut mutagenicity by increasing gut polyamine contents in healthy adult subjects

    Microsoft Academic Search

    Mitsuharu Matsumoto; Yoshimi Benno

    2004-01-01

    The possible role of probiotic metabolites on human health effects of probiotics has received little research attention. In this study, we investigated the effects of consumption of Bifidobacterium lactis LKM512-containing yogurt (LKM512 yogurt) on fecal probiotic metabolites (polyamines, lactate, and acetate) and mutagenicity in seven healthy adults (one male and six females; average age: 30.5 years). Each volunteer was provided

  16. Conjugative plasmid pIP501 undergoes specific deletions after transfer from Lactococcus lactis to Oenococcus oeni

    Microsoft Academic Search

    Manuel Zúñiga; Isabel Pardo; Sergi Ferrer

    2003-01-01

    Conjugal transfer of plasmids pIP501 and its derivative pVA797 from Lactococcus lactis to Oenococcus oeni was assayed by filter mating. Plasmid pIP501 was transferred to a number of O. oeni strains whereas a single transconjugant of O. oeni M42 was recovered when pVA797 was used. Physical analysis of the transconjugant plasmids revealed that pIP501 and pVA797 underwent extensive deletions in

  17. Oral Administration of Lactococcus lactis Expressing Synthetic Genes of Myelin Antigens in Decreasing Experimental Autoimmune Encephalomyelitis in Rats

    PubMed Central

    Kasarello, Kaja; Kwiatkowska-Patzer, Barbara; Lipkowski, Andrzej W.; Bardowski, Jacek K.; Szczepankowska, Agnieszka K.

    2015-01-01

    Background Multiple sclerosis is a human autoimmunological disease that causes neurodegeneration. One of the potential ways to stop its development is induction of oral tolerance, whose effect lies in decreasing immune response to the fed antigen. It was shown in animal models that administration of specific epitopes of the three main myelin proteins – myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP), and proteolipid protein (PLP) – results in induction of oral tolerance and suppression of disease symptoms. Use of bacterial cells to produce and deliver antigens to gut mucosa seems to be an attractive method for oral tolerance induction in treatment of diseases with autoimmune background. Material/Methods Synthetic genes of MOG35-55, MBP85-97, and PLP139-151 myelin epitopes were generated and cloned in Lactococcus lactis under a CcpA-regulated promoter. The tolerogenic effect of bacterial preparations was tested on experimental autoimmune encephalomyelitis, which is the animal model of MS. EAE was induced in rats by intradermal injection of guinea pig spinal cord homogenate into hind paws. Results Rats were administered preparations containing whole-cell lysates of L. lactis producing myelin antigens using different feeding schemes. Our study demonstrates that 20-fold, but not 4-fold, intragastric administration of autoantigen-expressing L. lactis cells under specific conditions reduces the clinical symptoms of EAE in rats. Conclusions The present study evaluated the use of myelin antigens produced in L. lactis in inhibiting the onset of experimental autoimmune encephalomyelitis in rats. Obtained results indicate that application of such recombinant cells can be an attractive method of oral tolerance induction. PMID:26026273

  18. Transcriptional, translational and metabolic regulation of glycolysis in Lactococcus lactis subsp. cremoris MG 1363 grown in continuous acidic cultures

    Microsoft Academic Search

    Sergine Even; Nic D. Lindley; Muriel Cocaign-Bousquet

    2003-01-01

    The physiological behaviour of Lactococcus lactis subsp. cremoris MG 1363 was characterized in continuous culture under various acidic conditions (pH 4?7-6?6). Biomass yield was diminished in cultures with low pH and the energy dedicated to maintenance increased due to organic acid inhibition and cytoplasmic acidification. Under such acidic conditions, the specific rate of glucose consumption by the bacterium increased, thereby

  19. Analysis of six prophages in Lactococcus lactis IL1403: different genetic structure of temperate and virulent phage populations

    Microsoft Academic Search

    Alain Chopin; Alexander Bolotin; Alexei Sorokin; S. Dusko Ehrlich; Marie-Christine Chopin

    2001-01-01

    We report the genetic organisation of six prophages present in the genome of Lactococcus lactis IL1403. The three larger prophages (36-42 kb), belong to the already described P335 group of temperate phages, whereas the three smaller ones (13-15 kb) are most probably satellites relying on helper phage(s) for multiplication. These data give a new insight into the genetic structure of

  20. Volatile Profile of Non-Fermented Milk and Milk Fermented by BifidoBacterium animalis subsp. lactis

    Microsoft Academic Search

    Dorota Zareba; Malgorzata Ziarno; Mieczyslaw Obiedzinski

    2012-01-01

    The aim of this work was to determine low-molecular volatile compounds in milk supplemented with the strain Bifidobacterium animalis subsp. lactis Bb-12 with or without fermentation process, stored at 6°C for 4 weeks. The chromatographic analysis of probiotic-supplemented non-fermented milk and milk fermented by strain Bb-12 revealed the presence of volatile compounds, such as ketones, organic acid, and alcohols. The

  1. Oral Administration of Lactococcus lactis Expressing Synthetic Genes of Myelin Antigens in Decreasing Experimental Autoimmune Encephalomyelitis in Rats.

    PubMed

    Kasarello, Kaja; Kwiatkowska-Patzer, Barbara; Lipkowski, Andrzej W; Bardowski, Jacek K; Szczepankowska, Agnieszka K

    2015-01-01

    Background Multiple sclerosis is a human autoimmunological disease that causes neurodegeneration. One of the potential ways to stop its development is induction of oral tolerance, whose effect lies in decreasing immune response to the fed antigen. It was shown in animal models that administration of specific epitopes of the three main myelin proteins - myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP), and proteolipid protein (PLP) - results in induction of oral tolerance and suppression of disease symptoms. Use of bacterial cells to produce and deliver antigens to gut mucosa seems to be an attractive method for oral tolerance induction in treatment of diseases with autoimmune background. Material and Methods Synthetic genes of MOG35-55, MBP85-97, and PLP139-151 myelin epitopes were generated and cloned in Lactococcus lactis under a CcpA-regulated promoter. The tolerogenic effect of bacterial preparations was tested on experimental autoimmune encephalomyelitis, which is the animal model of MS. EAE was induced in rats by intradermal injection of guinea pig spinal cord homogenate into hind paws. Results Rats were administered preparations containing whole-cell lysates of L. lactis producing myelin antigens using different feeding schemes. Our study demonstrates that 20-fold, but not 4-fold, intragastric administration of autoantigen-expressing L. lactis cells under specific conditions reduces the clinical symptoms of EAE in rats. Conclusions The present study evaluated the use of myelin antigens produced in L. lactis in inhibiting the onset of experimental autoimmune encephalomyelitis in rats. Obtained results indicate that application of such recombinant cells can be an attractive method of oral tolerance induction. PMID:26026273

  2. Detection of Bifidobacterium animalis subsp. lactis (Bb12) in the Intestine after Feeding of Sows and Their Piglets

    Microsoft Academic Search

    Gloria Solano-Aguilar; Harry Dawson; Marta Restrepo; Kate Andrews; Bryan Vinyard; Joseph F. Urban

    2008-01-01

    A real-time PCR method has been developed to distinguish Bifidobacterium animalis subspecies in the gastrointestinal tracts of pigs. Identification of a highly conserved single-copy tuf gene encoding the elongation factor Tu involved in bacterial protein biosynthesis was used as a marker to differentiate homologous Bi- fidobacterium animalis subsp. lactis (strain Bb12) from Bifidobacterium animalis subsp. animalis, as well as Bifidobacterium

  3. Interaction between ArgR and AhrC Controls Regulation of Arginine Metabolism in Lactococcus lactis

    Microsoft Academic Search

    Rasmus Larsen; Jan Kok; Oscar P. Kuipers

    2005-01-01

    The expression of arginine metabolism in Lactococcus lactis is controlled by the two homologous transcriptional regulators ArgR and AhrC. Genome sequence analyses have shown that the occurrence of multiple homologues of the ArgR family of transcriptional regulators is a common feature of many low-G + C Gram-positive bacteria. Detailed studies of ArgR type regulators have previously only been carried out

  4. A Foreign Protein Incorporated on the Tip of T3 Pili in Lactococcus lactis Elicits Systemic and Mucosal Immunity? †

    PubMed Central

    Quigley, Bernard R.; Hatkoff, Matthew; Thanassi, David G.; Ouattara, Mahamoudou; Eichenbaum, Zehava; Scott, June R.

    2010-01-01

    The use of Lactococcus lactis to deliver a chosen antigen to the mucosal surface has been shown to elicit an immune response in mice and is a possible method of vaccination in humans. The recent discovery on Gram-positive bacteria of pili that are covalently attached to the bacterial surface and the elucidation of the residues linking the major and minor subunits of such pili suggests that the presentation of an antigen on the tip of pili external to the surface of L. lactis might constitute a successful vaccine strategy. As a proof of principle, we have fused a foreign protein (the Escherichia coli maltose-binding protein) to the C-terminal region of the native tip protein (Cpa) of the T3 pilus derived from Streptococcus pyogenes and expressed this fusion protein (MBP*) in L. lactis. We find that MBP* is incorporated into pili in this foreign host, as shown by Western blot analyses of cell wall proteins and by immunogold electron microscopy. Furthermore, since the MBP* on these pili retains its native biological activity, it appears to retain its native structure. Mucosal immunization of mice with this L. lactis strain expressing pilus-linked MBP* results in production of both a systemic and a mucosal response (IgG and IgA antibodies) against the MBP antigen. We suggest that this type of mucosal vaccine delivery system, which we term UPTOP (for unhindered presentation on tips of pili), may provide an inexpensive and stable alternative to current mechanisms of immunization for many serious human pathogens. PMID:20028807

  5. Improved bioethanol production in an engineered Kluyveromyces lactis strain shifted from respiratory to fermentative metabolism by deletion of NDI1

    PubMed Central

    González-Siso, María Isabel; Touriño, Alba; Vizoso, Ángel; Pereira-Rodríguez, Ángel; Rodríguez-Belmonte, Esther; Becerra, Manuel; Cerdán, María Esperanza

    2015-01-01

    In this paper, we report the metabolic engineering of the respiratory yeast Kluyveromyces lactis by construction and characterization of a null mutant (?klndi1) in the single gene encoding a mitochondrial alternative internal dehydrogenase. Isolated mitochondria of the ?klndi1 mutant show unaffected rate of oxidation of exogenous NADH, but no oxidation of matrix NADH; this confirms that KlNdi1p is the only internal NADH dehydrogenase in K.?lactis mitochondria. Permeabilized cells of the ?klndi1 mutant do not show oxidation of matrix NADH, which suggests that shuttle systems to transfer the NADH from mitochondrial matrix to cytosol, for being oxidized by external dehydrogenases, are not functional. The ?klndi1 mutation decreases the chronological life span in absence of nutrients. The expression of KlNDI1 is increased by glutathione reductase depletion. The ?klndi1 mutation shifts the K.?lactis metabolism from respiratory to fermentative: the ?klndi1 strain shows reduced respiration rate and increased ethanol production from glucose, while it does not grow in non-fermentable carbon sources such as lactate. The biotechnological benefit of the ?klndi1 mutant for bioethanol production from waste cheese whey lactose was proved. PMID:25186243

  6. Gain-of-function mutation in the KlPDR1 gene encoding multidrug resistance regulator in Kluyveromyces lactis.

    PubMed

    Balazfyova, Zuzana; Hervay, Nora Toth; Gbelska, Yvetta

    2013-02-01

    KlPdr1p is a single Kluyveromyces lactis homologue of Saccharomyces cerevisiae ScPdr1p/ScPdr3p, the main transcriptional regulators of genes involved in S. cerevisiae multidrug resistance. KlPDR1 deletion leads to a sharp increase in K. lactis drug susceptibility. The presence of putative PDRE and YRE regulatory elements in the KlPDR1 gene promoter suggests an autoregulation of its transcription as well as its control by KlYap1p, the transcription factor involved in oxidative stress response. In this study, one plasmid-borne Klpdr1-1 allele that led to amino acid substitution (L273P) in the KlPdr1p was isolated. Overexpression of the Klpdr1-1 allele from a multicopy plasmid in the K. lactis wild-type and Klpdr1? mutant strain increased the tolerance of transformants to oligomycin. The plasmid-borne Klpdr1-1 allele increased the activation of the ScPDR5 promoter and complemented the drug hypersensitivity of the S. cerevisiae pdr1? pdr3? mutant strain. The results indicate that L273P amino acid substitution is the result of a gain-of-function mutation in the KlPDR1 gene that confers KlPdr1p hyperactivity, as revealed by a high expression of the ABC transporter gene KlPDR5, leading to multidrug resistance and rhodamine 6G efflux out of the cells. PMID:23361926

  7. Live probiotic Bifidobacterium lactis bacteria inhibit the toxic effects induced by wheat gliadin in epithelial cell culture

    PubMed Central

    Lindfors, K; Blomqvist, T; Juuti-Uusitalo, K; Stenman, S; Venäläinen, J; Mäki, M; Kaukinen, K

    2008-01-01

    Wheat gliadin induces severe intestinal symptoms and small-bowel mucosal damage in coeliac disease patients. At present, the only effective treatment for the disease is a strict life-long gluten-free diet. In this study we investigated whether probiotics Lactobacillus fermentum or Bifidobacterium lactis can inhibit the toxic effects of gliadin in intestinal cell culture conditions. The ability of live probiotics to inhibit peptic-tryptic digested gliadin-induced damage to human colon cells Caco-2 was evaluated by measuring epithelial permeability by transepithelial resistance, actin cytoskeleton arrangements by the extent of membrane ruffling and expression of tight junctional protein ZO-1. B. lactis inhibited the gliadin-induced increase dose-dependently in epithelial permeability, higher concentrations completely abolishing the gliadin-induced decrease in transepithelial resistance. The same bacterial strain also inhibited the formation of membrane ruffles in Caco-2 cells induced by gliadin administration. Furthermore, it also protected the tight junctions of Caco-2 cells against the effects of gliadin, as evinced by the pattern of ZO-1 expression. We conclude thus that live B. lactis bacteria can counteract directly the harmful effects exerted by coeliac-toxic gliadin and would clearly warrant further studies of its potential as a novel dietary supplement in the treatment of coeliac disease. PMID:18422736

  8. Bioluminescence imaging study of spatial and temporal persistence of Lactobacillus plantarum and Lactococcus lactis in living mice.

    PubMed

    Daniel, Catherine; Poiret, Sabine; Dennin, Véronique; Boutillier, Denise; Pot, Bruno

    2013-02-01

    Lactic acid bacteria, especially lactobacilli, are common inhabitants of the gastrointestinal tract of mammals, for which they have received considerable attention due to their putative health-promoting properties. In this study, we describe the development and application of luciferase-expressing Lactobacillus plantarum and Lactococcus lactis strains for noninvasive in vivo monitoring in the digestive tract of mice. We report for the first time the functional in vitro expression in Lactobacillus plantarum NCIMB8826 and in Lactococcus lactis MG1363 of the click beetle luciferase (CBluc), as well as Gaussia and bacterial luciferases, using a combination of vectors, promoters, and codon-optimized genes. We demonstrate that a CBluc construction is the best-performing luciferase system for the noninvasive in vivo detection of lactic acid bacteria after oral administration. The persistence and viability of both strains was studied by bioluminescence imaging in anesthetized mice and in mouse feces. In vivo bioluminescence imaging confirmed that after a single or multiple oral administrations, L. lactis has shorter survival times in the mouse gastrointestinal tract than L. plantarum, and it also revealed the precise gut compartments where both strains persisted. The application of luciferase-labeled bacteria has significant potential to allow the in vivo and ex vivo study of the interactions of lactic acid bacteria with their mammalian host. PMID:23204409

  9. Efficient Overproduction of Membrane Proteins in Lactococcus lactis Requires the Cell Envelope Stress Sensor/Regulator Couple CesSR

    PubMed Central

    Pinto, Joao P. C.; Kuipers, Oscar P.; Marreddy, Ravi K. R.; Poolman, Bert; Kok, Jan

    2011-01-01

    Background Membrane proteins comprise an important class of molecules whose study is largely frustrated by several intrinsic constraints, such as their hydrophobicity and added requirements for correct folding. Additionally, the complexity of the cellular mechanisms that are required to insert membrane proteins functionally in the membrane and to monitor their folding state makes it difficult to foresee the yields at which one can obtain them or to predict which would be the optimal production host for a given protein. Methods and Findings We describe a rational design approach to improve the lactic acid bacterium Lactococcus lactis as a producer of membrane proteins. Our transcriptome data shows that the two-component system CesSR, which senses cell envelope stresses of different origins, is one of the major players when L. lactis is forced to overproduce the endogenous membrane protein BcaP, a branched-chain amino acid permease. Growth of the BcaP-producing L. lactis strain and its capability to produce membrane proteins are severely hampered when the CesSR system itself or particular members of the CesSR regulon are knocked out, notably the genes ftsH, oxaA2, llmg_2163 and rmaB. Overexpressing cesSR reduced the growth defect, thus directly improving the production yield of BcaP. Applying this rationale to eukaryotic proteins, some of which are notoriously more difficult to produce, such as the medically-important presenilin complex, we were able to significantly diminish the growth defect seen in the wild-type strain and improve the production yield of the presenilin variant PS1?9-H6 more than 4-fold. Conclusions The results shed light into a key, and perhaps central, membrane protein quality control mechanism in L. lactis. Modulating the expression of CesSR benefited the production yields of membrane proteins from different origins. These findings reinforce L. lactis as a legitimate alternative host for the production of membrane proteins. PMID:21818275

  10. A fuzzy logic-based model for the multistage high-pressure inactivation of Lactococcus lactis ssp. cremoris MG 1363.

    PubMed

    Kilimann, K V; Hartmann, C; Delgado, A; Vogel, R F; Gänzle, M G

    2005-01-15

    The high-pressure inactivation (200 to 600 MPa) of Lactococcus lactis ssp. cremoris MG 1363 suspended in milk buffer was investigated with both experimental and theoretical methods. The inactivation kinetics were characterised by the determination of the viable cell counts, cell counts of undamaged cells, LmrP activity, membrane integrity, and metabolic activity. Pressures between 200 and 600 MPa were applied, and pressure holding times were varied between 0 and 120 min. Experiments were carried out in milk buffer at pH values ranging between 4.0 and 6.5, and the effect of the addition of molar concentrations of NaCl and sucrose was furthermore determined. The inactivation curves of L. lactis, as characterised by viable cell counts, exhibited typical sigmoid asymmetric shapes. Generally, inactivation of the membrane transport system LmrP was the most sensitive indicator of pressure-induced sublethal injury. Furthermore, the metabolic activity was inactivated concomitant with or prior to the loss of viability. Membrane integrity was lost concomitant with or later than cell death. For example, treatments at 200 MPa for 60 min in milk buffer did not inactivate L. lactis, but fully inactivated LmrP activity and reduced the metabolic activity by 50%. The membrane integrity was unaffected. Thus, the assay systems chosen are suitable to dissect the multistep high-pressure inactivation of L. lactis ssp. cremoris MG 1363. A fuzzy logic model accounting for the specific knowledge on the multistep pressure inactivation and allowing the prediction of the quantities of sublethally damaged cells was formulated. Furthermore, the fuzzy model could be used to accurately predict pressure inactivation of L. lactis using conditions not taken into account in model generation. It consists of 160 rules accounting for several dependent and independent variables. The rules were generated automatically with fuzzy clustering methods and rule-oriented statistical analysis. The set is open for the integration of further knowledge-based rules. A very good overall agreement between measured and predicted values was obtained. Single, deviating results have been identified and can be explained to be measurement errors or model intrinsic deficiencies. PMID:15617804

  11. Proteomic and Functional Consequences of Hexokinase Deficiency in Glucose-repressible Kluyveromyces lactis

    PubMed Central

    Mates, Nadia; Kettner, Karina; Heidenreich, Falk; Pursche, Theresia; Migotti, Rebekka; Kahlert, Günther; Kuhlisch, Eberhard; Breunig, Karin D.; Schellenberger, Wolfgang; Dittmar, Gunnar; Hoflack, Bernard; Kriegel, Thomas M.

    2014-01-01

    The analysis of glucose signaling in the Crabtree-positive eukaryotic model organism Saccharomyces cerevisiae has disclosed a dual role of its hexokinase ScHxk2, which acts as a glycolytic enzyme and key signal transducer adapting central metabolism to glucose availability. In order to identify evolutionarily conserved characteristics of hexokinase structure and function, the cellular response of the Crabtree-negative yeast Kluyveromyces lactis to rag5 null mutation and concomitant deficiency of its unique hexokinase KlHxk1 was analyzed by means of difference gel electrophoresis. In total, 2,851 fluorescent spots containing different protein species were detected in the master gel representing all of the K. lactis proteins that were solubilized from glucose-grown KlHxk1 wild-type and mutant cells. Mass spectrometric peptide analysis identified 45 individual hexokinase-dependent proteins related to carbohydrate, short-chain fatty acid and tricarboxylic acid metabolism as well as to amino acid and protein turnover, but also to general stress response and chromatin remodeling, which occurred as a consequence of KlHxk1 deficiency at a minimum 3-fold enhanced or reduced level in the mutant proteome. In addition, three proteins exhibiting homology to 2-methylcitrate cycle enzymes of S. cerevisiae were detected at increased concentrations, suggesting a stimulation of pyruvate formation from amino acids and/or fatty acids. Experimental validation of the difference gel electrophoresis approach by post-lysis dimethyl labeling largely confirmed the abundance changes detected in the mutant proteome via the former method. Taking into consideration the high proportion of identified hexokinase-dependent proteins exhibiting increased proteomic levels, KlHxk1 is likely to have a repressive function in a multitude of metabolic pathways. The proteomic alterations detected in the mutant classify KlHxk1 as a multifunctional enzyme and support the view of evolutionary conservation of dual-role hexokinases even in organisms that are less specialized than S. cerevisiae in terms of glucose utilization. PMID:24434903

  12. Proteomic and functional consequences of hexokinase deficiency in glucose-repressible Kluyveromyces lactis.

    PubMed

    Mates, Nadia; Kettner, Karina; Heidenreich, Falk; Pursche, Theresia; Migotti, Rebekka; Kahlert, Günther; Kuhlisch, Eberhard; Breunig, Karin D; Schellenberger, Wolfgang; Dittmar, Gunnar; Hoflack, Bernard; Kriegel, Thomas M

    2014-03-01

    The analysis of glucose signaling in the Crabtree-positive eukaryotic model organism Saccharomyces cerevisiae has disclosed a dual role of its hexokinase ScHxk2, which acts as a glycolytic enzyme and key signal transducer adapting central metabolism to glucose availability. In order to identify evolutionarily conserved characteristics of hexokinase structure and function, the cellular response of the Crabtree-negative yeast Kluyveromyces lactis to rag5 null mutation and concomitant deficiency of its unique hexokinase KlHxk1 was analyzed by means of difference gel electrophoresis. In total, 2,851 fluorescent spots containing different protein species were detected in the master gel representing all of the K. lactis proteins that were solubilized from glucose-grown KlHxk1 wild-type and mutant cells. Mass spectrometric peptide analysis identified 45 individual hexokinase-dependent proteins related to carbohydrate, short-chain fatty acid and tricarboxylic acid metabolism as well as to amino acid and protein turnover, but also to general stress response and chromatin remodeling, which occurred as a consequence of KlHxk1 deficiency at a minimum 3-fold enhanced or reduced level in the mutant proteome. In addition, three proteins exhibiting homology to 2-methylcitrate cycle enzymes of S. cerevisiae were detected at increased concentrations, suggesting a stimulation of pyruvate formation from amino acids and/or fatty acids. Experimental validation of the difference gel electrophoresis approach by post-lysis dimethyl labeling largely confirmed the abundance changes detected in the mutant proteome via the former method. Taking into consideration the high proportion of identified hexokinase-dependent proteins exhibiting increased proteomic levels, KlHxk1 is likely to have a repressive function in a multitude of metabolic pathways. The proteomic alterations detected in the mutant classify KlHxk1 as a multifunctional enzyme and support the view of evolutionary conservation of dual-role hexokinases even in organisms that are less specialized than S. cerevisiae in terms of glucose utilization. PMID:24434903

  13. Putrescine production via the agmatine deiminase pathway increases the growth of Lactococcus lactis and causes the alkalinization of the culture medium.

    PubMed

    del Rio, Beatriz; Linares, Daniel M; Ladero, Victor; Redruello, Begoña; Fernández, Maria; Martin, Maria Cruz; Alvarez, Miguel A

    2015-01-01

    Lactococcus lactis is the most important starter culture organism used in the dairy industry. Although L. lactis species have been awarded Qualified Presumption of Safety status by the European Food Safety Authority, and Generally Regarded as Safe status by the US Food and Drug Administration, some strains can produce the biogenic amine putrescine. One such strain is L. lactis subsp. cremoris CECT 8666 (formerly L. lactis subsp. cremoris GE2-14), which was isolated from Genestoso cheese. This strain catabolizes agmatine to putrescine via the agmatine deiminase (AGDI) pathway, which involves the production of ATP and two ammonium ions. The present work shows that the availability of agmatine and its metabolization to putrescine allows for greater bacterial growth (in a biphasic pattern) and causes the alkalinization of the culture medium in a dose-dependent manner. The construction of a mutant lacking the AGDI cluster (L. lactis CECT 8666 ?agdi) confirmed the latter's direct role in putrescine production, growth, and medium alkalinization. Alkalinization did not affect the putrescine production pattern and was not essential for increased bacterial growth. PMID:25341400

  14. Immunogenicity of oral vaccination with Lactococcus lactis derived vaccine candidate antigen (UreB) of Helicobacter pylori fused with the human interleukin 2 as adjuvant.

    PubMed

    Zhang, Hong-xin; Qiu, Yu-yu; Zhao, Ying-hui; Liu, Xin-ting; Liu, Ming; Yu, Ai-lian

    2014-02-01

    Helicobacter pylori (H. pylori) infection remains a significant global public health problem. Vaccine, especially edible vaccine, is considered to be effective in the management of H. pylori infections. By using recombinant technology, Lactococcus lactis (L. lactis) could serve as an antigen-delivering vehicle for the development of edible vaccine. The aim of this study was to produce edible UreB (urease B) vaccine derived from L. lactis against H. pylori. The UreB subunit is the most effective and common immunogen of all strains of H. pylori. The UreB was produced as a chimeric protein fused with IL-2 (human interleukin 2) as the mucosal adjuvant. Mucosal immunization of mice with recombinant L. lactis NZ9000 containing the UreB-IL-2 protein elicited more anti-UreB antibody that specifically bounded to the purified bacterial UreB protein and more cytokines such as IFN-?, IL-4, and IL-17, and had a lower H. pylori burden and urease activity than control mice. These results suggest that the recombinant L. lactis expressing UreB-IL-2 can be potentially used as an edible vaccine for controlling H. pylori infection. PMID:24036137

  15. Pyruvate metabolism in Lactococcus lactis is dependent upon glyceraldehyde-3-phosphate dehydrogenase activity.

    PubMed

    Even, S; Garrigues, C; Loubiere, P; Lindley, N D; Cocaign-Bousquet, M

    1999-07-01

    Modification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity from Lactococcus lactis was undertaken during batch fermentation on lactose, by adding various concentrations of iodoacetate (IAA), a compound which specifically inhibits GAPDH at low concentrations, to the culture medium. As IAA concentration is increased, GAPDH activity diminishes, provoking a decrease of both the glycolytic flux and the specific growth rate. This control exerted at the level of GAPDH was due partially to IAA covalent fixation but also to the modified NADH/NAD+ ratio. The mechanism of inhibition by NADH/NAD+ was studied in detail with the purified enzyme and various kinetic parameters were determined. Moreover, when GAPDH activity became limiting, the triose phosphate pool increased resulting in the inhibition of pyruvate formate lyase activity, while the lactate dehydrogenase is activated by the high NADH/NAD+ ratio. Thus, modifying the GAPDH activity provokes a shift from mixed-acid to homolactic metabolism, confirming the important role of this enzyme in controlling both the flux through glycolysis and the orientation of pyruvate catabolism. PMID:10937934

  16. Feedback Regulation of Glucose Transporter Gene Transcription in Kluyveromyces lactis by Glucose Uptake

    PubMed Central

    Milkowski, C.; Krampe, S.; Weirich, J.; Hasse, V.; Boles, E.; Breunig, K. D.

    2001-01-01

    In the respirofermentative yeast Kluyveromyces lactis, only a single genetic locus encodes glucose transporters that can support fermentative growth. This locus is polymorphic in wild-type isolates carrying either KHT1 and KHT2, two tandemly arranged HXT-like genes, or RAG1, a low-affinity transporter gene that arose by recombination between KHT1 and KHT2. Here we show that KHT1 is a glucose-induced gene encoding a low-affinity transporter very similar to Rag1p. Kht2p has a lower Km (3.7 mM) and a more complex regulation. Transcription is high in the absence of glucose, further induced by low glucose concentrations, and repressed at higher glucose concentrations. The response of KHT1 and KHT2 gene regulation to high but not to low concentrations of glucose depends on glucose transport. The function of either Kht1p or Kht2p is sufficient to mediate the characteristic response to high glucose, which is impaired in a kht1 kht2 deletion mutant. Thus, the KHT genes are subject to mutual feedback regulation. Moreover, glucose repression of the endogenous ?-galactosidase (LAC4) promoter and glucose induction of pyruvate decarboxylase were abolished in the kht1 kht2 mutant. These phenotypes could be partially restored by HXT gene family members from Saccharomyces cerevisiae. The results indicate that the specific responses to high but not to low glucose concentrations require a high rate of glucose uptake. PMID:11514503

  17. A Genome-Scale Integration and Analysis of Lactococcus lactis Translation Data

    PubMed Central

    Racle, Julien; Picard, Flora; Girbal, Laurence; Cocaign-Bousquet, Muriel; Hatzimanikatis, Vassily

    2013-01-01

    Protein synthesis is a template polymerization process composed by three main steps: initiation, elongation, and termination. During translation, ribosomes are engaged into polysomes whose size is used for the quantitative characterization of translatome. However, simultaneous transcription and translation in the bacterial cytosol complicates the analysis of translatome data. We established a procedure for robust estimation of the ribosomal density in hundreds of genes from Lactococcus lactis polysome size measurements. We used a mechanistic model of translation to integrate the information about the ribosomal density and for the first time we estimated the protein synthesis rate for each gene and identified the rate limiting steps. Contrary to conventional considerations, we find significant number of genes to be elongation limited. This number increases during stress conditions compared to optimal growth and proteins synthesized at maximum rate are predominantly elongation limited. Consistent with bacterial physiology, we found proteins with similar rate and control characteristics belonging to the same functional categories. Under stress conditions, we found that synthesis rate of regulatory proteins is becoming comparable to proteins favored under optimal growth. These findings suggest that the coupling of metabolic states and protein synthesis is more important than previously thought. PMID:24130467

  18. Chemical structure of the cell wall-associated polysaccharide of Bifidobacterium animalis subsp. lactis LKM512.

    PubMed

    Uemura, Yusuke; Matsumoto, Mitsuharu

    2014-11-01

    We have demonstrated that Bifidobacterium animalis subsp. lactis LKM512 had some probiotic properties in vivo and in vitro. To further understand their mechanisms, the chemical structure of the extracellular polysaccharide that constructs the cell envelope was determined. The strain was anaerobically cultured in MRS broth at 37 °C for 20 h, then the bacterial cells were harvested by centrifugation and washed. The cell wall-associated polysaccharide (CPS) was prepared from the cell wall component digested by lysozyme. The results of anion exchange and gel filtration chromatography showed that the polysaccharide was negatively charged and had a high molecular mass. The CPS was found to compose of galactopyranosyl, galactofuranosyl, glucopyranosyl and rhamnopyranosyl residues in the molar ratio of 1:1:1:3 by using methylation analysis with GC-MS and HPLC profiling. From the results of the structural characterization by 1 dimensional and 2 dimensional NMR spectroscopy, the polysaccharide was established to be a hexasaccharide repeating unit with the following structure: LKM512. PMID:25043203

  19. Survival, physiology, and lysis of Lactococcus lactis in the digestive tract.

    PubMed

    Drouault, S; Corthier, G; Ehrlich, S D; Renault, P

    1999-11-01

    The survival and the physiology of lactococcal cells in the different compartments of the digestive tracts of rats were studied in order to know better the fate of ingested lactic acid bacteria after oral administration. For this purpose, we used strains marked with reporter genes, the luxA-luxB gene of Vibrio harveyi and the gfp gene of Aequora victoria, that allowed us to differentiate the inoculated bacteria from food and the other intestinal bacteria. Luciferase was chosen to measure the metabolic activity of Lactococcus lactis in the digestive tract because it requires NADH, which is available only in metabolically active cells. The green fluorescent protein was used to assess the bacterial lysis independently of death. We report not only that specific factors affect the cell viability and integrity in some digestive tract compartments but also that the way bacteria are administrated has a dramatic impact. Lactococci which transit with the diet are quite resistant to gastric acidity (90 to 98% survival). In contrast, only 10 to 30% of bacteria survive in the duodenum. Viable cells are metabolically active in each compartment of the digestive tract, whereas most dead cells appear to be subject to rapid lysis. This property suggests that lactococci could be used as a vector to deliver specifically into the duodenum the proteins produced in the cytoplasm. This type of delivery vector would be particularly appropriate for targeting digestive enzymes such as lipase to treat pancreatic deficiencies. PMID:10543799

  20. Evaluation of the performance of Torulaspora delbrueckii, Williopsis saturnus, and Kluyveromyces lactis in lychee wine fermentation.

    PubMed

    Chen, Dai; Yap, Zhi Yin; Liu, Shao-Quan

    2015-08-01

    This study evaluated the effects of three non-Saccharomyces yeasts, namely Torulaspora delbrueckii PRELUDE, Williopsis saturnus NCYC22, and Kluyveromyces lactis KL71 on lychee juice fermentation. The fermentation performance of these non-Saccharomyces yeasts was significantly different. T. delbrueckii PRELUDE had the fastest rate of growth and high sugar consumption. W. saturnus NCYC22 used the lowest amount of sugars, but consumed the highest amount of nitrogen. Correspondingly, strain PRELUDE produced the highest level of ethanol (7.6% v/v), followed by strain KL71 (3.4% v/v) and strain NCYC22 (0.8% v/v). Aroma character-impact terpenes and terpenoids could be partially retained in all lychee wines, with higher odour activity values (OAVs) of geraniol and citronellol in strain KL71. However, strain KL71 and strain NCYC22 over-produced ethyl acetate. Strain PRELUDE had a better ability to generate high levels of ethanol, isoamyl alcohol, 2-phenylethyl alcohol, ethyl octanoate, and ethyl decanoate and retained high OAVs of lychee aroma-character compounds cis-rose oxide (16.5) and linalool (3.5). Thus, it is deemed to be a promising non-Saccharomyces yeast for lychee wine fermentation. PMID:25955287

  1. Regulation of glycolysis in Lactococcus lactis: an unfinished systems biological case study.

    PubMed

    Voit, E O; Almeida, J; Marino, S; Lall, R; Goel, G; Neves, A R; Santos, H

    2006-07-01

    The unexpectedly long, and still unfinished, path towards a reliable mathematical model of glycolysis and its regulation in Lactococcus lactis is described. The model of this comparatively simple pathway was to be deduced from in vivo nuclear magnetic resonance time-series measurements of the key glycolytic metabolites. As to be expected from any nonlinear inverse problem, computational challenges were encountered in the numerical determination of parameter values of the model. Some of these were successfully solved, whereas others are still awaiting improved techniques of analysis. In addition, rethinking of the model formulation became necessary, because some generally accepted assumptions during model design are not necessarily valid for in vivo models. Examples include precursor-product relationships and the homogeneity of cells and their responses. Finally, it turned out to be useful to model only some of the metabolites, while using time courses of ubiquitous compounds such as adenosine triphosphate, inorganic phosphate, nicotinamide adenine dinucleotide (oxidised) and nicotinamide adenine dinucleotide (reduced) as unmodelled input functions. With respect to our specific application, the modelling process has come a long way, but it is not yet completed. Nonetheless, the model analysis has led to interesting insights into the design of the pathway and into the principles that govern its operation. Specifically, the widely observed feedforward activation of pyruvate kinase by fructose 1,6-bisphosphate is shown to provide a crucial mechanism for positioning the starving organism in a holding pattern that allows immediate uptake of glucose, as soon as it becomes available. PMID:16986630

  2. Structural basis for arabinoxylo-oligosaccharide capture by the probiotic Bifidobacterium animalis subsp. lactis Bl-04.

    PubMed

    Ejby, Morten; Fredslund, Folmer; Vujicic-Zagar, Andreja; Svensson, Birte; Slotboom, Dirk Jan; Abou Hachem, Maher

    2013-12-01

    Glycan utilization plays a key role in modulating the composition of the gut microbiota, but molecular insight into oligosaccharide uptake by this microbial community is lacking. Arabinoxylo-oligosaccharides (AXOS) are abundant in the diet, and are selectively fermented by probiotic bifidobacteria in the colon. Here we show how selectivity for AXOS uptake is established by the probiotic strain Bifidobacterium animalis subsp. lactis Bl-04. The binding protein BlAXBP, which is associated with an ATP-binding cassette (ABC) transporter that mediates the uptake of AXOS, displays an exceptionally broad specificity for arabinosyl-decorated and undecorated xylo-oligosaccharides, with preference for tri- and tetra-saccharides. Crystal structures of BlAXBP in complex with four different ligands revealed the basis for this versatility. Uniquely, the protein was able to recognize oligosaccharides in two opposite orientations, which facilitates the optimization of interactions with the various ligands. Broad substrate specificity was further enhanced by a spacious binding pocket accommodating decorations at different mainchain positions and conformational flexibility of a lid-like loop. Phylogenetic and genetic analyses show that BlAXBP is highly conserved within Bifidobacterium, but is lacking in other gut microbiota members. These data indicate niche adaptation within Bifidobacterium and highlight the metabolic syntrophy (cross-feeding) among the gut microbiota. PMID:24279727

  3. Efficient isolation of the linear DNA killer plasmid of Kluyveromyces lactis: evidence for location and expression in the cytoplasm and characterization of their terminally bound proteins.

    PubMed Central

    Stam, J C; Kwakman, J; Meijer, M; Stuitje, A R

    1986-01-01

    Differential centrifugation of an osmotic lysate of K. lactis protoplasts showed that the linear DNA killer plasmids of K. lactis, pGKL1 and pGKL2, are almost exclusively present in the cytoplasmic fraction. This fractionation procedure allows the rapid isolation of large amounts of plasmid DNA without contamination by chromosomal and mitochondrial DNA. With these DNA preparations the size of the terminally bound proteins was estimated to be 28 and 36 kDal for pGKL1 and pGKL2, respectively. The entire pGKL1 sequence (except for 21 base pairs at the right terminus) was cloned in a shuttle vector that permits autonomous replication in the nucleus of K. lactis. However, killer gene expression could not be established in transformants. In connection with the observed cytoplasmic localization, this result suggests that gene expression of the killer DNA plasmids is entirely cytoplasmic. Images PMID:3763395

  4. Trimming of two major type 1 diabetes driving antigens, GAD65 and IA-2, allows for successful expression in Lactococcus lactis.

    PubMed

    Robert, S; Van Huynegem, K; Gysemans, C; Mathieu, C; Rottiers, P; Steidler, L

    2015-01-01

    Type 1 diabetes (T1D) is a chronic autoimmune disease characterised by excessive immune reactions against auto-antigens of pancreatic ?-cells. Restoring auto-antigen tolerance remains the superior therapeutic strategy. Oral auto-antigen administration uses the tolerogenic nature of the gut-associated immune system to induce antigen-specific tolerance. However, due to gastric degradation, proper mucosal product delivery often imposes a challenge. Recombinant Lactococcus lactis have proven to be effective and safe carriers for gastrointestinal delivery of therapeutic products: L. lactis secreting diabetes-associated auto-antigens in combination with interleukin (IL)-10 have demonstrated therapeutic efficacy in a well-defined mouse model for T1D. Here, we describe the construction of recombinant L. lactis secreting the 65 kDa isoform of glutamic acid decarboxylase (GAD65) and tyrosine phosphatase-like protein ICA512 (IA-2), two major T1D-related auto-antigens. Attempts to secrete full size human GAD65 and IA-2 protein by L. lactis were unsuccessful. Trimming of GAD65 and IA-2 was investigated to optimise antigen secretion while maintaining sufficient bacterial growth. GAD65370-575 and IA-2635-979 showed to be efficiently secreted by recombinant L. lactis. Antigen secretion was verified by immunoblotting. Plasmid-derived GAD65 and IA-2 expression was combined in single strains with human IL-10 expression, a desired combination to allow tolerance induction. This study reports the generation of recombinant L. lactis secreting two major diabetes-related auto-antigens: human GAD65 and IA-2, by themselves or combined with the anti-inflammatory cytokine human IL-10. Prohibitive sequence obstacles hampering antigen secretion were resolved by trimming the full size proteins. PMID:25576592

  5. Lactococcus lactis carrying the pValac DNA expression vector coding for IL-10 reduces inflammation in a murine model of experimental colitis

    PubMed Central

    2014-01-01

    Background Inflammatory bowel diseases (IBD) are intestinal disorders characterized by inflammation in the gastrointestinal tract. Interleukin-10 is one of the most important anti-inflammatory cytokines involved in the intestinal immune system and because of its role in downregulating inflammatory cascades, its potential for IBD therapy is under study. We previously presented the development of an invasive strain of Lactococcus lactis (L. lactis) producing Fibronectin Binding Protein A (FnBPA) which was capable of delivering, directly to host cells, a eukaryotic DNA expression vector coding for IL-10 of Mus musculus (pValac:il-10) and diminish inflammation in a trinitrobenzene sulfonic acid (TNBS)-induced mouse model of intestinal inflammation. As a new therapeutic strategy against IBD, the aim of this work was to evaluate the therapeutic effect of two L. lactis strains (the same invasive strain evaluated previously and the wild-type strain) carrying the therapeutic pValac:il-10 plasmid in the prevention of inflammation in a dextran sodium sulphate (DSS)-induced mouse model. Results Results obtained showed that not only delivery of the pValac:il-10 plasmid by the invasive strain L. lactis MG1363 FnBPA+, but also by the wild-type strain L. lactis MG1363, was effective at diminishing intestinal inflammation (lower inflammation scores and higher IL-10 levels in the intestinal tissues, accompanied by decrease of IL-6) in the DSS-induced IBD mouse model. Conclusions Administration of both L. lactis strains carrying the pValac:il-10 plasmid was effective at diminishing inflammation in this murine model of experimental colitis, showing their potential for therapeutic intervention of IBD. PMID:25106058

  6. Genome-scale metabolic model for Lactococcus lactis MG1363 and its application to the analysis of flavor formation.

    PubMed

    Flahaut, Nicolas A L; Wiersma, Anne; van de Bunt, Bert; Martens, Dirk E; Schaap, Peter J; Sijtsma, Lolke; Dos Santos, Vitor A Martins; de Vos, Willem M

    2013-10-01

    Lactococcus lactis subsp. cremoris MG1363 is a paradigm strain for lactococci used in industrial dairy fermentations. However, despite of its importance for process development, no genome-scale metabolic model has been reported thus far. Moreover, current models for other lactococci only focus on growth and sugar degradation. A metabolic model that includes nitrogen metabolism and flavor-forming pathways is instrumental for the understanding and designing new industrial applications of these lactic acid bacteria. A genome-scale, constraint-based model of the metabolism and transport in L. lactis MG1363, accounting for 518 genes, 754 reactions, and 650 metabolites, was developed and experimentally validated. Fifty-nine reactions are directly or indirectly involved in flavor formation. Flux Balance Analysis and Flux Variability Analysis were used to investigate flux distributions within the whole metabolic network. Anaerobic carbon-limited continuous cultures were used for estimating the energetic parameters. A thorough model-driven analysis showing a highly flexible nitrogen metabolism, e.g., branched-chain amino acid catabolism which coupled with the redox balance, is pivotal for the prediction of the formation of different flavor compounds. Furthermore, the model predicted the formation of volatile sulfur compounds as a result of the fermentation. These products were subsequently identified in the experimental fermentations carried out. Thus, the genome-scale metabolic model couples the carbon and nitrogen metabolism in L. lactis MG1363 with complete known catabolic pathways leading to flavor formation. The model provided valuable insights into the metabolic networks underlying flavor formation and has the potential to contribute to new developments in dairy industries and cheese-flavor research. PMID:23974365

  7. Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults

    PubMed Central

    Waller, Philip A; Gopal, Pramod K; Leyer, Gregory J; Ouwehand, Arthur C; Reifer, Cheryl; Stewart, Morgan E; Miller, Larry E

    2011-01-01

    Objective. To assess the impact of Bifidobacterium lactis HN019 supplementation on whole gut transit time (WGTT) and frequency of functional gastrointestinal (GI) symptoms in adults. Material and methods. We randomized 100 subjects (mean age: 44 years; 64% female) with functional GI symptoms to consume a proprietary probiotic strain, B. lactis HN019 (Fonterra Research Centre, Palmerston North, New Zealand), at daily doses of 17.2 billion colony forming units (CFU) (high dose; n = 33), 1.8 billion CFU (low dose; n = 33), or placebo (n = 34) for 14 days. The primary endpoint of WGTT was assessed by X-ray on days 0 and 14 and was preceded by consumption of radiopaque markers once a day for 6 days. The secondary endpoint of functional GI symptom frequency was recorded with a subject-reported numeric (1–100) scale before and after supplementation. Results. Decreases in mean WGTT over the 14-day study period were statistically significant in the high dose group (49 ± 30 to 21 ± 32 h, p < 0.001) and the low dose group (60 ± 33 to 41 ± 39 h, p = 0.01), but not in the placebo group (43 ± 31 to 44 ± 33 h). Time to excretion of all ingested markers was significantly shorter in the treatment groups versus placebo. Of the nine functional GI symptoms investigated, eight significantly decreased in frequency in the high dose group and seven decreased with low dose, while two decreased in the placebo group. No adverse events were reported in any group. Conclusions. Daily B. lactis HN019 supplementation is well tolerated, decreases WGTT in a dose-dependent manner, and reduces the frequency of functional GI symptoms in adults. PMID:21663486

  8. Production of human lysozyme in biofilm reactor and optimization of growth parameters of Kluyveromyces lactis K7.

    PubMed

    Ercan, Duygu; Demirci, Ali

    2013-07-01

    Lysozyme (1,4-?-N-acetylmuramidase) is a lytic enzyme, which degrades the bacterial cell wall. Lysozyme has been of interest in medicine, cosmetics, and food industries because of its anti-bactericidal effect. Kluyveromyces lactis K7 is a genetically modified organism that expresses human lysozyme. There is a need to improve the human lysozyme production by K. lactis K7 to make the human lysozyme more affordable. Biofilm reactor provides high biomass by including a solid support, which microorganisms grow around and within. Therefore, the aim of this study was to produce the human lysozyme in biofilm reactor and optimize the growth conditions of K. lactis K7 for the human lysozyme production in biofilm reactor with plastic composite support (PCS). The PCS, which includes polypropylene, soybean hull, soybean flour, bovine albumin, and salts, was selected based on biofilm formation on PCS (CFU/g), human lysozyme production (U/ml), and absorption of lysozyme inside the support. To find the optimum combination of growth parameters, a three-factor Box-Behnken design of response surface method was used. The results suggested that the optimum conditions for biomass and lysozyme productions were different (27 °C, pH 6, 1.33 vvm for biomass production; 25 °C, pH 4, no aeration for lysozyme production). Then, different pH and aeration shift strategies were tested to increase the biomass at the first step and then secrete the lysozyme after the shift. As a result, the lysozyme production amount (141 U/ml) at 25 °C without pH and aeration control was significantly higher than the lysozyme amount at evaluated pH and aeration shift conditions (p?

  9. N5-(1-carboxyethyl)-ornithine, a new amino acid from the intracellular pool of Streptococcus lactis.

    PubMed Central

    Thompson, J; Curtis, M A; Miller, S P

    1986-01-01

    Intracellular concentrations of amino acids were determined in cells of Streptococcus lactis 133 during growth in complex, spent, and chemically defined media. Glutamic and aspartic acids represented the major constituents of the amino acid pool. However, organisms grown in spent medium or in defined medium supplemented with ornithine also contained unusually high levels of two additional amino acids. One of these amino acids was ornithine. The second compound exhibited properties of a neutral amino acid by coelution with valine from the amino acid analyzer. The compound did not, however, comigrate with valine or any other standard amino acid by two-dimensional thin-layer chromatography. The unknown amino acid was purified by paper and thin-layer chromatography, and its molecular structure was determined by 1H and 13C nuclear magnetic resonance spectroscopy. This new amino acid was shown to be N5-(1-carboxyethyl)-ornithine. The 14C-labeled compound was formed by cells of S. lactis 133 during growth in spent medium or defined medium containing [14C]ornithine. Formation of the derivative by resting cells required ornithine and the presence of a metabolizable sugar. N5-(1-Carboxyethyl)-ornithine was synthesized chemically from both poly-S-ornithine and (2S)-N2-carbobenzyloxy-ornithine as a 1:1 mixture of two diastereomers. The physical and chemical properties of the amino acid purified from S. lactis 133 were identical to those of one of the synthetic diastereomers. The bis-N-trifluoroacetyl-di-n-butyl esters of the natural and synthetic compounds generated identical gas chromatography-mass spectrometry spectra. A mechanism is suggested for the in vivo synthesis of N5-(1-carboxyethyl)-ornithine, and the possible functions of this new amino acid are discussed. Images PMID:3090017

  10. Enhanced Production of Pediocin PA-1 and Coproduction of Nisin and Pediocin PA-1 by Lactococcus lactis

    PubMed Central

    Horn, Nikki; Martínez, María I.; Martínez, José M.; Hernández, Pablo E.; Gasson, Michael J.; Rodríguez, Juan M.; Dodd, Helen M.

    1999-01-01

    The production and secretion of class II bacteriocins share a number of features that allow the interchange of genetic determinants between certain members of this group of antimicrobial peptides. Lactococcus lactis IL1403 encodes translocatory functions able to recognize and mediate secretion of lactococcin A. The ability of this strain to also produce the pediococcal bacteriocin pediocin PA-1, has been demonstrated previously by the introduction of a chimeric gene, composed of sequences encoding the leader of lactococcin A and the mature part of pediocin PA-1 (N. Horn, M. I. Martínez, J. M. Martínez, P. E. Hernández, M. J. Gasson, J. M. Rodríguez, and H. M. Dodd, Appl. Environ. Microbiol. 64:818–823, 1998). This heterologous expression system has been developed further with the introduction of the lactococcin A-dedicated translocatory function genes, lcnC and lcnD, and their effect on bacteriocin yields in various lactococcal hosts was assessed. The copy number of lcnC and lcnD influenced production levels, as did the particular strain employed as host. Highest yields were achieved with L. lactis IL1403, which generated pediocin PA-1 at a level similar to that for the parental strain, Pediococcus acidilactici 347, representing a significant improvement over previous systems. The genetic determinants required for production of pediocin PA-1 were introduced into the nisin-producing strain L. lactis FI5876, where both pediocin PA-1 and nisin A were simultaneously produced. The implications of coproduction of these two industrially relevant antimicrobial agents by a food-grade organism are discussed. PMID:10508073

  11. A novel, lactase-based selection and strain improvement strategy for recombinant protein expression in Kluyveromyces lactis

    PubMed Central

    2012-01-01

    Background The Crabtree-negative yeast species Kluyveromyces lactis has been established as an attractive microbial expression system for recombinant proteins at industrial scale. Its LAC genes allow for utilization of the inexpensive sugar lactose as a sole source of carbon and energy. Lactose efficiently induces the LAC4 promoter, which can be used to drive regulated expression of heterologous genes. So far, strain manipulation of K. lactis by homologous recombination was hampered by the high rate of non-homologous end-joining. Results Selection for growth on lactose was applied to target the insertion of heterologous genes downstream of the LAC4 promoter into the K. lactis genome and found to yield high numbers of positive transformants. Concurrent reconstitution of the ?-galactosidase gene indicated the desired integration event of the expression cassette, and ?-galactosidase activity measurements were used to monitor gene expression for strain improvement and fermentation optimization. The system was particularly improved by usage of a cell lysis resistant strain, VAK367-D4, which allowed for protein accumulation in long-term fermentation. Further optimization was achieved by increased gene dosage of KlGAL4 encoding the activator of lactose and galactose metabolic genes that led to elevated transcription rates. Pilot experiments were performed with strains expressing a single-chain antibody fragment (scFvox) and a viral envelope protein (BVDV-E2), respectively. scFvox was shown to be secreted into the culture medium in an active, epitope-binding form indicating correct processing and protein folding; the E2 protein could be expressed intracellularly. Further data on the influence of protein toxicity on batch fermentation and potential post-transcriptional bottlenecks in protein accumulation were obtained. Conclusions A novel Kluyveromyces lactis host-vector system was developed that places heterologous genes under the control of the chromosomal LAC4 promoter and that allows monitoring of its transcription rates by ?-galactosidase measurement. The procedure is rapid and efficient, and the resulting recombinant strains contain no foreign genes other than the gene of interest. The recombinant strains can be grown non-selectively in rich medium and stably maintained even when the gene product exerts protein toxicity. PMID:22905717

  12. Monte-Carlo Modeling of the Central Carbon Metabolism of Lactococcus lactis: Insights into Metabolic Regulation

    PubMed Central

    Murabito, Ettore; Verma, Malkhey; Bekker, Martijn; Bellomo, Domenico; Westerhoff, Hans V.; Teusink, Bas; Steuer, Ralf

    2014-01-01

    Metabolic pathways are complex dynamic systems whose response to perturbations and environmental challenges are governed by multiple interdependencies between enzyme properties, reactions rates, and substrate levels. Understanding the dynamics arising from such a network can be greatly enhanced by the construction of a computational model that embodies the properties of the respective system. Such models aim to incorporate mechanistic details of cellular interactions to mimic the temporal behavior of the biochemical reaction system and usually require substantial knowledge of kinetic parameters to allow meaningful conclusions. Several approaches have been suggested to overcome the severe data requirements of kinetic modeling, including the use of approximative kinetics and Monte-Carlo sampling of reaction parameters. In this work, we employ a probabilistic approach to study the response of a complex metabolic system, the central metabolism of the lactic acid bacterium Lactococcus lactis, subject to perturbations and brief periods of starvation. Supplementing existing methodologies, we show that it is possible to acquire a detailed understanding of the control properties of a corresponding metabolic pathway model that is directly based on experimental observations. In particular, we delineate the role of enzymatic regulation to maintain metabolic stability and metabolic recovery after periods of starvation. It is shown that the feedforward activation of the pyruvate kinase by fructose-1,6-bisphosphate qualitatively alters the bifurcation structure of the corresponding pathway model, indicating a crucial role of enzymatic regulation to prevent metabolic collapse for low external concentrations of glucose. We argue that similar probabilistic methodologies will help our understanding of dynamic properties of small-, medium- and large-scale metabolic networks models. PMID:25268481

  13. High-Throughput Identification and Validation of In Situ-Expressed Genes of Lactococcus lactis?

    PubMed Central

    Bachmann, Herwig; Kleerebezem, Michiel; van Hylckama Vlieg, Johan E. T.

    2008-01-01

    Understanding the functional response of bacteria to their natural environment is one of the current challenges in microbiology. Over the past decades several techniques have been developed to study gene expression in complex natural habitats. Most of these methods, however, are laborious, and validation of results under in situ conditions is cumbersome. Here we report the improvement of the recombinase-based in vivo expression technology (R-IVET) by the implementation of two additional reporter genes. The first one is an ?-galactosidase gene (melA), which facilitates the rapid identification of in vivo-induced genes. Second, the bacterial luciferase genes (luxAB) are transcriptionally coupled to the resolvase gene, which allows rapid validation and characterization of in vivo-induced genes. The system is implemented and validated in the industrially important lactic acid bacterium Lactococcus lactis. We demonstrate the applicability of the advanced R-IVET system by the identification and validation of lactococcal promoter elements that are induced in minimal medium compared to the commonly used rich laboratory medium M17. R-IVET screening led to the identification of 19 promoters that predominantly control expression of genes involved in amino acid and nucleotide metabolism and in transport functions. Furthermore, the luciferase allows high-resolution transcription analysis and enabled the identification of complex medium constituents and specific molecules involved in promoter control. Rapid target validation exemplifies the high-throughput potential of the extended R-IVET system. The system can be applied to other bacterial species, provided that the reporter genes used are functional in the organism of interest. PMID:18539793

  14. Bifidobacterium animalis subsp. lactis BB-12 in reducing the risk of infections in infancy.

    PubMed

    Taipale, Teemu; Pienihäkkinen, Kaisu; Isolauri, Erika; Larsen, Charlotte; Brockmann, Elke; Alanen, Pentti; Jokela, Jorma; Söderling, Eva

    2011-02-01

    The impact of controlled administration of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) on the risk of acute infectious diseases was studied in healthy newborn infants. In this double-blind, placebo-controlled study, 109 newborn 1-month-old infants were assigned randomly to a probiotic group receiving a BB-12-containing tablet (n 55) or to a control group receiving a control tablet (n 54). Test tablets were administered to the infants twice a day (daily dose of BB-12 10 billion colony-forming units) from the age of 1-2 months to 8 months with a novel slow-release pacifier or a spoon. Breastfeeding habits, pacifier use, dietary habits, medications and all signs and symptoms of acute infections were registered. At the age of 8 months, faecal samples were collected for BB-12 determination (quantitative PCR method). The baseline characteristics of the two groups were similar, as was the duration of exclusive breastfeeding. BB-12 was recovered (detection limit log 5) in the faeces of 62% of the infants receiving the BB-12 tablet. The daily duration of pacifier sucking was not associated with the occurrence of acute otitis media. No significant differences between the groups were observed in reported gastrointestinal symptoms, otitis media or use of antibiotics. However, the infants receiving BB-12 were reported to have experienced fewer respiratory infections (65 v. 94%; risk ratio 0·69; 95% CI 0·53, 0·89; P = 0·014) than the control infants. Controlled administration of BB-12 in early childhood may reduce respiratory infections. PMID:20863419

  15. Biological characteristics and probiotic effect of Leuconostoc lactis strain isolated from the intestine of black porgy fish

    PubMed Central

    Zhang, Wei; Liu, Mingqi; Dai, Xianjun

    2013-01-01

    A strain of lactic acid bacteria, Leuconostoc lactis, was isolated from the intestinal tract of black porgy, Sparus macrocephalus, and identified by conventional biochemical characteristics and 16S rDNA gene sequence analysis. The isolated strain had the ability of bile tolerance and resistance to low pH, and survived well in the trypsinase and pepsin solution. But the highly concentrated dose of trypsinase and pepsin affect the viability of the isolated strain. The isolate was resistant to several antibiotics, including Cephalothin, Ceftriaxone, Imipenem and Tobramycin. The isolate could auto-aggregate itself and coaggregate with other bacteria in vitro. The autoaggregation percentage increased to 23.29% after 20 h of incubation. The percentage of coaggregation were respectively 31.21%, 29.44%, 10.74%, 16.49%, 24.36%, 24.41% and 20.99% for Vibrio parahaemolyticus, Listeria monocytogenes, Escherichia coli O157, Salmonella typhimurium, Shigella, Staphylococcus aureus and Proteusbacillus vulgaris after 20 h incubation of a mixed suspension. The supernatant of the strain inhibited the growth of several pathogens, such as V.parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Staphylococcus aureus, Escherichia coli O157, Salmonella typhimurium, Bacillus subtilis, Proteusbacillus vulgaris and Shigella. These results indicated that the isolate, Leuconostoc lactis, might be an attractive candidate for perspectival strain for probiotics in marine aquaculture. PMID:24516418

  16. Ability of Lactococcus lactis To Export Viral Capsid Antigens: a Crucial Step for Development of Live Vaccines

    PubMed Central

    Dieye, Yakhya; Hoekman, Arjan J. W.; Clier, Florence; Juillard, Vincent; Boot, Hein J.; Piard, Jean-Christophe

    2003-01-01

    Thefood grade bacterium Lactococcus lactis is a potential vehicle for protein delivery in the gastrointestinal tract. As a model, we constructed lactococcal strains producing antigens of infectious bursal disease virus (IBDV). IBDV infects chickens and causes depletion of B-lymphoid cells in the bursa of Fabricius and subsequent immunosuppression, morbidity, or acute mortality. The two major IBDV antigens, i.e., VP2 and VP3, that form the viral capsid were expressed and targeted to the cytoplasm, the cell wall, or the extracellular compartment of L. lactis. Whereas VP3 was successfully targeted to the three compartments by the use of relevant expression and export vectors, VP2 was recalcitrant to export, thus confirming the difficulty of translocating naturally nonsecreted proteins across the bacterial membrane. This defect could be partly overcome by fusing VP2 to a naturally secreted protein (the staphylococcal nuclease Nuc) that carried VP2 through the membrane. Lactococcal strains producing Nuc-VP2 and VP3 in various bacterial compartments were administered orally to chickens. The chickens did not develop any detectable immune response against VP2 and VP3 but did exhibit an immune response against Nuc when Nuc-VP2 was anchored to the cell wall of lactococci. PMID:14660377

  17. Pyrimidine motif triple helix in the Kluyveromyces lactis telomerase RNA pseudoknot is essential for function in vivo

    PubMed Central

    Cash, Darian D.; Cohen-Zontag, Osnat; Kim, Nak-Kyoon; Shefer, Kinneret; Brown, Yogev; Ulyanov, Nikolai B.; Tzfati, Yehuda; Feigon, Juli

    2013-01-01

    Telomerase is a ribonucleoprotein complex that extends the 3? ends of linear chromosomes. The specialized telomerase reverse transcriptase requires a multidomain RNA (telomerase RNA, TER), which includes an integral RNA template and functionally important template-adjacent pseudoknot. The structure of the human TER pseudoknot revealed that the loops interact with the stems to form a triple helix shown to be important for activity in vitro. A similar triple helix has been predicted to form in diverse fungi TER pseudoknots. The solution NMR structure of the Kluyveromyces lactis pseudoknot, presented here, reveals that it contains a long pyrimidine motif triple helix with unexpected features that include three individual bulge nucleotides and a C+•G-C triple adjacent to a stem 2–loop 2 junction. Despite significant differences in sequence and base triples, the 3D shape of the human and K. lactis TER pseudoknots are remarkably similar. Analysis of the effects of nucleotide substitutions on cell growth and telomere lengths provides evidence that this conserved structure forms in endogenously assembled telomerase and is essential for telomerase function in vivo. PMID:23776224

  18. Double-glycine-type leader peptides direct secretion of bacteriocins by ABC transporters: colicin V secretion in Lactococcus lactis.

    PubMed

    van Belkum, M J; Worobo, R W; Stiles, M E

    1997-03-01

    Many non-lantibiotic bacteriocins of lactic acid bacteria are produced as precursors which have N-terminal leader peptides that share similarities in amino acid sequence and contain a conserved processing site of two glycine residues in positions -1 and -2. A dedicated ATP-binding cassette (ABC) transporter is responsible for the proteolytic cleavage of the leader peptides and subsequent translocation of the bacteriocins across the cytoplasmic membrane. To investigate the role that these leader peptides play in the recognition of the precursor by the ABC transporters, the leader peptides of leucocin A, lactococcin A or colicin V were fused to divergicin A, a bacteriocin from Carnobacterium divergens that is secreted via the cell's general secretion pathway. Production of divergicin was monitored when these fusion constructs were introduced into Leuconostoc gelidum, Lactococcus lactis and Escherichia coli, which carry the secretion apparatus for leucocin A, lactococcins A and B, and colicin V, respectively. The different leader peptides directed the production of divergicin in the homologous hosts. In some cases production of divergicin was also observed when the leader peptides were used in heterologous hosts. For ABC-transporter-dependent secretion in E. coli the outer membrane protein TolC was required. Using this strategy, colicin V was produced in L. lactis by fusing this bacteriocin behind the leader peptide of leucocin A. PMID:9106219

  19. Growth phase-dependent proteomes of the Malaysian isolated Lactococcus lactis dairy strain M4 using label-free qualitative shotgun proteomics analysis.

    PubMed

    Yap, Theresa Wan Chen; Rabu, Amir; Abu Bakar, Farah Diba; Rahim, Raha Abdul; Mahadi, Nor Muhammad; Illias, Rosli Md; Murad, Abdul Munir Abdul

    2014-01-01

    Lactococcus lactis is the most studied mesophilic fermentative lactic acid bacterium. It is used extensively in the food industry and plays a pivotal role as a cell factory and also as vaccine delivery platforms. The proteome of the Malaysian isolated L. lactis M4 dairy strain, obtained from the milk of locally bred cows, was studied to elucidate the physiological changes occurring between the growth phases of this bacterium. In this study, ultraperformance liquid chromatography nanoflow electrospray ionization tandem mass spectrometry (UPLC- nano-ESI-MS(E)) approach was used for qualitative proteomic analysis. A total of 100 and 121 proteins were identified from the midexponential and early stationary growth phases, respectively, of the L. lactis strain M4. During the exponential phase, the most important reaction was the generation of sufficient energy, whereas, in the early stationary phase, the metabolic energy pathways decreased and the biosynthesis of proteins became more important. Thus, the metabolism of the cells shifted from energy production in the exponential phase to the synthesis of macromolecules in the stationary phase. The resultant proteomes are essential in providing an improved view of the cellular machinery of L. lactis during the transition of growth phases and hence provide insight into various biotechnological applications. PMID:24982972

  20. Homology modelling of the Lactococcus lactis leader peptidase NisP and its interaction with the precursor of the lantibiotic nisin

    Microsoft Academic Search

    Willem M. de Vos; Oscar P. Kuipers; Harry S. Rollema; Roland J. Siezen

    1995-01-01

    A model is presented for the 3-D structure of the catalytic domain of the putative leader peptidase NisP of Lactococcus lactis, and the interaction with its specific substrate, the precursor of the lantibiotic nisin. This homology model is based on the crystal structures of subtilisin BPN' and thermitase in complex with the inhibitor eglin. Predictions are made of the general

  1. A novel multi-locus sequence typing (MLST) protocol for Leuconostoc lactis isolates from traditional dairy products in China and Mongolia

    PubMed Central

    2014-01-01

    Background Economically, Leuconostoc lactis is one of the most important species in the genus Leuconostoc. It plays an important role in the food industry including the production of dextrans and bacteriocins. Currently, traditional molecular typing approaches for characterisation of this species at the isolate level are either unavailable or are not sufficiently reliable for practical use. Multilocus sequence typing (MLST) is a robust and reliable method for characterising bacterial and fungal species at the molecular level. In this study, a novel MLST protocol was developed for 50 L. lactis isolates from Mongolia and China. Results Sequences from eight targeted genes (groEL, carB, recA, pheS, murC, pyrG, rpoB and uvrC) were obtained. Sequence analysis indicated 20 different sequence types (STs), with 13 of them being represented by a single isolate. Phylogenetic analysis based on the sequences of eight MLST loci indicated that the isolates belonged to two major groups, A (34 isolates) and B (16 isolates). Linkage disequilibrium analyses indicated that recombination occurred at a low frequency in L. lactis, indicating a clonal population structure. Split-decomposition analysis indicated that intraspecies recombination played a role in generating genotypic diversity amongst isolates. Conclusions Our results indicated that MLST is a valuable tool for typing L. lactis isolates that can be used for further monitoring of evolutionary changes and population genetics. PMID:24912963

  2. Construction of upp deletion mutant strains of Lactobacillus casei and Lactococcus lactis based on counterselective system using temperature-sensitive plasmid.

    PubMed

    Song, Li; Cui, Hongyu; Tang, Lijie; Qiao, Xinyuan; Liu, Min; Jiang, Yanping; Cui, Wen; Li, Yijing

    2014-07-01

    Integration plasmids are often used in constructing chromosomal mutations, as it enables the alternation of genes at any location by integration or replacement. Food-grade integration vectors can integrate into the host genome without introducing any selectable markers or residual bases, and the recombination often happens in non-coding region. In this study we used the temperature-sensitive pWV01 replicon to construct 2 chloramphenicol-resistant integration plasmids (pGBHC32-upp) containing the uracil phosphoribosyl transferase (upp) gene as a counterselective marker for Lactobacillus casei (L. casei) ATCC393 and Lactococcus lactis (L. lactis) MG1363. We then ligated the designed homologous arms to the pGBHC32-upp plasmids to allow their integration to the bacterial chromosome, and selected upp deletion mutants of L. casei ATCC393 and L. lactis MG1363 in the presence of 5-fluorouracil (5-FU). Analysis of genetic stability, growth curve, carbon utilization and scanning electronic microscopy showed that, except for 5-FU resistance, there were no significant differences between the wild type and mutant lactic acid bacteria. The integration system and the upp deletion strains could be used in the insertion or deletion of genes at any location of the chromosome of both L. casei ATCC 393 and L. lactis MG1363, and the homologous recombination would not introduce any selectable markers or residual bases. These mutant strains can be further investigated for heterologous protein expression and construction of a live mucosal vaccine carrier. PMID:24798148

  3. Characteristics of the bacteriocin produced by Lactococcus lactis subsp. cremoris CTC 204 and the effect of this compound on the mesophilic bacteria associated with raw beef

    Microsoft Academic Search

    R. Bromberg; I. Moreno; R. R. Delboni; H. C. Cintra; P. T. V Oliveira

    2005-01-01

    Summary >Screening for the bacteriocin production of strains of lactic acid bacteria from various meat and meat products resulted in the detection of a bacteriocin-producing Lactococcus lactis subsp. cremoris CTC 204, isolated from chicken. The bacteriocin inhibited not only closely related lactic acid bacteria (Lactobacillus helveticus), but also pathogenic microorganisms (Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Clostridium perfringens). It

  4. High-level expression of Lactobacillus beta-galactosidases in Lactococcus lactis using the food-grade, nisin-controlled expression system NICE.

    PubMed

    Maischberger, Thomas; Mierau, Igor; Peterbauer, Clemens K; Hugenholtz, Jeroen; Haltrich, Dietmar

    2010-02-24

    In this work the overlapping genes (lacL and lacM) encoding heterodimeric beta-galactosidases from Lactobacillus reuteri , Lb. acidophilus , Lb. sakei , and Lb. plantarum were cloned into two different nisin-controlled expression (NICE) vectors and expressed using Lactococcus lactis NZ9000 and NZ3900 as hosts. The lacL gene, encoding the large subunit of the beta-galactosidases, was fused translationally downstream of the nisin-inducible promoter nisA. Chloramphenicol was employed as selection marker for the standard system using L. lactis NZ9000, whereas lactose utilization based on the complementation of the lacF gene was used as a dominant selection marker for the food-grade system employing L. lactis NZ3900. Comparison of the standard and the food-grade expression system, differing only in their selection markers, gave considerable differences in volumetric beta-galactosidase activity, ranging from 1.17 to 14 kU/L of fermentation broth, depending on both the origin of the lacLM genes and the selection marker used. The occurrence of codons less frequently used by L. lactis especially at the beginning of the lacL gene could be an explanation for the significant differences between the expression levels of lacLM from different origins, while plasmid stability might cause the difference obtained when employing the different selection markers. PMID:20092320

  5. Nisin production in a chitin-including continuous fermentation system with Lactococcus lactis displaying a cell wall chitin-binding domain.

    PubMed

    ?im?ek, Ömer

    2014-03-01

    The limiting factors in the continuous production of nisin are high amount of biomass loss and low dilution rate application. In this study, a chitin-including continuous nisin fermentation system (CICON-FER) was constructed for high volumetric nisin production using nisin producer L. lactis displaying cell wall chitin-binding domain (ChBD) together with chitin in the reactor. In this respect, the highest binding conditions of relevant L. lactis cells to chitin were determined. Then the chitin flakes carrying nisin-producing L. lactis cells were used within the CICON-FER system at different dilution rates (0.1-0.9 h?¹) and initial glucose concentrations (20-60 g l?¹). The results revealed that the pH 7 conditions and the use of 100 mM sodium phosphate buffer with 0.1 % Tween 20 and Triton X-100 significantly increased the binding capacity of ChBD displaying L. lactis cells to chitin. The constructed CICON-FER system maintained the presence of the ChBD surface displaying L. lactis cells in the reactor system until 0.9 h?¹ dilution rate that resulted in a considerably high level of volumetric nisin production and productivity (10,500 IU ml?¹ and 9,450 IU ml?¹ h?¹, respectively) with the combination of a 0.9-h?¹ dilution rate and a 40-g l?¹ initial glucose concentration. In conclusion, an innovative nisin fermentation system that yielded the highest nisin production thus far and that was feasible for industrial application was created. PMID:24342966

  6. Growth of infants fed formula supplemented with Bifidobacterium lactis Bb12 or Lactobacillus GG: a systematic review of randomized controlled trials

    PubMed Central

    2013-01-01

    Background Growth is an essential outcome measure for evaluating the safety of any new ingredients, including probiotics, added to infant formulae. The aim of this systematic review was to determine the effects of supplementation of infant formulae with Bifidobacterium lactis Bb12 (B lactis) and/or Lactobacillus rhamnosus GG (LGG) compared with unsupplemented formula on the growth of healthy infants. Methods The MEDLINE, EMBASE, and Cochrane Library databases were searched in June 2013 for relevant randomized controlled trials (RCTs) conducted in healthy term infants. Unpublished data were obtained from the manufacturer of B lactis-supplemented formula. The primary outcome measures were weight, length, and head circumference. Results Nine eligible trials were identified. Compared with unsupplemented controls, supplementation of infant formula with B lactis had no effect on weight gain [4 RCTs, n?=?266, mean difference (MD) 0.96 g/day, 95% confidence interval (CI) -0.70 to 2.63)], length gain (4 RCTs, n?=?261, MD ?0.39 mm/month, 95% CI ?1.32 to 0.53), or head circumference gain (3 RCTs, n?=?207, MD 0.56 mm/month, 95% CI ?0.17 to 1.30). Data limited to one small (n?=?105) trial suggest that infants who received standard infant formula supplemented with LGG grew significantly better. No such effect was observed in infants fed hydrolyzed formula supplemented with LGG. Conclusions Supplementation of infant formula with B lactis results in growth similar to what is found in infants fed unsupplemented formula. Limited data do not allow one to reach a conclusion regarding the effect of LGG supplementation on infant growth. PMID:24215626

  7. Novel phage group infecting Lactobacillus delbrueckii subsp. lactis, as revealed by genomic and proteomic analysis of bacteriophage Ldl1.

    PubMed

    Casey, Eoghan; Mahony, Jennifer; Neve, Horst; Noben, Jean-Paul; Dal Bello, Fabio; van Sinderen, Douwe

    2015-02-01

    Ldl1 is a virulent phage infecting the dairy starter Lactobacillus delbrueckii subsp. lactis LdlS. Electron microscopy analysis revealed that this phage exhibits a large head and a long tail and bears little resemblance to other characterized phages infecting Lactobacillus delbrueckii. In vitro propagation of this phage revealed a latent period of 30 to 40 min and a burst size of 59.9 +/- 1.9 phage particles. Comparative genomic and proteomic analyses showed remarkable similarity between the genome of Ldl1 and that of Lactobacillus plantarum phage ATCC 8014-B2. The genomic and proteomic characteristics of Ldl1 demonstrate that this phage does not belong to any of the four previously recognized L. delbrueckii phage groups, necessitating the creation of a new group, called group e, thus adding to the knowledge on the diversity of phages targeting strains of this industrially important lactic acid bacterial species. PMID:25501478

  8. Recombinant Lactococcus lactis can make the difference in antigen-specific immune tolerance induction, the Type 1 Diabetes case

    PubMed Central

    2014-01-01

    Especially in western civilizations, immune diseases that are driven by innocuous (auto- or allo-) antigens are gradually evolving to become pandemic threats. A particularly poignant example is type 1 diabetes, where young children are confronted with the perspective and consequences of total pancreatic ?-cell destruction. Along these disquieting observations we find ourselves equipped with impressively accumulating molecular immunological knowledge on the ins and outs of these pathologies. Often, however, it is difficult to translate this wealth into efficacious medicines. The molecular understanding, the concept of oral tolerance induction, the benefit of using recombinant Lactococcus lactis therein and recent openings towards their clinical use may well enable turning all colors to their appropriate fields on this Rubik's cube. PMID:25185797

  9. Cloning and characterization of a NADH-dependent aldo-keto reductase from a newly isolated Kluyveromyces lactis XP1461.

    PubMed

    Luo, Xi; Wang, Ya-Jun; Zheng, Yu-Guo

    2015-09-01

    An aldo-keto reductase gene (klakr) from Kluyveromyces lactis XP1461 was cloned and heterologously expressed in Escherichia coli. The aldo-keto reductase KlAKR was purified and found to be NADH-dependent with a molecular weight of approximately 36kDa. It is active and stable at 30°C and pH 7.0. The maximal reaction rate (vmax), apparent Michaelis-Menten constant (Km) for NADH and t-butyl 6-cyano-(5R)-hydroxy-3-oxohexanoate (1a) and catalytic number (kcat) were calculated as 7.63Umg(-1), 0.204mM, 4.42mM and 697.4min(-1), respectively. Moreover, the KlAKR has broad substrate specificity to a range of aldehydes, ketones and keto-esters, producing chiral alcohol with e.e. or d.e. >99% for the majority of test substrates. PMID:26138402

  10. Preliminary X-ray crystallographic analysis of the d-­xylulose 5-phosphate phospho­ketolase from Lactococcus lactis

    PubMed Central

    Petrareanu, Georgiana; Balasu, Mihaela C.; Zander, Ulrich; Scheidig, Axel J.; Szedlacsek, Stefan E.

    2010-01-01

    Phosphoketolases are thiamine diphosphate-dependent enzymes which play a central role in the pentose-phosphate pathway of heterofermentative lactic acid bacteria. They belong to the family of aldehyde-lyases and in the presence of phosphate ion cleave the carbon–carbon bond of the specific substrate d-­xylulose 5-phosphate (or d-fructose 6-phosphate) to give acetyl phosphate and d-­glyceraldehyde 3-phosphate (or d-erythrose 4-phosphate). Structural information about phosphoketolases is particularly important in order to fully understand their mechanism as well as the steric course of phosphoketolase-catalyzed reactions. Here, the purification, preliminary crystallization and crystallographic characterization of d-xylulose 5-phosphate phosphoketolase from Lactococcus lactis are reported. The presence of thiamine diphosphate during purification was essential for the enzymatic activity of the purified protein. The crystals belonged to the monoclinic space group P21. Diffraction data were obtained to a resolution of 2.2?Å. PMID:20606278

  11. Benchmarking Various Green Fluorescent Protein Variants in Bacillus subtilis, Streptococcus pneumoniae, and Lactococcus lactis for Live Cell Imaging

    PubMed Central

    Overkamp, Wout; Beilharz, Katrin; Detert Oude Weme, Ruud; Solopova, Ana; Karsens, Harma; Kovács, Ákos T.; Kok, Jan

    2013-01-01

    Green fluorescent protein (GFP) offers efficient ways of visualizing promoter activity and protein localization in vivo, and many different variants are currently available to study bacterial cell biology. Which of these variants is best suited for a certain bacterial strain, goal, or experimental condition is not clear. Here, we have designed and constructed two “superfolder” GFPs with codon adaptation specifically for Bacillus subtilis and Streptococcus pneumoniae and have benchmarked them against five other previously available variants of GFP in B. subtilis, S. pneumoniae, and Lactococcus lactis, using promoter-gfp fusions. Surprisingly, the best-performing GFP under our experimental conditions in B. subtilis was the one codon optimized for S. pneumoniae and vice versa. The data and tools described in this study will be useful for cell biology studies in low-GC-rich Gram-positive bacteria. PMID:23956387

  12. CTAB-mediated, single-step preparation of competent Escherichia coli, Bifidobacterium sp. and Kluyveromyces lactis cells

    PubMed Central

    Rajagopal, Kammara; Singh, Praveen Kumar; Kumar, Rajesh; Siddiqui, Kaneez Fatima

    2014-01-01

    An efficient and reproducible method for transformation depends on the competency of the organism. We have developed a simple method for the preparation of competent Escherichia coli, Kluyveromyces lactis, and Bifidobacterium sp. by using a buffer containing cetyl trimethyl ammonium bromide (CTAB) and permits efficient uptake of plasmid DNA and ligation-reaction products. Cells are harvested, washed, mixed with 1–10 ?g/ml CTAB, incubated, and followed by a buffer wash. For long-term storage of competent cells, bacteria may be frozen in 10% glycerol without the addition of other components. The transformation process is very simple; plasmid DNA and the cells are mixed and incubated for 5–60 min at 4 °C; no heat pulse is required, and the duration of incubation at 4 °C is not crucial. PMID:25606463

  13. The influence of different polymers on viability of Bifidobacterium lactis 300b during encapsulation, freeze-drying and storage.

    PubMed

    Pop, Oana Lelia; Brandau, Thorsten; Schwinn, Jens; Vodnar, Dan Cristian; Socaciu, Carmen

    2015-07-01

    Seven different types of natural polymers namely hydroxypropyl methylcellulose (HPMC), sodium-carboxymethyl cellulose (Na-CMC), microcrystalline cellulose (MCC), starch BR-07, starch BR-08, dextrin and pullulan were used in order to develop the optimal formula for the entrapment of Bifidobacterium lactis 300B in Ca-alginate based granules. Laminar flow drip casting with Brace-Encapsulator was used in order to prepare the granules. The results showed that alginate/pullulan and alginate/HPMC formulation provide high protection for the bacterial strain used for encapsulation. These two formulations were further used to obtain freeze dried granules, for which the viability in time and at different temperatures was tested. The final results showed a higher viability than the level of the therapeutic minimum (>10(7) CFU/g) after 15 days of storage. Other parameters like entrapment efficiency, production rate, sphericity, flowability were also discussed. PMID:26139879

  14. Expression of Lactococcus lactis NADH oxidase increases 2,3-butanediol production in Pdc-deficient Saccharomyces cerevisiae.

    PubMed

    Kim, Jin-Woo; Seo, Seung-Oh; Zhang, Guo-Chang; Jin, Yong-Su; Seo, Jin-Ho

    2015-09-01

    To minimize glycerol production during 2,3-BD fermentation by the engineered Saccharomyces cerevisiae, the Lactococcus lactis water-forming NADH oxidase gene (noxE) was expressed at five different levels. The expression of NADH oxidase substantially decreased the intracellular NADH/NAD(+) ratio. The S. cerevisiae BD5_T2nox strain expressing noxE produced 2,3-BD with yield of 0.359g 2,3-BD/gglucose and glycerol with 0.069gglycerol/gglucose, which are 23.8% higher and 65.3% lower than those of the isogenic strain without noxE. These results demonstrate that the carbon flux could be redirected from glycerol to 2,3-BD through alteration of the NADH/NAD(+) ratio by the expression of NADH oxidase. PMID:25769689

  15. The genes for secretion and maturation of lactococcins are located on the chromosome of Lactococcus lactis IL1403.

    PubMed Central

    Venema, K; Dost, M H; Beun, P A; Haandrikman, A J; Venema, G; Kok, J

    1996-01-01

    Southern hybridization and PCR analysis were used to show that Lactococcus lactis IL1403, a plasmid-free strain that does not produce bacteriocin, contains genes on its chromosome that are highly homologous to lcnC and lcnD and encode the lactococcin secretion and maturation system. The lcnC and lcnD homologs on the chromosome of IL1403 were interrupted independently by Campbell-type integrations. Both insertion mutants were unable to secrete active lactococcin. Part of the chromosomal lcnC gene was cloned and sequenced. Only a few nucleotide substitutions occurred, compared with the plasmid-encoded lcnC gene, and these did not lead to changes in the deduced amino acid sequence. No genes homologous to those for lactococcin A, B, or M could be detected in IL1403, and the strain does not produce bacteriocin activity. PMID:8633867

  16. Engineering of EPA/DHA omega-3 fatty acid production by Lactococcus lactis subsp. cremoris MG1363.

    PubMed

    Amiri-Jami, Mitra; Lapointe, Gisele; Griffiths, Mansel W

    2014-04-01

    Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to be of major importance in human health. Therefore, these essential polyunsaturated fatty acids have received considerable attention in both human and farm animal nutrition. Currently, fish and fish oils are the main dietary sources of EPA/DHA. To generate sustainable novel sources for EPA and DHA, the 35-kb EPA/DHA synthesis gene cluster was isolated from a marine bacterium, Shewanella baltica MAC1. To streamline the introduction of the genes into food-grade microorganisms such as lactic acid bacteria, unnecessary genes located upstream and downstream of the EPA/DHA gene cluster were deleted. Recombinant Escherichia coli harboring the 20-kb gene cluster produced 3.5- to 6.1-fold more EPA than those carrying the 35-kb DNA fragment coding for EPA/DHA synthesis. The 20-kb EPA/DHA gene cluster was cloned into a modified broad-host-range low copy number vector, pIL252m (4.7 kb, Ery) and expressed in Lactococcus lactis subsp. cremoris MG1363. Recombinant L. lactis produced DHA (1.35?±?0.5 mg g(-1) cell dry weight) and EPA (0.12?±?0.04 mg g(-1) cell dry weight). This is believed to be the first successful cloning and expression of EPA/DHA synthesis gene cluster in lactic acid bacteria. Our findings advance the future use of EPA/DHA-producing lactic acid bacteria in such applications as dairy starters, silage adjuncts, and animal feed supplements. PMID:24389665

  17. Sphingobacterium lactis sp. nov. and Sphingobacterium alimentarium sp. nov., isolated from raw milk and a dairy environment.

    PubMed

    Schmidt, Verena S J; Wenning, Mareike; Scherer, Siegfried

    2012-07-01

    Four non-fermenting, rod-shaped, Gram-staining-negative bacterial strains, designated WCC 4512(T), WS 4555, WCC 4521(T) and WS 4556, were isolated from raw milk and the dairy environment. Phylogenetic analyses based on 16S rRNA and groEL gene sequences demonstrated the affiliation of the four strains to two distinct clusters within the class Sphingobacteriia, phylum 'Bacteroidetes'. Strains WCC 4512(T) and WS 4555 showed the highest 16S rRNA gene sequence similarity to the type strain of S. daejeonense (97.3 and 97.2%, respectively), whereas strains WCC 4521(T) and WS 4556 were most closely related to S. composti LMG 23401(T) (97.6% 16S rRNA gene sequence similarity). The DNA G+C contents of strains WCC 4512(T) and WCC 4521(T) were 44.2 and 39.3 mol%, respectively. The major cellular fatty acids and the presence of menaquinone MK-7 as the predominant quinone for both strains WCC 4512(T) and WCC 4521(T) supported their affiliation to the genus Sphingobacterium. DNA-DNA hybridization experiments between strain WCC 4512(T) and S. daejeonense LMG 23402(T) and between strain WCC 4521(T) and S. composti LMG 23401(T) revealed DNA relatedness values of 2% (repetition, 3%) and 8% (repetition, 17%), respectively. On the basis of phenotypic and genetic properties, as well as phylogenetic distinctiveness, it is suggested that the four strains represent two novel Sphingobacterium species with strain WCC 4512(T) (=DSM 22361(T)=LMG 25272(T)) as the type strain of Sphingobacterium lactis sp. nov. (WS 4555 is a reference strain of S. lactis) and strain WCC 4521(T) (=DSM 22362(T)=LMG 25273(T)) as the type strain of Sphingobacterium alimentarium sp. nov. (WS 4556 is a reference strain of S. alimentarium). PMID:21856986

  18. Immunomodulatory Activity of Lactococcus lactis A17 from Taiwan Fermented Cabbage in OVA-Sensitized BALB/c Mice

    PubMed Central

    Mei, Hui-Ching; Liu, Yen-Wenn; Chiang, Yi-Chin; Chao, Shiou-Huei; Mei, Nai-Wen; Liu, Yu-Wen; Tsai, Ying-Chieh

    2013-01-01

    From fermented Taiwan foods, we have isolated numerous lactic acid bacteria (LAB) of plant origin and investigated their biological activities. This study aimed to investigate the immunomodulatory effect and mechanism of Lactococcus lactis A17 (A17), isolated from Taiwan fermented cabbage, on ovalbumin (OVA)-sensitized mice. Human peripheral blood mononuclear cells were used to verify immune responses of A17 by IFN-? production. Live (A17-A) and heat-killed A17 (A17-H) were orally administered to OVA-sensitized BALB/c mice to investigate their effects on immunoglobulin (Ig) and cytokine production. The mRNA expression of Toll-like receptors (TLR) and nucleotide binding oligomerization domain (NOD)-like protein receptors in spleen cells was analyzed by real-time RT-PCR. Both live and heat-killed A17 modulate OVA-induced allergic effects. B-cell response was modulated by diminishing IgE production and raising OVA-specific IgG2a production, while T-cell response was modulated by increasing IFN-? production and decreasing IL-4 production. The mRNA expression of NOD-1, NOD-2, and TLR-4 was down-regulated by A17 as well. This is the first report to describe a naïve Lactococcus lactis A17 strain as a promising candidate for prophylactic and therapeutic treatments of allergic diseases via oral administration. Our results suggest the ameliorative effects of A17 may be caused by modulating NOD-1 NOD-2, and TLR-4 expression. PMID:23401710

  19. Genetic Dissection of the Kluyveromyces lactis Telomere and Evidence for Telomere Capping Defects in TER1 Mutants with Long Telomeres

    PubMed Central

    Underwood, Dana H.; Carroll, Coleen; McEachern, Michael J.

    2004-01-01

    In the yeast Kluyveromyces lactis, the telomeres are composed of perfect 25-bp repeats copied from a 30-nucleotide RNA template defined by 5-nucleotide terminal repeats. A genetic dissection of the K. lactis telomere was performed by using mutant telomerase RNA (TER1) alleles to incorporate mutated telomeric repeats. This analysis has shown that each telomeric repeat contains several functional regions, some of which may physically overlap. Mutations in the terminal repeats of the template RNA typically lead to telomere shortening, as do mutations in the right side of the Rap1p binding site. Mutations in the left half of the Rap1p binding site, however, lead to the immediate formation of long telomeres. When mutated, the region immediately 3? of the Rap1p binding site on the TG-rich strand of the telomere leads to telomeres that are initially short but eventually undergo extreme telomere elongation. Mutations between this region and the 3? terminal repeat cause elevated recombination despite the presence of telomeres of nearly wild-type length. Mutants with highly elongated telomeres were further characterized and exhibit signs of telomere capping defects, including elevated levels of subtelomeric recombination and the formation of extrachromosomal and single-stranded telomeric DNA. Lengthening caused by some Rap1 binding site mutations can be suppressed by high-copy-number RAP1. Mutated telomeric repeats from a delayed elongation mutant are shown to be defective at regulating telomere length in cells with wild-type telomerase, indicating that the telomeric repeats are defective at telomere length regulation. PMID:15075267

  20. In vitro inhibition of Citrobacter freundii, a red-leg syndrome associated pathogen in raniculture, by indigenous Lactococcus lactis CRL 1584.

    PubMed

    Pasteris, Sergio E; Guidoli, Marcos G; Otero, María C; Bühler, Marta I; Nader-Macías, María E

    2011-08-01

    Red-leg syndrome (RLS) is one of the main infectious diseases that cause economic losses in Lithobates catesbeianus hatcheries, Citrobacter freundii being an etiological agent. Treatment or prevention with therapeutics or chemicals results in modifications of the indigenous microbiota, development of antibiotic resistance, presence of their residues in food and enhancement of production costs. Thus, probiotics could be used as an alternative therapy. Lactic acid bacteria are part of the indigenous microbiota of healthy frogs and can prevent pathogen colonization by different mechanisms, including the production of antagonistic substances. In this work, the evaluation and characterization of the inhibition of C. freundii CFb by Lactococcus lactis subsp. lactis CRL 1584, a potentially probiotic candidate, were carried out. This strain produced lactic acid, H(2)O(2) and bacteriocin in static and shaken conditions and inhibited pathogen growth in associative cultures, with an earlier inhibition under agitated conditions. The elimination of each of the antimicrobial metabolites partially abolished the inhibition of the pathogen, suggesting that the inhibitory effect could be attributed to a combined action of the three antagonistic molecules. Electron microphotographs revealed the damage caused by L. lactis CRL 1584 supernatants to C. freundii cells. The addition of pure lactic acid, H(2)O(2) and bacteriocin to the culture media showed that each metabolite caused different morphological modifications in C. freundii, in agreement with the effect on viable cell counts. The results support the possibility that L. lactis CRL 1584 might be considered as a probiotic to be used in the prevention of RLS in raniculture. PMID:21531092

  1. Immobilization of ?-galactosidase from Kluyveromyces lactis onto a polysiloxane–polyvinyl alcohol magnetic (mPOS–PVA) composite for lactose hydrolysis

    Microsoft Academic Search

    David F. M. Neri; Victor M. Balcão; Maria G. Carneiro-da-Cunha; Luiz B. Carvalho Jr.; José A. Teixeira

    2008-01-01

    ?-Galactosidase from Kluyveromyces lactis was covalently immobilized onto a mPOS–PVA, using glutaraldehyde as activating agent and its properties were evaluated. The enzymatic water insoluble derivative displayed the same optimum pH (6.5) and optimum temperature (50°C) of the soluble enzyme. The apparent Kmapp and activation energy for both soluble and immobilized enzyme derivative were found to be not significantly different. The

  2. Surface Expression of the Conserved C Repeat Region of Streptococcal M6 Protein within the Pip Bacteriophage Receptor of Lactococcus lactis

    Microsoft Academic Search

    BRUCE L. GELLER; NADINE WADE; THOMAS D. GILBERTS; DENNIS E. HRUBY; RYAN JOHANSON; LJUBISA TOPISIROVIC

    2001-01-01

    The C repeat region of the M6 protein (M6c) from Streptococcus pyogenes was expressed within the Pip bacteriophage receptor on the surface of Lactococcus lactis. M6c was also detected in the culture medium. The pip-emm6c allele was integrated into the chromosome and stably expressed without antibiotic selection. The level of cell-associated surface expression of PipM6c was 0.015% of total cellular

  3. Probiotic lactic acid bacteria ( Lactobacillus acidophilus HN017, Lactobacillus rhamnosus HN001 and Bifidobacterium lactis HN019) have no adverse effects on the health of mice

    Microsoft Academic Search

    Quan Shu; Joseph S Zhou; Kay J. Rutherfurd; Mervyn J Birtles; Jaya Prasad; Pramod K Gopal; Harsharnjit S Gill

    1999-01-01

    The safety of the probiotic lactic acid bacteria Lactobacillus acidophilus (HN017), Lactobacillus rhamnosus (HN001, DR20™), and Bifidobacterium lactis (HN019, DR10™), was studied in BALB\\/c mice fed with different doses (5×107, 109 or 5×1010cfu\\/mouse\\/day) of the bacteria for 7 days. No abnormal clinical signs were observed in any of the groups during the period of the experiment. There were no significant

  4. Safety assessment of potential probiotic lactic acid bacterial strains Lactobacillus rhamnosus HN001, Lb. acidophilus HN017, and Bifidobacterium lactis HN019 in BALB\\/c mice

    Microsoft Academic Search

    J. S Zhou; Q Shu; K. J Rutherfurd; J Prasad; M. J Birtles; P. K Gopal; H. S Gill

    2000-01-01

    The general safety of immune-enhancing lactic acid bacteria (LAB) strains Lactobacillus rhamnosus HN001 (DR20™), Lb. acidophilus HN017, and Bifidobacterium lactis HN019 (DR10™) was investigated in a feeding trial. Groups of BALB\\/c mice were orally administered test LAB strains or the commercial reference strain Lb. acidophilus LA-1 at 2.5×109, 5×1010 or 2.5×1012 colony forming units (CFU)\\/kg body weight\\/day for 4 weeks.

  5. In vitro adherence properties of Lactobacillus rhamnosus DR20 and Bifidobacterium lactis DR10 strains and their antagonistic activity against an enterotoxigenic Escherichia coli

    Microsoft Academic Search

    Pramod K Gopal; Jaya Prasad; John Smart; Harsharanjit S Gill

    2001-01-01

    Adhesion and colonisation properties of three probiotic strains namely, Lactobacillus rhamnosus DR20, L. acidophilus HN017, and Bifidobacterium lactis DR10, were determined in vitro using the differentiated human intestinal cell-lines including HT-29, Caco-2, and HT29-MTX, and compared with properties of L. acidophilus LA-1 and L. rhamnosus GG (two commercial probiotic strains). Two independent methods were employed to quantitate the “adhesiveness” of

  6. Potential probiotic lactic acid bacteria Lactobacillus rhamnosus (HN001), Lactobacillus acidophilus (HN017) and Bifidobacterium lactis (HN019) do not degrade gastric mucin in vitro

    Microsoft Academic Search

    J. S. Zhou; P. K. Gopal; H. S. Gill

    2001-01-01

    The mucus layer (mucin) coating the surface of the gastrointestinal tract (GIT) plays an important role in the mucosal barrier system. Any damage or disturbance of this mucin layer will compromise the host’s mucosal defence function. In the present study, the ability of three potential probiotic lactic acid bacteria (LAB) strains (Lactobacillus rhamnosus HN001, Lactobacillus acidophilus HN017, Bifidobacterium lactis HN019)

  7. Effects of the consumption of Bifidobacterium lactis HN019 (DR10 TM) and galacto-oligosaccharides on the microflora of the gastrointestinal tract in human subjects

    Microsoft Academic Search

    Pramod K Gopal; Jaya Prasad; Harsharnjit S Gill

    2003-01-01

    The effects of dietary consumption of milk derived oligosaccharides and a probiotic bacterium Bifidobacterium lactis HN019 (also known as DR10TM) on the microbial composition of the gastrointestinal tract of human subjects was examined using a randomized, double blind, placebo-controlled study design. Thirty subjects (age range 20–60 years) were divided randomly into three groups. After two weeks of a pre-intervention period,

  8. Dose–response study of probiotic bacteria Bifidobacterium animalis subsp lactis BB12 and Lactobacillus paracasei subsp paracasei CRL341 in healthy young adults

    Microsoft Academic Search

    C N Larsen; S Nielsen; P Kæstel; E Brockmann; M Bennedsen; H R Christensen; D C Eskesen; B L Jacobsen; K F Michaelsen

    2006-01-01

    Objective:This study was performed to investigate the dose–response effects of supplementation with Bifidobacterium animalis subsp lactis (BB-12) and Lactobacillus paracasei subsp paracasei (CRL-431) on blood lipids, recovery from feces and bowel habits. Changes of the fecal microflora was analyzed in the 1010 CFU\\/day probiotic and placebo group.Design:The study was designed as a randomized, placebo-controlled, double-blinded, parallel dose–response study.Subjects:Healthy young adults

  9. Microencapsulation of L. acidophilus (La-05) and B. lactis (Bb-12) and evaluation of their survival at the pH values of the stomach and in bile.

    PubMed

    Fávaro-Trindade, C S; Grosso, C R F

    2002-01-01

    Microcapsules were prepared using the probiotic microorganisms Lactobacillus acidophilus (La-05) and Bifidobacterium lactis (Bb-12) and the spray drying technique and cellulose acetate phthalate as the wall material. This study evaluated the resistance of these microorganisms to drying at three temperatures and also the in vitro tolerance of the free and microencapsulated form to pH values and bile concentrations similar to those found in the human stomach and intestine. With an air entry temperature of 130 degrees C and exit temperature of 75 degrees C, the number of viable cells of B. lactis was practically unaltered, whereas the population of L. acidophilus was reduced by two logarithmic cycles. B. lactis was more resistant to the drying process than L. acidophilus under all conditions tested. The morphology of the microcapsules was determined by scanning electron microscopy and the microcapsules presented a rounded external surface containing concavities, a continuous wall with no apparent porosity, average size of 22 microm, moisture content varying from 5.3 to 3.2% and water activity between 0.230 and 0.204. After inoculation into HCl solutions with pH values adjusted to 1 and 2, incubated anaerobically at 37 degrees C, and plated after 0, 1 and 2 h of incubation, microcapsules were effective in protecting the microorganisms, while the populations of both free microorganisms were eliminated after only 1 h at the acidic conditions. Microencapsulated B. lactis and L. acidophilus, both free and microencapsulated, were also resistant after 12h to bile solutions. PMID:12396385

  10. The SWI/SNF KlSnf2 Subunit Controls the Glucose Signaling Pathway To Coordinate Glycolysis and Glucose Transport in Kluyveromyces lactis

    PubMed Central

    Soulard, Alexandre; Wésolowski-Louvel, Micheline; Lemaire, Marc

    2012-01-01

    In Kluyveromyces lactis, the expression of the major glucose permease gene RAG1 is controlled by extracellular glucose through a signaling cascade similar to the Saccharomyces cerevisiae Snf3/Rgt2/Rgt1 pathway. We have identified a key component of the K. lactis glucose signaling pathway by characterizing a new mutation, rag20-1, which impairs the regulation of RAG1 and hexokinase RAG5 genes by glucose. Functional complementation of the rag20-1 mutation identified the KlSNF2 gene, which encodes a protein 59% identical to S. cerevisiae Snf2, the major subunit of the SWI/SNF chromatin remodeling complex. Reverse transcription-quantitative PCR and chromatin immunoprecipitation analyses confirmed that the KlSnf2 protein binds to RAG1 and RAG5 promoters and promotes the recruitment of the basic helix-loop-helix Sck1 activator. Besides this transcriptional effect, KlSnf2 is also implicated in the glucose signaling pathway by controlling Sms1 and KlRgt1 posttranscriptional modifications. When KlSnf2 is absent, Sms1 is not degraded in the presence of glucose, leading to constitutive RAG1 gene repression by KlRgt1. Our work points out the crucial role played by KlSnf2 in the regulation of glucose transport and metabolism in K. lactis, notably, by suggesting a link between chromatin remodeling and the glucose signaling pathway. PMID:23002104

  11. Co-evolution of segregation guide DNA motifs and the FtsK translocase in bacteria: identification of the atypical Lactococcus lactis KOPS motif

    PubMed Central

    Nolivos, Sophie; Touzain, Fabrice; Pages, Carine; Coddeville, Michele; Rousseau, Philippe; El Karoui, Meriem; Le Bourgeois, Pascal; Cornet, François

    2012-01-01

    Bacteria use the global bipolarization of their chromosomes into replichores to control the dynamics and segregation of their genome during the cell cycle. This involves the control of protein activities by recognition of specific short DNA motifs whose orientation along the chromosome is highly skewed. The KOPS motifs act in chromosome segregation by orienting the activity of the FtsK DNA translocase towards the terminal replichore junction. KOPS motifs have been identified in ?-Proteobacteria and in Bacillus subtilis as closely related G-rich octamers. We have identified the KOPS motif of Lactococcus lactis, a model bacteria of the Streptococcaceae family harbouring a compact and low GC% genome. This motif, 5?-GAAGAAG-3, was predicted in silico using the occurrence and skew characteristics of known KOPS motifs. We show that it is specifically recognized by L. lactis FtsK in vitro and controls its activity in vivo. L. lactis KOPS is thus an A-rich heptamer motif. Our results show that KOPS-controlled chromosome segregation is conserved in Streptococcaceae but that KOPS may show important variation in sequence and length between bacterial families. This suggests that FtsK adapts to its host genome by selecting motifs with convenient occurrence frequencies and orientation skews to orient its activity. PMID:22373923

  12. Use of the Integration Elements Encoded by the Temperate Lactococcal Bacteriophage TP901-1 To Obtain Chromosomal Single-Copy Transcriptional Fusions in Lactococcus lactis

    PubMed Central

    Brøndsted, Lone; Hammer, Karin

    1999-01-01

    Previously we showed that only one phage-expressed protein (Orf1), a 425-bp region upstream of the orf1 gene (presumably encoding a promoter), and the attP region are necessary and also sufficient for integration of the bacteriophage TP901-1 genome into the chromosome of Lactococcus lactis subsp. cremoris (B. Christiansen, L. Brøndsted, F. K. Vogensen, and K. Hammer, J. Bacteriol. 178:5164–5173, 1996). In this work, a further analysis of the phage-encoded elements involved in integration was performed. Here we demonstrate that even when the orf1 gene is separated from the attP region, the Orf1 protein is able to promote site-specific integration of an attP-carrying plasmid into the attB site on the L. lactis subsp. cremoris chromosome. Furthermore, the first detailed deletion analysis of an attP region of a phage infecting lactic acid bacteria was carried out. We show that a fragment containing 56 bp of the attP region, including the core, is sufficient for the site-specific integration of a nonreplicating plasmid into the chromosome of L. lactis subsp. cremoris when the orf1 gene is donated in trans. The functional 56-bp attP region of TP901-1 is substantially smaller than minimal attP regions identified for other phages. Based on the deletion analysis, several repeats located within the attP region seem to be necessary for site-specific integration of the temperate bacteriophage TP901-1. By use of the integrative elements (attP and orf1) expressed by the temperate lactococcal bacteriophage TP901-1, a system for obtaining stable chromosomal single-copy transcriptional fusions in L. lactis was constructed. Two promoter-reporter integration vectors containing the reporter gene gusA or lacLM, encoding ?-glucuronidase or ?-galactosidase, respectively, were constructed. Immediately upstream of both genes are found translational stop codons in all three reading frames as well as multiple restriction enzyme sites suitable for cloning of the promoter of interest. By transformation of L. lactis subsp. cremoris MG1363 containing the integrase gene on a replicating plasmid, the promoter-reporter integration vectors integrated with a high frequency site specifically into the chromosomal attachment site attB used by bacteriophage TP901-1. PMID:9925612

  13. Catabolism of glucose and lactose in Bifidobacterium animalis subsp. lactis, studied by 13C Nuclear Magnetic Resonance.

    PubMed

    González-Rodríguez, Irene; Gaspar, Paula; Sánchez, Borja; Gueimonde, Miguel; Margolles, Abelardo; Neves, Ana Rute

    2013-12-01

    Bifidobacteria are widely used as probiotics in several commercial products; however, to date there is little knowledge about their carbohydrate metabolic pathways. In this work, we studied the metabolism of glucose and lactose in the widely used probiotic strain Bifidobacterium animalis subsp. lactis BB-12 by in vivo (13)C nuclear magnetic resonance (NMR) spectroscopy. The metabolism of [1-(13)C]glucose was characterized in cells grown in glucose as the sole carbon source. Moreover, the metabolism of lactose specifically labeled with (13)C on carbon 1 of the glucose or the galactose moiety was determined in suspensions of cells grown in lactose. These experiments allowed the quantification of some intermediate and end products of the metabolic pathways, as well as determination of the consumption rate of carbon sources. Additionally, the labeling patterns in metabolites derived from the metabolism of glucose specifically labeled with (13)C on carbon 1, 2, or 3 in cells grown in glucose or lactose specifically labeled in carbon 1 of the glucose moiety ([1-(13)Cglucose]lactose), lactose specifically labeled in carbon 1 of the galactose moiety ([1-(13)Cgalactose]lactose), and [1-(13)C]glucose in lactose-grown cells were determined in cell extracts by (13)C NMR. The NMR analysis showed that the recovery of carbon was fully compatible with the fructose 6-phosphate, or bifid, shunt. The activity of lactate dehydrogenase, acetate kinase, fructose 6-phosphate phosphoketolase, and pyruvate formate lyase differed significantly between glucose and lactose cultures. The transcriptional analysis of several putative glucose and lactose transporters showed a significant induction of Balat_0475 in the presence of lactose, suggesting a role for this protein as a lactose permease. This report provides the first in vivo experimental evidence of the metabolic flux distribution in the catabolic pathway of glucose and lactose in bifidobacteria and shows that the bifid shunt is the only pathway involved in energy recruitment from these two sugars. On the basis of our experimental results, a model of sugar metabolism in B. animalis subsp. lactis is proposed. PMID:24077711

  14. The metabolic network of Lactococcus lactis: distribution of (14)C-labeled substrates between catabolic and anabolic pathways.

    PubMed

    Novák, L; Loubiere, P

    2000-02-01

    Lactococcus lactis NCDO 2118 was grown in a simple synthetic medium containing only six essential amino acids and glucose as carbon substrates to determine qualitatively and quantitatively the carbon fluxes into the metabolic network. The specific rates of substrate consumption, product formation, and biomass synthesis, calculated during the exponential growth phase, represented the carbon fluxes within the catabolic and anabolic pathways. The macromolecular composition of the biomass was measured to distribute the global anabolic flux into the specific anabolic pathways. Finally, the distribution of radiolabeled substrates, both into the excreted fermentation end products and into the different macromolecular fractions of biomass, was monitored. The classical end products of lactic acid metabolism (lactate, formate, and acetate) were labeled with glucose, which did not label other excreted products, and to a lesser extent with serine, which was deaminated to pyruvate and represented approximately 10% of the pyruvate flux. Other minor products, keto and hydroxy acids, were produced from glutamate and branched-chain amino acids via deamination and subsequent decarboxylation and/or reduction. Glucose labeled all biomass fractions and accounted for 66% of the cellular carbon, although this represented only 5% of the consumed glucose. PMID:10648541

  15. The efflux of a fluorescent probe is catalyzed by an ATP-driven extrusion system in Lactococcus lactis.

    PubMed Central

    Molenaar, D; Bolhuis, H; Abee, T; Poolman, B; Konings, W N

    1992-01-01

    Many bacteria, both gram positive and gram negative, extrude in an energy-dependent manner the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5[and -6]-carboxyfluorescein (BCECF) (D. Molenaar, T. Abee, and W. N. Konings, Biochim. Biophys. Acta 1115:75-83, 1991). This efflux was studied in detail in Lactococcus lactis, and several indications that a transport system is involved were found. This transport system is most likely driven by ATP or a related compound. The evidence is that BCECF extrusion (i) occurs against a BCECF gradient, (ii) is strictly correlated with ATP concentration and not with the proton motive force, and (iii) is inhibited by vanadate and to a lesser extent by N,N'-dicyclohexylcarbodiimide. Most convincingly, a UV mutant with a strongly reduced efflux rate was isolated. Such a mutant was isolated from a BCECF-loaded and lactose-energized population by selection of highly fluorescent cells in a flow cytometer-cell sorter. The physiological function of this extrusion system is unknown, but its characteristics classify it among the traffic ATPases. PMID:1577684

  16. A QM/MM free energy study of the oxidation mechanism of dihydroorotate dehydrogenase (class 1A) from Lactococcus lactis.

    PubMed

    Silva, José Rogério A; Roitberg, Adrian E; Alves, Cláudio Nahum

    2015-01-29

    The dihydroorotate dehydrogenase (DHOD) class 1A enzyme catalyzes is the only redox enzyme in the biosynthetic pathway (de novo) of pyrimidines where dihydroorotate (DHO) is oxidized to orotate (OA) coupled to reduction of a flavin mononucleotide (FMN) cofactor. The rupture of two DHO C-H bonds can proceed in a concerted or stepwise way. Herein, the catalytic mechanism of DHOD from Lactococcus lactis involving DHO oxidation (first half-reaction) was described using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach and molecular dynamics simulations. The free energy profile obtained from self-consistent charge-density functional tight binding/molecular mechanics calculations (corrected by DFT/MM) reveals that this occurs with the proton abstraction from DHO C5 to Cys130 deprotonated and DHO H6 is transferred to FMN N5 in a concerted mechanism with a very low barrier of 5.64 kcal/mol. Finally, through a residual decomposition analysis, the residues that have the main influence on the redox reaction were identified. PMID:25564307

  17. The Metabolic Network of Lactococcus lactis: Distribution of 14C-Labeled Substrates between Catabolic and Anabolic Pathways

    PubMed Central

    Novák, L.; Loubiere, P.

    2000-01-01

    Lactococcus lactis NCDO 2118 was grown in a simple synthetic medium containing only six essential amino acids and glucose as carbon substrates to determine qualitatively and quantitatively the carbon fluxes into the metabolic network. The specific rates of substrate consumption, product formation, and biomass synthesis, calculated during the exponential growth phase, represented the carbon fluxes within the catabolic and anabolic pathways. The macromolecular composition of the biomass was measured to distribute the global anabolic flux into the specific anabolic pathways. Finally, the distribution of radiolabeled substrates, both into the excreted fermentation end products and into the different macromolecular fractions of biomass, was monitored. The classical end products of lactic acid metabolism (lactate, formate, and acetate) were labeled with glucose, which did not label other excreted products, and to a lesser extent with serine, which was deaminated to pyruvate and represented approximately 10% of the pyruvate flux. Other minor products, keto and hydroxy acids, were produced from glutamate and branched-chain amino acids via deamination and subsequent decarboxylation and/or reduction. Glucose labeled all biomass fractions and accounted for 66% of the cellular carbon, although this represented only 5% of the consumed glucose. PMID:10648541

  18. Characterization of ?-galacto-oligosaccharides formed via heterologous expression of ?-galactosidases from Lactobacillus reuteri in Lactococcus lactis.

    PubMed

    Wang, Yvonne; Black, Brenna A; Curtis, Jonathan M; Gänzle, Michael G

    2014-03-01

    ?-Galacto-oligosaccharides (?-GOS) are produced by transgalactosylation reactions of ?-galactosidase (?-Gal) or by conversion of raffinose family oligosaccharides by levansucrase. Similarly to ?-GOS, ?-GOS have the potential to mimic glycan receptors on eukaryotic cells and act as molecular decoys to prevent bacterial infection; however, data on transgalactosylation reactions of ?-Gal remain scarce. The ?-Gal gene sequence from Lactobacillus reuteri was cloned into an ?-Gal negative strain of Lactococcus lactis. Transgalactosylation reactions were achieved using crude cell extracts with melibiose or raffinose as galactosyl donor and fucose, N-acetylglucosamine or lactose as galactosyl acceptor. The composition, sequence and most linkage types of ?-GOS formed with acceptors saccharides were determined by liquid chromatography-tandem mass spectrometry. ?-Gal of Lactobacillus reuteri formed (1???3)-, (1???4)- or (1???6)-linked ?-GOS but exhibited a preference for formation of (1???6)-linkages. Fucose, N-acetylglucosamine and lactose were suitable galactosyl acceptors for ?-Gal of L. reuteri, resulting in formation of (1???3)-, (1???4)- or (1???6)-linked hetero-oligosaccharides. By determining the structural specificity of ?-Gal and increasing the variation of oligosaccharides produced by introducing alternative acceptor sugars, this work supports further studies to assess ?-GOS pathogen adhesion prevention in mammalian hosts. PMID:23942880

  19. Characterization of Multiple Regions Involved in Replication and Mobilization of Plasmid pNZ4000 Coding for Exopolysaccharide Production in Lactococcus lactis

    PubMed Central

    van Kranenburg, Richard; de Vos, Willem M.

    1998-01-01

    We characterized the regions involved in replication and mobilization of the 40-kb plasmid pNZ4000, encoding exopolysaccharide (EPS) production in Lactococcus lactis NIZO B40. The plasmid contains four highly conserved replication regions with homologous rep genes (repB1, repB2, repB3, and repB4) that belong to the lactococcal theta replicon family. Subcloning of each replicon individually showed that all are functional and compatible in L. lactis. Plasmid pNZ4000 and genetically labeled derivatives could be transferred to different L. lactis strains by conjugation, and pNZ4000 was shown to be a mobilization plasmid. Two regions involved in mobilization were identified near two of the replicons; both included an oriT sequence rich in inverted repeats. Conjugative mobilization of the nonmobilizable plasmid pNZ124 was promoted by either one of these oriT sequences, demonstrating their functionality. One oriT sequence was followed by a mobA gene, coding for a trans-acting protein, which increased the frequency of conjugative transfer 100-fold. The predicted MobA protein and the oriT sequences show protein and nucleotide similarity, respectively, with the relaxase and with the inverted repeat and nic site of the oriT from the Escherichia coli plasmid R64. The presence on pNZ4000 of four functional replicons, two oriT sequences, and several insertion sequence-like elements strongly suggests that this EPS plasmid is a naturally occurring cointegrate. PMID:9765557

  20. Key Role of Ser562/661 in Snf1-Dependent Regulation of Cat8p in Saccharomyces cerevisiae and Kluyveromyces lactis

    PubMed Central

    Charbon, Godefroid; Breunig, Karin D.; Wattiez, Ruddy; Vandenhaute, Jean; Noël-Georis, Isabelle

    2004-01-01

    Utilization of nonfermentable carbon sources by Kluyveromyces lactis and Saccharomyces cerevisiae requires the Snf1p kinase and the Cat8p transcriptional activator, which binds to carbon source-responsive elements of target genes. We demonstrate that KlSnf1p and KlCat8p from K. lactis interact in a two-hybrid system and that the interaction is stronger with a kinase-dead mutant form of KlSnf1p. Of two putative phosphorylation sites in the KlCat8p sequence, serine 661 was identified as a key residue governing KlCat8p regulation. Serine 661 is located in the middle homology region, a regulatory domain conserved among zinc cluster transcription factors, and is part of an Snf1p consensus phosphorylation site. Single mutations at this site are sufficient to completely change the carbon source regulation of the KlCat8p transactivation activity observed. A serine-to-glutamate mutant form mimicking constitutive phosphorylation results in a nearly constitutively active form of KlCat8p, while a serine-to-alanine mutation has the reverse effect. Furthermore, it is shown that KlCat8p phosphorylation depends on KlSNF1. The Snf1-Cat8 connection is evolutionarily conserved: mutation of corresponding serine 562 of ScCat8p gave similar results in S. cerevisiae. The enhanced capacity of ScCat8S562E to suppress the phenotype caused by snf1 strengthens the hypothesis of direct phosphorylation of Cat8p by Snf1p. Unlike that of S. cerevisiae ScCAT8, KlCAT8 transcription is not carbon source regulated, illustrating the prominent role of posttranscriptional regulation of Cat8p in K. lactis. PMID:15121831

  1. Rapid identification of stress-related fingerprint from whole bacterial cells of Bifidobacterium lactis using matrix assisted laser desorption\\/ionization mass spectrometry

    Microsoft Academic Search

    Laure F. Marvin-Guy; Stephan Parche; Sandrine Wagnière; Julie Moulin; Ralf Zink; Martin Kussmann; Laurent B. Fay

    2004-01-01

    Whole cells of Bifidobacterium lactis were analyzed by matrix-assisted laser desorption\\/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Characteristic\\u000a and reproducible mass spectra were obtained in the mass range from 6 to 19 kDa. After several days of bacterial cell storage\\u000a at 4 °C (D0, D2, and D6), only minor signal differences were observed. Under identical and reproducible conditions, fourteen\\u000a relevant diagnostic ions

  2. Trehalose-Mediated Inhibition of the Plasma Membrane H+-ATPase from Kluyveromyces lactis: Dependence on Viscosity and Temperature

    PubMed Central

    Sampedro, José G.; Muñoz-Clares, Rosario A.; Uribe, Salvador

    2002-01-01

    The effect of increasing trehalose concentrations on the kinetics of the plasma membrane H+-ATPase from Kluyveromyces lactis was studied at different temperatures. At 20°C, increasing concentrations of trehalose (0.2 to 0.8 M) decreased Vmax and increased S0.5 (substrate concentration when initial velocity equals 0.5 Vmax), mainly at high trehalose concentrations (0.6 to 0.8 M). The quotient Vmax/S0.5 decreased from 5.76 ?mol of ATP mg of protein?1 min?1 mM?1 in the absence of trehalose to 1.63 ?mol of ATP mg of protein?1 min?1 mM?1 in the presence of 0.8 M trehalose. The decrease in Vmax was linearly dependent on solution viscosity (?), suggesting that inhibition was due to hindering of protein domain diffusional motion during catalysis and in accordance with Kramer's theory for reactions in solution. In this regard, two other viscosity-increasing agents, sucrose and glycerol, behaved similarly, exhibiting the same viscosity-enzyme inhibition correlation predicted. In the absence of trehalose, increasing the temperature up to 40°C resulted in an exponential increase in Vmax and a decrease in enzyme cooperativity (n), while S0.5 was not modified. As temperature increased, the effect of trehalose on Vmax decreased to become negligible at 40°C, in good correlation with the temperature-mediated decrease in viscosity. The trehalose-mediated increase in S0.5 was similar at all temperatures tested, and thus, trehalose effects on Vmax/S0.5 were always observed. Trehalose increased the activation energy for ATP hydrolysis. Trehalose-mediated inhibition of enzymes may explain why yeast rapidly hydrolyzes trehalose when exiting heat shock. PMID:12142408

  3. Influence of cofermentation by amylolytic Lactobacillus plantarum and Lactococcus lactis strains on the fermentation process and rheology of sorghum porridge.

    PubMed

    Mukisa, Ivan M; Byaruhanga, Yusuf B; Muyanja, Charles M B K; Aijuka, Matthew; Schüller, Reidar B; Sahlstrøm, Stefan; Langsrud, Thor; Narvhus, Judith A

    2012-08-01

    Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB, Lactobacillus plantarum MNC 21 and Lactococcus lactis MNC 24, isolated from Obushera, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain Lb. plantarum A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (P < 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (G'), loss modulus (G?), phase angle (?), and complex viscosity (?*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (P < 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials. PMID:22610432

  4. Activity of the Kluyveromyces lactis Pdr5 Multidrug Transporter Is Modulated by the Sit4 Protein Phosphatase

    PubMed Central

    Chen, Xin Jie

    2001-01-01

    A possible role for posttranslational modifications in regulating the activity of ATP-binding cassette (ABC) transporters has not been well established. In this study, the drug efflux ABC transporter gene KlPDR5 was isolated from the budding yeast Kluyveromyces lactis, and it was found that the encoded KlPdr5 drug pump is posttranslationally regulated by the type 2A-related Ser/Thr protein phosphatase, Sit4p. The KlPdr5 transporter is a protein of 1,525 amino acids sharing 63.8% sequence identity with its Saccharomyces cerevisiae counterpart, ScPdr5p. Overexpression of the KlPDR5 gene confers resistance to oligomycin, antimycin, econazole, and ketoconazole, whereas cells with a disrupted allele of KlPDR5 are hypersensitive to the drugs and have a decreased capacity to carry out efflux of the anionic fluorescent dye rhodamine 123. It was found that a chromosomal disruption of KlPDR5 abolishes the drug-resistant phenotype associated with sit4 mutations and that a synergistic hyperresistance to the drugs can be created by overexpressing KlPDR5 in sit4 mutants. These data strongly indicate that the multidrug-resistant phenotype of sit4 mutants is mediated by negatively modulating the activity of KlPdr5p. As the transcriptional level of KlPDR5 and the steady-state level of KlPdr5p are not significantly affected by mutations in SIT4, the regulation by Sit4p appears to be a posttranslational process. PMID:11395457

  5. Production of Fibronectin Binding Protein A at the Surface of Lactococcus lactis Increases Plasmid Transfer In Vitro and In Vivo

    PubMed Central

    del Carmen, Silvina; Almeida, Juliana Franco; LeBlanc, Jean-Guy; de Moreno de LeBlanc, Alejandra; Blugeon, Sébastien; Cherbuy, Claire; Lefèvre, François; Azevedo, Vasco; Miyoshi, Anderson; Langella, Philippe; Chatel, Jean-Marc

    2012-01-01

    Lactococci are noninvasive lactic acid bacteria frequently used as protein delivery vectors and, more recently, as DNA delivery vehicles. We previously showed that Lactococcus lactis (LL) expressing the Fibronectin-Binding Protein A of Staphylococcus aureus (LL-FnBPA+) showed higher internalization rates in vitro in Caco-2 cells than the native (wt) lactococci and were able to deliver a eukaryotic Green Fluorescent Protein (GFP) expression plasmid in 1% of human Caco-2 cells. Here, using the bovine beta-lactoglobulin (BLG), one of the major cow's milk allergen, and GFP we characterized the potential of LL-FnBPA+ as an in vivo DNA vaccine delivery vehicle. We first showed that the invasive strain LL-FnBPA+ carrying the plasmid pValac:BLG (LL-FnBPA+ BLG) was more invasive than LL-BLG and showed the same invasivity as LL-FnBPA+. Then we demonstrated that the Caco-2 cells, co-incubated with LL-FnBPA+ BLG produced up to 30 times more BLG than the Caco-2 cells co-incubated with the non invasive LL-BLG. Using two different gene reporters, BLG and GFP, and two different methods of detection, EIA and fluorescence microscopy, we showed in vivo that: i) in order to be effective, LL-FnBPA+ required a pre-coating with Fetal Calf Serum before oral administration; ii) plasmid transfer occurred in enterocytes without regard to the strains used (invasive or not); iii) the use of LL-FnBPA+ increased the number of mice producing BLG, but not the level of BLG produced. We thus confirmed the good potential of invasive recombinant lactic acid bacteria as DNA delivery vector in vivo. PMID:23028664

  6. Increased Biomass Yield of Lactococcus lactis by Reduced Overconsumption of Amino Acids and Increased Catalytic Activities of Enzymes

    PubMed Central

    Adamberg, Kaarel; Seiman, Andrus; Vilu, Raivo

    2012-01-01

    Steady state cultivation and multidimensional data analysis (metabolic fluxes, absolute proteome, and transcriptome) are used to identify parameters that control the increase in biomass yield of Lactococcus lactis from 0.10 to 0.12 C-mol C-mol?1 with an increase in specific growth rate by 5 times from 0.1 to 0.5 h?1. Reorganization of amino acid consumption was expressed by the inactivation of the arginine deiminase pathway at a specific growth rate of 0.35 h?1 followed by reduced over-consumption of pyruvate directed amino acids (asparagine, serine, threonine, alanine and cysteine) until almost all consumed amino acids were used only for protein synthesis at maximal specific growth rate. This balanced growth was characterized by a high glycolytic flux carrying up to 87% of the carbon flow and only amino acids that relate to nucleotide synthesis (glutamine, serine and asparagine) were consumed in higher amounts than required for cellular protein synthesis. Changes in the proteome were minor (mainly increase in the translation apparatus). Instead, the apparent catalytic activities of enzymes and ribosomes increased by 3.5 times (0.1 vs 0.5 h?1). The apparent catalytic activities of glycolytic enzymes and ribosomal proteins were seen to follow this regulation pattern while those of enzymes involved in nucleotide metabolism increased more than the specific growth rate (over 5.5 times). Nucleotide synthesis formed the most abundant biomonomer synthetic pathway in the cells with an expenditure of 6% from the total ATP required for biosynthesis. Due to the increase in apparent catalytic activity, ribosome translation was more efficient at higher growth rates as evidenced by a decrease of protein to mRNA ratios. All these effects resulted in a 30% decrease of calculated ATP spilling (0.1 vs 0.5 h?1). Our results show that bioprocesses can be made more efficient (using a balanced metabolism) by varying the growth conditions. PMID:23133574

  7. Microbiology of Cheddar cheese made with different fat contents using a Lactococcus lactis single-strain starter.

    PubMed

    Broadbent, J R; Brighton, C; McMahon, D J; Farkye, N Y; Johnson, M E; Steele, J L

    2013-07-01

    Flavor development in low-fat Cheddar cheese is typified by delayed or muted evolution of desirable flavor and aroma, and a propensity to acquire undesirable meaty-brothy or burnt-brothy off-flavor notes early in ripening. The biochemical basis for these flavor deficiencies is unclear, but flavor production in bacterial-ripened cheese is known to rely on microorganisms and enzymes present in the cheese matrix. Lipid removal fundamentally alters cheese composition, which can modify the cheese microenvironment in ways that may affect growth and enzymatic activity of starter or nonstarter lactic acid bacteria (NSLAB). Additionally, manufacture of low-fat cheeses often involves changes to processing protocols that may substantially alter cheese redox potential, salt-in-moisture content, acid content, water activity, or pH. However, the consequences of these changes on microbial ecology and metabolism remain obscure. The objective of this study was to investigate the influence of fat content on population dynamics of starter bacteria and NSLAB over 9 mo of aging. Duplicate vats of full fat, 50% reduced-fat, and low-fat (containing <6% fat) Cheddar cheeses were manufactured at 3 different locations with a single-strain Lactococcus lactis starter culture using standardized procedures. Cheeses were ripened at 8°C and sampled periodically for microbiological attributes. Microbiological counts indicated that initial populations of nonstarter bacteria were much lower in full-fat compared with low-fat cheeses made at all 3 sites, and starter viability also declined at a more rapid rate during ripening in full-fat compared with 50% reduced-fat and low-fat cheeses. Denaturing gradient gel electrophoresis of cheese bacteria showed that the NSLAB fraction of all cheeses was dominated by Lactobacillus curvatus, but a few other species of bacteria were sporadically detected. Thus, changes in fat level were correlated with populations of different bacteria, but did not appear to alter the predominant types of bacteria in the cheese. PMID:23684037

  8. Consumption of Bifidobacterium lactis Bi-07 by healthy elderly adults enhances phagocytic activity of monocytes and granulocytes.

    PubMed

    Maneerat, Sujira; Lehtinen, Markus J; Childs, Caroline E; Forssten, Sofia D; Alhoniemi, Esa; Tiphaine, Milin; Yaqoob, Parveen; Ouwehand, Arthur C; Rastall, Robert A

    2013-01-01

    Elderly adults have alterations in their gut microbiota and immune functions that are associated with higher susceptibility to infections and metabolic disorders. Probiotics and prebiotics, and their synbiotic combinations are food supplements that have been shown to improve both gut and immune function. The objective of this randomised, double-blind, placebo-controlled, cross-over human clinical trial was to study immune function and the gut microbiota in healthy elderly adults. Volunteers (n 37) consumed prebiotic galacto-oligosaccharides (GOS; 8 g/d), probiotic Bifidobacterium lactis Bi-07 (Bi-07; 10(9) colony-forming units/d), their combination (Bi-07 + GOS) and maltodextrin control (8 g/d) in four 3-week periods separated by 4-week wash-out periods. Immune function was analysed by determining the phagocytic and oxidative burst activity of monocytes and granulocytes, whole-blood response to lipopolysaccharide, plasma chemokine concentrations and salivary IgA levels. Gut microbiota composition and faecal SCFA content were determined using 16S ribosomal RNA fluorescence in situ hybridisation and HPLC, respectively. Primary statistical analyses indicated the presence of carry-over effects and thus measurements from only the first supplementation period were considered valid. Subsequent statistical analysis showed that consumption of Bi-07 improved the phagocytic activity of monocytes (P < 0·001) and granulocytes (P = 0·02). Other parameters were unchanged. We have for the first time shown that the probiotic Bi-07 may provide health benefits to elderly individuals by improving the phagocytic activity of monocytes and granulocytes. The present results also suggest that in the elderly, the effects of some probiotics and prebiotics may last longer than in adults. PMID:25191600

  9. Influence of Cofermentation by Amylolytic Lactobacillus plantarum and Lactococcus lactis Strains on the Fermentation Process and Rheology of Sorghum Porridge

    PubMed Central

    Byaruhanga, Yusuf B.; Muyanja, Charles M. B. K.; Aijuka, Matthew; Schüller, Reidar B.; Sahlstrøm, Stefan; Langsrud, Thor; Narvhus, Judith A.

    2012-01-01

    Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB, Lactobacillus plantarum MNC 21 and Lactococcus lactis MNC 24, isolated from Obushera, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain Lb. plantarum A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (P < 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (G?), loss modulus (G?), phase angle (?), and complex viscosity (?*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (P < 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials. PMID:22610432

  10. The Ll.LtrB intron from Lactococcus lactis excises as circles in vivo: insights into the group II intron circularization pathway.

    PubMed

    Monat, Caroline; Quiroga, Cecilia; Laroche-Johnston, Felix; Cousineau, Benoit

    2015-07-01

    Group II introns are large ribozymes that require the assistance of intron-encoded or free-standing maturases to splice from their pre-mRNAs in vivo. They mainly splice through the classical branching pathway, being released as RNA lariats. However, group II introns can also splice through secondary pathways like hydrolysis and circularization leading to the release of linear and circular introns, respectively. Here, we assessed in vivo splicing of various constructs of the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis. The study of excised intron junctions revealed, in addition to branched intron lariats, the presence of perfect end-to-end intron circles and alternatively circularized introns. Removal of the branch point A residue prevented Ll.LtrB excision through the branching pathway but did not hinder intron circle formation. Complete intron RNA circles were found associated with the intron-encoded protein LtrA forming nevertheless inactive RNPs. Traces of double-stranded head-to-tail intron DNA junctions were also detected in L. lactis RNA and nucleic acid extracts. Some intron circles and alternatively circularized introns harbored variable number of non-encoded nucleotides at their splice junction. The presence of mRNA fragments at the splice junction of some intron RNA circles provides insights into the group II intron circularization pathway in bacteria. PMID:25956521

  11. Deletion of Various Carboxy-Terminal Domains of Lactococcus lactis SK11 Proteinase: Effects on Activity, Specificity, and Stability of the Truncated Enzyme

    PubMed Central

    Bruinenberg, Paul G.; De Vos, Willem M.; Siezen, Roland J.

    2000-01-01

    The Lactococcus lactis SK11 cell envelope proteinase is an extracellular, multidomain protein of nearly 2,000 residues consisting of an N-terminal serine protease domain, followed by various other domains of largely unknown function. Using a strategy of deletion mutagenesis, we have analyzed the function of several C-terminal domains of the SK11 proteinase which are absent in cell envelope proteinases of other lactic acid bacteria. The various deletion mutants were functionally expressed in L. lactis and analyzed for enzyme stability, activity, (auto)processing, and specificity toward several substrates. C-terminal deletions of first the cell envelope W (wall) and AN (anchor) domains and then the H (helix) domain leads to fully active, secreted proteinases of unaltered specificity. Gradually increasing the C-terminal deletion into the so-called B domain leads to increasing instability and autoproteolysis and progressively less proteolytic activity. However, the mutant with the largest deletion (838 residues) from the C terminus and lacking the entire B domain still retains proteolytic activity. All truncated enzymes show unaltered proteolytic specificity toward various substrates. This suggests that the main role played by these domains is providing stability or protection from autoproteolysis (B domain), spacing away from the cell (H domain), and anchoring to the cell envelope (W and AN domains). In addition, this study allowed us to more precisely map the main C-terminal autoprocessing site of the SK11 proteinase and the epitope for binding of group IV monoclonal antibodies. PMID:10877779

  12. Folate fortification of skim milk by a probiotic Lactococcus lactis CM28 and evaluation of its stability in fermented milk on cold storage.

    PubMed

    Divya, Jayakumar Beena; Nampoothiri, Kesavan Madhavan

    2015-06-01

    In order to enhance folate levels in fermented foods, a folate producing probiotic lactic acid bacterium isolated from cow's milk and identified as Lactococcus lactis CM28 by 16S rRNA sequencing was used to fortify skim milk. Optimization of medium additives such as folate precursors, prebiotics and reducing agents along with suitable culture conditions enhanced folate levels in skim milk. Optimization resulted in a four fold increase in the extracellular folate (61.02?±?1.3 ?g/L) and after deconjugation the total folate detected was 129.53?±?1.2 ?g/L. The effect of refrigerated storage on the viability of L. lactis, pH, titratable acidity (TA) in terms of percentage lactic acid and finally on the stability of folate was determined. Only a slight variation in pH (4.74?±?0.02 to 4.415?±?0.007) and acidity (0.28?±?0.028 to 0.48?±?0.014 %) was noted during folate fermentation. During storage, only less than a log unit reduction was noted in the viable count of the probiotic after 15 days and about 90 % of the produced folate was retained in an active state. PMID:26028733

  13. Evolution of yeast ribosomal DNA: Molecular cloning of the rDNA units of Kluyveromyces lactis and Hansenula wingei and their comparison with the rDNA units of other Saccharomycetoideae

    Microsoft Academic Search

    Martin Ph. Verbeet; Harm Heerikhuizen; Jacobus Klootwijk; Ruud D. Fontijn; Rudi J. Planta

    1984-01-01

    We have studied the evolution of the yeast ribosomal DNA unit to search for regions outside the rRNA genes that exhibit evolutionary constraints and therefore might be involved in control of ribosome biosynthesis. We have cloned one complete rDNA unit of Kluyveromyces lactis and Hansenula wingei and established the physical and genetic organisation of both units. Both species belong to

  14. PATHOLOGIE VGTALE Dynamique des populations fongiques et bact-

    E-print Network

    Paris-Sud XI, Université de

    nutrition des arbres et sur la pérennité de la symbiose sont discutées. Mots clés additionnels : Symhiose, actinomycetes or non-fluorescent bacteria. However, fluorescent Pseurlonrn- nas spp. showed high seasonal variations strongly correlated with the water content of the soil. The relationship between the nutrition

  15. A highly efficient and stable system for site-specific integration of genes and plasmids into the phage phiLC3 attachment site (attB) of the Lactococcus lactis chromosome.

    PubMed

    Lillehaug, D; Nes, I F; Birkeland, N K

    1997-03-25

    An integration vector system based on the site-specific integration apparatus of the temperate lactococcal bacteriophage phiLC3 was developed. A 1.6-kb recombinogenic DNA cassette, containing the phiLC3 integrase gene (int) and the phage attachment site (attP), mediated site-specific integration of a single marker-gene, as well as of a replication-thermosensitive (-ts) plasmid (pINT2), into the phiLC3 attB site of Lactococcus lactis subsp. lactis LM0230 chromosome after introduction of the DNA into the cells by electroporation. Both the marker gene and the pINT2 plasmid were stably inserted as single copies in an orientation-specific and integrase-dependent manner, the pINT2-ts replicon being stably maintained at temperatures both permissive and non-permissive for plasmid-directed replication. Essentially all transformants obtained with the pINT2 plasmid appeared to be integrants, demonstrating the remarkably high efficiency of the system. This high efficiency rendered possible the detection of transformation-plus-integration events using DNA directly obtained from ligase reaction mixtures, thus avoiding initial subcloning in a non-lactococcal strain and subsequent cointegration of foreign replication functions into the chromosome of L. lactis. The above results, the observation that the phiLC3 attB site appear to be conserved in L. lactis, and the fact that the int-attP cassette functions efficiently in a non-phiLC3-host strain, show that the phiLC3 site-specific integration apparatus provides an efficient and 'food grade' tool for stable integration of genetic elements into the chromosome of L. lactis. PMID:9099871

  16. Genetic response to bacteriophage infection in Lactococcus lactis reveals a four-strand approach involving induction of membrane stress proteins, D-alanylation of the cell wall, maintenance of proton motive force, and energy conservation.

    PubMed

    Fallico, Vincenzo; Ross, R Paul; Fitzgerald, Gerald F; McAuliffe, Olivia

    2011-11-01

    In this study, whole-genome microarrays were used to gain insights into the global molecular response of Lactococcus lactis subsp. lactis IL1403 at an early stage of infection with the lytic phage c2. The bacterium differentially regulated the expression of 61 genes belonging to 14 functional categories, including cell envelope processes (12 genes), regulatory functions (11 genes), and carbohydrate metabolism (7 genes). The nature of these genes suggests a complex response involving four main mechanisms: (i) induction of membrane stress proteins, (ii) d-alanylation of cell wall lipoteichoic acids (LTAs), (iii) maintenance of the proton motive force (PMF), and (iv) energy conservation. The phage presence is sensed as a membrane stress in L. lactis subsp. lactis IL1403, which activated a cell wall-targeted response probably orchestrated by the concerted action of membrane phage shock protein C-like homologues, the global regulator SpxB, and the two-component system CesSR. The bacterium upregulated genes (ddl and dltABCD) responsible for incorporation of d-alanine esters into LTAs, an event associated with increased resistance to phage attack in Gram-positive bacteria. The expression of genes (yshC, citE, citF) affecting both PMF components was also regulated to restore the physiological PMF, which was disrupted following phage infection. While mobilizing the response to the phage-mediated stress, the bacterium activated an energy-saving program by repressing growth-related functions and switching to anaerobic respiration, probably to sustain the PMF and the overall cell response to phage. To our knowledge, this represents the first detailed description in L. lactis of the molecular mechanisms involved in the host response to the membrane perturbations mediated by phage infection. PMID:21880765

  17. Effect of the consumption of a fermented dairy product containing Bifidobacterium lactis DN-173 010 on constipation in childhood: a multicentre randomised controlled trial (NTRTC: 1571)

    PubMed Central

    Tabbers, Merit M; Chmielewska, Ania; Roseboom, Maaike G; Boudet, Claire; Perrin, Catherine; Szajewska, Hania; Benninga, Marc A

    2009-01-01

    Background Constipation is a frustrating symptom affecting 3% of children worldwide. Randomised controlled trials show that both polyethylene glycol and lactulose are effective in increasing defecation frequency in children with constipation. However, in 30–50%, these children reported abdominal pain, bloating, flatulence, diarrhoea, nausea and bad taste of the medication. Two recent studies have shown that the fermented dairy product containing Bifidobacterium lactis strain DN-173 010 is effective in increasing stool frequency in constipation-predominant irritable bowel syndrome patients with a defecation frequency < 3/week and in constipated women with a defecation frequency < 3/week. Goal of this study is to determine whether this fermented dairy product is effective in the treatment of constipated children with a defecation frequency < 3/week. Methods/design It is a two nation (The Netherlands and Poland) double-blind, placebo-controlled randomised multicentre trial in which 160 constipated children (age 3–16 years) with a defecation frequency <3/week will be randomly allocated to consume a fermented dairy product containing Bifidobacterium lactis DN-173 010 or a control product, twice a day, for 3 weeks. During the study all children are instructed to try to defecate on the toilet for 5–10 minutes after each meal (3 times a day) and daily complete a standardized bowel diary. Primary endpoint is stool frequency. Secondary endpoints are stool consistency, faecal incontinence frequency, pain during defecation, digestive symptoms (abdominal pain, flatulence), adverse effects (nausea, diarrhoea, bad taste) and intake of rescue medication (Bisacodyl). Rate of success and rate of responders are also evaluated, with success defined as ? 3 bowel movements per week and ?1 faecal incontinence episode over the last 2 weeks of product consumption and responder defined as a subject reporting a stool frequency ? 3 on the last week of product consumption. To demonstrate that the success percentage in the intervention group will be 35% and the success percentage in the control group (acidified milk without ferments, toilet training, bowel diary) will be 15%, with alpha 0.05 and power 80%, a total sample size of 160 patients was calculated. Conclusion This study is aimed to show that the fermented dairy product containing Bifidobacterium lactis strain DN-173 010 is effective in increasing stool frequency after 3 weeks of product consumption in children with functional constipation and a defecation frequency < 3/week. PMID:19296845

  18. Backbone NMR resonance assignments of the nucleotide binding domain of the ABC multidrug transporter LmrA from Lactococcus lactis in its ADP-bound state.

    PubMed

    Hellmich, Ute A; Duchardt-Ferner, Elke; Glaubitz, Clemens; Wöhnert, Jens

    2012-04-01

    LmrA from Lactococcus lactis is a multidrug transporter and a member of the ATP binding cassette (ABC) transporter family. ABC transporters consist of a transmembrane domain (TMD) and a nucleotide binding domain (NBD). The NBD contains the highly conserved signature motifs of this transporter superfamily. In the case of LmrA, the TMD and the NBD are expressed as a single polypeptide. LmrA catalyzes the extrusion of hydrophobic compounds including antibiotics from the cell membrane at the expense of ATP hydrolysis. ATP binds to the NBD, where binding and hydrolysis induce conformational changes that lead to the extrusion of the substrate via the TMD. Here, we report the (1)H, (13)C and (15)N backbone chemical shift assignments of the isolated 263 amino acid containing NBD of LmrA in its ADP bound state. PMID:21786024

  19. AcmD, a Homolog of the Major Autolysin AcmA of Lactococcus lactis, Binds to the Cell Wall and Contributes to Cell Separation and Autolysis

    PubMed Central

    Visweswaran, Ganesh Ram R.; Steen, Anton; Leenhouts, Kees; Szeliga, Monika; Ruban, Beata; Hesseling-Meinders, Anne; Dijkstra, Bauke W.; Kuipers, Oscar P.; Kok, Jan; Buist, Girbe

    2013-01-01

    Lactococcus lactis expresses the homologous glucosaminidases AcmB, AcmC, AcmA and AcmD. The latter two have three C-terminal LysM repeats for peptidoglycan binding. AcmD has much shorter intervening sequences separating the LysM repeats and a lower iso-electric point (4.3) than AcmA (10.3). Under standard laboratory conditions AcmD was mainly secreted into the culture supernatant. An L. lactis acmAacmD double mutant formed longer chains than the acmA single mutant, indicating that AcmD contributes to cell separation. This phenotype could be complemented by plasmid-encoded expression of AcmD in the double mutant. No clear difference in cellular lysis and protein secretion was observed between both mutants. Nevertheless, overexpression of AcmD resulted in increased autolysis when AcmA was present (as in the wild type strain) or when AcmA was added to the culture medium of an AcmA-minus strain. Possibly, AcmD is mainly active within the cell wall, at places where proper conditions are present for its binding and catalytic activity. Various fusion proteins carrying either the three LysM repeats of AcmA or AcmD were used to study and compare their cell wall binding characteristics. Whereas binding of the LysM domain of AcmA took place at pHs ranging from 4 to 8, LysM domain of AcmD seems to bind strongest at pH 4. PMID:23951292

  20. Combined Transcriptome and Proteome Analysis of Bifidobacterium animalis subsp. lactis BB-12 Grown on Xylo-Oligosaccharides and a Model of Their Utilization? †

    PubMed Central

    Gilad, Ofir; Jacobsen, Susanne; Stuer-Lauridsen, Birgitte; Pedersen, Martin Bastian; Garrigues, Christel; Svensson, Birte

    2010-01-01

    Recent studies have demonstrated that xylo-oligosaccharides (XOS), which are classified as emerging prebiotics, selectively enhance the growth of bifidobacteria in general and of Bifidobacterium animalis subsp. lactis strains in particular. To elucidate the metabolism of XOS in the well-documented and widely used probiotic strain B. animalis subsp. lactis BB-12, a combined proteomic and transcriptomic approach was applied, involving DNA microarrays, real-time quantitative PCR (qPCR), and two-dimensional difference gel electrophoresis (2D-DIGE) analyses of samples obtained from cultures grown on either XOS or glucose. The analyses show that 9 of the 10 genes that encode proteins predicted to play a role in XOS catabolism (i.e., XOS-degrading and -metabolizing enzymes, transport proteins, and a regulatory protein) were induced by XOS at the transcriptional level, and the proteins encoded by three of these (?-d-xylosidase, sugar-binding protein, and xylose isomerase) showed higher abundance on XOS. Based on the obtained results, a model for the catabolism of XOS in BB-12 is suggested, according to which the strain utilizes an ABC (ATP-binding cassette) transport system (probably for oligosaccharides) to bind XOS on the cell surface and transport them into the cell. XOS are then degraded intracellularly through the action of xylanases and xylosidases to d-xylose, which is subsequently metabolized by the d-fructose-6-P shunt. The findings obtained in this study may have implications for the design of a synbiotic application containing BB-12 and the XOS used in the present study. PMID:20851982

  1. Isolation of a bacteriocin-producing lactococcus lactis and application of its bacteriocin to manage spoilage bacteria in high-value marine fish under different storage temperatures.

    PubMed

    Sarika, A R; Lipton, A P; Aishwarya, M S; Dhivya, R S

    2012-07-01

    The bacteriocins of lactic acid bacteria have considerable potential for biopreservation. The Lactococcus lactis strain PSY2 (GenBank account no. JF703669) isolated from the surface of marine perch Perca flavescens produced antibacterial activity against pathogenic and spoilage-causing Gram-positive and Gram-negative bacteria viz. Arthrobacter sp., Acinetobacter sp., Bacillus subtilis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus and possessed broad inhibitory spectrum. The biopreservative efficacy of the bacteriocin PSY2 was evaluated using fillets of reef cod, Epinephelus diacanthus. The fillets (10 g) were sprayed with 2.0 ml of 1,600 AU/ml bacteriocin, wrapped and kept under different storage temperatures viz., 4, 0 and -18 °C. The biopreservative extended the shelf-life of fillets stored at 4 °C to >21 days as against <14 days observed in the untreated samples. The total count of spoilage bacteria was reduced by 2.5 logarithmic units in the treated sample during the 14th day of storage as against the control. Chemical analysis revealed a significant change (P?lactis PSY2 gave increased protection against spoilage bacteria and offers an alternative for the preservation of high-value sea foods. PMID:22555500

  2. Lactococcus lactis TrxD represents a subgroup of thioredoxins prevalent in Gram-positive bacteria containing WCXDC active site motifs.

    PubMed

    Björnberg, Olof; Efler, Petr; Ebong, Epie Denis; Svensson, Birte; Hägglund, Per

    2014-12-15

    Three protein disulfide reductases of the thioredoxin superfamily from the industrially important Gram-positive Lactococcus lactis (LlTrxA, LlTrxD and LlNrdH) are compared to the "classical" thioredoxin from Escherichia coli (EcTrx1). LlTrxA resembles EcTrx1 with a WCGPC active site motif and other key residues conserved. By contrast, LlTrxD is more distantly related and contains a WCGDC motif. Bioinformatics analysis suggests that LlTrxD represents a subgroup of thioredoxins from Gram-positive bacteria. LlNrdH is a glutaredoxin-like electron donor for ribonucleotide reductase class Ib. Based on protein-protein equilibria LlTrxA (E°'=-259mV) and LlNrdH (E°'=-238mV) show approximately 10mV higher standard state redox potentials than the corresponding E. coli homologues, while E°' of LlTrxD is -243mV, more similar to glutaredoxin than "classical" thioredoxin. EcTrx1 and LlTrxA have high capacity to reduce insulin disulfides and their exposed active site thiol is alkylated at a similar rate at pH 7.0. LlTrxD on the other hand, is alkylated by iodoacetamide at almost 100 fold higher rate and shows no activity towards insulin disulfides. LlTrxA, LlTrxD and LlNrdH are all efficiently reduced by NADPH dependent thioredoxin reductase (TrxR) from L. lactis and good cross-reactivity towards E. coli TrxR was observed with LlTrxD as the notable exception. PMID:25255970

  3. The C-terminus of nisin is important for the ABC transporter NisFEG to confer immunity in Lactococcus lactis

    PubMed Central

    AlKhatib, Zainab; Lagedroste, Marcel; Zaschke, Julia; Wagner, Manuel; Abts, André; Fey, Iris; Kleinschrodt, Diana; Smits, Sander H J

    2014-01-01

    The lantibiotic nisin is a small 3.4 kDa antimicrobial peptide, which acts against Gram-positive bacteria in the nmol/L range. Nisin is produced and secreted by several Lactococcus lactis strains to ensure advantages against other bacteria in their habitat. Nisin contains five specific lanthionine rings of which the first two are important for Lipid II binding and the last two are crucial for the pore formation in the membrane. To gain immunity against nisin, the producing strain is expressing an ABC transporter called NisFEG, which expels nisin from the membrane. As a result six to eightfold more nisin is needed to affect the cells. The hydrolysis of ATP by NisFEG is required for this immunity as shown by a mutant, where the ATP hydrolysis is disrupted (NisFH181AEG). Furthermore, NisFEG recognizes the C-terminus of nisin, since deletion of the last six amino acids as well as of the last ring lowered the fold of immunity displayed by NisFEG. PMID:25176038

  4. Dynamic response of catabolic pathways to autoacidification in Lactococcus lactis: transcript profiling and stability in relation to metabolic and energetic constraints.

    PubMed

    Even, Sergine; Lindley, Nic D; Loubière, Pascal; Cocaign-Bousquet, Muriel

    2002-08-01

    The dynamic response of the central metabolic pathways to autoacidification (accumulation of organic acid fermentation products) in Lactococcus lactis was investigated in a global manner by integrating molecular data (cellular transcript concentrations, mRNA turnover) within physiological investigations of metabolic and energetic parameters. The decrease in pH associated with the accumulation of organic acids modified the physiological state of the cell considerably. Cytoplasmic acidification led to inhibition of enzyme activities and, consequently, to a diminished catabolic flux through glycolysis and a decreased rate of biochemical energy synthesis. This decrease in energy production together with the increased energy expenditure to counter cytoplasmic acidification led to energetic limitations for biomass synthesis. In these conditions, the specific growth rate decreased progressively, and growth ultimately stopped, although a diminished catabolic flux was maintained in the absence of growth. The cellular response to this phenomenon was to maintain significant levels of mRNA of catabolic genes, involving both continued transcription of the genes and also, in certain cases, an increase in transcript stability. Thus, translation was maintained, and intracellular concentration of certain enzymes increased, partially compensating for the inhibition of activity provoked by the diminished pH. When catabolic activity ceased after prolonged exposure to stress-induced stationary phase, endogenous RNA catabolism was observed. PMID:12180931

  5. Genome-Wide Identification of Small RNAs in Bifidobacterium animalis subsp. lactis KLDS 2.0603 and Their Regulation Role in the Adaption to Gastrointestinal Environment

    PubMed Central

    Zhu, De-Quan; Liu, Fei; Sun, Yu; Yang, Li-Mei; Xin, Li; Meng, Xiang-Chen

    2015-01-01

    Objective Bifidobacteria are one of the predominant bacterial species in the human gastrointestinal tract (GIT) and play a vital role in the host’s health by acting as probiotics. However, how they regulate themselves to adapt to GIT of their host remains unknown. Methods Eighteen bifidobacterial strains were used to analyze their adaptive capacities towards simulated GIT environment. The strain with highest survival rate and adhesion ability was selected for comparative genome as well as transcriptomic analysis. Results The Bifidobacterium animalis subsp. lactis KLDS 2.0603 strain was demonstrated to have the highest survival rate and adhesion ability in simulated GIT treatments. The comparative genome analysis revealed that the KLDS 2.0603 has most similar whole genome sequence compared with BB-12 strain. Eleven intergenic sRNAs were identified after genomes prediction and transcriptomic analysis of KLDS 2.0603. Transcriptomic analysis also showed that genes (mainly sRNAs targeted genes) and sRNAs were differentially expressed in different stress conditions, suggesting that sRNAs might play a crucial role in regulating genes involved in the stress resistance of this strain towards environmental changes. Conclusions This study first provided deep and comprehensive insights into the regulation of KLDS 2.0603 strain at transcription and post-transcription level towards environmental. PMID:25706951

  6. Comparison of killing of gram-negative and gram-positive bacteria by pure singlet oxygen. [Salmonella typhimurium; Escherichia coli; Sarcina lutea; Staphylococcus aureus; Streptococcus lactis; Streptococcus faecalis

    SciTech Connect

    Dahl, T.A.; Midden, W.R. (Bowling Green State Univ., OH (USA)); Hartman, P.E. (Johns Hopkins Univ., Baltimore, MD (USA))

    1989-04-01

    Gram-negative and gram-positive bacteria were found to display different sensitivities to pure singlet oxygen generated outside of cells. Killing curves for Salmonella typhimurium and Escherichia coli strains were indicative of multihit killing, whereas curves for Sarcina lutea, Staphylococcus aureus, Streptococcus lactis, and Streptococcus faecalis exhibited single-hit kinetics. The S. typhimurium deep rough strain TA1975, which lacks nearly all of the cell wall lipopolysaccharide coat and manifests concomitant enhancement of penetration by some exogenous substances, responded to singlet oxygen with initially faster inactivation than did the S. typhimurium wild-type strain, although the maximum rates of killing appeared to be quite similar. The structure of the cell wall thus plays an important role in susceptibility to singlet oxygen. The outer membrane-lipopolysaccharide portion of the gram-negative cell wall initially protects the bacteria from extracellular singlet oxygen, although it may also serve as a source for secondary reaction products which accentuate the rates of cell killing. S. typhimurium and E. coli strains lacking the cellular antioxidant, glutathione, showed no difference from strains containing glutathione in response to the toxic effects of singlet oxygen. Strains of Sarcina lutea and Staphylococcus aureus that contained carotenoids, however, were far more resistant to singlet oxygen lethality than were both carotenoidless mutants of the same species and other gram-positive species lacking high levels of protective carotenoids.

  7. Administration of Bifidobacterium animalis subsp. lactis BB-12 in early childhood: a post-trial effect on caries occurrence at four years of age.

    PubMed

    Taipale, T; Pienihäkkinen, K; Alanen, P; Jokela, J; Söderling, E

    2013-01-01

    Probiotic bifidobacteria are widely used in the prevention of childhood diseases. These bacteria are also associated with caries occurrence. The present secondary analysis in a low-caries population evaluated the effect of early administration of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) on caries occurrence and identified markers of dental decay in early childhood. In the original randomized, double-blind, placebo-controlled study (NCT00638677, http://www.clinicaltrials.gov), infants (n = 106) received BB-12, xylitol or sorbitol tablets from the age of 1-2 months to 2 years with a slow-release pacifier or a spoon (daily dose of BB-12 10(10) colony-forming units, polyol 200-600 mg). The present data were collected using clinical examinations and questionnaires at the age of 4 years. The occurrence of dental caries was assessed using the International Caries Detection and Assessment System. Oral hygiene status and mutans streptococci (MS) levels were also determined. No differences were detected between the study groups in the occurrence of enamel caries (p = 0.268) or obvious dentinal caries (p = 0.201). The occurrence of caries was associated with daily consumption of sweet drinks (p = 0.028), visible plaque observed (p = 0.002) and MS detected in the dental plaque (p = 0.002). Administration of BB-12 in infancy does not seem to increase or decrease the occurrence of caries by 4 years of age in a low-caries population. PMID:23571819

  8. Enzymatic synthesis and identification of oligosaccharides obtained by transgalactosylation of lactose in the presence of fructose using ?-galactosidase from Kluyveromyces lactis.

    PubMed

    Shen, Qiuyun; Yang, Ruijin; Hua, Xiao; Ye, Fayin; Wang, He; Zhao, Wei; Wang, Kun

    2012-12-01

    The enzymatic transgalactosylation of lactose in the presence of fructose using ?-galactosidase from Kluyveromyces lactis (Kl?Gal) leading to the formation of oligosaccharides was investigated in detail. The reaction mixture was analyzed by high performance liquid chromatography with differential refraction detector (HPLC-RI) and two main transgalactosylation products were discovered. To elucidate their overall structures, the products were isolated and purified using preparative liquid chromatography and analyzed by LC/MS, one-dimensional (1D) and two-dimensional (2D) NMR studies. Allo-lactulose(?-d-galactopyranosyl-(1?1)-d-fructose) with two main isomers in D(2)O was identified to be the major transgalactosylation product while lactulose(?-d-galactopyranosyl-(1?4)-d-fructose) turned out to be the minor one, indicating that Kl?Gal was regioselective with respect to the primary C-1 hydroxyl group of fructose. The maximum yields of allo-lactulose and lactulose were 47.5 and 15.4g/l, respectively, at 66.5% lactose conversion (200g/l initial lactose concentration). PMID:22953892

  9. Effects of ingesting milk fermented by Lactococcus lactis H61 on skin health in young women: a randomized double-blind study.

    PubMed

    Kimoto-Nira, H; Nagakura, Y; Kodama, C; Shimizu, T; Okuta, M; Sasaki, K; Koikawa, N; Sakuraba, K; Suzuki, C; Suzuki, Y

    2014-09-01

    We conducted a randomized double-blind trial to evaluate the effects of fermented milk produced using only Lactococcus lactis strain H61 as a starter bacterium (H61-fermented milk) on the general health and various skin properties of young women. Healthy female volunteers (n=23; age=19-21r) received H61-fermented milk (10(10) cfu of strain H61/d) or conventional yogurt (10(10) cfu of both Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus per day), as a reference food, daily for 4 wk. Before and at the end of 4 wk, blood samples were taken, and skin hydration (inner forearms and cheek) and melanin content, elasticity, and sebum content (cheek only) were measured. Skin hydration at the inner forearm was higher at wk 4 than at wk 0 in both groups. Sebum content in cheek rose significantly after intervention in the H61-fermented milk group, but not the conventional yogurt group. Other skin parameters did not differ in either group. Serum analysis showed that total protein concentration and platelet count were elevated and reactive oxygen species decreased in both groups after the intervention. Although H61-fermented milk and conventional yogurt had similar effects on skin status and some blood characteristics of participants, an increase of sebum content in cheek is preferable to H61-fermented milk. As skin lipids contribute to maintaining the skin barrier, H61-fermented milk would provide beneficial effects on skin for young women. PMID:25022690

  10. Extrachromosomal oligomycin-resistant mutants of the petite-negative yeast Kluyveromyces lactis. Properties of mitochondrial ATPase and cross-resistance to inhibitors of phosphoryl transfer reactions.

    PubMed

    Brunner, A; Tuena de Cobos, A

    1980-01-01

    The mitochondrial ATPase from oligomycin-resistant mutants which map on different regions of an extrachromosomal DNA (01 and 011 class mutants) showed an increased resistance to oligomycin and venturicidin when assayed in vitro as compared to the sensitive strains. The resistance to oligomycin of the isolated mitochondrial ATPase from 01 class mutants was higher than that of the 011 class mutants. Cross resistance of the oligomycin-resistant mutants to the antibiotics peliomycin and ossamycin, which also inhibit phosphoryl transfer reactions in mitochondria (Walter et al., 1967), was observed, 01 mutants being more resistant to ossamycin than 011 class mutants. At the concentrations of peliomycin studied, no difference in sensitivity among both groups of oligomycin-resistant mutants could be detected. Mitochondrial respiration and isolated mitochondrial ATPase activity are sensitive to venturicidin, suggesting that the previously observed (Brunner et al., 1977) in vivo venturicidin resistance of K. lactis is probably due to an impairment of the influx of the drug at the level of the plasma membrane. PMID:6446648

  11. Biochemical and kinetic characterisation of a novel xylooligosaccharide-upregulated GH43 ?-d-xylosidase/?-l-arabinofuranosidase (BXA43) from the probiotic Bifidobacterium animalis subsp. lactis BB-12

    PubMed Central

    2013-01-01

    The Bifidobacterium animalis subsp. lactis BB-12 gene BIF_00092, assigned to encode a ?-d-xylosidase (BXA43) of glycoside hydrolase family 43 (GH43), was cloned with a C-terminal His-tag and expressed in Escherichia coli. BXA43 was purified to homogeneity from the cell lysate and found to be a dual-specificity exo-hydrolase active on para-nitrophenyl-?-d-xylopyranoside (pNPX), para-nitrophenyl-?-L-arabinofuranoside (pNPA), ?-(1???4)-xylopyranosyl oligomers (XOS) of degree of polymerisation (DP) 2–4, and birchwood xylan. A phylogenetic tree of the 92 characterised GH43 enzymes displayed five distinct groups (I???V) showing specificity differences. BXA43 belonged to group IV and had an activity ratio for pNPA:pNPX of 1:25. BXA43 was stable below 40°C and at pH 4.0–8.0 and showed maximum activity at pH 5.5 and 50°C. Km and kcat for pNPX were 15.6?±?4.2 mM and 60.6?±?10.8 s-1, respectively, and substrate inhibition became apparent above 18 mM pNPX. Similar kinetic parameters and catalytic efficiency values were reported for ?-d-xylosidase (XynB3) from Geobacillus stearothermophilus T?6 also belonging to group IV. The activity of BXA43 for xylooligosaccharides increased with the size and was 2.3 and 5.6 fold higher, respectively for xylobiose and xylotetraose compared to pNPX. BXA43 showed clearly metal inhibition for Zn2+ and Ag+, which is different to its close homologues. Multiple sequence alignment and homology modelling indicated that Arg505Tyr506 present in BXA43 are probably important for binding to xylotetraose at subsite +3 and occur only in GH43 from the Bifidobacterium genus. PMID:24025736

  12. Administration of a probiotic associated with nasal vaccination with inactivated Lactococcus lactis-PppA induces effective protection against pneumoccocal infection in young mice

    PubMed Central

    Vintiñi, E; Villena, J; Alvarez, S; Medina, M

    2010-01-01

    Streptococcus pneumoniae is a serious public health problem, especially in developing countries, where available vaccines are not part of the vaccination calendar. We evaluated different respiratory mucosa immunization protocols that included the nasal administration of Lactococcus lactis-pneumococcal protective protein A (PppA) live, inactivated, and in association with a probiotic (Lc) to young mice. The animals that received Lc by the oral and nasal route presented the highest levels of immunoglobulin (Ig)A and IgG anti-PppA antibodies in bronchoalveolar lavages (BAL) and IgG in serum, which no doubt contributed to the protection against infection. However, only the groups that received the live and inactivated vaccine associated with the oral administration of the probiotic were able to prevent lung colonization by S. pneumoniae serotypes 3 and 14 in a respiratory infection model. This would be related to a preferential stimulation of the T helper type 1 (Th1) cells at local and systemic levels and with a moderate Th2 and Th17 response, shown by the cytokine profile induced in BAL and by the results of the IgG1/IgG2a ratio at local and systemic levels. Nasal immunization with the inactivated recombinant strain associated with oral Lc administration was able to stimulate the specific cellular and humoral immune response and afford protection against the challenge with the two S. pneumoniae serotypes. The results obtained show the probiotic-inactivated vaccine association as a valuable alternative for application to human health, especially in at-risk populations, and are the first report of a safe and effective immunization strategy using an inactivated recombinant strain. PMID:20002449

  13. Lactococcus lactis ZitR Is a Zinc-Responsive Repressor Active in the Presence of Low, Nontoxic Zinc Concentrations In Vivo?†

    PubMed Central

    Llull, Daniel; Son, Olivier; Blanié, Sandrine; Briffotaux, Julien; Morello, Eric; Rogniaux, Hélène; Danot, Olivier; Poquet, Isabelle

    2011-01-01

    In the family Streptococcaceae, the genes encoding zinc ABC uptake systems (called zit or adc) are regulated by a coencoded MarR family member (i.e., ZitR or AdcR), whereas in the great majority of bacteria, these genes are regulated by Zur, the Fur-like zinc-responsive repressor. We studied the zit operon from Lactococcus lactis and its regulation in response to Zn(II) in vivo. zit transcription is repressed by Zn(II) in a wide concentration range starting from nontoxic micromolar levels and is derepressed at nanomolar concentrations. The level of zit promoter downregulation by environmental Zn(II) is correlated with the intracellular zinc content. The helix-turn-helix domain of ZitR is required for downregulation. In vitro, the purified protein is a dimer that complexes up to two zinc ligands per monomer and specifically binds two intact palindromic operator sites overlapping the ?35 and ?10 boxes of the zit promoter. DNA binding is abolished by the chelator EDTA or TPEN and fully restored by Zn(II) addition, indicating that the active repressor complexes Zn(II) with high affinity. These results suggest that derepression under starvation conditions could be an essential emergency mechanism for preserving Zn(II) homeostasis by uptake; under Zn(II)-replete conditions, the function of ZitR repression could be to help save energy rather than to avoid Zn(II) toxicity. The characterization of a MarR family zinc-responsive repressor in this report gives insight into the way Streptococcaceae efficiently adapt to Zn(II) fluctuations in their diverse ecological niches. PMID:21317326

  14. Safety assessment of potential probiotic lactic acid bacterial strains Lactobacillus rhamnosus HN001, Lb. acidophilus HN017, and Bifidobacterium lactis HN019 in BALB/c mice.

    PubMed

    Zhou, J S; Shu, Q; Rutherfurd, K J; Prasad, J; Birtles, M J; Gopal, P K; Gill, H S

    2000-05-25

    The general safety of immune-enhancing lactic acid bacteria (LAB) strains Lactobacillus rhamnosus HN001 (DR20), Lb. acidophilus HN017, and Bifidobacterium lactis HN019 (DR10) was investigated in a feeding trial. Groups of BALB/c mice were orally administered test LAB strains or the commercial reference strain Lb. acidophilus LA-1 at 2.5 x 10(9), 5 x 10(10) or 2.5 x 10(12) colony forming units (CFU)/kg body weight/day for 4 weeks. Throughout this time, their feed intake, water intake, and live body weight were monitored. At the end of the 4 week observation period, samples of blood, liver, spleen, kidney, mesenteric lymph nodes, and gut tissues (ileum, caecum, and colon) were collected to determine: haematological parameters (red blood cell and platelet counts, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration); differential leukocyte counts; blood biochemistry (plasma total protein, albumin, cholesterol, and glucose); mucosal histology (epithelial cell height, mucosal thickness, and villus height); and bacterial translocation to extra-gut tissues (blood, liver, spleen, kidney and mesenteric lymph nodes). DNA finger printing techniques were used to identify any viable bacterial strains recovered from these tissues. The results demonstrated that 4 weeks consumption of these LAB strains had no adverse effects on animals' general health status, haematology, blood biochemistry, gut mucosal histology parameters, or the incidence of bacterial translocation. A few viable LAB cells were recovered from the tissues of animals in both control and test groups, but DNA fingerprinting did not identify any of these as the inoculated strains. The results obtained in this study suggest that the potentially probiotic LAB strains HN001, HN017, and HN019 are non-toxic for mice and are therefore likely to be safe for human use. PMID:10857928

  15. Experimental and numerical study of heterogeneous pressure-temperature-induced lethal and sublethal injury of Lactococcus lactis in a medium scale high-pressure autoclave.

    PubMed

    Kilimann, K V; Kitsubun, P; Delgado, A; Gänzle, M G; Chapleau, N; Le Bail, A; Hartmann, C

    2006-07-01

    The present contribution is dedicated to experimental and theoretical assessment of microbiological process heterogeneities of the high-pressure (HP) inactivation of Lactococcus lactis ssp. cremoris MG 1363. The inactivation kinetics are determined in dependence of pressure, process time, temperature and absence or presence of co-solutes in the buffer system namely 4 M sodium chloride and 1.5 M sucrose. The kinetic analysis is carried out in a 0.1-L autoclave in order to minimise thermal and convective effects. Upon these data, a deterministic inactivation model is formulated with the logistic equation. Its independent variables represent the counts of viable cells (viable but injured) and of the stress-resistant cells (viable and not injured). This model is then coupled to a thermo-fluiddynamical simulation method, high-pressure computer fluid dynamics technique (HP-CFD), which yields spatiotemporal temperature and flow fields occurring during the HP application inside any considered autoclave. Besides the thermo-fluiddynamic quantities, the coupled model predicts also the spatiotemporal distribution of both viable (VC) and stress-resistant cell counts (SRC). In order to assess the process non-uniformity of the microbial inactivation in a 3.3-L autoclave experimentally, microbial samples are placed at two distinct locations and are exposed to various process conditions. It can be shown with both, experimental and theoretical models that thermal heterogeneities induce process non-uniformities of more than one decimal power in the counts of the viable cells at the end of the treatment. PMID:16514677

  16. Bifidobacterium animalis subsp. lactis BB-12 administration in early childhood: a randomized clinical trial of effects on oral colonization by mutans streptococci and the probiotic.

    PubMed

    Taipale, T; Pienihäkkinen, K; Salminen, S; Jokela, J; Söderling, E

    2012-01-01

    A randomized clinical trial studied the effects of early administration of Bifidobacterium animalis subsp. lactis BB-12 (BB-12) on oral colonization of (1) mutans streptococci (MS), and (2) BB-12. In this double-blind, placebo-controlled study, infants (n = 106) received probiotic bacteria (BB-12 group), xylitol (X group), or sorbitol (S group). Test tablets were administered twice a day (from the age of 1-2 months) with a novel slow-release pacifier or a spoon (daily dose of BB-12 10(10) CFU, polyol 200-600 mg). Samples were collected from mucosa/teeth at the age of 8 months and 2 years for BB- 12 determination (qPCR) and plate culturing of MS (MSB, TYCSB), lactobacilli (Rogosa) and yeasts (Sabouraud). The MS levels of the mothers were determined (Dentocult SM Strip Mutans). The baseline characteristics of the three groups were similar. Mean duration of tablet delivery was 14.9 ± 6.7 months. In all groups, >90% of the mothers showed high MS counts (log CFU ?5). MS colonization percentages of the children at the age of 2 years were rather low (BB-12 group: 6%; X group: 31%; S group: 10%; p < 0.05). The levels of lactobacilli and yeasts did not differ between the groups. BB-12 cell counts barely exceeding the detection limit were found in three of the oral samples of the 8-month-old children; however, the 2-year samples did not contain BB-12. The early administration of BB-12 did not result in permanent oral colonization of this probiotic or significantly affect MS colonization in the children. PMID:22327347

  17. Three Target Genes for the Transcriptional Activator Cat8p of Kluyveromyces lactis: Acetyl Coenzyme A Synthetase Genes KlACS1 and KlACS2 and Lactate Permease Gene KlJEN1

    PubMed Central

    Lodi, Tiziana; Saliola, Michele; Donnini, Claudia; Goffrini, Paola

    2001-01-01

    The aerobic yeast Kluyveromyces lactis and the predominantly fermentative Saccharomyces cerevisiae share many of the genes encoding the enzymes of carbon and energy metabolism. The physiological features that distinguish the two yeasts appear to result essentially from different organization of regulatory circuits, in particular glucose repression and gluconeogenesis. We have isolated the KlCAT8 gene (a homologue of S. cerevisiae CAT8, encoding a DNA binding protein) as a multicopy suppressor of a fog1 mutation. The Fog1 protein is a homologue of the Snf1 complex components Gal83p, Sip1p, and Sip2p of S. cerevisiae. While CAT8 controls the key enzymes of gluconeogenesis in S. cerevisiae, KlCAT8 of K. lactis does not (I. Georis, J. J. Krijger, K. D. Breunig, and J. Vandenhaute, Mol. Gen. Genet. 264:193–203, 2000). We therefore examined possible targets of KlCat8p. We found that the acetyl coenzyme A synthetase genes, KlACS1 and KlACS2, were specifically regulated by KlCAT8, but very differently from the S. cerevisiae counterparts. KlACS1 was induced by acetate and lactate, while KlACS2 was induced by ethanol, both under the control of KlCAT8. Also, KlJEN1, encoding the lactate-inducible and glucose-repressible lactate permease, was found under a tight control of KlCAT8. PMID:11514507

  18. Unsaturated fatty acids-dependent linkage between respiration and fermentation revealed by deletion of hypoxic regulatory KlMGA2 gene in the facultative anaerobe-respiratory yeast Kluyveromyces lactis.

    PubMed

    Ottaviano, Daniela; Montanari, Arianna; De Angelis, Lorenzo; Santomartino, Rosa; Visca, Andrea; Brambilla, Luca; Rinaldi, Teresa; Bello, Cristiano; Reverberi, Massimo; Bianchi, Michele M

    2015-08-01

    In the yeast Kluyveromyces lactis, the inactivation of structural or regulatory glycolytic and fermentative genes generates obligate respiratory mutants which can be characterized by sensitivity to the mitochondrial drug antimycin A on glucose medium (Rag(-) phenotype). Rag(-) mutations can occasionally be generated by the inactivation of genes not evidently related to glycolysis or fermentation. One such gene is the hypoxic regulatory gene KlMGA2. In this work, we report a study of the many defects, in addition to the Rag(-) phenotype, generated by KlMGA2 deletion. We analyzed the fermentative and respiratory metabolism, mitochondrial functioning and morphology in the Klmga2? strain. We also examined alterations in the regulation of the expression of lipid biosynthetic genes, in particular fatty acids, ergosterol and cardiolipin, under hypoxic and cold stress and the phenotypic suppression by unsaturated fatty acids of the deleted strain. Results indicate that, despite the fact that the deleted mutant strain had a typical glycolytic/fermentative phenotype and KlMGA2 is a hypoxic regulatory gene, the deletion of this gene generated defects linked to mitochondrial functions suggesting new roles of this protein in the general regulation and cellular fitness of K. lactis. Supplementation of unsaturated fatty acids suppressed or modified these defects suggesting that KlMga2 modulates membrane functioning or membrane-associated functions, both cytoplasmic and mitochondrial. PMID:26019145

  19. Phenotypical Analysis of the Lactobacillus rhamnosus GG Fimbrial spaFED Operon: Surface Expression and Functional Characterization of Recombinant SpaFED Pili in Lactococcus lactis

    PubMed Central

    Kant, Ravi; Palva, Airi; von Ossowski, Ingemar

    2014-01-01

    A noticeable genomic feature of many piliated Gram-positive bacterial species is the presence of more than one pilus-encoding operon. Paradigmatically, the gut-adapted Lactobacillus rhamnosus GG strain contains two different fimbrial operons in its genome. However, whereas one of these operons (called spaCBA) is encoding for the functionally mucus-/collagen-binding SpaCBA pilus, for the other operon (called spaFED) any native expression of the SpaFED-called pili is still the subject of some uncertainty. Irrespective of such considerations, we decided it would be of relevance or interest to decipher the gross structure of this pilus type, and as well assess its functional capabilities for cellular adhesion and immunostimulation. For this, and by following the approach we had used previously to explicate the immuno-properties of SpaCBA pili, we constructed nisin-inducible expression clones producing either wild-type or SpaF pilin-deleted surface-assembled L. rhamnosus GG SpaFED pili on Lactococcus lactis cells. Using these piliated lactococcal constructs, we found that the pilin-polymerized architecture of a recombinant-produced SpaFED pilus coincides with sequence-based functional predictions of the related pilins, and in fact is prototypical of those other sortase-dependent pilus-like structures thus far characterized for piliated Gram-positive bacteria. Moreover, we confirmed that among the different pilin subunits encompassing spaFED operon-encoded pili, the SpaF pilin is a main adhesion determinant, and when present in the assembled structure can mediate pilus binding to mucus, certain extracellular matrix proteins, and different gut epithelial cell lines. However, somewhat unexpectedly, when recombinant SpaFED pili are surface-attached, we found that they could not potentiate the existing lactococcal cell-induced immune responses so elicited from intestinal- and immune-related cells, but rather instead, they could dampen them. Accordingly, we have now provided the first phenotypical description of a spaFED pilus operon, and with that furthered the functional understanding of surface piliation for a particular gut-commensalic genre of piliated Gram-positive bacteria. PMID:25415357

  20. Hydrogen-driven asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol by Ralstonia eutropha transformant expressing alcohol dehydrogenase from Kluyveromyces lactis

    PubMed Central

    2013-01-01

    Background Conversion of industrial processes to more nature-friendly modes is a crucial subject for achieving sustainable development. Utilization of hydrogen-oxidation reactions by hydrogenase as a driving force of bioprocess reaction can be an environmentally ideal method because the reaction creates no pollutants. We expressed NAD-dependent alcohol dehydrogenase from Kluyveromyces lactis in a hydrogen-oxidizing bacterium: Ralstonia eutropha. This is the first report of hydrogen-driven in vivo coupling reaction of the alcohol dehydrogenase and indigenous soluble NAD-reducing hydrogenase. Asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol, which is a commercial building block for antibacterial agents, was performed using the transformant as the microbial cell catalyst. Results The two enzymes coupled in vitro in vials without a marked decrease of reactivity during the 20 hr reaction because of the hydrogenase reaction, which generates no by-product that affects enzymes. Alcohol dehydrogenase was expressed functionally in R. eutropha in an activity level equivalent to that of indigenous NAD-reducing hydrogenase under the hydrogenase promoter. The hydrogen-driven in vivo coupling reaction proceeded only by the transformant cell without exogenous addition of a cofactor. The decrease of reaction velocity at higher concentration of hydroxyacetone was markedly reduced by application of an in vivo coupling system. Production of (R)-1,2-propanediol (99.8% e.e.) reached 67.7 g/l in 76 hr with almost a constant rate using a jar fermenter. The reaction velocity under 10% PH2 was almost equivalent to that under 100% hydrogen, indicating the availability of crude hydrogen gas from various sources. The in vivo coupling system enabled cell-recycling as catalysts. Conclusions Asymmetric reduction of hydroxyacetone by a coupling reaction of the two enzymes continued in both in vitro and in vivo systems in the presence of hydrogen. The in vivo reaction system using R. eutropha transformant expressing heterologous alcohol dehydrogenase showed advantages for practical usage relative to the in vitro coupling system. The results suggest a hopeful perspective of the hydrogen-driven bioprocess as an environmentally outstanding method to achieve industrial green innovation. Hydrogen-oxidizing bacteria can be useful hosts for the development of hydrogen-driven microbial cell factories. PMID:23305396

  1. Glutamate Biosynthesis in Lactococcus lactis subsp. lactis NCDO 2118

    Microsoft Academic Search

    P. LAPUJADE; M. COCAIGN-BOUSQUET; P. LOUBIERE; L. A. INRA

    1998-01-01

    lag phase of about 2 days and with a reduced growth rate (0.11 h 21 ) compared to that in the reference medium containing glutamate (0.16 h 21 ). The enzymatic studies showed that a phosphoenolpyruvate carboxylase ac- tivity was present, while the malic enzyme and the enzymes of the glyoxylic shunt were not detected. As in most anaerobic bacteria,

  2. Characterization of metal-substituted Klebsiella aerogenes urease.

    PubMed

    Yamaguchi, K; Cosper, N J; Stålhandske, C; Scott, R A; Pearson, M A; Karplus, P A; Hausinger, R P

    1999-08-01

    Urease possesses a dinuclear Ni active site with the protein providing a bridging carbamylated lysine residue as well as an aspartyl and four histidyl ligands. The apoprotein can be activated in vitro by incubation with bicarbonate/CO2 and Ni(II); however, only approximately 15% forms active enzyme (Ni-CO2-ureaseA), with the remainder forming inactive carbamylated Ni-containing protein (Ni-CO2-ureaseB). In the absence of CO2, apoprotein plus Ni(II) forms a distinct inactive Ni-containing species (Ni-urease). The studies described here were carried out to better define the metal-binding sites for the inactive Ni-urease and Ni-CO2-ureaseB species, and to examine the properties of various forms of Co-, Mn-, and Cu-substituted ureases. Xray absorption spectroscopy (XAS) indicated that the two Ni atoms present in the Ni-urease metallocenter are coordinated by an average of two histidines and 3-4 N/O ligands, consistent with binding to the usual enzyme ligands with the lysine carbamate replaced by solvent. Neither XAS nor electronic spectroscopy provided evidence for thiolate ligation in the inactive Ni-containing species. By contrast, comparative studies of Co-CO2-urease and its C319A variant by electronic spectroscopy were consistent with a portion of the two Co being coordinated by Cys319. Whereas the inactive Co-CO2-urease possesses a single histidyl ligand per metal, the species formed using C319A apoprotein more nearly resembles the native metallocenter and exhibits low levels of activity. Activity is also associated with one of two species of Mn-CO2-urease. A crystal structure of the inactive Mn-CO2-urease species shows a metallocenter very similar in structure to that of native urease, but with a disordering of the Asp360 ligand and movement in the Mn-coordinated solvent molecules. Cu(II) was bound to many sites on the protein in addition to the usual metallocenter, but most of the adventitious metal was removed by treatment with EDTA. Cu-treated urease was irreversibly inactivated, even in the C319A variant, and was not further characterized. Metal speciation between Ni, Co, and Mn most affected the higher of two pKa values for urease activity, consistent with this pKa being associated with the metal-bound hydrolytic water molecule. Our results highlight the importance of precisely positioned protein ligands and solvent structure for urease activity. PMID:10555581

  3. Xylo-oligosaccharides alone or in synbiotic combination with Bifidobacterium animalis subsp. lactis induce bifidogenesis and modulate markers of immune function in healthy adults: a double-blind, placebo-controlled, randomised, factorial cross-over study.

    PubMed

    Childs, Caroline E; Röytiö, Henna; Alhoniemi, Esa; Fekete, Agnes A; Forssten, Sofia D; Hudjec, Natasa; Lim, Ying Ni; Steger, Cara J; Yaqoob, Parveen; Tuohy, Kieran M; Rastall, Robert A; Ouwehand, Arthur C; Gibson, Glenn R

    2014-03-24

    Prebiotics, probiotics and synbiotics are dietary ingredients with the potential to influence health and mucosal and systemic immune function by altering the composition of the gut microbiota. In the present study, a candidate prebiotic (xylo-oligosaccharide, XOS, 8 g/d), probiotic (Bifidobacterium animalis subsp. lactis Bi-07, 109 colony-forming units (CFU)/d) or synbiotic (8 g XOS+109 CFU Bi-07/d) was given to healthy adults (25-65 years) for 21 d. The aim was to identify the effect of the supplements on bowel habits, self-reported mood, composition of the gut microbiota, blood lipid concentrations and immune function. XOS supplementation increased mean bowel movements per d (P= 0·009), but did not alter the symptoms of bloating, abdominal pain or flatulence or the incidence of any reported adverse events compared with maltodextrin supplementation. XOS supplementation significantly increased participant-reported vitality (P= 0·003) and happiness (P= 0·034). Lowest reported use of analgesics was observed during the XOS+Bi-07 supplementation period (P= 0·004). XOS supplementation significantly increased faecal bifidobacterial counts (P= 0·008) and fasting plasma HDL concentrations (P= 0·005). Bi-07 supplementation significantly increased faecal B. lactis content (P= 0·007), lowered lipopolysaccharide-stimulated IL-4 secretion in whole-blood cultures (P= 0·035) and salivary IgA content (P= 0·040) and increased IL-6 secretion (P= 0·009). XOS supplementation resulted in lower expression of CD16/56 on natural killer T cells (P= 0·027) and lower IL-10 secretion (P= 0·049), while XOS and Bi-07 supplementation reduced the expression of CD19 on B cells (XOS × Bi-07, P= 0·009). The present study demonstrates that XOS induce bifidogenesis, improve aspects of the plasma lipid profile and modulate the markers of immune function in healthy adults. The provision of XOS+Bi-07 as a synbiotic may confer further benefits due to the discrete effects of Bi-07 on the gut microbiota and markers of immune function. PMID:24661576

  4. Overexpression of Peptidases in Lactococcus and Evaluation of Their Release from Leaky Cells

    Microsoft Academic Search

    T. R. Tuler; M. J. Callanan; T. R. Klaenhammer

    2002-01-01

    Walker and Klaenhammer (2001) developed a novel expression system in Lactococcus lactis that facilitated the release of ?-galactosidase (117 kDa monomer) with- out the need for secretion or export signals. The system is based on the controlled expression of integrated pro- phage holin and lysin cassettes via a lactococcal bacte- riophage ?31 transcriptional activator (Tac31A) that resides on a high-copy

  5. Structures of apo- and ssDNA-bound YdbC from Lactococcus lactis uncover the function of protein domain family DUF2128 and expand the single-stranded DNA-binding domain proteome

    PubMed Central

    Rossi, Paolo; Barbieri, Christopher M.; Aramini, James M.; Bini, Elisabetta; Lee, Hsiau-Wei; Janjua, Haleema; Xiao, Rong; Acton, Thomas B.; Montelione, Gaetano T.

    2013-01-01

    Single-stranded DNA (ssDNA) binding proteins are important in basal metabolic pathways for gene transcription, recombination, DNA repair and replication in all domains of life. Their main cellular role is to stabilize melted duplex DNA and protect genomic DNA from degradation. We have uncovered the molecular function of protein domain family domain of unknown function DUF2128 (PF09901) as a novel ssDNA binding domain. This bacterial domain strongly associates into a dimer and presents a highly positively charged surface that is consistent with its function in non-specific ssDNA binding. Lactococcus lactis YdbC is a representative of DUF2128. The solution NMR structures of the 20 kDa apo-YdbC dimer and YdbC:dT19G1 complex were determined. The ssDNA-binding energetics to YdbC were characterized by isothermal titration calorimetry. YdbC shows comparable nanomolar affinities for pyrimidine and mixed oligonucleotides, and the affinity is sufficiently strong to disrupt duplex DNA. In addition, YdbC binds with lower affinity to ssRNA, making it a versatile nucleic acid-binding domain. The DUF2128 family is related to the eukaryotic nuclear protein positive cofactor 4 (PC4) family and to the PUR family both by fold similarity and molecular function. PMID:23303792

  6. Evaluation of the immune benefits of two probiotic strains Bifidobacterium animalis ssp. lactis, BB-12® and Lactobacillus paracasei ssp. paracasei, L. casei 431® in an influenza vaccination model: a randomised, double-blind, placebo-controlled study.

    PubMed

    Rizzardini, Giuliano; Eskesen, Dorte; Calder, Philip C; Capetti, Amedeo; Jespersen, Lillian; Clerici, Mario

    2012-03-01

    The present study investigated the ability of Bifidobacterium animalis ssp. lactis (BB-12®) and Lactobacillus paracasei ssp. paracasei (L. casei 431®) to modulate the immune system using a vaccination model in healthy subjects. A randomised, double-blind, placebo-controlled, parallel-group study was conducted in 211 subjects (56 % females, mean age 33·2 (sd 13·1) years). Subjects consumed a minimum of 10? colony-forming units of BB-12® (capsule) or L. casei 431® (dairy drink) or a matching placebo once daily for 6 weeks. After 2 weeks, a seasonal influenza vaccination was given. Plasma and saliva samples were collected at baseline and after 6 weeks for the analysis of antibodies, cytokines and innate immune parameters. Changes from baseline in vaccine-specific plasma IgG, IgG1 and IgG3 were significantly greater in both probiotic groups v. the corresponding placebo group (L. casei 431®, P = 0·01 for IgG; P < 0·001 for remaining comparisons). The number of subjects obtaining a substantial increase in specific IgG (defined as ? 2-fold above baseline) was significantly greater in both probiotic groups v. placebo (BB-12®, P < 0·001 for IgG, IgG1 and IgG3; L. casei 431®, P < 0·001 for IgG1 and IgG3). Significantly greater mean fold increases for vaccine-specific secretory IgA in saliva were observed in both probiotic groups v. placebo (BB-12®, P = 0·017; L. casei 431®, P = 0·035). Similar results were observed for total antibody concentrations. No differences were found for plasma cytokines or innate immune parameters. Data herein show that supplementation with BB-12® or L. casei 431® may be an effective means to improve immune function by augmenting systemic and mucosal immune responses to challenge. PMID:21899798

  7. 15N- and 13C-labeled media from Anabaena sp. for universal isotopic labeling of bacteriocins: NMR resonance assignments of leucocin A from Leuconostoc gelidum and nisin A from Lactococcus lactis.

    PubMed

    Sailer, M; Helms, G L; Henkel, T; Niemczura, W P; Stiles, M E; Vederas, J C

    1993-01-12

    A procedure for universal 13C and/or 15N labeling of microbial peptides which are produced by fermentation in complex media and its application to two food-preserving bacteriocins from lactic acid bacteria are described. Isotopic enrichment of nisin A (from Lactococcus lactis) and of leucocin A (from Leuconostoc gelidum) is readily achieved using a soluble peptone derived from enzymatic hydrolysis (pepsin and chymopapain) of Anabaena sp. ATCC 27899 cells grown on sodium [13C]bicarbonate and/or sodium [15N]nitrate as sole carbon and nitrogen sources. Combustion of this peptone followed by mass spectrometric analysis indicates that 45% of the labeled carbon and 65% of the labeled nitrogen added to the Anabaena culture are utilized in the amino acids of the peptone and that the isotopic purity for both 13C and 15N remains essentially unchanged provided that the cells are grown under argon atmosphere to avoid nitrogen fixation. NMR analyses of [13C,15N]nisin A using H[13C]MQC, H[13C]MBC, 2D INADEQUATE, and H[15N]MQC techniques confirmed 1H spectral assignments previously reported for unlabeled material and readily provided carbon and nitrogen assignments. The results show that universal but not uniform 13C labeling occurs unless the nutrient source is completely isotopically enriched at high level (> or = 98%) because of differential levels of de novo amino acid synthesis. Application of NMR techniques such as TOCSY, DQF-COSY, NOESY, and H[13C]MQC to unlabeled and [13C]leucocin A afforded the complete 1H and 13C assignment. Leucocin A does not possess clearly defined conformational structure in DMSO or aqueous solutions. PMID:8418850

  8. Geoffrey Layton Slack OBE (Mil), CBE, TD, BDS DDS, FDSRCS, FDS Glas, FFDRCSI, Dip Bact (1912-1991).

    PubMed

    Gelbier, Stanley

    2014-02-01

    It is with some pride that the author worked in Geoffrey Slack's department from 1963 to 1967 and even retained a working relationship with him after that time. Slack was Professor of Dental Surgery (1959-1976) and later Professor of Community Dental Health (1976-1977) at The London Hospital Medical College, within the University of London. The change in titles came about as a result of recognition of his contribution to developments in public health and community dental care and services, for many of which he was directly responsible. He was Dental Dean from 1965 until 1969. Upon retirement in 1977 he became Emeritus Professor. In addition, he was Dean of the Faculty of Dental Surgery at the Royal College of Surgeons of England from 1974 to 1977. PMID:24585843

  9. Control of the activity and synthesis of aspartate transcarbamylase in Aerobacter aerogenes 

    E-print Network

    Deutsch, Walter Andrew

    1971-01-01

    CONTROL OF THE ACTIVITY AND SYNTHESIS OF ASPARTATE TRANSCARBAMYLASE IN AEBOBACTER AEB0GENES A Thesis by Walter Andrew Deutsch Submitted to the Graduate College of Texas A&M University in partial fulfillsmnt of the requirements for the degree... of MASTER OF SCIENCE December, l97l - Ma)or Sub)ect: Genetics CONTROL OF THE ACTIVITY AND SYNTHESIS OF ASPARTATE TRANSCARBAMYLASE IN AEROBAGTER AEBOGENES A Thesis by Walter Andrew Deutsch Approved as to style and content by: (Chairman of Committee...

  10. The Effects of varying pH on Plasmid Transfer from Escherichia coli to Enterobacter aerogenes

    Microsoft Academic Search

    Willie Norman

    Antibiotic resistance in bacteria is turning into a major cause for concern in the medical profession. With increased resistance of illness causing bacteria for modern drugs, the need for new drugs is becoming increasingly important. This was a study to determine if pH effects conjugation; the means by which genetic information is transferred from bacterium to bacterium.

  11. Biotransformation of Ferulic acid to 4-Vinylguaiacol by Enterobacter soli and E. aerogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the conversion of ferulic acid to 4-vinylguaiacol (4-VG), vanillin, vanillyl alcohol and vanillic acid by five Enterobacter strains. These high-value chemicals are usually synthesized using chemical methods but biological synthesis adds value. Ferulic acid, a relatively inexpensive...

  12. Evolution of Aminobenzoate Synthases: Nucleotide Sequences of Salmonella typhimurium and Klebsiella aerogenes pabB 1

    Microsoft Academic Search

    Paul Goncharoff; Brian P. Nichols

    1988-01-01

    p_Aminobenzoate synthase (PS) and anthranilate synthase (AS) are structurally related enzymes that catalyze similar reactions and produce similar products, pam- and o&o-aminobenzoate (anthranilate) . Each enzyme is composed of two non- identical subunits: a glutamine amidotransferase subunit (Co11 ) and a subunit that produces an aminobenzoate product ( CoI) . Nucleotide sequence comparisons of the Escherichia coli genes encoding each

  13. Some thoughts on recruitment and mentoring of grad students and post-docs (1/29/09). Gary Roberts, Bacteriology groberts@bact.wisc.edu

    E-print Network

    Sheridan, Jennifer

    that grad school is a time to learn to become a scientist is not viscerally apparent to them. So you recruit1 Some thoughts on recruitment and mentoring of grad students and post-docs (1/29/09). Gary Roberts. Right now I am ending my research career with two NIH grants. Importantly, I do NOT claim

  14. Cloning and Expression of the Vitreoscilla Hemoglobin Gene in Enterobacter Aerogenes: Effect on Cell Growth and Oxygen Uptake

    Microsoft Academic Search

    Sebnem O. Erenler; Salih Gencer; Hikmet Geckil; Benjamin C. Stark; Dale A. Webster

    2004-01-01

    The hemoglobins found in unicellular organisms show a great deal of chemical reactivity, protecting cells against oxidative stress, and hence have been implicated in a wider variety of potential functions than those traditionally associated with animal and plant hemoglobins. There are well-documented studies showing that bacteria expressing Vitreoscilla hemoglobin (VHb), the first prokaryotic hemoglobin characterized, have better growth and oxygen

  15. Lait (1995) 75, 331-343 Elsevier/INRA

    E-print Network

    Paris-Sud XI, Université de

    1995-01-01

    (LAB) (Lactobacillus helveticus, Lb acidophilus, Lb lactis, Streptococ- cus thermophilus) (Lactobacillus helveticus, Lb acidophilus, Lb lactis, Streptococcus ther- mophilus et Lactococcus lactis) et 4

  16. Anaerobic arginine metabolism of Mycobacterium tuberculosis is mediated by arginine deiminase (arcA), but is not essential for chronic persistence in an aerogenic mouse model of infection.

    PubMed

    Sürken, Michael; Keller, Christine; Röhker, Claudia; Ehlers, Stefan; Bange, Franz-Christoph

    2008-10-01

    In many pathogens, degradation of arginine via the arginine deiminase pathway supports anaerobic metabolism. Here we show by deletion of Rv1001 (arcA) in Mycobacterium tuberculosis that this gene functions as an arginine deiminase. Arginine metabolism in the presence of oxygen was not affected by the mutation, indicating a separate pathway for arginine degradation under aerobic conditions. Following aerosol infection in mice, the DeltaarcA mutant and wild-type strain of M. tuberculosis multiplied and persisted in infected organs in a similar fashion. PMID:18032107

  17. Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum.

    PubMed

    Pachapur, Vinayak Laxman; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Le Bihan, Yann; Buelna, Gerardo; Verma, Mausam

    2015-10-01

    Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15g/L of CG, 5g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07±1.57mmol H2/L of medium. The p-value of 0.0017 indicated that APH at lower concentration had a significant effect on H2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46mmol H2/L. However, with APH, oxidative pathway was favored with higher H2 production (26.07±1.57mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H2 production, and decreased substrate inhibition. PMID:26142996

  18. E240V Substitution Increases Catalytic Efficiency toward Ceftazidime in a New Natural TEMType Extended-Spectrum  Lactamase, TEM149, from Enterobacter aerogenes and Serratia marcescens Clinical Isolates

    Microsoft Academic Search

    Mariagrazia Perilli; Giuseppe Celenza; Francesca De Santis; Cristina Pellegrini; Chiara Forcella; Gian Maria Rossolini; Stefania Stefani; Gianfranco Amicosante

    2008-01-01

    The aim of this study was to characterize a novel extended-spectrum -lactamase that belongs to the TEM family, the TEM-149 enzyme, and that was isolated from the urine of two hospitalized patients from different hospitals in southern Italy. The peculiarity of this enzyme was the finding of a valine residue at position 240. The array of amino acid substitutions found

  19. Survival of Bifidobacterium animalis ssp. lactis DSMZ 10140 and Bifidobacterium animalis ssp. animalis ATCC 25527

    E-print Network

    Omiecinski, Curtis

    of Food Science College of Agriculture, Pennsylvania State University Summer 2009 Abstract Probiotic bacteria are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host" (FAO/WHO 2002); Based on this definition, to exert health benefits the organisms must

  20. Cooperation between Lactococcus lactis and Nonstarter Lactobacilli in the Formation of Cheese Aroma from Amino Acids

    Microsoft Academic Search

    Agnieszka Kieronczyk; Siv Skeie; Thor Langsrud; Mireille Yvon

    2003-01-01

    In Gouda and Cheddar type cheeses the amino acid conversion to aroma compounds, which is a major process for aroma formation, is essentially due to lactic acid bacteria (LAB). In order to evaluate the respective role of starter and nonstarter LAB and their interactions in cheese flavor formation, we compared the catabolism of phenylalanine, leucine, and methionine by single strains

  1. Regulation of the metC-cysK Operon, Involved in Sulfur Metabolism in Lactococcus lactis

    PubMed Central

    Fernández, María; Kleerebezem, Michiel; Kuipers, Oscar P.; Siezen, Roland J.; van Kranenburg, Richard

    2002-01-01

    Sulfur metabolism in gram-positive bacteria is poorly characterized. Information on the molecular mechanisms of regulation of genes involved in sulfur metabolism is limited, and no regulator genes have been identified. Here we describe the regulation of the lactococcal metC-cysK operon, encoding a cystathionine ?-lyase (metC) and cysteine synthase (cysK). Its expression was shown to be negatively affected by high concentrations of cysteine, methionine, and glutathione in the culture medium, while sulfur limitation resulted in a high level of expression. Other sulfur sources tested showed no significant effect on metC-cysK gene expression. In addition we found that O-acetyl-l-serine, the substrate of cysteine synthase, was an inducer of the metC-cysK operon. Using a random mutagenesis approach, we identified two genes, cmbR and cmbT, involved in regulation of metC-cysK expression. The cmbT gene is predicted to encode a transport protein, but its precise role in regulation remains unclear. Disruption of cmbT resulted in a two- to threefold reduction of metC-cysK transcription. A 5.7-kb region containing the cmbR gene was cloned and sequenced. The encoded CmbR protein is homologous to the LysR family of regulator proteins and is an activator of the metC-cysK operon. In analogy to CysB from Escherichia coli, we propose that CmbR requires acetylserine to be able to bind the activation sites and subsequently activate transcription of the metC-cysK operon. PMID:11741847

  2. Evolved Lactococcus lactis strains for enhanced expression of recombinant membrane proteins.

    PubMed

    Linares, Daniel M; Geertsma, Eric R; Poolman, Bert

    2010-08-01

    The production of complex multidomain (membrane) proteins is a major hurdle in structural genomics and a generic approach for optimizing membrane protein expression is still lacking. We have devised a selection method to isolate mutant strains with improved functional expression of recombinant membrane proteins. By fusing green fluorescent protein and an erythromycin resistance marker (ErmC) to the C-terminus of a target protein, one simultaneously selects for variants with enhanced expression (increased erythromycin resistance) and correct folding (green fluorescent protein fluorescence). Three evolved hosts, displaying 2- to 8-fold increased expression of a plethora of proteins, were fully sequenced and shown to carry single-site mutations in the nisK gene. NisK is the sensor protein of a two-component regulatory system that directs nisin-A-mediated expression. The levels of recombinant membrane proteins were increased in the evolved strains, and in some cases their folding states were improved. The generality and simplicity of our approach allow rapid improvements of protein production yields by directed evolution in a high-throughput way. PMID:20542040

  3. A dynamic, genome-scale flux model of Lactococcus lactis to increase specific recombinant protein expression

    Microsoft Academic Search

    Gian M. Oddone; David A. Mills; David E. Block

    2009-01-01

    Recently, lactic acid bacteria (LAB) have attracted a great deal of interest because of their potential to serve as oral delivery vehicles for recombinant protein vaccines. An important limitation to their use is the typically low level of heterologous expression obtained in LAB. To address this, a dynamic flux balance analysis (DFBA) model was used to identify gene targets for

  4. Citrate utilization by free and immobilized Streptococcus lactis subsp. diacetylactis in continuous culture

    Microsoft Academic Search

    P. Schmitt; C. Couvreur; J. F. Cavin; H. Prévost; Ch. Diviès

    1988-01-01

    The effects of pH, temperature and concentration of citrate were investigated to achieve an optimal production of diacetyl, acetoin and C2 compounds such as acetaldehyde, acetate and ethanol for free and immobilized cells. The critical conditions of culture, 22°C, pH 4.8, increased the production of C4 compounds (diacetyl, acetoin, 2, 3 butylene glycol), C2 compounds (acetaldehyde, ethanol, acetate) and formate.

  5. Effect of Bromide-Hypochlorite Bactericides on Microorganisms1

    PubMed Central

    Shere, Lewis; Kelley, Maurice J.; Richardson, J. Harold

    1962-01-01

    A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

  6. Effect of bromidehypochlorite bactericides on microorganisms.

    PubMed

    SHERE, L; KELLEY, M J; RICHARDSON, J H

    1962-11-01

    A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% "available chlorine" and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% "available chlorine" and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

  7. Technological characterization of lactic acid bacteria isolated from Armada cheese (a Spanish goats’ milk cheese)

    Microsoft Academic Search

    M. A Herreros; J. M Fresno; M. J González Prieto; M. E Tornadijo

    2003-01-01

    Thirty-one strains of lactic acid bacteria (LAB) isolated from Armada cheese, Sobado variety, (eight strains of Lactococcus lactis subsp. lactis, four strains of Lactococcus lactis subsp. cremoris, two strains of L. lactis subsp. lactis biovar. diacetylactis, two strains of Leuconostoc mesenteroides subsp. mesenteroides, two strains of Leuconostoc mesenteroides subsp. dextranicum, five strains of Lactobacillus plantarum, six strains of Lactobacillus casei

  8. Physiology, metabolism Carbamoyl-phosphate synthetases (CPS)

    E-print Network

    Boyer, Edmond

    components. Two to zero CPS are present in the four lactic acid bacteria studied (Lactobacillus plantarum, Enterococcus faecalis, Lactococcus lactis and Lactobacillus delbrueckii ssp. lactis). Only L. plantarum les 4 bactéries lactiques étudiées (Lactobacillus plantarum, Enterococcus faecalis, Lactococcus lactis

  9. Effect of probiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis on lipid profile in individuals with type 2 diabetes mellitus

    Microsoft Academic Search

    H. S. Ejtahed; J. Mohtadi-Nia; A. Homayouni-Rad; M. Niafar; M. Asghari-Jafarabadi; V. Mofid; A. Akbarian-Moghari

    2011-01-01

    The purpose of this study was to investigate the effects of probiotic and conventional yogurt on the lipid profile in type 2 diabetic people. In a randomized double-blind controlled trial, 60 people (23 males and 37 females) with type 2 diabetes and low-density lipoprotein cholesterol (LDL-C) greater than 2.6 mmol\\/L were assigned to 2 groups. Participants consumed daily 300g of

  10. Phenotypic and genetic characterization of a selected set of Lactococcus lactis strains isolated from a starter-free farmhouse cheese

    Microsoft Academic Search

    Mar??a M Sánchez; Teresa Delgado; Leocadio Alonso; Baltasar Mayo

    2000-01-01

    Eleven strains of lactococci isolated from a farmhouse starter-free cheese manufactured from raw cow's milk were analysed in detail for some technologically-related properties. Large phenotypic differences were encountered between the isolates, some of which could be of practical relevance. Several strains produced lactic acid at a rate and at a final concentration suitable for large-scale cheesemaking. The enzymatic capabilities assayed

  11. Production of 1-lactulose and lactulose using commercial ?-galactosidase from Kluyveromyces lactis in the presence of fructose.

    PubMed

    Hua, Xiao; Yang, Ruijin; Shen, Qiuyun; Ye, Fayin; Zhang, Wenbin; Zhao, Wei

    2013-04-15

    Production of 1-lactulose and lactulose using commercial ?-galactosidase DSM Maxilact® 5000 in the presence of fructose was investigated. Experiments were performed at 40 °C and pH 7.5. Lactose starting concentration was constantly 250 g/l. A novel transgalactosylation product 1-lactulose was detected besides lactulose. Effects of fructose concentration, reaction time and enzyme concentration on transgalactosylation reactions were discussed. In all reactions, the yield ratio 1-lactulose:lactulose was close to 3:1 due to the regioselectivity of ?-galactosidase. The maximum production of 1-lactulose and lactulose was approximately 22 and 8 g/l, respectively, when fructose concentration was increased to 100 g/l. Lactose hydrolysis was significantly retarded since fructose strongly attracted water molecules. Higher enzyme concentration can accelerate transgalactosylation reactions without affecting the maximum production of transgalactosylation products. Fructose was a more preferred galactosyl acceptor than lactose, since the synthesis of galactooligosacchairdes was found to be absolutely inhibited in the presence of fructose. PMID:23199983

  12. A group I intron in the terminase gene of Lactobacillus delbrueckii subsp. lactis phage LL-H

    Microsoft Academic Search

    Merja Mikkonen; Tapani Alatossava

    1995-01-01

    An 837 nt long group IA intron was discovered in the Ladobacillus delbnreckii subsp. \\/actis virulent phage LL-H genome. The LL-H intron conforms well to the secondary structure that is common to all group I introns. The only exception is that the extreme 3' nucleotide of the intron is an A residue instead of the usual G; despite this the

  13. Original article Effect of monensin on the crop microflora

    E-print Network

    Paris-Sud XI, Université de

    Department of Microbiology and Biotechnology, Czech University of Agriculture Prague, 165 21 Prague 6, 1992). Crop bacte- ria are presumably susceptible to ionophore antibiotics (monensin, salinomycin, lasa

  14. This article was downloaded by:[University of Colorado, Boulder campus] On: 5 December 2007

    E-print Network

    Pace, Norman

    Engineering ultraviolet irradiation systems as a control against infectious airborne diseases requires a knowledge of intrinsic ultraviolet (UV) inactivation rates of airborne bacte- ria. Ultraviolet inactivation

  15. Bacteria Fate and Movement Dr. Claire Baffaut

    E-print Network

    Bacteria Fate and Movement Dr. Claire Baffaut Dr. Jeff Arnold And John Schumacher #12;Foliar Application Die-off/Re-growth Washoff Infiltration Leaching Runoff Surface Application Bacteria Fate Die-off/Re-growth Die-off/Re-growth #12;Movement in runoff and leaching On plants Bact_Plt = GC*Bact_App Bacteria

  16. Robust Multivariable Flutter Suppression for Benchmark Active Control Technology Wind-Tunnel Model

    Microsoft Academic Search

    Martin R. Waszak

    2001-01-01

    The Benchmark Active Controls Technology (BACT) project is part of NASA Langley Research Center's Benchmark Models Program for studying transonic aeroelastic phenomena. In January of 1996 the BACT wind-tunnel model was used to successfully demonstrate the application of robust multivariable control design methods (H ? and µ-synthesis) to flutter suppression. This paper addresses the design and experimental evaluation of robust

  17. In vitro inhibition of Citrobacter freundii, a red-leg syndrome associated pathogen in raniculture, by indigenous Lactococcus lactis CRL 1584

    Microsoft Academic Search

    Sergio E. Pasteris; Marcos G. Guidoli; María C. Otero; Marta I. Bühler; María E. Nader-Macías

    2011-01-01

    Red-leg syndrome (RLS) is one of the main infectious diseases that cause economic losses in Lithobates catesbeianus hatcheries, Citrobacter freundii being an etiological agent. Treatment or prevention with therapeutics or chemicals results in modifications of the indigenous microbiota, development of antibiotic resistance, presence of their residues in food and enhancement of production costs. Thus, probiotics could be used as an

  18. A Comparative Study of the Biochemical Activity of Streptococcus Lactis, Streptococcus Citrovorus, and Streptococcus Paracitrovorus when Grown in Cow's Milk and Soybean Milk

    Microsoft Academic Search

    Charles W. Gehrke; Harry H. Weiser

    1948-01-01

    The importance of acetylmethylcarbinol and diacetyl from the stand- point of imparting a desirable flavor and aroma to butter and other food products is widely known. The value of selected cultures of bacteria for the development of these compounds has been well established through comparative studies on butter made with and without the use of butter cultures. Hammer and Babel

  19. Shewanella oneidensis in a lactate-fed pure-culture and a glucose-fed co-culture with Lactococcus lactis with an electrode as electron acceptor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bioelectrochemical systems (BESs) employing mixed microbial communities as biocatalysts are gaining importance as potential renewable energy, bioremediation, or biosensing devices. While we are beginning to understand how individual microbial species interact with an electrode as electron donor, li...

  20. Gene Responses to Oxygen Availability in Kluyveromyces lactis: an Insight on the Evolution of the Oxygen-Responding System in Yeast

    Microsoft Academic Search

    Zi-An Fang; Guang-Hui Wang; Ai-Lian Chen; You-Fang Li; Jian-Ping Liu; Yu-Yang Li; Monique Bolotin-Fukuhara; Wei-Guo Bao; Dana Davis

    2009-01-01

    The whole-genome duplication (WGD) may provide a basis for the emergence of the very characteristic life style of Saccharomyces cerevisiae—its fermentation-oriented physiology and its capacity of growing in anaerobiosis. Indeed, we found an over-representation of oxygen-responding genes in the ohnologs of S. cerevisiae. Many of these duplicated genes are present as aerobic\\/hypoxic(anaerobic) pairs and form a specialized system responding to

  1. Control of the Shift from Homolactic Acid to Mixed-Acid Fermentation in Lactococcus lactis: Predominant Role of the NADH\\/NAD1 Ratio

    Microsoft Academic Search

    CHRISTEL GARRIGUES; PASCAL LOUBIERE; NIC D. LINDLEY; MURIEL COCAIGN-BOUSQUET

    1997-01-01

    rapid growth, with a diminished flux through glycolysis, and a lower NADH\\/NAD1 ratio. Under such condi- tions, the major pathway bottleneck was most probably at the level of sugar transport rather than glyceral- dehyde-3-phosphate dehydrogenase. Consequently, the pool concentrations of phosphorylated glycolytic inter- mediates upstream of glyceraldehyde-3-phosphate dehydrogenase decreased. However, the intracellular concentration of fructose-1,6-bisphosphate remained sufficiently high to ensure

  2. Heterologous Processing and Export of the Bacteriocins Pediocin PA1 and Lactococcin A in Lactococcus Lactis : A Study with Leader Exchange

    Microsoft Academic Search

    M. Chikindas; E. Emond; A. J. Haandrikman; J. Kok; K. Leenhouts; S. Pandian; G. Venema; K. Venema

    2010-01-01

    The bacteriocins pediocin PA-1 and lactococcin A are synthesized as precursors carrying N-terminal extensions with a conserved\\u000a cleavage site preceded by two glycine residues in positions -2 and -1. Each bacteriocin is translocated through the cytoplasmic\\u000a membrane by an integral membrane protein of the ABC cassette superfamily which, in the case of pediocin PA-1, has been shown\\u000a to possess peptidase

  3. Le Lait, 1986, 66 (4), 445-451 NOTE TECHNIQUE

    E-print Network

    Paris-Sud XI, Université de

    Lactobacillus helveticus, L. bulgaricus et L. Lac- tis des activités dipeptidasiques et aminopeptidasiques - Dipeptidase - Aminopeptidase - Lactobacillus helveticus - L. bulgaricus - L. lactis - Thermobacterium. lactis and L. acidophilus (EL SODA and DESMA- ZEAUD, 1982). It was shown that each Bacterium had

  4. MMOIRES ORIGINAUX 437 Contribution l'tude comparative concernant

    E-print Network

    Paris-Sud XI, Université de

    savoir: Les cinq cultures mixtes sont : Streptococcus thermophilus et Lactobacillus bulgaricus. Streptococcus lactis et Lactobacillus acidophilus. Streptococcus thermophilus et Lactobacillus helveticus. Streptococcus lactis et Lactobacillus helveticus. Streptococcus thermophilus et Lactobacillus acidophilus. Les

  5. PEDIOCIN PRODUCTION IN MILK BY PEDIOCOCCUS ACIDILACTICI IN CO-CULTURE WITH STREPTOCOCCUS THERMOPHILUS AND LACTOBACILLUS DELBRUECKII SUBSP. BULGARICUS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The production of pediocin in milk by Pediococcus acidilactici was evaluated in co-culture with the dairy fermentation cultures Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lactococcus lactis subsp. lactis. The cultures were tested singly or in different combinations...

  6. Dairy Sci. Technol. 88 (2008) 445455 Available online at: c INRA, EDP Sciences, 2008 www.dairy-journal.org

    E-print Network

    Paris-Sud XI, Université de

    2008-01-01

    consisted of Lactobacillus paracasei, Lactococcus lactis subsp. lactis, Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus brevis, Lactobacillus rhamnosus, Lactobacil- lus curvatus, Enterococcus faecalis, Enterococcus durans and Lactobacillus perolens. A combined typing approach including (GTG)5-PCR and amplified

  7. Oxidative Metabolism of Lactic Acid Bacteria Associated with Pink Discoloration in Italian Cheese

    Microsoft Academic Search

    E. L. Shannon; N. F. Olson; R. H. Deibel

    1977-01-01

    Metabolism of Lactobacillus bulgaricus ATCC 12278 and Lactobacillus belveticus ATCC 10797, associated with pink dis- coloration of cheese, was compared to that of Lactobacillus lactis ATCC 11061 which never caused the defect. Hydrogen peroxide was produced in various media by L. lactis but did not accumulate during growth of the other two strains. Cell suspensions of L. lactis consumed oxygen

  8. Examination of soil and cotton root-associated fungal and bacterial populations under conservation tillage management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Conservation tillage is common management practice utilized in the hopes of reducing soil erosion and increasing soil carbon. Additional evidence indicates that conservation tillage may lead to habitat improvement for soil microorganisms. Potential beneficial changes in rhizosphere bacte...

  9. 76 FR 43149 - Approval and Promulgation of Air Quality Implementation Plans; New Mexico; Prevention of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-20

    ...related to Best Available Control Technology (BACT), New Source Performance Standards (NSPS) for GHG, Carbon Capture Sequestration (CCS) and GHG Reporting and Cap and Trade issues. Response 5: This current rulemaking action concerns...

  10. 77 FR 33642 - Regional Haze: Revisions to Provisions Governing Alternatives to Source-Specific Best Available...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-07

    ...commenters' assertions of ``best'' technology for BART ignore other factors, including...the use of current combustion control technology including low NO X burners, over-fire...distinct from a best available control technology (BACT) determination made under...

  11. Digitizing Historical Plague TO THE EDITOR Outbreaks of bubonic

    E-print Network

    Esper, Jan

    -borne bacte- rium Yersinia pestis have repeatedly af- flicted the Old World since the onset of the `Justinian of Yersinia pestis, and was a wildlife reservoir in- volved? Historical documentary reports and dendro

  12. ENVIRONMENTAL ENGINEERING SCIENCE Volume 24, Number 2, 2007

    E-print Network

    Caron, David

    (Falkowski, 1994), while archaea, bacteria, and heterotrophic protists (protozoa) consume or degrade much AQUATIC MICROORGANISMS (viruses, archaea, bacte- ria, microalgae, protozoa) play fundamental roles and recreational fisheries (particularly shellfish resources) and tourism (Anderson et al., 2000). Similarly

  13. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Apr. 2006, p. 30793083 Vol. 72, No. 4 0099-2240/06/$08.00 0 doi:10.1128/AEM.72.4.30793083.2006

    E-print Network

    Murray, James W.

    diversity was found. The distributions of known anaerobic ammonium oxidation (anammox) bacteria, many that can produce N2 gas from NO2 and NH4 , i.e., anaerobic ammonium oxidation (anammox) bacte- ria, were

  14. Mol. Cells 28, 407-415, November 30, 2009 DOI/10.1007/s10059-009-0169-x

    E-print Network

    Gartner, Anton

    we describe a phylogenetic analysis of sirtuins. Based on their phylogenetic relationship, sirtuins-acetyl-ADP-ribose and deacetylated lysine. One or more sirtuins are present in virtually all species from bacte- ria to mammals. Here

  15. 78 FR 16452 - Approval and Promulgation of Implementation Plans; North Dakota; Regional Haze State...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-15

    ...signification deterioration. The initials SCR mean or refer to selective catalytic reduction...rejected selective catalytic reduction (SCR), a more effective NO X control technology...this decision, North Dakota eliminated SCR as BACT based on its finding that SCR...

  16. REACTIVATION AND REGROWTH OF INDICATOR ORGANISMS ASSOCIATED WITH ANAEROBICALLY DIGESTED AND DEWATERED BIOSOLIDS: EPA’S PERSPECTIVE

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  17. FECAL COLIFORM INCREASE AFTER CENTRIFUGATION

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  18. FECAL COLIFORM INCREASE AFTER CENTRIFUGATION: EPA PERSPECTIVE

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  19. pastel-00711965,version1-26Jun2012 UNIVERSITY OF LJUBLJANA

    E-print Network

    Paris-Sud XI, Université de

    bactériocines par PCR. L'ADN a été extrait directement à partir des fromages ainsi qu'à partir de consortia gènes de bactériocines par PCR dépendait de l'efficacité d'extraction de l'ADN. L'extraction de l'ADN citrate de sodium. Dans l'ADN issu des fromages et consortia microbiens, nous avons détecté plusieurs

  20. Influence of autochthonous lactic acid bacteria and enzymatic yeast extracts on the microbiological, biochemical and sensorial properties of Lben generic products.

    PubMed

    Mangia, Nicoletta P; Garau, Giovanni; Murgia, Marco A; Bennani, Abdelmajid; Deiana, Pietrino

    2014-05-01

    In this study we identified Lactococcus lactis subsp. lactis, Lc. lactis subsp. lactis biovar diacetylactis, Kluyveromices lactis and Saccharomyces cerevisiae as the dominant microorganisms of traditional Moroccan acid-alcoholic fermented milk named Lben. The low pH (3·8±0·3), lactose (16·8±3·4 mg/l) and lactic acid (8·16±0·6 mg/l) content indicated that a strong fermentation occurred in the traditional product which was also characterised by the substantial presence of ethanol and typical volatile carbonyl compounds (i.e., acetoin, diacetyl and acetaldehyde). Microbiological analyses of experimental Lben manufactured with selected strains (isolated from the traditional product) of Lc. lactis subsp. lactis and Lc. lactis subsp. lactis biovar. diacetylactis alone (batch A) and in combination with enzymatic extract of a K. lactis strain (batch B) indicated a good effectiveness of the starters employed (?1010 CFU/g of lactococci after 8 h of incubation) and a significant effect of the yeast enzyme extract on lactococci viability. Despite slight changes in the physicochemical characteristics of the two Lben during the 15 d storage period, volatile compounds (i.e. ethanol, acetaldehyde, diacetyl and acetoin) were consistently higher in batch B. Moreover, sensorial analysis performed after 15 d of storage, highlighted higher odour and flavour intensity, vegetable odour and viscosity in batch B while batch A displayed higher astringency. PMID:24642233

  1. Deoxyribonucleic Acid Homology Among Lactic Streptococci

    PubMed Central

    Jarvis, Audrey W.; Jarvis, Brion D. W.

    1981-01-01

    A comparison was made by deoxyribonucleic acid homology of 45 strains of lactic streptococci, using two strains of Streptococcus cremoris and three strains of Streptococcus lactis as reference strains. All S. cremoris strains were grouped together by deoxyribonucleic acid homology. S. lactis strains formed a second group, except that three strains of S. lactis showed a high degree of homology with S. cremoris strains. The three Streptococcus diacetylactis strains could not be differentiated from S. lactis strains. In spite of these differences between S. lactis and S. cremoris strains, the majority of S. cremoris, S. lactis, and S. diacetylactis strains studied had at least 50% of their base sequences in common. In contrast, Streptococcus thermophilus strains generally showed little relationship with the other strains of lactic streptococci. The relevance of these findings to the selection of starter strains for cheese making is discussed. PMID:16345703

  2. Improved Enumeration of Lactic Acid Bacteria in Mesophilic Dairy Starter Cultures by Using Multiplex Quantitative Real-Time PCR and Flow Cytometry-Fluorescence In Situ Hybridization

    Microsoft Academic Search

    Udo Friedrich; Jan Lenke

    2006-01-01

    Nucleic acid-based assays were developed to enumerate members of the three taxa Lactococcus lactis subsp. cremoris, L. lactis subsp. lactis, and Leuconostoc spp. in mesophilic starter cultures. To our knowledge the present is the first study to present a multiplex quantitative PCR (qPCR) strategy for the relative enumeration of bacteria. The multiplex qPCR strategy was designed to quantify the target

  3. LE LAIT / SEPTEMBRE-ocrOBRE 1969 / N" 488520 Influence de la conglation et de la cryo-dessiccation

    E-print Network

    Boyer, Edmond

    , - Lactobacillus acidophilus, au lieu du Streptococcus thermophilus et du Lactobacillus bulgaricus. Ces deux- toire : · Streptococcus lactis, · Lactobacillus acidophilus. Etuver à 43° C pendant 2 h. Refroidissement

  4. Phenotypic and genotypic characterization of lactic acid bacteria isolated from raw goat milk and effect of farming practices on the dominant species of lactic acid bacteria.

    PubMed

    Tormo, Hélène; Ali Haimoud Lekhal, Djamila; Roques, C

    2015-10-01

    Lactic acid bacteria, in particular Lactococcus lactis, play a decisive role in the cheese making process and more particularly in lactic cheeses which are primarily produced on goat dairy farms. The objective of this study was therefore to identify the main lactic acid bacteria found in raw goats' milk from three different regions in France and evaluate if certain farming practices have an effect on the distribution of species of lactic acid bacteria in the various milk samples. Identification at genus or species level was carried out using phenotypic tests and genotypic methods including repetitive element REP-PCR, species-specific PCR and 16S rRNA gene sequencing. The distribution of the main bacterial species in the milk samples varied depending on farms and their characteristics. Out of the 146 strains identified, L. lactis was the dominant species (60% of strains), followed by Enterococcus (38%) of which Enterococcus faecalis and Enterococcus faecium. Within the species L. lactis, L. lactis subsp lactis was detected more frequently than L. lactis subsp cremoris (74% vs. 26%). The predominance of L. lactis subsp cremoris was linked to geographical area studied. It appears that the animals' environment plays a role in the balance between the dominance of L. lactis and enterococci in raw goats' milk. The separation between the milking parlor and the goat shed (vs no separation) and only straw in the bedding (vs straw and hay) seems to promote L. lactis in the milk (vs enterococci). PMID:26082325

  5. Lait (1999) 79, 3-22 Inra/Elsevier, Paris

    E-print Network

    Paris-Sud XI, Université de

    1999-01-01

    ripening. Lactobacillus helveticus, which originated only from the starter, died off rapidly during. lactis were identified. Among FHL, L. paracasei ssp. paracasei dominated; L. plantarum and L. rhamnosus

  6. Influence of synbiotic containing Lactobacillus acidophilus La5 , Bifidobacterium lactis Bb 12 , Streptococcus thermophilus, Lactobacillus bulgaricus and oligofructose on gut barrier function and sepsis in critically ill patients: a randomised controlled trial

    Microsoft Academic Search

    Prashant K Jain; Clare E McNaught; Alexander D. G Anderson; John MacFie; Charles J Mitchell

    2004-01-01

    Background & aims: Infective complications are a common cause of mortality and morbidity in critically ill patients. Many factors affect sepsis, one of which is gut barrier function. The aim of this study was to determine whether the oral administration of a synbiotic preparation could alter gut barrier function in critically ill patients and thus reduce sepsis.Methods: A total of

  7. Intranasal Coadministration of Live Lactococci Producing Interleukin12 and a Major Cow's Milk Allergen Inhibits Allergic Reaction in Mice

    Microsoft Academic Search

    Naima G. Cortes-Perez; Sandrine Ah-Leung; Luis G. Bermudez-Humaran; Gerard Corthier; Jean-Michel Wal; Philippe Langella; Karine Adel-Patient

    2007-01-01

    The Th1\\/Th2 balance deregulation toward a Th2 immune response plays a central role in allergy. We previously demonstrated that administration of recombinant Lactococcus lactis strains expressing bovine -lactoglobulin (BLG), a major cow's milk allergen, partially prevents mice from sensitization. In the present study, we aimed to improve this preventive effect by coadministration of L. lactis BLG and a second recombi-

  8. Use of a probiotic Bifidobacterium in a dry food matrix, an in vivo study

    Microsoft Academic Search

    Arthur C Ouwehand; Teija Kurvinen; Päivi Rissanen

    2004-01-01

    Probiotics are commonly included in dairy products. These products require cold storage and transportation, which limits their use. Here, we describe the inclusion of the probiotic strain Bifidobacterium lactis Bb-12 in a dry food matrix, an oat-based cereal bar, and its detection in faeces after consumption of this product. One week after cessation of B. lactis Bb-12 feeding, it could

  9. Effects of cultivation conditions on folate production by lactic acid bacteria

    Microsoft Academic Search

    Wilbert Sybesma; Marjo Starrenburg; Linda Tijsseling; Marcel H. N. Hoefnagel; Jeroen Hugenholtz

    2003-01-01

    A variety of lactic acid bacteria were screened for their ability to produce folate intracellularly and\\/or extracellularly. Lactococcus lactis, Streptococcus thermophilus, and Leuconostoc spp. all produced folate, while most Lactobacillus spp., with the exception of Lactobacillus plantarum, were not able to produce folate. Folate production was further investigated in L. lactis as a model organism for metabolic engineering and in

  10. Polyphasic characterization of the lactic acid bacteria in kefir

    Microsoft Academic Search

    Isabelle Mainville; Normand Robert; Byong Lee; Edward R. Farnworth

    2006-01-01

    The lactic acid bacteria of kefir were isolated and characterized using phenotypical, biochemical, and genotypical methods. Polyphasic analyses of results permitted the identification of the microflora to the strain level. The genus Lactobacillus was represented by the species Lb. kefir and Lb. kefiranofaciens. Both subspecies of Lactococcus lactis (lactis and cremoris) were isolated. Leuconostoc mesenteroides subsp. cremoris was also found.The

  11. Lait 86 (2006) 317331 INRA, EDP Sciences, 2006

    E-print Network

    Paris-Sud XI, Université de

    2006-01-01

    ) isolated from artisanal Egyptian Ras cheese including Lacto- coccus (15), Lactobacillus (95), Enterococcus and in the presence of 4% NaCl. Six L. lactis subsp. lactis, one strain of subsp. cremoris and 95% of Lactobacillus Lactobacillus and 32 Enterococcus, were selected for an application in Ras cheese according to their production

  12. Angiotensin I converting enzyme (ACE) inhibitory activity and antihypertensive effect of fermented milk

    Microsoft Academic Search

    Anne Pihlanto; Tarja Virtanen; Hannu Korhonen

    2010-01-01

    Milk was fermented with a total of 25 lactic acid bacteria to assay in vitro inhibitory activity towards angiotensin I converting enzyme (ACE). The tested strains belonged to Lactobacillus acidophilus, Lactobacillus casei, Lacobacillus helveticus, Lactobacillus jensenii, Lactobacillus reuteri, Lactobacillus rhamnosus, Lactococcus lactis ssp. lactis, Lactococcus. raffinolactis and Leuconostoc mesenteroides ssp. cremoris. The ACE inhibitory potencies of theses strains varied and

  13. The effects of baobab pulp powder on the micro flora involved in tempe fermentation

    Microsoft Academic Search

    O. R. Afolabi; T. O. S. Popoola

    2005-01-01

    Locally prepared tempe that underwent natural fermentation was characterized by the growth of Lactobacillus plantarum, Streptococcus lactis , Bacillus sp., Salmonella sp., Klebsiella sp., Lactococcus lactis , Rhizopus sp. and Staphylococcus sp., while fermentation carried out with the addition of varying levels of baobab pulp powder had mainly lactic acid bacteria (LAB)— Lactobacillus plantarum, Lactobacillus fermentum , Lactobacillus acidophilus and

  14. Reusable solid phase immunoassay for the detection of citrate lyase

    Microsoft Academic Search

    C. Joyeux; E. Chrzavzez; C. Y. Boquien; D. Picque; G. Corrieu

    1996-01-01

    An enzymatic immunoassay on a solid phase was developed to detect citrate lyase, an intracellular enzyme of Lactococcus lactis subsp. lactis biovar. diacetylactis. A monoclonal antibody to citrate lyase was immobilized on a nylon membrane. The capture of the antigen was proved by measurement of citrate lyase activity. The immunologie support could capture citrate lyase either in a purified solution

  15. Cytotoxic, antibacterial and antioxidant activities of extracts of the bark of Melia azedarach (China Berry).

    PubMed

    Zahoor, Muhammad; Ahmed, Manzoor; Naz, Sumaira; Ayaz, Musarrat

    2015-06-01

    Nature provides a variety of drugs and medicinal agents derived from plants. This study was conducted to determine antimicrobial, antioxidant and cytotoxic activities of extracts of Melia azedarach bark with methanol/water (9:1 v/v), chloroform, butanol, hexane, water and ethyl acetate. For the determination of the antimicrobial activities, the agar well diffusion method was employed. Cytotoxicity was studied by brine shrimp lethality assay; antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl. The chloroform extract was active against Enterobacter aerogenes and Proteus mirabilis, the ethyl acetate extract had highest antibacterial spectrum against Pseudomonas aeruginosa, the n-hexane extract had highest inhibition against E. aerogenes, the aqueous extract showed highest activities against P. mirabilis, the butanol fraction showed highest activities against E. aerogenes and the methanolic extract was highly active against P. mirabilis. PMID:25426766

  16. Multirate flutter suppression system design for the Benchmark Active Controls Technology Wing

    NASA Technical Reports Server (NTRS)

    Berg, Martin C.; Mason, Gregory S.

    1994-01-01

    To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies will be applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing (also called the PAPA wing). Eventually, the designs will be implemented in hardware and tested on the BACT wing in a wind tunnel. This report describes a project at the University of Washington to design a multirate flutter suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing. The contributions of this project are (1) development of an algorithm for synthesizing robust low order multirate control laws (the algorithm is capable of synthesizing a single compensator which stabilizes both the nominal plant and multiple plant perturbations; (2) development of a multirate design methodology, and supporting software, for modeling, analyzing and synthesizing multirate compensators; and (3) design of a multirate flutter suppression system for NASA's BACT wing which satisfies the specified design criteria. This report describes each of these contributions in detail. Section 2.0 discusses our design methodology. Section 3.0 details the results of our multirate flutter suppression system design for the BACT wing. Finally, Section 4.0 presents our conclusions and suggestions for future research. The body of the report focuses primarily on the results. The associated theoretical background appears in the three technical papers that are included as Attachments 1-3. Attachment 4 is a user's manual for the software that is key to our design methodology.

  17. Bacteriologic study of cirrhotic patients with non-neutrocytic ascites

    PubMed Central

    Dabiri, Hossein; Azimi Rad, Masoumeh; Tavafzadeh, Ramin; Taheri, Effat; Safakar, Soudabeh; Nazemalhosseini Mojarad, Ehsan; Farzaneh, Neda; Zali, Mohammad Reza

    2014-01-01

    Aim: We aimed for detection of bacterial DNA (bactDNA) in spontaneous bacterial peritonitis (SBP) by polymerase chain reaction (PCR) and its prognostic relevance in cirrhotic patients with culture-negative non-neutrocytic ascites (CNNNA). Background: approximately 60% of patients with spontaneous bacterial peritonitis (SBP) are ascites culture negative. Patients and methods: Of each 77 patients with cirrhosis and ascites, two samples including blood and ascitic fluid (AF) were taken. Blood samples were obtained for routine biochemical study and PMN count. AF samples were used for biochemical analysis and aerobic and anaerobic culture. BactDNA was detected by polymerase chain reaction (PCR) using bacterial universal 16srRNA gene primer. Results: Of all AF samples, 3 (3.9%) were positive for bacterial culture (one streptococcus ? hemolytic and two E.coli). The mean number of PMN in AF was 63. BactDNA was detected in 33 (42.9%) of 77 of samples (group A) and bactDNA was absent in 41 (53.2%) of samples (group B). Blood WBC, prothrombin time, LDH, serum total protein, AF WBC, serum albumin, AF albumin, AF total protein, serum total bilirubin, AST, ALT and BUN were not statically different among group A and B. Hepatitis B, 41(45%), was the most frequent cause of cirrhosis. Conclusion: Hepatitis B is the common cause of cirrhosis in Iranian cirrhotic patients. Also, current study showed that high number of Iranian cirrhotic patients with CNNNA carries bactDNA in their AF. The clinical findings as well as clinical laboratory data in patients with CNNNA are independent to bactDNA status in their ascitic fluid. PMID:25289137

  18. Development of a model for evaluation of microbial cross-contamination in the kitchen.

    PubMed

    Zhao, P; Zhao, T; Doyle, M P; Rubino, J R; Meng, J

    1998-08-01

    Foods can become contaminated with pathogenic microorganisms from hands, the cutting board, and knives during preparation in the kitchen. A laboratory model was developed to determine occurrence of cross-contamination and efficacy of decontamination procedures in kitchen food-handling practices. Enterobacter aerogenes B199A, an indicator bacterium with attachment characteristics similar to that of Salmonella spp., was used. Chicken meat with skin inoculated with 10(6) CFU of E. aerogenes B199A/g was cut into small pieces on a sterile cutting board. The extent of cross-contamination occurring from meat to the cutting board and from the cutting board to vegetables (lettuce and cucumbers) subsequently cut on the board was determined. Swab samples from the cutting board, hand washings, and lettuce and cucumber samples revealed that approximately 10(5) CFU of E. aerogenes/cm2 were transferred to the board and hands and approximately 10(3) to 10(4) CFU of E. aerogenes/g to the lettuce and cucumbers. The surfaces of the cutting board and hands were treated with antibacterial agents after cutting the meat, and counts of E. aerogenes on the cutting board and vegetables (lettuce and cucumbers) were determined. Results revealed that use of the disinfectant reduced the population of E. aerogenes to almost nondetectable levels on the cutting boards. The average counts after treatment were < 20 CFU/g of vegetable and ranged from < 20 to 200 CFU per cm2 or g on the cutting board and subsequently on the vegetables. These results indicate that bacteria with attachment characteristics similar to Salmonella spp. can be readily transferred to cutting boards during food preparation and then cross-contaminate fresh vegetables if the boards are not cleaned. Application of a kitchen disinfectant can greatly reduce bacterial contamination on cutting boards. PMID:9713754

  19. Minimum leak size determination, under laboratory and commercial conditions, for bacterial entry into polymeric trays used for shelf-stable food packaging.

    PubMed

    Ravishankar, Sadhana; Maks, Nicole D; Teo, Alex Y L; Strassheim, Henry E; Pascall, Melvin A

    2005-11-01

    This study sought to determine the minimum leak size for entry of Enterobacter aerogenes under laboratory conditions, and normal flora under commercial conditions, into tryptic soy broth with yeast extract (TSBYE), homestyle chicken, and beef enchilada packaged in 355-ml polyethylene terephthalate/ethylene vinyl alcohol/polypropylene trays. Channel leaks (diameters of 50 to 200 microm) were made across the sealing area of the trays. Pinholes (diameters of 5 to 50 microm) were made by imbedding laser-drilled metal and plastic disks into the tray lids. For the laboratory simulation, all trays were submerged and agitated for 30 min at 25 degrees C in phosphate-buffered saline that contained 10(7) CFU/ml of E. aerogenes. Under commercial conditions, trays with channel leaks were processed in retorts to achieve commercial sterility. All trays were subsequently incubated at 37 degrees C for 2 weeks, and their contents plated onto eosin-methylene blue agar (for laboratory simulation) to enumerate E. aerogenes and brain heart infusion agar (for commercial conditions) to determine the presence of any bacteria. Under laboratory conditions, minimum pinhole sizes for E. aerogenes entry approximated 5 microm (TSBYE, metal disks; homestyle chicken, plastic disks), 20 microm (beef, plastic disks), and 30 microm (beef, metal disks). The minimum channel leak sizes for entry of E. aerogenes approximated 10 microm (TSBYE), 70 microm (chicken), and 200 microm (beef enchilada). Under commercial conditions, the minimum channel leak size for bacterial entry approximated 40 microm (TSBYE), 50 microm (homestyle chicken), and more than 200 microm (beef). Results showed that E. aerogenes can enter pinholes as small as 5 microm under a worst-case scenario. This information can be used to set pass and fail parameters for leak detection devices. PMID:16300076

  20. Complete genome sequence of Hirschia baltica type strain (IFAM 1418T)

    SciTech Connect

    Chertkov, Olga [Los Alamos National Laboratory (LANL); Brown, Pamela J.B. [Indiana University; Kysela, David T. [Indiana University; De Pedro, Miguel A. [Universidad Autonoma de Madrid, Madrid; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Glavina Del Rio, Tijana [U.S. Department of Energy, Joint Genome Institute; Tice, Hope [U.S. Department of Energy, Joint Genome Institute; Bruce, David [Los Alamos National Laboratory (LANL); Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Larimer, Frank W [ORNL; Chang, Yun-Juan [ORNL; Jeffries, Cynthia [Oak Ridge National Laboratory (ORNL); Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Ovchinnikova, Galina [U.S. Department of Energy, Joint Genome Institute; Tindall, Brian [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Brun, Yves V. [Indiana University

    2011-01-01

    The family Hyphomonadaceae within the Alphaproteobacteria is largely comprised of bacte- ria isolated from marine environments with striking morphologies and an unusual mode of cell growth. Here, we report the complete genome sequence Hirschia baltica, which is only the second a member of the Hyphomonadaceae with a published genome sequence. H. bal- tica is of special interest because it has a dimorphic life cycle and is a stalked, budding bacte- rium. The 3,455,622 bp long chromosome and 84,492 bp plasmid with a total of 3,222 pro- tein-coding and 44 RNA genes were sequenced as part of the DOE Joint Genome Institute Program CSP 2008.

  1. Growth of nisin-producing lactococci in cooked rice supplemented with soybean extract and its application to inhibition of Bacillus subtilis in rice miso.

    PubMed

    Kato, T; Inuzuka, L; Kondo, M; Matsuda, T

    2001-02-01

    Lactic acid fermentation of cooked rice and rice koji by supplementation with soybean extract (SBE) and its application to rice miso fermentation were investigated. By supplementing the cooked rice with SBE, lactic acid bacteria (LAB) grew well without any unfavorable effects on the rice such as off-flavor or coloration. Lactococcus lactis subsp. lactis IFO12007 (Lc. lactis, a producer of the bacteriocin nisin) proliferated at 10(8 to approximately 9) cells/g after 24 h of incubation and produced high activity of nisin. The fermented rice with Lc. lactis strongly inhibited not only Bacillus subtilis ATCC19659 but also the other Bacillus strains. While some strains of LAB markedly inhibited the growth of Asp. oryzae, resulting in failure of koji fermentation, Lc. lactis did not affect the growth of these molds. When Lc. lactis was used for rice miso fermentation as a lactic acid starter culture, Lc. lactis rapidly proliferated and produced high nisin activity of 6,400 IU/g, in the steamed rice, resulting in complete growth inhibition of B. subtilis, which had been inoculated at the beginning of the koji fermentation. The rice miso after 12 weeks of aging had a suitable pH, and favorable taste and color. Furthermore, hyposalting of rice miso could be done without difficulty by lactic acid fermentation of both rice and soybeans. PMID:11302166

  2. Probing the conformational changes of the yeast mitochondrial ADP/ATP carrier

    E-print Network

    Ashton, Valerie Lauren

    2013-03-12

    .4. Lactococcus lactis cultures and harvesting 66 2.5. Labelling methods 67 2.5.1. Labelling of whole Lactococcus lactis cells with eosin-5-malemide 67 2.5.2. Labelling of whole Lactococcus lactis cells with 1,2-ethanediyl... in proliferating cells, AAC3 is ubiquitous and AAC4 is expressed in testis, brain and liver (Fontanesi et al., 2004; Dolce et al., 2005). In Saccharomyces cerevisiae, isoforms Aac1p and Aac3p are not required for growth of yeast on non-fermentable carbon...

  3. Conservation of the Major Cold Shock Protein in Lactic Acid Bacteria

    Microsoft Academic Search

    Woojin S. Kim; Nongpanga Khunajakr; Jun Ren; Noel W. Dunn

    1998-01-01

    .   Primers designed from consensus regions of the major cold shock gene of different bacterial species were used in PCR amplification\\u000a of Lactic Acid Bacteria (LAB). An appropriately-sized PCR product was obtained from Lactococcus lactis subsp. lactis LL43-1 and MG1363; Lactococcus lactis subsp. cremoris LC10-1, LC11-1, and LC12-1; Streptococcus thermophilus ST1-1; Enterococcus faecalis EF1-1; Lactobacillus acidophilus LA1-1; Lactobacillus helveticus LH1-1;

  4. AEROMONAS SPP. ASSOCIATED WITH COMMERCIAL POULTRY PROCESSING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Trials were conducted to examine the effect of commercial processing and refrigerated storage on Aeromonas bacteria in the native bacterial flora of broilers. The whole carcass rinse procedure was used to recover bacteria from prescalded, picked, prechilled, chilled, and refrigerated carcasses. Bact...

  5. Breathing rust -and new life into bug science | csmonitor.com WORLD USA COMMENTARY WORK & MONEY LEARNING LIVING SCI / TECH ARTS & LEISURE BOOKS THE HOME FORUM

    E-print Network

    Lovley, Derek

    predict its behavior in other applications. If the US today were to try to clean all its nuclear sites of The Christian Science Monitor AMHERST, MASS. ­ Iron lungs may be the answer. To the problem of nuclear pollution a favorite geobacter food - acetate, or vinegar - into the ground, they caused a native population of bacte

  6. Interactions between Periodontal Bacteria and Human Oral Epithelial Cells: Fusobacterium nucleatum Adheres to and Invades Epithelial Cells

    Microsoft Academic Search

    YIPING W. HAN; WENYUAN SHI; GEORGE T.-J. HUANG; SUSAN KINDER HAAKE; NO-HEE PARK; HOWARD KURAMITSU; ROBERT J. GENCO

    2000-01-01

    Bacteria are causative agents of periodontal diseases. Interactions between oral bacteria and gingival epi- thelial cells are essential aspects of periodontal infections. Using an in vitro tissue culture model, a selected group of gram-negative anaerobic bacteria frequently associated with periodontal diseases, including Bacte- roides forsythus, Campylobacter curvus, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia, were examined for their

  7. EFFECT OF EXPERIMENTAL CHLORATE PRODUCT ON SALMONELLA CONTAMINATION OF POULTRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    E. coli and Salmonella are members of the family Enterobacteriacea, a common commensal family of bacteria. Salmonella and E. coli have a nitrate reductase enzyme that allows respiration in anaerobic conditions. Nitrate reductase can also co-metabolize chlorate to chlorite which will kill the bacte...

  8. INTRODUCTION Because symbiotic systems exhibit a variety of behav-

    E-print Network

    Nishiguchi, Michele

    INTRODUCTION Because symbiotic systems exhibit a variety of behav- iors ranging from mutualistic. 1996). Comparing closely related symbiotic bacte- ria, which have a wide range of host preference for understanding the evolution of infection and disease in a number of eukaryotic-microbe associations. The ability

  9. www.sciencemag.org SCIENCE VOL 332 1 APRIL 2011 43 PERSPECTIVES

    E-print Network

    Lazzaro, Brian

    the "immune" system has also evolved to maintain homeostasis and regulate commensal microbes that normally of conserved molecules in the prokaryotic cell wall called "microbe- associated molecular patterns" (MAMPs recognize and kill bacteria, how are symbiotic bacte- ria, which have enormous importance to the health

  10. Synthetic Mimics of Antimicrobial Peptides--A Versatile Ring-Opening Metathesis Polymerization Based Platform for the Synthesis of Selective

    E-print Network

    Tew, Gregory N.

    of methicillin-resistant S. aureus bacte- ria (MRSA) jumped from 3 to 52%.[3,4] Two million people in the US are infected annually with MRSA during hospital- ization, and the follow-up costs of these MRSA infections add of and contagion with MRSA and other multiple-resistant organisms. For example, a "first-in-man Phase I clinical

  11. Worming into the cell: Viral reproduction in Caenorhabditis elegans

    E-print Network

    Shaham, Shai

    mature viral particles, and exit the cell to initiate a subsequent round of infection. At all, genetic analysis has proven to be a powerful tool for studying virus (phage)­host interactions in bacte- ria. Mutants of both phage and their host bacteria have allowed detailed under- standing

  12. Decontamination of airborne bacteria in meat processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in a meat processing environment was determined. Bacterial strains found in ground beef were used to artificially contaminate the air using a 6-jet Collison nebulizer. Airborne bact...

  13. High Prevalence of Respiratory Viral Infections in Patients Hospitalized in an Intensive Care Unit for Acute Respiratory Infections as Detected by Nucleic Acid-Based Assays

    Microsoft Academic Search

    Jerome Legoff; Emmanuel Guerot; Angelique Ndjoyi-Mbiguino; Mathieu Matta; Ali Si-Mohamed; Laurent Gutmann; Jean-Yves Fagon; Laurent Belec

    2005-01-01

    Severe community-acquired pneumonia is caused by bacte- rial infections in around 60% of cases (7, 20), and it requires admission to an intensive care unit (ICU) for about 10% of patients. Pneumonia is also the most commonly reported nos- ocomial infection in the ICU, with an incidence ranging from

  14. The use of dermal fibroblasts as a predictive tool of the TLR4 response pathway and its development in Holstein heifers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The innate immune system comprises the host’s first line of defense against invading pathogens, and variation in the magnitude of this response between animals has been shown to affect susceptibility to mastitis. The toll-like receptor (TLR) family of proteins initiates the response to invading bact...

  15. EVALUATION OF BEST AVAILABLE CONTROL TECHNOLOGY FOR TOXICS (TBACT) DOUBLE SHELL TANK FARMS PRIMARY VENTILATION SYSTEM SUPPORTING WASTE TRANSFER OPERATIONS

    Microsoft Academic Search

    KELLY SE; HAASS CC; KOVACH JL; TURNER DA

    2010-01-01

    This report is an evaluation of Best Available Control Technology for Toxics (tBACT) for installation and operation of the Hanford double shell (DST) tank primary ventilation systems. The DST primary ventilation systems are being modified to support Hanford's waste retrieval, mixing, and delivery of single shell tank (SST) and DST waste throught the DST storage system to the Waste Treatment

  16. EVALUATION OF BEST AVAILABLE CONTROL TECHNOLOGY FOR TOXICS -TBACT- DOUBLE SHELL TANK FARMS PRIMARY VENTILATION SYSTEMS SUPPORTING WASTE TRANSFER OPERATIONS

    Microsoft Academic Search

    HAAS CC; KOVACH JL; KELLY SE; TURNER DA

    2010-01-01

    This report is an evaluation of Best Available Control Technology for Toxics (tBACT) for installation and operation of the Hanford double shell (DST) tank primary ventilation systems. The DST primary ventilation systems are being modified to support Hanford's waste retrieval, mixing, and delivery of single shell tank (SST) and DST waste through the DST storage system to the Waste Treatment

  17. Leading Edge Bacterial Genomics and Pathogen Evolution

    E-print Network

    Mekalanos, John

    Leading Edge Review Bacterial Genomics and Pathogen Evolution David M. Raskin,1 Rekha Seshadri,2 Medical School, Boston, MA 02115, USA 2 The Institute for Genomic Research, 9712 Medical Center Drive.02.002 The availability of hundreds of bacterial genome sequences has altered the study of bacte- rial pathogenesis

  18. Raphanin, an Antibacterial Principle of the Radish (Raphanus sativus)

    Microsoft Academic Search

    George Ivánovics; Stephan Horváth

    1947-01-01

    IN the course of investigation of the watery extracts of different plants by the cylinder plate method on plates seeded with Staphylococcus and Bact. coli, it was found that the extracts of the seeds of radish (Raphanus sativus) gave a very marked zone of inhibition in both cases, whereas the extract of the root and the leaves did not affect

  19. APPLICATION OF THE TRANSPIRATION METHOD FOR AEROSERVOELASTIC PREDICTION USING CFD

    Microsoft Academic Search

    Cole H. Stephens; Andrew S. Arena; Kajal K. Gupta

    Research presented in this paper illustrates the implementation of the transpiration boundary condition in steady and unsteady aeroelastic and aeroservoelastic simulations. For two reference cases, the AGARD 445.6 wing and the BACT wing with a finite-span flap, application of the transpiration method has demonstrated the effectiveness of applying the transpiration boundary condition at a variety of Mach numbers on configurations

  20. FOURIER-TRANSFORMED DIFFUSE REFLECTANCE TO MEASURE HERBICIDE INJURY IN THE NIR AND MID-IR IN SOYBEAN AND WEED SPECIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research was conducted to determine if spectral reflectance in the NIR and Mid-IR can be used to identify various levels of herbicide injury in soybean and weed species. Plants were sprayed with various rates of the herbicide glyphosate. Glyphosate inhibits a pathway unique to plants and bacte...

  1. Rhizosphere Bacteria Enhance Selenium Accumulation and Volatilization by Indian Mustard

    Microsoft Academic Search

    Mark P. de Souza; Dara Chu; May Zhao; Adel M. Zayed; Steven E. Ruzin; Denise Schichnes; Norman Terry

    1999-01-01

    Indian mustard (Brassica juncea L.) accumulates high tissue Se concentrations and volatilizes Se in relatively nontoxic forms, such as dimethylselenide. This study showed that the presence of bacte- ria in the rhizosphere of Indian mustard was necessary to achieve the best rates of plant Se accumulation and volatilization of selenate. Experiments with the antibiotic ampicillin showed that bacteria facilitated 35%

  2. TLR4dependent hepcidin expression by myeloid cells in response to bacterial pathogens

    E-print Network

    Nizet, Victor

    PHAGOCYTES TLR4­dependent hepcidin expression by myeloid cells in response to bacterial pathogens, intraperi- toneal challenge with Pseudomonas aeruginosa induced TLR4­dependent hepcidin expression and iron to bacte- rial pathogens in a toll-like receptor 4 (TLR4)­dependent fashion. Conversely, bacterial

  3. TLR4-dependent hepcidin expression by myeloid cells in response to bacterial pathogens

    Microsoft Academic Search

    Carole Peyssonnaux; Annelies S. Zinkernagel; Vivekanand Datta; Xavier Lauth; Randall S. Johnson; Victor Nizet

    2006-01-01

    Hepcidin is an antimicrobial peptide se- creted by the liver during inflammation that plays a central role in mammalian iron homeostasis. Here we demonstrate the endogenous expression of hepcidin by macrophages and neutrophils in vitro and in vivo. These myeloid cell types produced hepcidin in response to bacte- rial pathogens in a toll-like receptor 4 (TLR4)-dependent fashion. Conversely, bacterial stimulation

  4. Quantitative Detection of Chlamydia psittaci and C. pecorum by High-Sensitivity Real-Time PCR Reveals High Prevalence of Vaginal Infection in Cattle

    Microsoft Academic Search

    Fred J. DeGraves; Dongya Gao; Hans-Robert Hehnen; Tobias Schlapp; Bernhard Kaltenboeck

    2003-01-01

    Over the last 40 years, evidence has accumulated to suggest the ubiquitous presence of infections with intracellular bacte- ria of the genus Chlamydia in cattle and other livestock species. Despite some improvement in diagnostic techniques, our un- derstanding about the prevalence and pathogenetic signifi- cance of these infections, succinctly reviewed by Shewen (11) in 1980, has not substantially changed since

  5. SULFIDE PRODUCTION BY SOME RUMEN BACTERIA C.W. FORSBERG

    E-print Network

    Paris-Sud XI, Université de

    SULFIDE PRODUCTION BY SOME RUMEN BACTERIA C.W. FORSBERG Department of Microbio%gy, University of Guelph, Guelph, Ontario, Canada Sulfide is a key intermediate in rumen sul- fur metabolism, with excep- tion of the use of sulfide production as a cri- teria for the classification of rumen bacte- ria

  6. Journal of Wildlife Diseases, 42(1), 2006, pp. 164169 # Wildlife Disease Association 2006

    E-print Network

    Foresman, Kerry R.

    -borne zoonotic disease caused by the bacterium Yersinia pestis, which can cause extensive mortality among prairie following an epizootic. Key words: Cynomys, fleas, prairie dogs, sylvatic plague, Yersinia pestis. Sylvatic plague is a flea-borne zoonotic disease of mammals caused by the bacte- rium Yersinia pestis. The disease

  7. Volatiles emitted from eight wound-isolated bacteria differentially attract and stimulate gravid screwworm flies (Diptera: Calliphoridae) to oviposit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine blood inoculated with bacteria isolated from screwworm-infested animal wounds was tested against gravid screwworm flies, Cochliomyia hominivorax (Coquerel) in the laboratory in a cage bioassay as an attractant for oviposition. Eight species of gram-negative coliform (Enterobacteriaceae) bacte...

  8. MICROBIAL CONTROL OF THE POTATO TUBER MOTH (LEPIDOPTERA: GELECHIIDAE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato tuber moth (PTM) is a serious pest of stored potato in most countries where potatoes are grown. Pathogens that are specific to insects offer promise as alternatives to broad spectrum insecticides for management of this pest. A diverse spectrum of microscopic and multicellular organisms (bact...

  9. DOI: 10.1126/science.1105299 , 258 (2005);307Science

    E-print Network

    Kornfeld, S. Kerry

    2005-01-01

    . typhimurium infection. Thus, they succumbed within 6 days of oral administration of 1 Â 109 bacte- ria as a gateway for the uptake and transport of the intestinal microbiota. We have identified and charac- terized. The intrinsic functional programs and subspecifications of CX3CR1-positive and -negative DCs in mucosal innate

  10. Reconstitution of infectious laryngotracheitis from a collection of overlapping cosmid clones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have generated overlapping cosmids that span the complete genome of infectious laryngotracheitis virus (ILTV) and have used these clones in transfection experiments to reconstitute the virus. This is the first example of the use of large deoxyribose nucleic acid fragment(s) (cosmid, fosmid, bact...

  11. MULTIPLE RINSES OF EGGSHELLS FOR RECOVERY OF AEROBES AND ENTEROBACTERIACEAE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been demonstrated that when broiler carcasses are rinsed repeatedly, specific bacterial species can be recovered on later rinses that were recovered on the initial rinse. Though eggshells are less convoluted than chicken skin, they do have numerous pores that are large enough to harbor bacte...

  12. Functional analyses of the cell wall hydrolase from Lactobacillus paracasei NRRL B-50314 expressed in Bacillus megaterium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study reports the production and characterization of a novel antibacterial polypeptide, designated laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. Crude laparaxin has antibacterial activity against a range of Gram-positive bacteria including the following: lactic acid bact...

  13. Gram-positive DsbE Proteins Function Differently from Gram-negative DsbE Homologs

    E-print Network

    Bardwell, James

    Gram-positive DsbE Proteins Function Differently from Gram-negative DsbE Homologs A STRUCTURE 07103 Mycobacterium tuberculosis, a Gram-positive bacte- rium, encodes a secreted Dsb-like protein oxidoreductase is an oxidant, unlike Gram-negative bacteria DsbE proteins, which have been shown to be weak

  14. Pattern Formation inside Bacteria: Fluctuations due to the Low Copy Number of Proteins Martin Howard1,* and Andrew D. Rutenberg2

    E-print Network

    Howard, Martin

    of the oscillating MinCDE protein system regulating accurate cell division in E. coli. We find that, for some of subcellular bacte- rial structure. In this Letter, we examine, for the first time, the impact of fluctuations of both reactions and diffusion. Although the effects of noise have been studied in subcellular models

  15. Microbiology Mary Jane Ferraro and

    E-print Network

    Mootha, Vamsi K.

    303 Chapter Microbiology Mary Jane Ferraro and Robert C. Moellering Jr. The history of Microbiology (or Bacte- riology, as it was originally known) at the Massachusetts General Hospital (MGH of appendicitis in 1886 (15, 41; and see chapter 2), the laboratory specialty of microbiology owes its origins

  16. www.sciencemag.org SCIENCE VOL 333 23 SEPTEMBER 2011 1709 PERSPECTIVES

    E-print Network

    Willig, Michael

    unclear whether sperm bind to all human ZP glycoproteins (ZP1 to ZP4) containing SLeX or whether binding on human sperm that recognize and bind to SLeX. Perhaps deriv- atives of SLeX could be used as effective, binding of bacte- ria to plants and of pollen to the plant stigma, binding of amphibian and marine sperm

  17. BIOLOGIJA. 2013. Vol. 59. No. 1. P. 45140 Lietuvos moksl akademija, 2013

    E-print Network

    as primary producers, biofuels and a variety of phycocolloids for various industrial applications. We noticed that some species of algae of the genus Chara grow there too. Xerophytic grasses grow;48 Abstracts of International Scientific Conference Potential of alGae anD cyanoBacteRia foR RuRal Develo

  18. Emissions from gas fired agricultural burners

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of the Federal Clean Air Act, the San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) began defining Best Available Control Technology (BACT) for NOx emissions from cotton gin drying system gas fired burners in its jurisdiction. The NOx emission levels of conventionally used...

  19. www.ext.vt.edu Produced by Communications and Marketing, College of Agriculture and Life Sciences,

    E-print Network

    Liskiewicz, Maciej

    : · Somatic cell count equal to or less than 200,000 · Standard plate count equal to or less than 5 high raw milk bacte- ria counts involve improper cleaning and sanitizing of dairy equipment, poor of sample by hauler or carrier of sample from plant to lab. Preliminary Incubation Count (PICount)- A milk

  20. Edema Toxin Impairs Anthracidal Phospholipase A2 Expression by Alveolar

    E-print Network

    Paris-Sud XI, Université de

    ´nie Bacte´rienne, Paris, France, 5 CNRS, URA-2172, Paris, France Bacillus anthracis, the etiological agent Bacillus anthracis, the etiological agent of anthrax, is a spore- forming Gram-positive bacterium [1]. Even dysfunction and death. The pathogenicity of B. anthracis is due to the production of virulence factors

  1. GUEST COMMENTARY

    Microsoft Academic Search

    Robert B. Bourret; Max A. Keniry; Ah Young Park; Elisabeth A. Owen; Samir M. Hamdan; Guido Pintacuda; Gottfried Otting; Catherine L. Lawson; Brian H. Yung; Alan G. Barbour; Wolfram R. Zuckert; Pyridoxal Kinases; Martin K. Safo; Faik N. Musayev; Sharyn Hunt; Jean-Baptiste Claude; Verne Schirch; Peter Redder; Roger A. Garrett

    2006-01-01

    The overwhelming majority of life on our planet is microbial, both in terms of phylogenetic diversity (15, 19) and sheer numbers of organisms (25). Virtually every conceivable envi- ronmental niche harbors microorganisms capable of growing there. This evolutionary success likely depends in part on sig- nal transduction, the ability to sense changing environmental conditions and then implement appropriate responses. Bacte-

  2. Articledoi:10.1006/geno.2001.6616, available online at http://www.idealibrary.com on IDEAL INTRODUCTION

    E-print Network

    Cross, George

    sequences of bacte- ria, yeast, fruit fly, worm (Caenorhabditis elegans), mouse, and human genomes chromo- some (BAC) cloning system and the construction of repre- sentative genomic BAC libraries [1 of random clones. Furthermore, the routine gene-cloning strategy cannot be applied to the study

  3. Article original Dgradation et prlvement de peptides de casines

    E-print Network

    Boyer, Edmond

    Article original Dégradation et prélèvement de peptides de caséines marqués au 14C par des and uptake of4C-labelled casein peptides by mixed rumen bacte- ria. This work studied the in vitro degradation by mixed rumen bacteria of various 14C-labelled fractions of casein peptides, of known molecular

  4. Environmental factors affecting twitching motility, biofilm development, and aggregation by Xylella fastidiosa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bacterial pathogen Xylella fastidiosa causes many important plant diseases in different crops such as citrus, grapes, almond and coffee. While disease symptoms expressed by this pathogen are not completely understood, it is widely accepted that blockage of xylem vessels by aggregates of the bact...

  5. UNDERGRADUATE PROJECT ON VIRUS REMOVAL IN SLOW SAND FILTERS FOR RURAL MAYAN COMMUNITIES

    EPA Science Inventory

    Long-Term Removal in Columns To simulate the normal operation of a biosand filter, 4 glass columns (Figure 1) packed with different iron orientations were charged daily with 1 PV of aquifer water containing ~108 pfu/mL of MS-2 bacte...

  6. Immunoglobulin A Response in Murine Schistosomiasis: Stimulatory Role of Egg Antigens

    Microsoft Academic Search

    ODILE POULAIN-GODEFROY; SOPHIE GAUBERT; SOPHIA LAFITTE; ANDJEAN-MARIE GRZYCH

    The role of immunoglobulin A (IgA) antibodies has been widely investigated during the past decades in various bacte- rial, viral, and parasitic infections. These studies have allowed the identification of some of the functional properties of this isotype and indicated its participation in several mechanisms involved either in host defense or in pathological events (24). IgA antibodies were shown to

  7. Love Handles in Aquatic Ecosystems: The Role of Dissolved

    E-print Network

    NOAA Great Lakes Environmental Research Laboratory, Episodic Events

    Sediments, and Terrigenous Inputs in the Carbon Balance of Lake Michigan Bopaiah A. Biddanda* and James B examined carbon (C) dynamics in the upper water column of southern Lake Michigan. We found that (a) bacte; terrigenous matter; southern Lake Michigan. INTRODUCTION A lake is the landscape's most beautiful

  8. Proc. Natl. Acad. Sci. USA Vol. 96, pp. 49084913, April 1999

    E-print Network

    van Oudenaarden, Alexander

    to move. Listeria monocytogenes is a Gram-positive intracellular bacte- rial pathogen that moves rapidly lamellipodia and filopodia and also at the surface of motile intracellular bacterial pathogens such as Listeria monocytogenes. Local catalysis of actin filament polymerization is accomplished in L. monocytogenes

  9. Occurrence of antibiotic-resistant enterobacteria in agricultural foodstuffs

    Microsoft Academic Search

    Sybille Boehme; Guido Werner; Ingo Klare; Rolf Reissbrodt; Wolfgang Witte

    2004-01-01

    seven sprout samples showed a some orders of magnitude higher contamination with coliform bacte- ria (10 7 -1 0 9 cfu\\/g) including a remarkable amount of resistant isolates (up to 10 7 cfu\\/g). Multiple resistances (up to 9) in single isolates were more common in sprout isolates. Resistant bacteria did not originate from sprout seeds. The most common genera among

  10. Dgradation et fermentation de la cellulose par Neocallimastix sp. seul ou associ quelques espces bactriennes du rumen

    E-print Network

    Boyer, Edmond

    Dégradation et fermentation de la cellulose par Neocallimastix sp. seul ou associé à quelques bactériennes du rumen. Matériel et méthodes. Nous avons étudié la dégradation et la fermentation de la.f.) souche 007 ou Bacte- roides succinogenes (B.s.) souche S85] ou en coculture avec une espèce fermentative

  11. Article original La flore microbienne de laits crus de vache

    E-print Network

    Boyer, Edmond

    rue métropole, 73000 Chambéry, France b ITFF, Pré Germain, BP30, 74800 La Roche sur Foron, France aerobic bacteria count as well as numeration of some useful cheesemaking microorganisms (lactic acid bacteria, halophilic bacte- ria, propionic acid bacteria...), spoilage bacteria (Pseudomonas

  12. New emission controls for Missouri batch-type charcoal kilns

    SciTech Connect

    Yronwode, P.; Graf, W.J.

    1999-07-01

    Charcoal kilns have been exempted from air emission regulation in the state of Missouri. Today, 80% of US charcoal production takes place in Missouri. As a result of a petition filed by people in the area around an installation in southern Missouri, the US Environmental Protection Agency (EPA) set up air monitors and measured ambient air levels at that charcoal manufacturing installation. These monitors yielded the highest particulate matter less than 10 micron (PM{sub 10}) levels ever recorded in the state. Earlier stack testing at another charcoal manufacturing installation indicated that toxics and carcinogens are present in charcoal kiln air emissions. A Charcoal Kiln Workgroup was formed to determine the Best Available Control Technology (BACT) for charcoal kilns and to draft a charcoal kiln rule that requires BACT. The BACT report determined that afterburners were suitable for controlling emissions from batch-type charcoal kilns. In addition, the charcoal industry supported incorporating the BACT limits and requirements into an enforceable state rule and submitting this rule to the EPA for federal approval. A consent agreement between the EPA and three major charcoal companies was signed with provisions to install, operate, and maintain emission control devices on charcoal kilns. This agreement was to settle complaints alleging that the three major charcoal producers had failed to report toxic air emissions to federal and state regulators. The agreement provided that industry would install control devices on a set schedule with some charcoal kilns being shut down.

  13. Nocardial Endophthalmitis and Subretinal Abscess: CT and MR Imaging Features with Pathologic Correlation: A Case Report

    Microsoft Academic Search

    Eugene Yu; Suzanne Laughlin; Edward E. Kassel; Hans A. Messner; Yeni H. Yucel

    Summary: Ocular nocardiosis is a rare but potentially aggressive process. Clinically, it can mimic other disease entities, including neoplasia and other types of infection. We present a case of nocardial panophthalmitis progress- ing to subretinal abscess and emphasize the radiologic and clinical features. Intraocular nocardial infection is most commonly caused by an aerobic, filamentous, branching bacte- rium called Nocardia asteroides

  14. www.landesbioscience.com Plant Signaling & Behavior 1245 article addendumarticle addendum

    E-print Network

    Citovsky, Vitaly

    by Agrobacterium infection and that recognizes and binds VIP1. VBF destabilizes VirE2 and VIP1 in yeast and plant.chom.2010.02.009. Key words: arabidopsis, defense response, proteasomal degradation, bacte- rial infection race" between Agrobacterium infectivity and plant defense. Agrobacterium infection of plants consists

  15. NOx emission constraints on high-temperature processes. Final report, April 1988November 1990

    Microsoft Academic Search

    R. A. Brown; H. B. Mason; J. A. Nicholson; C. I. Okoh

    1990-01-01

    Current and emerging NOx emission regulations were reviewed to identify possible constraints on high-performance burner application in industrial furnaces. Industrial furnace regulations were evaluated for new and existing sources in air quality attainment and nonattainment areas. Processes emphasized were ferrous and nonferrous metals heating and heat-treating furnaces, glass melting furnaces, and mineral kilns. Regulation of best available control technology (BACT)

  16. Subinhibitory Bismuth-Thiols Reduce Virulence of Pseudomonas aeruginosa

    Microsoft Academic Search

    Chieh-Liang Wu; Philip Domenico; Daniel J. Hassett; Terry J. Beveridge; Alan R. Hauser; Jeffrey A. Kazzaz

    Pseudomonas aeruginosa is a common pathogen in mechani- cally ventilated patients and produces a wide array of virulence factors. Bismuth-thiols (BTs) are active in vitro against all bacte- rial lung pathogens, including P. aeruginosa . The objective of these studies was to examine the biochemical and morphologic effects of sublethal BT concentrations on P. aeruginosa and to evaluate virulence in

  17. Effective disinfection methods of kitchen sponges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogenic foodborne bacteria can be disseminated in households through the use of contaminated sponges. Several household disinfecting treatments to kill bacteria, yeasts and molds on sponges were evaluated. Sponges were incubated in a suspension of ground beef and tryptic soy broth to develop bact...

  18. 214 | MARCH 2005 | VOLUME 3 www.nature.com/reviews/micro R E V I E W S

    E-print Network

    Pawlowski, Wojtek

    of replication initiation with respect to the cell-division cycle,and the mainte- nanceof NUCLEOID position are tightly controlled in bacte- ria,master cell-cycle regulators have only been identified in C.crescentus9214 | MARCH 2005 | VOLUME 3 www.nature.com/reviews/micro R E V I E W S Conceptually, cell

  19. JOURNAL OF BACTERIOLOGY, July 2005, p. 45314541 Vol. 187, No. 13 0021-9193/05/$08.00 0 doi:10.1128/JB.187.13.45314541.2005

    E-print Network

    Utrecht, Universiteit

    for the manufacture of fermented dairy products (2). The milk fermentation process is susceptible to infection of the classical type of immunoglobu- lins. A panel of p2-specific single-domain antibody fragments was obtained by bacte- riophages found in raw milk (3, 19, 32­34) or by induction of prophages from lysogenic starter

  20. Geraniol restores antibiotic activities against multidrug-resistant isolates from gram-negative species.

    PubMed

    Lorenzi, Vannina; Muselli, Alain; Bernardini, Antoine François; Berti, Liliane; Pagès, Jean-Marie; Amaral, Leonard; Bolla, Jean-Michel

    2009-05-01

    The essential oil of Helichrysum italicum significantly reduces the multidrug resistance of Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Combinations of the two most active fractions of the essential oil with each other or with phenylalanine arginine beta-naphthylamide yield synergistic activity. Geraniol, a component of one fraction, significantly increased the efficacy of beta-lactams, quinolones, and chloramphenicol. PMID:19258278

  1. Chemical Composition and Biological Activity of the Centipeda minima (Asteraceae)

    Microsoft Academic Search

    Surjani Soetardjo; Jong Poh Chan; Ahmad Mohamad Noor; Yoga Latha Lachimanan; Sasidharan Sreenivasan

    The antimicrobial activity of the Centipeda minima L. (Asteraceae) extract was evaluated against seven microorganisms using the disc diffusion method. The extract showed a broad spectrum of antimicrobial activity against all the tested bacterial strains, especially Enterobacter aerogenes, Klebsiella pneumonia, Staphylococcus aureus and Yersinia enterocolitica. The chemical composition of the extract obtained fromCentipedaminima was analysed by GC-MS. Twenty - three

  2. ESSAIS DE PRVENTION DE LA MAMMITE EXPRIMENTALE STAPHYLOCOCCUS AUREUS

    E-print Network

    Paris-Sud XI, Université de

    ESSAIS DE PRÉVENTION DE LA MAMMITE EXPÉRIMENTALE À STAPHYLOCOCCUS AUREUS PAR IMMUNISATION ET with two strains of Staphylococcus aureus was investigated 30 days after calving. These cows were intramammaires expé- rimentales à Staphylococcus aureus (Poutrel et Lerondelle, 1978) ou à Enterobacter aerogenes

  3. Early Events in the Pathogenesis of Foot-and-Mouth Disease in Cattle After Controlled Aerosol Exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this study was to identify the primary sites of replication of foot-and-mouth disease virus (FMDV) in cattle subsequent to aerogenous inoculation. A novel aerosol inoculation method was developed to simulate natural, airborne transmission and thereby allow the identification of early rep...

  4. Antibacterial Activity of Alpinia galanga (L) Willd Crude Extracts

    Microsoft Academic Search

    Kiranmayee Rao; Bhuvaneswari Ch; Lakshmi M. Narasu; Archana Giri

    2010-01-01

    Methanol, acetone and diethyl ether extracts of Alpinia galanga have been evaluated against pathogens viz. Bacillus subtilis MTCC 2391, Enterobacter aerogene, Enterobacter cloacae, Enterococcus faecalis, Escherichia coli MTCC 1563, Klebsiella pneumoniae, Pseudomonas aeruginosa MTCC 6642, Salmonella typhimurium, Staphylococcus aureus and Streptococcus epidermis using Agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of\\u000a all the extracts

  5. Invasion of Epithelial Cells by Yersinia pestis: Evidence for a Y. pestis-Specific Invasin

    Microsoft Academic Search

    CLARISSA COWAN; HEATHER A. JONES; YASEMIN H. KAYA; ROBERT D. PERRY; SUSAN C. STRALEY

    2000-01-01

    The causative agent of plague, Yersinia pestis, is regarded as being noninvasive for epithelial cells and lacks the major adhesins and invasins of its enteropathogenic relatives Yersinia enterocolitica and Yersinia pseudotu- berculosis. However, there are studies indicating that Y. pestis invades and causes systemic infection from ingestive and aerogenic routes of infection. Accordingly, we developed a gentamicin protection assay and

  6. A Simple Alternative to the IMViC Test in Microbiology.

    ERIC Educational Resources Information Center

    Benathen, Isaiah A.

    1992-01-01

    Presents a singular alternative to the Indole Methyl-red Voges-Proskauer Citrate (IMViC) test that uses bile-esculin agar to distinguish between the Escherichia coli and Enterobacter aerogenes bacteria. Includes materials and methods, results, and conclusions for the test. (MDH)

  7. Geraniol Restores Antibiotic Activities against Multidrug-Resistant Isolates from Gram-Negative Species? †

    PubMed Central

    Lorenzi, Vannina; Muselli, Alain; Bernardini, Antoine François; Berti, Liliane; Pagès, Jean-Marie; Amaral, Leonard; Bolla, Jean-Michel

    2009-01-01

    The essential oil of Helichrysum italicum significantly reduces the multidrug resistance of Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Combinations of the two most active fractions of the essential oil with each other or with phenylalanine arginine ?-naphthylamide yield synergistic activity. Geraniol, a component of one fraction, significantly increased the efficacy of ?-lactams, quinolones, and chloramphenicol. PMID:19258278

  8. Vanillin inhibits pathogenic and spoilage microorganisms in vitro and aerobic microbial growth in fresh-cut apples

    Microsoft Academic Search

    H. P. Vasantha Rupasinghe; Jeanine Boulter-Bitzer; Taehyun Ahn; Joseph A. Odumeru

    2006-01-01

    The antimicrobial effect of vanillin against four pathogenic or indicator organisms; Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, and Salmonella enterica subsp. enterica serovar Newport and four spoilage organisms; Candida albicans, Lactobacillus casei, Penicillum expansum, and Saccharomyces cerevisiae that could be associated with contaminated fresh-cut produce, was examined. The minimal inhibitory concentration (MIC) of vanillin was dependent upon the microorganism and

  9. Hydroxamate recognition during iron transport from hydroxamate-iron chelates

    Microsoft Academic Search

    A. H. Haydon; W. B. Davis; E. L. Arceneaux; B. R. Byers

    1973-01-01

    Kinetics of radioactive iron transport from three structurally different ; secondary hydroxandate-iron chelates (schizokineniron, produced by Bacillus ; megaterium ATCC 19213; Desferaliron, produced by an actinomycete; and aerobactin-; iron, produced by Aerobacter aerogenes 62-1) revealed that B. megateriurm SK 11 ; (a mutant that cannot synthesize schizokinen) has a specific transport system for ; utilization of ferric hydroxamates with a

  10. Effect of CO 2 removal on hydrogen production by fermentation

    Microsoft Academic Search

    S. Tanisho; M. Kuromoto; N. Kadokura

    1998-01-01

    The improvement of the yield of hydrogen at fermentative production using molasses as a substrate was investigated from two points of view; i.e. firstly, through the control of production pathway and secondly, by the condition of nutrient source for growing. It was shown that succinate, one of the products of Enterobacter aerogenes strain E.82005, was produced inductively by accumulation of

  11. Antibacterial potentiality and phytochemical analysis of mature leaves of Polyalthia longifolia (Magnoliales: Annonaceae)

    Microsoft Academic Search

    Anupam Ghosh; Bidus Kanti Das; Soroj Kumar Chatterjee; Goutam Chandra

    2008-01-01

    The present study evaluated the antibacterial potentiality of hot aqueous and methanol solvent extract of mature leaves of Polyalthia longifolia (Sonn.) Thwaites (Magnoliales: Annonaceae) against six reference bacteria viz. Staphylococcus aureus MTCC 2940, Bacillus subtilis MTCC 441, Escherichia coli MTCC 739, Klebsiella pneumoniae MTCC 530, Proteus vulgaris MTCC 426 and Enterobacter aerogenes MTCC 111. A sensitivity test performed with commercially

  12. IN VITRO ANTIBACTERIAL ACTIVITY OF CLOVE AGAINST GRAM NEGATIVE BACTERIA

    Microsoft Academic Search

    SABAHAT SAEED; PERWEEN TARIQ

    A study was carried out to investigate the potential of using aqueous infusion, decoction and essential oil of clove (Syzygium aromaticum) as natural antibacterial agents against 100 isolates belonging to 10 different species of Gram -ve bacilli viz., Escherichia coli (36), Proteus mirabilis (6), Pseudomonas aeruginosa (10), Enterobacter aerogenes (5), Klebsiella ozaenae (2), Klebsiella pneumoniae (24), Serratia marcescens (4), Salmonella

  13. DOI: 10.1126/science.272.5268.1665 , 1665 (1996);272Science

    E-print Network

    Ballard, Dana H.

    1996-01-01

    by mutagene- sis of a GAL 1 -containing plasmid with hydroxy- lamine. Regulatory-deficient mutant plasmids, 2% lactate, and 2% galactose. The wild-type gene resulted in blue colonies because the K. lactis a

  14. Le Lait (1982), 62, 681-687 Inhibition de quelques bactries pathognes

    E-print Network

    Boyer, Edmond

    1982-01-01

    pathogènes par streptococcus lactis, streptococcus thermophilus, lactobacillus acidophilus et lactobacillus et Lactobacillus acidophilus inhibent plus ou moins cer- taines bactéries pathogènes et helveticus semble produire une substance inhibitrice moins efficace que celle de Lactobacillus acidophilus

  15. MMOIRES ORIGINAUX Effet stimulant de la microflore lactique sur l'activit

    E-print Network

    Boyer, Edmond

    'influence inhibitrice des souches de Lbc. lactis, Lbc. helveticus et Lbc. acidophilus sur les bactéries pro- pioniques Lactobacillus - étaient actives, le niveau de la vitamine Bu dimi- nuait considérablement [1, 5]. Karlin [6

  16. Le Lait, 1986, 66 (4), 431-443 The esterolytic and lipolytic activities of the Lactobacilli

    E-print Network

    Boyer, Edmond

    . Detection of the este rase system of Lactobacillus helveticus, Lactobacillus bulgaricus, Lactobacillus lactis and Lactobacillus acidophilus M. EL SODA*, Howaida ABD EL WAHAB*, Nihal EZZAT*, M.J. DESMAZEAUD - Physiological age - Thermobacte- rium - Lactobacilli - Lactobacillus helveticus - Lactobacillus bulgaricus

  17. 160 LE LAIT / MARS-AVRIL 1969 / N" 483-484 Influence de la conglation

    E-print Network

    Paris-Sud XI, Université de

    : - Lactobacillus bulgaricus, - Streptococcus therrnophilus. Nous étudions également la survie et la viabilité des des ferments lactiques (Streptococcus thermophilus et Lactobacillus bulgaricus) dans le yaourt. #12: - Streptococcus lactis, - Lactobacillus acidophilus, - Lactobacillus helveticus. PROTOCOLE D'ESSAI Première partie

  18. Dairy Sci. Technol. 89 (2009) 3141 Available online at: c INRA, EDP Sciences, 2008 www.dairy-journal.org

    E-print Network

    Paris-Sud XI, Université de

    2009-01-01

    Lactobacillus cultures or with various amounts of plasmin added. Marked differences in stretchability were observed among the Lactobacillus cultures. Lactobacillus helveti- cus strains yielded higher stretchability than Lactobacillus delbrueckii subsp. lactis strains and than mixed cultures of both species. Plasmin

  19. Study to investigate the potential of probiotics in children attending school

    Microsoft Academic Search

    D Merenstein; J Gonzalez; A G Young; R F Roberts; M E Sanders; S Petterson

    2011-01-01

    Background\\/Objectives:To determine if consumption of yogurt containing a high dose of probiotic (1 × 1010 colony-forming unit per 100 ml), Bifidobacterium animalis subsp. lactis (B. lactis), decreases absences in children 2–4 years attending daycare\\/school centers.Subjects\\/Methods:We conducted a double-blinded, randomized, placebo-controlled, allocation concealment clinical trial in the Washington, DC area. Our active intervention was a strawberry yogurt-based drink supplemented with B.

  20. Lactic acid bacteria and yeasts in kefir grains and kefir made from them

    Microsoft Academic Search

    E Simova; D Beshkova; A Angelov; Ts Hristozova; G Frengova; Z Spasov

    2002-01-01

      In an investigation of the changes in the microflora along the pathway: kefir grains (A)?kefir made from kefir grains (B)?kefir\\u000a made from kefir as inoculum (C), the following species of lactic acid bacteria (83–90%) of the microbial count in the grains)\\u000a were identified: Lactococcus lactis subsp. lactis, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lactobacillus casei subsp. pseudoplantarum and