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1

Nitrate reduction in Aerobacter aerogenes  

Microsoft Academic Search

Mutants of Aerobacter aerogenes have been isolated, which are blocked in nitrate assimilation or which are resistant against chlorate. Chlorate resistance was always determined in the presence of cysteine, as it was found that chlorate interfered with the biosynthesis of this amino acid. All chlorate resistant mutants have lost the possibility to reduce chlorate, indicating that its reduction products are

A. H. Stouthamer

1967-01-01

2

Motility Testing of Bact. coli O Group III Strains  

Microsoft Academic Search

Hilton and Taylor1 obtained highly motile cultures of Bact. coli D 433 and of four other Bact. coli O group 111 strains by repeated subculture in nutrient broth and semi-solid agar and incubation at 22° C.; the period of passage required for this change was three to four weeks in semi-solid agar and slightly longer in broth. In this Laboratory,

Joyce Wright

1951-01-01

3

Succinoxidase System in Aerobacter aerogenes1  

Microsoft Academic Search

Previous studies conducted in this laboratory indicated that diethyl­ stilbestrol inhibits the succinoxidase system of Aerobacter aerogenes (Dur­ ham and Perry, 19:>7). Results obtained from manometric experiments showed that stilbestrol inhibited the rate of succinate oxidation by intact cells of A. aerogenes. Dehydrogenase assays employing cell-free extracts were performed by conventional Thunberg procedures. Results from these experiments indicated that stilbestrol

MARGIE D. PERRY; NORMAN N. DURHAM

4

[Microbiology method validation: illustration with Bact'Alert 3D].  

PubMed

As far as laboratories accreditation according to ISO 15189 is concerned, validation of each method used has to be achieved. Manufacturer's recommendations are not always helpful in this context. That's why each laboratory must proceed systematically to a logical risk analysis. Few publications are available on this subject concerning microbiology. We propose to illustrate it with the example of a blood culture automate: the Bact'Alert 3D commercialised by Biomérieux(®). PMID:23747676

Védy, Serge

5

Differentiation of Enterobacter aerogenes from Klebsiellae by Deoxyribonucleic Acid Reassociation  

Microsoft Academic Search

Polynucleotide sequence relatedness tests were carried out to determine the extent of deoxyribonucleic acid (DNA) divergence among species of Klebsiella and Enterobacter aerogenes strains. Labeled, denatured DNA fragments from K. pneumoniae type 2 and E. aerogenes 1627-66 were each incubated with an excess of unlabeled DNA fragments from Klebsielia species and strains of E. aerogenes. Reassociated DNA duplexes were separated

DON J. BRENNER; A. G. STEIGERWALT; G. R. FANNING

1972-01-01

6

Dechlorination of DDT by Aerobacter aerogenes  

Microsoft Academic Search

Dechlorination of DDT to DDD in higher animals requires the presence of molecular oxygen, but in microorganisms the presence of oxygen hinders dechlorination. In cell-free preparations of Aerobacter aerogenes, the use of selected metabolic inhibitors indicated that reduced Fe(II) cytochrome oxidase was responsible for DDT dechlorination. This finding may possibly explain the persistence of DDT residues in soils and sediments.

Gary Wedemeyer

1966-01-01

7

Metabolism of Histidine by Peptococcus Aerogenes.  

National Technical Information Service (NTIS)

Peptococcus aerogenes ferments histidine-alpha-14C to acetic, butyric, and formic acids. The distribution of carbon-14 in acetic and butyric acids was consistent with that expected if the urocanic acid pathway was used for the metabolism of histidine. Rad...

W. B. McConnell D. F. Horler D. W. S. Westlake

1966-01-01

8

Cloning, Sequencing, and Expression of the Pyruvate Carboxylase Gene in Lactococcus lactis subsp. lactis C2†  

PubMed Central

A functional pyc gene was isolated from Lactococcus lactis subsp. lactis C2 and was found to complement a Pyc defect in L. lactis KB4. The deduced lactococcal Pyc protein was highly homologous to Pyc sequences of other bacteria. The pyc gene was also detected in Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis bv. diacetylactis strains.

Wang, H.; O'Sullivan, D. J.; Baldwin, K. A.; McKay, L. L.

2000-01-01

9

mar Operon Involved in Multidrug Resistance of Enterobacter aerogenes  

Microsoft Academic Search

We determined the sequence of the entire marRAB operon in Enterobacter aerogenes. It is functionally and structurally analogous to the Escherichia coli operon. The overexpression of E. aerogenes MarA induces a multidrug resistance phenotype in a susceptible strain, demonstrated by a noticeable resistance to various antibiotics, a decrease in immunodetected porins, and active efflux of norfloxacin.

Renaud Chollet; Claude Bollet; Jacqueline Chevalier; M. Mallea; J.-M. Pages; Anne Davin-Regli

2002-01-01

10

Complete genome sequence of Enterobacter aerogenes KCTC 2190.  

PubMed

This is the first complete genome sequence of the Enterobacter aerogenes species. Here we present the genome sequence of E. aerogenes KCTC 2190, which contains 5,280,350 bp with a G + C content of 54.8 mol%, 4,912 protein-coding genes, and 109 structural RNAs. PMID:22493190

Shin, Sang Heum; Kim, Sewhan; Kim, Jae Young; Lee, Soojin; Um, Youngsoon; Oh, Min-Kyu; Kim, Young-Rok; Lee, Jinwon; Yang, Kap-Seok

2012-05-01

11

Methyl Sulfide Production by Aerobacter aerogenes in Milk1  

Microsoft Academic Search

Aerobacter aerogenes was isolated as the causative organism in samples of commercial milk having defects described as cowy or reedy, or both. The fact that aqueous solutions of trace amounts of methyl sulfide (Me2S) give similar flavors led to a study of its production by A. aerogenes in milk. Inoculation of the organ- ism into vacuum heat-treated, homogenized milk was

Tran T. Toan; R. Bassette; T. J. Claydon

1965-01-01

12

Gene transfer between Escherichia coli and Enterobacter aerogenes  

Microsoft Academic Search

Transfer of chromosomal genes between Escherichia coli K12 and Enterobacter aerogenes was carried out by P1-mediated transduction as well as by transformation of genes cloned in vitro on plasmid vectors. The efficient expression of E. coli genes in E. aerogenes probably reflects the existance of a poor restriction system in the latter, and suggests that this strain might be useful

Shulamit Michaeli; Eliora Z. Ron

1983-01-01

13

Complete Genome Sequence of Enterobacter aerogenes KCTC 2190  

PubMed Central

This is the first complete genome sequence of the Enterobacter aerogenes species. Here we present the genome sequence of E. aerogenes KCTC 2190, which contains 5,280,350 bp with a G + C content of 54.8 mol%, 4,912 protein-coding genes, and 109 structural RNAs.

Shin, Sang Heum; Kim, Sewhan; Kim, Jae Young; Lee, Soojin; Um, Youngsoon; Oh, Min-Kyu; Kim, Young-Rok; Lee, Jinwon

2012-01-01

14

Bronchial carcinoid with multiple aerogenous implanted foci.  

PubMed

A case of bronchial carcinoid with intrapulmonary dissemination was demonstrated. A right upper lobectomy was performed because of an abnormal shadow in the lung detected by an X-ray mass survey. A carcinoid tumor originated from the spur region of the right upper lobe bronchus. The tumor protruded into the bronchial lumen and also extensively expanded into the surrounding alveolar tissue. The tumor showed typical histological features of bronchial carcinoid with a mixed insular, trabecular, and glandular pattern. Multiple implanted foci of tumor cells were found in the periphery of the lobe. The implanted tumor cells replaced the alveolar epithelium without destruction of the alveolar structure, which suggests the possibility of aergenous spread of bronchial carcinoid. This is the first report on bronchial carcinoid with aerogenous spread. PMID:2434804

Suzuki, K; Kimula, Y; Ogata, T; Nakagawa, H

1987-03-01

15

Metabolism of Gentiobiose in Aerobacter aerogenes  

PubMed Central

Cleavage of gentiobiose in cell extracts of gentiobiose-grown Aerobacter aerogenes was dependent on the presence of adenosine 5?-triphosphate (ATP). The enzymes that participate in the overall reaction were shown to be a ?-glucoside kinase, which catalyzes the phosphorylation of gentiobiose with ATP to form gentiobiose monophosphate [6-O-phosphoryl-?-d-glucopyranosyl-(1 ? 6)-d-glucose], and a phospho-?-glucosidase, which catalyzes the hydrolytic cleavage of gentiobiose monophosphate to form equimolar amounts of d-glucose and d-glucose 6-phosphate. Although the ?-glucoside kinase was previously shown to catalyze the phosphorylation of many ?-glucosides that serve as growth substrates (i.e., gentiobiose, cellobiose, cellobiitol, salicin, arbutin, methyl ?-d-glucoside, and phenyl ?-d-glucoside), mutant analysis and induction studies indicate that it functions only in the metabolism of gentiobiose, cellobiose, and cellobiitol.

Palmer, Richard E.; Anderson, Richard L.

1972-01-01

16

BACT\\/LAER Clearinghouse: A compilation of control-technology determinations. Volume 1. Report summary and appendices AG. Final report  

Microsoft Academic Search

The Clean Air Act as amended in 1977 prescribes several technology-based limitations affecting new or modified air pollution sources: (1) new source performance standards (NSPS); (2) best available control technology (BACT); and (3) lowest achievable emission rate (LAER). The basic purposes of the BACT\\/LAER Clearinghouse are to: (1) provide State and local air pollution control agencies with current information on

Steigerwald

1990-01-01

17

D-apiose reductase from Aerobacter aerogenes.  

PubMed

A strain of Aerobacter aerogenes PRL-R3 has been isolated which utilizes d-apiose as its sole source of carbon. A new enzyme, d-apiose reductase, was discovered in this strain. The enzyme was not present when the strain was grown on d-glucose. d-Apiose reductase catalyzes the nicotinamide adenine dinucleotide-dependent interconversion of d-apiose and d-apiitol. The enzyme is specific for d-apiose and d-apiitol, with a few possible exceptions. The K(m) for d-apiose is 0.02 m. The K(m) for d-apiitol is 0.01 m. The enzyme is almost completely specific for the reduced and oxidized forms of nicotinamide adenine dinucleotide. When cell-free extracts were centrifuged at 100,000 x g for 1 hr, the enzyme remained in solution. Optimal activity for the reduction of d-apiose was obtained at pH 7.5 in glycylglycine buffer, whereas for the oxidation of d-apiitol it was obtained at pH 10.5 in glycine buffer. Enzymatic reduction of d-apiose was not appreciably affected by the presence of 0.02 m ethylenediaminetetraacetate. Paper chromatography and specific spray reagents were used to identify d-apiitol and d-apiose as the products of this reversible reaction. d-Apiose and d-apiitol did not serve as substrates for ribitol dehydrogenase and d-arabitol dehydrogenase from A. aerogenes PRL-R3. PMID:4314545

Neal, D L; Kindel, P K

1970-03-01

18

Effects of Formate on Fermentative Hydrogen Production by Enterobacter aerogenes  

Microsoft Academic Search

This paper describes the effects of formate on fermentative hydrogen production by Enterobacter aerogenes by way of batch culture. When 20 mM formate was added to pH 6.3 and pH 5.8 E. aerogenes glucose cultures (formate culture) at the beginning of cultivation, hydrogen evolution through both glucose consumption and decomposition of the extrinsic formate occurred together, while hydrogen evolution occurred

Tatsuo Kurokawa; Shigeharu Tanisho

2005-01-01

19

Utilization of arginine by Klebsiella aerogenes.  

PubMed

Klebsiella aerogenes utilized arginine as the sole source of carbon or nitrogen for growth. Arginine was degraded to 2-ketoglutarate and not to succinate, since a citrate synthaseless mutant grows on arginine as the only nitrogen source. When glucose was the energy source, all four nitrogen atoms of arginine were utilized. Three of them apparently did not pass through ammonia but were transferred by transamination, since a mutant unable to produce glutamate by glutamate synthase or glutamate dehydrogenase utilized three of four nitrogen atoms of arginine. Urea was not involved as intermediate, since a unreaseless mutant did not accumulate urea and grew on arginine as efficiently as the wild-type strain. Ornithine appeared to be an intermediate, because cells grown either on glucose and arginine or arginine alone could convert arginine in the presence of hydroxylamine to ornithine. This indicates that an amidinotransferase is the initiating enzyme of arginine breakdown. In addition, the cells contained a transaminase specific for ornithine. In contrast to the hydroxylamine-dependent reaction, this activity could be demonstrated in extracts. The arginine-utilizing system (aut) is apparently controlled like the enzymes responsible for the degradation of histidine (hut) through induction, catabolite repression, and activation by glutamine synthetase. PMID:342501

Friedrich, B; Magasanik, B

1978-02-01

20

TEM Derivative-Producing Enterobacter aerogenes Strains: Dissemination of a Prevalent Clone  

Microsoft Academic Search

TEM-24 (CAZ-6) extended-spectrum -lactamase (ESBL) was detected in 1988 in Clermont-Ferrand, France, in Klebsiella pneumoniae (blaTEM-24) and Enterobacter aerogenes (blaTEM-24b), and since 1994, a TEM- 24-producing E. aerogenes clonal strain has been observed elsewhere in the country. To determine if the spread of this clonal strain was restricted to TEM-24-producing E. aerogenes strains, 84 E. aerogenes strains (non- TEM\\/SHV-producing strains,

P. Dumarche; C. De Champs; D. Sirot; C. Chanal; R. Bonnet; J. Sirot

2002-01-01

21

Genome plasticity in Lactococcus lactis  

Microsoft Academic Search

Comparative genome analyses contribute significantly to our understanding of bacterial evolution and indicate that bacterial genomes are constantly evolving structures. The gene content and organisation of chromosomes of lactic acid bacteria probably result from a strong evolutionary pressure toward optimal growth of these microorganisms in milk. The genome plasticity of Lactococcus lactis was evaluated at inter- and intrasubspecies levels by

Nathalie Campo; Miguel J. Dias; Marie-Line Daveran-Mingot; Paul Ritzenthaler; Pascal Le Bourgeois

2002-01-01

22

Single-cell protein from methanol with Enterobacter aerogenes  

SciTech Connect

An identified Enterobacter aerogenes utilizing methanol as a sole carbon source was studied for the optimization of biomass production and the reduction of its nucleic acid content. Results indicated that the highest yield and conversion were obtained at 0.5% methanol. The addition of seawater as a source of trace elements has an adverse effect. However, the addition of urea as source of nitrogen enhanced the growth of E. aerogenes. Heat shock at 60 degrees C for one minute followed by incubation at 50 degrees C for 2 hours caused 72.6% reduction in the nucleic acid. 12 references.

Gnan, S.O.; Abodreheba, A.O.

1987-02-20

23

The Citrate Transport System of Lactococcus lactis subsp. lactis biovar diacetylactis Is Induced by Acid Stress  

Microsoft Academic Search

Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrate permease P (CitP), which is encoded by the plasmidic citP gene. We have shown previously that citP is included in the citQRP operon, which is mainly transcribed from the P1 promoter in L. lactis subsp. lactis biovar diacetylactis. Furthermore, transcription of citQRP and citrate transport are not

NIEVES GARCIA-QUINTANS; CHRISTIAN MAGNI; DIEGO DE MENDOZA; PALOMA LOPEZ

1998-01-01

24

Diacetyl production by different strains of Lactococcus lactis subsp. lactis var. diacetylactis and Leuconostoc spp  

Microsoft Academic Search

Several strains of Lactococcus lactis subsp. lactis var. diacetylactis and Leuconostoc spp. were compared for product formation from citrate in milk cultures. Most strains produced acetoin and butanediol. Some strains derived from buffer starter cultures produced, in addition, a-acetolactate. Lactococcus lactis strain C17, which produced acetoin and butanediol but no a-acetolactate in culture, was compared physiologically with L. lactis strain

Jeroen Hugenholtz; Marjo J. C. Starrenburg

1992-01-01

25

Inhibitors of antibiotic efflux pump in resistant Enterobacter aerogenes strains  

Microsoft Academic Search

Enterobacter aerogenes, a nosocomial pathogen, is frequently exhibiting multidrug resistance mechanisms associated with a change in membrane permeability. In clinical isolates, active efflux plays a prominent role in antibiotic resistance. We report here the effect of three unrelated compounds that are able to restore a noticeable antibiotic susceptibility to resistant strains. The targeting of various parameters which contribute to the

Monique Malléa; Jacqueline Chevalier; Annie Eyraud; Jean-Marie Pagès

2002-01-01

26

Chloramphenicol and expression of multidrug efflux pump in Enterobacter aerogenes  

Microsoft Academic Search

Chloramphenicol has been reported to act as an inducer of the multidrug resistance in Escherichia coli. A resistant variant able to grow on plates containing 64?g\\/ml chloramphenicol was obtained from the Enterobacter aerogenes ATCC 13048-type strain. Chloramphenicol resistance was due to an active efflux of this antibiotic and it was associated with resistance to fluoroquinolones and tetracycline, but not to

Didier Ghisalberti; Muriel Masi; Jean-Marie Pagès; Jacqueline Chevalier

2005-01-01

27

Imipenem and expression of multidrug efflux pump in Enterobacter aerogenes  

Microsoft Academic Search

Imipenem is often used to treat intensive care unit patients infected by Enterobacter aerogenes, but it is leading to an increasing number of antibiotic resistant strains. Clinical isolates and imipenem resistant variants presented a high level of resistance to ?-lactam antibiotic group and to chemically unrelated drugs. We report here that imipenem selects strains which contain active efflux pumps ejecting

Charléric Bornet; Renaud Chollet; Monique Malléa; Jacqueline Chevalier; Anne Davin-Regli; Jean-Marie Pagès; Claude Bollet

2003-01-01

28

Carbapenem Resistance in Enterobacter aerogenes is due to Lipopolysaccharide Alterations  

Microsoft Academic Search

The extensive characterization of 2 clinical Enterobacter aerogenes isolates resistant to all ?-lactam antibiotics including imipenem revealed that imipenem resistance could not be attributed to overproduction of the chromosomal ?-lactamase; moreover, it was lost after subcultivation and can be thus considered as unstable. The comparison of sensitive and resistant clones revealed that the ?-lactamase in the resistant clones was less

Hermann Leying; Wolfgang Cullmann; Wolfgang Dick

1991-01-01

29

Effects of Nitrogen Supplements on Nitrogen Fixation by Aerobacter Aerogenes.  

National Technical Information Service (NTIS)

The effects of limiting concentrations of NH4(+) and amino acids on nitrogen fixation by Aerobacter aerogenes have been compared. The organism exhibited typical diphasic growth during the fixation of nitrogen in the presence of NH4(+), whereas in the pres...

R. B. Patil R. M. Pengra D. C. Yoch

1966-01-01

30

Energy Production During Nitrate Respiration by Aerobacter aerogenes  

Microsoft Academic Search

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

LIGERI P. HADJIPETROU; A. H. STOUTHAMER

1965-01-01

31

Magnesium-limited growth of Aerobacter aerogenes in a chemostat  

Microsoft Academic Search

SUMMARY The influence of Mg2+-lirnitationy compared with carbon-limitation, on bacterial concentration, and on protein, carbohydrate, RNA and DNA contents of Aerobacter aerogenes cultures (grown in the chemostat at several dilution rates) was determined. In both types of culture the bacterial protein, carbohydrate and DNA contents varied slightly, and the RNA content grossly, with changes in dilution rate. Bacterial yield varied

D. W. TEMPEST; J. R. HUNTER; J. SYKES

1965-01-01

32

The functional significance of glucose dehydrogenase in Klebsiella aerogenes  

Microsoft Academic Search

In order to assess the functional significance of the quinoprotein glucose dehydrogenase recently found to be present in K+-limited Klebsiella aerogenes, a broad study was made of the influence of specific environmental conditions on the cellular content of this enzyme. Whereas high activities were manifest in cells from glucose containing chemostat cultures that were either potassium- or phosphate-limited, only low

R. W. J. Hommes; B. van Hell; P. W. Postma; O. M. Neijssel; D. W. Tempest

1985-01-01

33

Movement and retention of Klebsiella aerogenes in soil columns  

Microsoft Academic Search

The movement and retention of two strains of Klebsiella aerogenes into saturated soil columns was found to depend on soil type, pH, and bacterial size. The movement of the cells was considered as a specific case of gel permeantion chromatography. The infiltration of the bacterial cells into dry soil columns was affected by soil type, and their upward movement was

Gabriel Bitton; N. Lahav; Y. Henis

1974-01-01

34

Abortion of a sow caused by Pasteurella aerogenes.  

PubMed

Three strains of the Pasteurella aerogenes complex were isolated as sole pathogens from aborted fetuses of a sow aborted at the 12th week of gestation on a farm of 600 sows. Gross pathology showed no characteristic lesions. The isolates were biochemically identical and resembled P. pneumotropica on the basis of their strong indole and urease positivity but they produced gas, were ornithine decarboxylase negative and fermented mannitol but not trehalose. Only a few differences were apparent in biochemical characteristics between the isolated strains and P. aerogenes. They differed from the type strain of P. aerogenes in ornithine decarboxylase activity, indole production and lactose and mannitol fermentation; however, such strains do occur within this heterogeneous species. At the time of abortion the antibody titre of the aborted sow was 1 in 16 when examined with live bacterial suspension and 1 in 128 if boiled antigen was used. Similar strains could not be isolated from the vaginas of aborted sows or pregnant and newly farrowed sows in the same group. The bacteriological, serological and histological findings support the opinion of other workers on the occasional pathogenic nature of P. aerogenes. PMID:1750360

Fodor, L; Hajtós, I; Glávits, R

1991-01-01

35

Functionality of Sortase A in Lactococcus lactis?  

PubMed Central

Lactococcus lactis IL1403 harbors a putative sortase A (SrtA) and 11 putative sortase substrates that carry the canonical LPXTG signature of such substrates. We report here on the functionality of SrtA to anchor five LPXTG substrates to the cell wall, thus suggesting that SrtA is the housekeeping sortase in L. lactis IL1403.

Dieye, Yakhya; Oxaran, Virginie; Ledue-Clier, Florence; Alkhalaf, Walid; Buist, Girbe; Juillard, Vincent; Lee, Chang Won; Piard, Jean-Christophe

2010-01-01

36

Physiological Role of  Phosphoglucomutase in Lactococcus lactis  

Microsoft Academic Search

A -phosphoglucomutase (-PGM) mutant of Lactococcus lactis subsp. lactis ATCC 19435 was constructed using a minimal integration vector and double-crossover recombination. The mutant and the wild-type strain were grown under controlled conditions with different sugars to elucidate the role of -PGM in carbohydrate catabolism and anabolism. The mutation did not significantly affect growth, product formation, or cell com- position when

FREDRIK LEVANDER; ULRIKA ANDERSSON; P. Radstrom

2001-01-01

37

Thermodynamic study and optimization of hydrogen production by Enterobacter aerogenes  

Microsoft Academic Search

This paper investigates the influence of pH and temperature on hydrogen bioproduction by Enterobacter aerogenes (NCIMB 10102) utilizing starch hydrolysate as substrate. An optimum pH range corresponding to 6.1–6.6 is the main evidence of batch runs carried out at different pHs. An optimum value of temperature corresponding to 40°C is experimentally determined by means of batch fermentation runs carried out

B. Fabiano; P. Perego

2002-01-01

38

Glutamate Biosynthesis in Lactococcus lactis subsp. lactis NCDO 2118  

PubMed Central

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 ?-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 ?-ketoglutarate. The metabolic bottleneck responsible for the limited growth rate was located in this latter pathway. As regards the synthesis of glutamate from ?-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 ?-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.

Lapujade, P.; Cocaign-Bousquet, M.; Loubiere, P.

1998-01-01

39

Molecular Analysis of Tetracycline Resistance in Pasteurella aerogenes  

PubMed Central

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.

Kehrenberg, Corinna; Schwarz, Stefan

2001-01-01

40

Characterization of arylamine N-acetyltransferase in Enterobacter aerogenes.  

PubMed

N-acetyltransferase (NAT) activity was determined by incubation of purified Enterobacter aerogenes enzyme with 2-aminofluorene (2-AF) as the substrate, followed by high pressure liquid chromatography assays. The NAT activity from E. aerogenes was 0.58 +/- 0.08 nmol/min/mg protein for 2-AF. The values of apparent K(m) and Vmax were 0.72 +/- 0.14 mM and 2.45 +/- 0.29 nmol/min/mg protein, respectively, for 2-AF. The optimal pH value for the enzyme activity was 7.5 for the 2-AF tested. The optimal temperature for enzyme activity was 37 degrees C for the 2-AF substrate. The molecular weight of NAT from E. aerogenes was 44.9 kD. Among a series of divalent cations and salts, Zn2+, Ca2+, and Fe2+ were demonstrated to be the most potent protease inhibitors, and only ethylenediaminetetraacetic acid significantly protected the NAT. Iodoacetamide, in contrast to other agents, markedly inhibited NAT. PMID:9853378

Tsou, M F; Chung, J G; Wu, L T; Cheng, K S; Hung, C F

1998-01-01

41

BACT\\/LAER Clearinghouse: A compilation of control-technology determinations. Volume 3. Appendix H, source codes 4 to 6. Final report  

Microsoft Academic Search

The Clean Air Act as amended in 1977 prescribes several technology-based limitations affecting new or modified air pollution sources: (1) new source performance standards (NSPS); (2) best available control technology (BACT); and (3) lowest achievable emission rate (LAER). The basic purposes of the BACT\\/LAER Clearinghouse are to: (1) provide State and local air pollution control agencies with current information on

Speigerwald

1990-01-01

42

BACT\\/LAERR Clearinghouse: A compilation of control-technology determinations. Volume 4. Appendix H, source codes 7 to 12. Final report  

Microsoft Academic Search

The Clean Air Act as amended in 1977 prescribes several technology-based limitations affecting new or modified air pollution sources: (1) new source performance standards (NSPS); (2) best available control technology (BACT); and (3) lowest achievable emission rate (LAER). The basic purposes of the BACT\\/LAER Clearinghouse are to: (1) provide State and local air pollution control agencies with current information on

Steigerwald

1990-01-01

43

BACT\\/LAER Clearinghouse: A compilation of control-technology determinations. Volume 2. Appendix H, source codes 1-3. Final report  

Microsoft Academic Search

The Clean Air Act as amended in 1977 prescribes several technology-based limitations affecting new or modified air pollution sources: (1) new source performance standards (NSPS); (2) best available control technology (BACT); and (3) lowest achievable emission rate (LAER). The basic purposes of the BACT\\/LAER Clearinghouse are to: (1) provide State and local air pollution control agencies with current information on

Steigerwald

1990-01-01

44

Thermosensitive plasmid replication, temperature-sensitive host growth, and chromosomal plasmid integration conferred by Lactococcus lactis subsp. cremoris lactose plasmids in Lactococcus lactis subsp. lactis.  

PubMed Central

Evidence is presented that lactose-fermenting ability (Lac+) in Lactococcus lactis subsp. cremoris AM1, SK11, and ML1 is associated with plasmid DNA, even though these strains are difficult to cure of Lac plasmids. When the Lac plasmids from these strains were introduced into L. lactis subsp. lactis LM0230, they appeared to replicate in a thermosensitive manner; inheritance of the plasmid was less efficient at 32 to 40 degrees C than at 22 degrees C. The stability of the L. lactis subsp. cremoris Lac plasmids in lactococci appeared to be a combination of both host and plasmid functions. Stabilized variants were isolated by growing the cultures at 32 to 40 degrees C; these variants contained the Lac plasmids integrated into the L. lactis subsp. lactis LM0230 chromosome. In addition, the presence of the L. lactis subsp. cremoris Lac plasmids in L. lactis subsp. lactis resulted in a temperature-sensitive growth response; growth of L. lactis subsp. lactis transformants was significantly inhibited at 38 to 40 degrees C, thereby resembling some L. lactis subsp. cremoris strains with respect to temperature sensitivity of growth. Images

Feirtag, J M; Petzel, J P; Pasalodos, E; Baldwin, K A; McKay, L L

1991-01-01

45

Hyaluronic acid production by recombinant Lactococcus lactis  

Microsoft Academic Search

Microbial hyaluronic acid (HA), commonly produced by pathogenic Streptococcus, was made possible to be produced by a generally recognized as safe Lactococcus lactis by coexpressing HA synthase and uridine diphosphate–glucose dehydrogenase (UDP-GlcDH) of Streptococcus equi subsp. zooepidemicus in a nisin-controlled expression (NICE) system. With scarce expressed HA synthase alone, the constructed recombinant L. lactis (LL-NA) strain could produce HA with

Liang-Jung Chien; Cheng-Kang Lee

2007-01-01

46

Bact. Vaginosis  

Center for Biologics Evaluation and Research (CBER)

Text Version... Chlamydia trachomatis, N. gonorrhoeae, Candida albicans, and ... wet mount is negative for clue cells ! ... show minimal systemic absorption (based on ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

47

Molecular Epidemiological Study of Nosocomial Enterobacter aerogenes Isolates in a Belgian Hospital  

Microsoft Academic Search

In 1995, the rate of isolation of Enterobacter aerogenes in the Saint-Pierre University Hospital in Brussels, Belgium, was higher than that in the preceding years. A total of 45 nosocomial E. aerogenes strains were collected from 33 patients of different units during that year, and they were isolated from 19 respiratory specimens, 13 pus specimens, 7 blood specimens, 4 urinary

SHEIKH JALALUDDIN; JEANNE-MARIE DEVASTER; ROBERT SCHEEN; MICHELE GERARD; JEAN-PAUL BUTZLER

1998-01-01

48

Regulation of hydrogen production by Enterobacter aerogenes by external NADH and NAD +  

Microsoft Academic Search

Experiments involving the addition of external nicotinamide adenine dinucleotide, reduced form (NADH) or nicotinamide adenine dinucleotide (NAD+) have been designed to examine how the hydrogen in Enterobacter aerogenes is liberated by NADH or NAD+. The addition of external NADH or NAD+ was found to regulate hydrogen production by E. aerogenes in resting cells, batch cultures, and chemostat cultures. Particularly in chemostat

Chong Zhang; Kun Ma; Xin-Hui Xing

2009-01-01

49

Extended-Spectrum ?-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena  

Microsoft Academic Search

BACKGROUND: Enterobacter aerogenes and Klebsiella pneumoniae are common isolates in clinical microbiology and important as producers of extended spectrum ?-lactamases (ESBL). The discrimination between both species, which is routinely based on biochemical characteristics, is generally accepted to be straightforward. Here we report that genotypically unrelated strains of E. aerogenes can be misidentified as K. pneumoniae by routine laboratories using standard

Geert Claeys; Thierry De Baere; Georges Wauters; Patricia Vandecandelaere; Gerda Verschraegen; An Muylaert; Mario Vaneechoutte

2004-01-01

50

Characteristics of the melibiose transporter and its primary structure in Enterobacter aerogenes  

Microsoft Academic Search

Cells of Enterobacter aerogenes can grow on melibiose as a sole source of carbon. This suggests the presence of melibiose operon in this organism. We found that E. aerogenes cells possess both ?-galactosidase activity and melibiose transport activity, which were induced by melibiose. Neither Na+ nor Li+ stimulated the melibiose transport. However, transport of methyl-?-thiogalactoside (TMG) was stimulated by Li+

Noriko Okazaki; Masayuki Kuroda; Toshi Shimamoto; Tadashi Shimamoto; Tomofusa Tsuchiya

1997-01-01

51

[Detection among "E. aerogenes" strains of capsular antigens related to those of "klebsiella". Interest of growth in metahydroxybenzoate to differenciate "E. aerogenes" and "K. pneumoniae" (author's transl)].  

PubMed

Forty-three strains of E. aerogenes isolated chiefly in Morocco and France have been studied. Thirty-five strains (81%) are surrounded with a thin capsule, antigenically related to Klebsiella capsular antigens: K4 (2 strains), K4, 59 (1 strain), K11 (2 strains), K26 (7 strains), K42 (5 strains), K59 (3 strains), K68 (14 strains). One strain is capsulated but not typable with Klebsiella capsular antisera. E. aerogenes and Klebsiella capsular antigens are not identical but share common fractions yielding cross reactions. To differenciate E. aerogenes from K. pneumoniae in addition with the three major characters, i.e. motility, ornithine-decarboxylase and urease, the author points out the value of growth in metahydroxybenzoate as sole source of carbon and energy (positive test with E. aerogenes and negative with K. pneumoniae). PMID:72514

Richard, C

1977-04-01

52

Kinetic Behaviour of Lactococcus lactis ssp. lactis bv. diacetylactis Immobilized in Calcium Alginate Gel Beads  

Microsoft Academic Search

Alginate beads with entrapped Lactococcus lactis spp. lactis bv. diacetylactis were used as biocatalysts in continuous fermentation and the dynamics of the system analysed. Colonization by cells changed during fermentation, concentrating at the periphery (where cell densities reach 350 g litre?1). In the steady state, colonization of the gel was interrupted while growth continued, producing cells that were released into

R. Cachon; M. Catté; R. Nommé; H. Prévost; C. Diviès

1995-01-01

53

Transcriptome analysis and related databases of Lactococcus lactis  

Microsoft Academic Search

Several complete genome sequences of Lactococcus lactis and their annotations will become available in the near future, next to the already published genome sequence of L. lactis ssp. lactis IL1403. This will allow intraspecies comparative genomics studies as well as functional genomics studies aimed at a better understanding of physiological processes and regulatory networks operating in lactococci. This paper decribes

Oscar P. Kuipers; Anne de Jong; Richard J. S. Baerends; Aldert L. Zomer; Harma A. Karsens; Chris D. den Hengst; Naomi E. Kramer; Girbe Buist; Jan Kok

2002-01-01

54

Transcriptome analysis and related databases of Lactococcus lactis  

Microsoft Academic Search

Several complete genome sequences of Lactococcus lactis and their annotations will become available in the near future, next to the already published genome sequence of L. lactis ssp. lactis IL1403. This will allow intra-species comparative genomics studies as well as functional genomics studies aimed at a better understanding of physiological processes and regulatory networks operating in lactococci. This paper decribes

Oscar P. Kuipers; Anne de Jong; Richard J. S. Baerends; Sacha A. F. T. van Hijum; Aldert L. Zomer; Harma A. Karsens; Chris D. den Hengst; Naomi E. Kramer; Girbe Buist; Jan Kok

2002-01-01

55

Glycolysis and the regulation of glucose transport in Lactococcus lactis spp. lactis in batch and fed-batch culture  

Microsoft Academic Search

BACKGROUND: Despite the fact that many reports deal with glycolysis in Lactococcus lactis, there is not much information on the regulation of uptake of glucose itself. The aim of the present work was to investigate the effect of the glucose level on its specific uptake rate. RESULTS: Studies on aeration levels in pH controlled L. lactis spp. lactis batch cultures

Maria Papagianni; Nicholaos Avramidis; George Filiousis

2007-01-01

56

Necrotising pneumonia caused by Lactococcus lactis cremoris.  

PubMed

Lactococcus lactis cremoris is a facultative anaerobic, gram-positive coccus whose natural host is bovine livestock. It may form part of the normal human bacterial flora found in the oropharynx, the gastrointestinal tract and the vagina. This bacterium is essential in the food industry, where it is used in milk fermentation to obtain cheese, yoghurt, etc. Exposure to unpasteurised dairy products has thus been recognised as a risk factor for infection by this organism. It is generally considered to be non-pathogenic, although it appears that pathogenicity may be emerging. We present an atypical case of necrotising pneumonia caused by L. lactis cremoris. PMID:23485391

Buchelli-Ramirez, H L; Alvarez-Alvarez, C; Rojo-Alba, S; García-Clemente, M; Cimadevilla-Suárez, R; Pando-Sandoval, A; Casan-Clará, P

2013-04-01

57

Rapid PCR-Based Method Which Can Determine Both Phenotype and Genotype of Lactococcus lactis Subspecies  

Microsoft Academic Search

A highly efficient, rapid, and reliable PCR-based method for distinguishing Lactococcus lactis subspecies (L. lactis subsp. lactis and L. lactis subsp. cremoris) is described. Primers complementary to positions in the glutamate decarboxylase gene have been constructed. PCR analysis with extracted DNA or with cells of different L. lactis strains resulted in specific fragments. The length polymorphism of the PCR fragments

Masaru Nomura; Miho Kobayashi; Takashi Okamoto

2002-01-01

58

Hydrogen production from biodiesel byproduct by immobilized Enterobacter aerogenes.  

PubMed

The recent rapid growth of the biodiesel industry has generated a significant amount of glycerol as a byproduct. As a result, the price of glycerol is currently relatively low, making it an attractive starting material for the production of chemicals with higher values. Crude glycerol can be directly converted through microbial fermentation into various chemicals such as hydrogen. In this study, we optimized immobilization of a facultative hydrogen producing microorganism, Enterobacter aerogenes, with the goal of developing biocatalysts that was appropriate for the continuous hydrogen production from glycerol. Several carriers were tested and agar was found to be the most effective. In addition, it was clearly shown that variables such as the carrier content and cell loading should be controlled for the immobilization of biocatalysts with high hydrogen productivity, stability, and reusability. After optimization of these variables, we were able to obtain reusable biocatalysts that could directly convert the byproduct stream from biodiesel processes into hydrogen in continuous processes. PMID:21915673

Han, Jinmi; Lee, Dohoon; Cho, Jinku; Lee, Jeewon; Kim, Sangyong

2011-09-14

59

Ribitol dehydrogenase of Klebsiella aerogenes. Sequence of the structural gene.  

PubMed Central

The ribitol dehydrogenase gene was cloned from wild-type Klebsiella aerogenes and also from a transducing phage lambda prbt which expresses the rbt operon constitutively. The coding sequence for 249 amino acids is separated from the following D-ribulokinase gene by 31 base pairs containing three stop codons, one of which overlaps the ribosome binding site for D-ribulokinase. Three residues in the amino acid sequence differ from that predicted from the DNA sequence: Asp-212 for Asn-212 is probably a protein sequencing error, but -Ala-Val- for -Ser-Ser- at 146-147 appears to be a 'neutral mutation' that may have arisen during prolonged chemostat selection of a strain that superproduces the enzyme from which the protein sequence was determined.

Loviny, T; Norton, P M; Hartley, B S

1985-01-01

60

The isolation and incidence of bact. Coli G.E. (a) in cases of diarrhœa and enteritis  

Microsoft Academic Search

Conclusions  The investigation was undertaken to demonstrate the presence of Bact. coli G. E. (a) in fæcal specimens from infants with diarrhœa and enteritis of varying ætiology. Though the pathogenic significance of the\\u000a organism has not been proved, the high mortality rate associated with its presence in this and other investigations makes\\u000a its presence of prognostic significance. A comparison of the

P. D. J. Holland

1951-01-01

61

Bioconversion of glycerol to ethanol by a mutant Enterobacter aerogenes.  

PubMed

The main objective of this research is to develop, by adaptive evolution, mutant strains of Enterobacter aerogenes ATCC 13048 that are capable of withstanding high glycerol concentration as well as resisting ethanol-inhibition. The mutant will be used for high ethanol fermentation from glycerol feedstock. Ethanol production from pure (P-) and recovered (R-) glycerol using the stock was evaluated. A six-tube-subculture-generations method was used for developing the mutant. This involved subculturing the organism six consecutive times in tubes containing the same glycerol and ethanol concentrations at the same culture conditions. Then, the glycerol and/or ethanol concentration was increased and the six subculture generations were repeated. A strain capable of growing in 200 g/L glycerol and 30 g/L ethanol was obtained. The ability of this mutant, vis-à-vis the original strain, in utilizing glycerol in a high glycerol containing medium, with the concomitant ethanol yield, was assessed. Tryptic soy broth without dextrose (TSB) was used as the fermentation medium. Fermentation products were analyzed using HPLC.In a 20 g/L glycerol TSB, E. aerogenes ATCC 13048 converted 18.5 g/L P-glycerol and 17.8 g/L R-glycerol into 12 and 12.8 g/L ethanol, respectively. In a 50 g/L P-glycerol TSB, it utilized only 15.6 g/L glycerol; but the new strain used up 39 g/L, yielding 20 g/L ethanol after 120 h, an equivalence of 1.02 mol ethanol/mol-glycerol. This is the highest ethanol yield reported from glycerol bioconversion. The result of this P-glycerol fermentation can be duplicated using the R-glycerol from biodiesel production. PMID:22455837

Nwachukwu, Res; Shahbazi, A; Wang, L; Ibrahim, S; Worku, M; Schimmel, K

2012-03-29

62

A descriptive model for citrate utilization by Lactococcus lactis ssp lactis bv diacetylactis  

Microsoft Academic Search

A model for the use of citrate by Lactococcus lactis ssp lactis bv diacetylactis CNRZ 125 is proposed. Citrate metabolism by this strain leads to the production of acetate, CO2 and C4 compounds (diacetyl, acetoin, 2,3-butylene glycol). The model furnishes correct simulations, consistent with published results on the pathways used and on lactose-citrate co-metabolism. Citric acid is incorporated independently of

R. Cachon; C. Divdies

1993-01-01

63

Cloning and Characterization of a Novel tuf Promoter from Lactococcus lactis subsp. lactis IL1403  

Microsoft Academic Search

Genetic engineering of lactic acid bacteria (LAB) requires a reliable gene expression system. Especially, a stable promoter\\u000a is an important genetic element to induce gene expression in such a system. We report on a novel tuf promoter (Ptuf) of Lactococcus lactis subsp. lactis IL1403 that was screened and selected through analysis of previously published microarray data. Ptuf activity was examined

Eun Bae Kim; Da Chuan Piao; Jee Soo Son; Yun Jaie Choi

2009-01-01

64

Introduction of Peptidase Genes from Lactobacillus delbrueckii subsp. lactis into Lactococcus lactis and Controlled Expression  

Microsoft Academic Search

Peptidases PepI, PepL, PepW, and PepG from Lactobacillus delbrueckii subsp. lactis, which have no counterparts in Lactococcus lactis, and peptidase PepQ were examined to determine their potential to confer new peptidolytic properties to lactococci. Controllable expression of the corresponding genes (pep genes) was achieved by constructing translational fusions with the promoter of the nisA gene (PnisA). A suitable host strain,

U. Wegmann; J. R. Klein; I. Drumm; O. P. Kuipers; B. Henrich

1999-01-01

65

Batch cultures of recombinant Lactococcus lactis subsp. lactis in a stirred fermentor  

Microsoft Academic Search

The effect of plasmid introduction into Lactococcus lactis subsp. lactis IL2661 on the growth of this strain and on plasmid stability was studied in pure batch cultures. The plasmids used (coding for erythromycin or chloramphenicol resistance) were the following: pIL205 (42 kb), pIL252 (4.6 kb, 6–9 copies), pIL253 (4.8 kb, 45–85 copies) and pE194 (inserted in the chromosome). Growth and

Najat El Alami; Clair-Yves Boquien; Georges Corrieu

1992-01-01

66

Possible role of membrane proteins in mercury resistance of Enterobacter aerogenes  

Microsoft Academic Search

Mercury resistance shown by a strain of Enterobacter aerogenes was found to be determined by a plasmid. The resistance appeared to be not due to enzymatic volatilization of mercury, but due to the alteration in cellular permeability to mercury.

Hidemitsu S Pan-Hou; Masayo Nishimoto; Nobumasa Imura

1981-01-01

67

Magnesium Requirement of Aerobacter Aerogenes for Assimilation of Molecular and Combined Nitrogen.  

National Technical Information Service (NTIS)

It was shown that the magnesium requirement for the anaerobic nitrogen fixer, A. aerogenes, was nearly the same, whether the organism was assimilating ammoniacal, nitrate, or glutamic acid nitrogen. When the organism was fixing molecular nitrogen, the exp...

D. C. Yoch R. M. Pengra

1964-01-01

68

Glutaconic Acid, a Product of the Fermentation of Glutamic Acid by Peptococcus Aerogenes.  

National Technical Information Service (NTIS)

Radioactive glutaconic acid was isolated from reaction mixtures in which Peptococcus aerogenes fermented glutamic acid-2-14C. The infrared spectrum, X-ray diffraction pattern, and melting point of the biological product is identical with that of chemicall...

D. F. Horler W. B. McConnell D. W. S. Westlake

1966-01-01

69

RACT/BACT/LAER clearinghouse: A compilation of control technology determinations. First supplement to 1990 edition. Final report  

SciTech Connect

The Clean Air Act as amended in 1977 prescribes several technology-based limitations affecting new or modified air pollution sources: (1) new source performance stds. (NSPS); (2) best available control technology (BACT); (3) lowest achievable emission rate (LAER). The basic purposes of the RACT/BACT/LAER Clearinghouse are to: (1) provide State and local air pollution control agencies with current information on case-by-case control technology determinations that are made nationwide and (2) promote communication, cooperation, and sharing of control technology information among the permitting agencies. The information presented in this compilation was abstracted from preconstruction permits and submitted voluntarily by the State and local air pollution control agencies. The Clearinghouse is intended as a reference for State and local agencies in making RACT/BACT/LAER decisions. Since the 1985 BLC document was published in June of that year, annual supplements containing only those determinations inserted or revised during the previous 12 months were published. A master edition containing all new/revised determinations completed during the past 5 years was published in June 1990. This is the first supplement to that edition.

Di Mauro, D.; Duffy, C.

1991-07-01

70

Resistance to imipenem, cefepime, and cefpirome associated with mutation in Omp36 osmoporin of Enterobacter aerogenes  

Microsoft Academic Search

Enterobacter aerogenes develops increased multidrug resistance via a functional alteration of outer-membrane permeability associated with a decrease in porin function. We have sequenced the gene coding the major porin of Enterobacter aerogenes, omp36. The sequence shows a high similarity with the Klebsiella pneumoniae ompK36 gene and is closely related to the enterobacterial OmpC family. Sequence analysis of several Omp36 issued

Aurélie Thiolas; Charléric Bornet; Anne Davin-Régli; Jean-Marie Pagès; Claude Bollet

2004-01-01

71

Plasmid-Mediated Resistance to Expanded-Spectrum Cephalosporins among Enterobacter aerogenes Strains  

Microsoft Academic Search

Resistance to expanded-spectrum cephalosporins commonly develops in Enterobacter aerogenes during ther- apy due to selection of mutants producing high levels of the chromosomal Bush group 1 b-lactamase. Recently, resistant strains producing plasmid-mediated extended-spectrum b-lactamases (ESBLs) have been isolated as well. A study was designed to investigate ESBL production among 31 clinical isolates of E. aerogenes from Richmond, Va., with decreased

JOHANN D. D. PITOUT; KENNETH S. THOMSON; NANCY D. HANSON; ANTON F. EHRHARDT; PHILIP COUDRON; CHRISTINE C. SANDERS

1998-01-01

72

RamA Is an Alternate Activator of the Multidrug Resistance Cascade in Enterobacter aerogenes  

Microsoft Academic Search

Multidrug resistance (MDR) in Enterobacter aerogenes can be mediated by induction of MarA, which is triggered by certain antibiotics and phenolic compounds. In this study, we identified the gene encoding RamA, a 113-amino-acid regulatory protein belonging to the AraC-XylS transcriptional activator family, in the Enterobacter aerogenes ATCC 13048 type strain and in a clinical multiresistant isolate. Overexpression of RamA induced

Renaud Chollet; Jacqueline Chevalier; Claude Bollet; Jean-Marie Pages; Anne Davin-Regli

2004-01-01

73

A model for multiproduct-inhibited growth of Enterobacter aerogenes in 2,3-butanediol fermentation  

Microsoft Academic Search

Ethanol is identified as a strongly inhibitory metabolite in addition to acetic acid and 2,3-butanediol in 2,3-butanediol production by Enterobacter aerogenes. A model is proposed to describe the multiproduct-inhibited growth of E. aerogenes in 2,3-butanediol fermentation. The model is verified with data from anaerobic and microaerobic continuous culture. On the basis of this model the difference in biomass production and

An-Ping Zeng; Wolf-Dieter Deckwer

1991-01-01

74

Enhanced hydrogen production in altered mixed acid fermentation of glucose by Enterobacter aerogenes  

Microsoft Academic Search

Hydrogen (H2) production by mutants of Enterobacter aerogenes HU-101, a strain isolated and characterized in our laboratory, was found to be enhanced compared with that of HU-101 due to blockage of production of other metabolites. The mutants were isolated by the allyl alcohol (AA) and\\/or proton suicide method. Among the AA resistant mutants isolated after NTG treatment of E. aerogenes

Mahyudin Abdul Rachman; Yoshinori Furutani; Yutaka Nakashimada; Toshihide Kakizono; Naomichi Nishio

1997-01-01

75

Novel Antibacterial Activity of Lactococcus Lactis Subspecies Lactis Z11 Isolated from Zabady  

PubMed Central

The purpose of this study was to select and characterize a probiotic bacterium with distinctive antimicrobial activities. In this respect, Lactococcus lactis subspecies lactis Z11 (L. lactis Z11) isolated from Zabady (Arabian yoghurt) inhibited other strains of lactic acid bacteria and some food-born pathogens including Listeria monocytogenes, Bacillus cereus and staphylococcus aureus. The inhibitory activity of cell free supernatant (CFS) of L. lactis Z11 isolated from zabady was lost by proteolytic enzymes, heat resistant. Consequently, the active substance(s) of CFS was characterized as a bacteriocin. This bacteriocin has been shown to consist of protein but has no lipidic or glucidic moieties in its active molecule. Its activity was stable in the pH range 2.0 to 7.0 and was not affected by organic solvents. The L. lactis Z11 bacteriocin was produced in CFS throughout the mide to the late exponential phase of growth of the producer organism and maximum bacteriocin production was obtained at initial pH 6.5 at incubation temperature of about 30°C.

Enan, Gamal; Abdel-Shafi, Seham; Ouda, Sahar; Negm, Sally

2013-01-01

76

Antimicrobial potential of immobilized Lactococcus lactis subsp. lactis ATCC 11454 against selected bacteria.  

PubMed

Immobilization of living cells of lactic acid bacteria could be an alternative or complementary method of immobilizing organic acids and bacteriocins and inhibit undesirable bacteria in foods. This study evaluated the inhibition potential of immobilized Lactococcus lactis subsp. lactis ATCC 11454 on selected bacteria by a modified method of the agar spot test. L. lactis was immobilized in calcium alginate (1 to 2%)-whey protein concentrate (0 and 1%) beads. The antimicrobial potential of immobilized L. lactis was evaluated in microbiological media against pathogenic bacteria (Escherichia coli, Salmonella, and Staphylococcus aureus) or Pseudomonas putida, a natural meat contaminant, and against seven gram-positive bacteria used as indicator strains. Results obtained in this study indicated that immobilized L. lactis inhibited the growth of S. aureus, Enterococcus faecalis, Enterococcus faecium, Lactobacillus curvatus, Lactobacillus sakei, Kocuria varians, and Pediococcus acidilactici. Only 4 h of incubation at 35 degrees C resulted in a clear inhibition zone around the beads that increased with time. With the addition of 10 mM of a chelating agent (EDTA) to the media, results showed growth inhibition of E. coli; however, P. putida and Salmonella Typhi were unaffected by this treatment. These results indicate that immobilized lactic acid bacteria strains can be successfully used to produce nisin and inhibit bacterial growth in semisolid synthetic media. PMID:15222547

Millette, M; Smoragiewicz, W; Lacroix, M

2004-06-01

77

Novel antibacterial activity of lactococcus lactis subspecies lactis z11 isolated from zabady.  

PubMed

The purpose of this study was to select and characterize a probiotic bacterium with distinctive antimicrobial activities. In this respect, Lactococcus lactis subspecies lactis Z11 (L. lactis Z11) isolated from Zabady (Arabian yoghurt) inhibited other strains of lactic acid bacteria and some food-born pathogens including Listeria monocytogenes, Bacillus cereus and staphylococcus aureus. The inhibitory activity of cell free supernatant (CFS) of L. lactis Z11 isolated from zabady was lost by proteolytic enzymes, heat resistant. Consequently, the active substance(s) of CFS was characterized as a bacteriocin. This bacteriocin has been shown to consist of protein but has no lipidic or glucidic moieties in its active molecule. Its activity was stable in the pH range 2.0 to 7.0 and was not affected by organic solvents. The L. lactis Z11 bacteriocin was produced in CFS throughout the mide to the late exponential phase of growth of the producer organism and maximum bacteriocin production was obtained at initial pH 6.5 at incubation temperature of about 30°C. PMID:24151453

Enan, Gamal; Abdel-Shafi, Seham; Ouda, Sahar; Negm, Sally

2013-09-01

78

Liposome-enhanced transformation of Streptococcus lactis and plasmid transfer by intergeneric protoplast fusion of Streptococcus lactis and Bacillus subtilis  

Microsoft Academic Search

An efficient protoplast transformation system and a procedure of plasmid transfer by means of protoplast fusion is described for Streptococcus lactis. Protoplasts of S. lactis IL1403 and S. lactis MG1363 were transformed by pGK12 [2.9 MDa erythromycin resistance (Emr)] with an efficiency of 3 × 10^5 transformants per µg plasmid DNA. This high efficiency was obtained by the inclusion in

Jos M. B. M. van der Vossen; Jan Kok; Daniel van der Lelie; Gerard Venema

1988-01-01

79

Transport of cyclitols by a proton symport in Klebsiella aerogenes.  

PubMed

The respiration and the ATP content of Klebsiella aerogenes in the presence of various inhibitors were compared to the transport of scyllo-inositol. The ATPase was found to be inhibited by dicyclohexyl carbodiimide. The transport has been tested in anaerobiosis and aerobiosis. From the results obtained it is concluded that either ATP or respiration can sustain the transport activity in independent manner. 2. The energy derived from the respiratory chain reactions or the ATP hydrolysis results in electrogenic extrusion of protons. The electrochemical potential created drives the accumulation of scyllo-inositol, as shown by an increase of pH of the medium on addition of the substrate to cells in anaerobiosis. With non-induced cells no change in pH occurs, which demonstrates that proton flow is really linked to the transport. No H+/Na+ or K+ exchange is observed and the proton conductor carbonylcyanide m-chlorophenylhydrazone abolishes the pH shift caused by substrate addition. The stoichiometry of the symport H+/cyclitol is 1 and the half-maximum value of the pH variation as a function of the amount of scyllo-inositol added corresponds to a concentration of scyllo-inositol very close to the KT of influx. PMID:12979

Reber, G; Mermod, M; Deshusses, J

1977-01-01

80

Isolation and characterization of an alginate lyase from Klebsiella aerogenes.  

PubMed

The bacterium Klebsiella aerogenes (type 25) produced an inducible alginate lyase, whose major activity was located intracellularly during all growth phases. The enzyme was purified from the soluble fraction of sonicated cells by ammonium sulfate precipitation, anion- and cation-exchange chromatography and gel filtration. The apparent molecular weight of purified alginate lyase of 28,000 determined by gel filtration and of 31,600 determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the active enzyme was composed of a single polypeptide. The alginate lyase displayed a pH optimum around 7.0 and a temperature optimum around 37 degrees C. The purified enzyme depolymerized alginate by a lyase reaction in an endo manner releasing products which reacted in the thiobarbituric acid assay and absorbed strongly in the ultraviolet region at 235 nm. The alginate lyase was specific for guluronic acid-rich alginate preparations. Propylene glycol esters of alginate and O-acetylated bacterial alginates were poorly degraded by the lyase compared with unmodified polysaccharide. The guluronate-specific lyase activity was applied in an enzymatic method to detect mannuronan C-5 epimerase in three different mucoid (alginate-synthesizing) strains of Pseudomonas aeruginosa. This enzyme which converts polymannuronate to alginate could not be demonstrated either extracellularly or intracellularly in all strains suggesting the absence of a polymannuronate-modifying enzyme in P. aeruginosa. PMID:2673122

Lange, B; Wingender, J; Winkler, U K

1989-01-01

81

Lactococcus lactis cremoris infection: not rare anymore?  

PubMed

A middle-aged female patient with diabetes was admitted with a right neck abscess. Ultrasound scan revealed a necrotic abscess suspicious of malignancy and biopsy showed evidence of chronic inflammation. In order to isolate the primary source of malignancy, we performed MRI and positron emission tomography scans but neither had conclusive results. Subsequently, we performed an incision and drainage of the mass in order to alleviate pressure symptoms. The ensuing histological examination revealed that the mass was caused by Lactococcus lactis cremoris. As such, the patient was treated with antibiotics and made a complete recovery. This report reinforces the scarce existing evidence that L lactis cremoris is a potential pathogen in adults. The case shows that atypical organisms should always be considered in the working diagnosis of an atypical neck abscess especially due to the rise in popularity of organic farming. PMID:23667218

Hadjisymeou, Simone; Loizou, Peter; Kothari, Prasad

2013-05-09

82

Efficient gene targeting in Kluyveromyces lactis.  

PubMed

Integration of a DNA fragment in a host genome requires the action of a double-strand break (DSB) repair mechanism. Homologous recombination (HR) is initiated by binding of Rad52p to DNA ends and results in targeted integration. Binding of the Ku heterodimer (Ku70p/Ku80p) results in random integration via non-homologous end joining (NHEJ). In contrast to Saccharomyces cerevisiae, the budding yeast Kluyveromyces lactis shows variable, but in general low, gene targeting efficiency. To study and to improve gene targeting efficiency, K. lactis has been used as a model. The KlRAD51, KlRAD52 and KlKU80 genes have been isolated and deletion mutants for these genes have been constructed. Efficiency of gene targeting was determined at the KlADE2 locus using targeting constructs with different lengths of homologous flanking sequences. In wild-type K. lactis, the gene targeting efficiency ranged from 0% with 50 to 88% with 600 bp flanks. The Klku80 mutant, however, showed >97% gene targeting efficiency independently of the size of the homologous flanks. These results demonstrate that deletion of the NHEJ mechanism results in a higher gene targeting efficiency. Furthermore, increased gene targeting efficiency was achieved by the transformation of wild-type K. lactis with the KlADE2 deletion construct in the presence of excess small DNA fragments. Using this method, PCR-generated deletion constructs containing only 50 bp of homologous flanking sequences resulted in efficient targeted gene replacement. PMID:15282801

Kooistra, Rolf; Hooykaas, Paul J J; Steensma, H Yde

2004-07-15

83

Kefir-isolated Lactococcus lactis subsp. lactis inhibits the cytotoxic effect of Clostridium difficile in vitro.  

PubMed

Kefir is a dairy product obtained by fermentation of milk with a complex microbial population and several health-promoting properties have been attributed to its consumption. In this work, we tested the ability of different kefir-isolated bacterial and yeast strains (Lactobacillus kefir, Lb. plantarum, Lactococcus lactis subps. lactis, Saccharomyces cerevisiae and Kluyveromyces marxianus) or a mixture of them (MM) to antagonise the cytopathic effect of toxins from Clostridium difficile (TcdA and TcdB). Cell detachment assays and F-actin network staining using Vero cell line were performed. Although incubation with microbial cells did not reduce the damage induced by C. difficile spent culture supernatant (SCS), Lc. lactis CIDCA 8221 and MM supernatants were able to inhibit the cytotoxicity of SCS to Vero cells. Fraction of Lc. lactis CIDCA 8221 supernatant containing components higher than 10 kDa were responsible for the inhibitory activity and heating of this fraction for 15 min at 100 °C completely abrogated this ability. By dot-blot assay with anti-TcdA or anti-TcdB antibodies, concentration of both toxins seems to be reduced in SCS treated with Lc. lactis CIDCA 8221 supernatant. However, protective effect was not affected by treatment with proteases or proteases-inhibitors tested. In conclusion, we demonstrated that kefir-isolated Lc. lactis CIDCA 8221 secreted heat-sensitive products able to protect eukaryotic cells from cytopathic effect of C. difficile toxins in vitro. Our findings provide new insights into the probiotic action of microorganisms isolated from kefir against virulence factors from intestinal pathogens. PMID:23217732

Bolla, Patricia Araceli; Carasi, Paula; Serradell, María de los Angeles; De Antoni, Graciela Liliana

2012-12-10

84

The AcrAB-TolC Efflux Pump Contributes to Multidrug Resistance in the Nosocomial Pathogen Enterobacter aerogenes  

Microsoft Academic Search

For the last decade, Enterobacter aerogenes, a commensal gram-negative bacterium of human intestinal flora, has been rapidly emerging as an important nosocomial pathogen (14, 18). Of concern is the increasing frequency of E. aerogenes isolates that are resistant to antibiotics and antiseptics (3). Several types of systems have evolved in gram-negative bac- teria to pump deleterious molecules out of the

Elizabeth Pradel; Jean-Marie Pages

2002-01-01

85

Comparison of the clinical and microbiologic characteristics of patients with Enterobacter cloacae and Enterobacter aerogenes bacteremia: a prospective observation study.  

PubMed

We compared the characteristics and outcomes of 172 Enterobacter cloacae bacteremia and 67 Enterobacter aerogenes bacteremia (EAB) cases. Antimicrobial resistance rates to E. cloacae were higher than those to E. aerogenes. However, EAB more frequently presented as septic shock and was associated with poorer outcomes. PMID:20071128

Song, Eun Hee; Park, Ki-Ho; Jang, Eun-Young; Lee, Eun Jung; Chong, Yong Pil; Cho, Oh-Hyun; Kim, Sung-Han; Lee, Sang-Oh; Sung, Heungsup; Kim, Mi-Na; Jeong, Jin-Yong; Kim, Yang Soo; Woo, Jun Hee; Choi, Sang-Ho

2010-01-13

86

Characterization of PaxA and Its Operon: a Cohemolytic RTX Toxin Determinant from Pathogenic Pasteurella aerogenes  

Microsoft Academic Search

Pasteurella aerogenes is known as a commensal bacterium or as an opportunistic pathogen, as well as a primary pathogen found to be involved in abortion cases of humans, swine, and other mammals. Using broad- range DNA probes for bacterial RTX toxin genes, we cloned and subsequently sequenced a new operon named paxCABD encoding the RTX toxin PaxA in P. aerogenes.

PETER KUHNERT; BENEDICTE HEYBERGER-MEYER; JACQUES NICOLET; JOACHIM FREY

2000-01-01

87

Multivitamin production in Lactococcus lactis using metabolic engineering  

Microsoft Academic Search

The dairy starter bacterium Lactococcus lactis has the potential to synthesize both folate (vitamin B11) and riboflavin (vitamin B2). By directed mutagenesis followed by selection and metabolic engineering we have modified two complicated biosynthetic pathways in L. lactis resulting in simultaneous overproduction of both folate and riboflavin: Following exposure to the riboflavin analogue roseoflavin we have isolated a spontaneous mutant

Wilbert Sybesma; Catherine Burgess; Marjo Starrenburg; Douwe van Sinderen; Jeroen Hugenholtza

2004-01-01

88

Novel sucrose transposons from plant strains of Lactococcus lactis  

Microsoft Academic Search

Lactococcus lactis strains isolated from vegetable products transferred the ability to ferment sucrose in conjugation experiments with the recipient strain L. lactis MG1614. Nisin production and sucrose fermentation were transferred together from two strains, but transfer also occurred from several other strains which did not produce nisin. Pulsed-field gel electrophoresis analysis showed that all transconjugants had acquired large chromosomal insertions

William J. Kelly; Graham P. Davey; Lawrence J. H. Ward

2000-01-01

89

Expression of Bovine Prochymosin Gene in Lactococcus Lactis  

Microsoft Academic Search

Bovine prochymosin (bPC) could act to initiate milk clotting. NICE (Nisin Controlled gene Expression system) in lactococcus lactis was one of the most successful and widely using Grampositive gene expression systems. It was composed by six experiments in this study. They are cloning of bovine preprochymosin gene, electrotransformation in lactococcus lactis, construction of expression vector of bPC gene, detection of

Daqing Sun; Xingguang Qu; Xiyan Han; Yuhan Bi; Guanghui Zhang; Bin Li; Lanxia Qin; Yujun Jiang

2009-01-01

90

Production and secretion of heterologous proteins by Lactococcus lactis  

Microsoft Academic Search

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

Asseldonk van M

1994-01-01

91

National Epidemiologic Surveys of Enterobacter aerogenes in Belgian Hospitals from 1996 to 1998  

PubMed Central

Two national surveys were conducted to describe the incidence and prevalence of Enterobacter aerogenes in 21 Belgian hospitals in 1996 and 1997 and to characterize the genotypic diversity and the antimicrobial resistance profiles of clinical strains of E. aerogenes isolated from hospitalized patients in Belgium in 1997 and 1998. Twenty-nine hospitals collected 10 isolates of E. aerogenes, which were typed by arbitrarily primed PCR (AP-PCR) using two primers and pulsed-field gel electrophoresis. MICs of 10 antimicrobial agents were determined by the agar dilution method. Beta-lactamases were detected by the double-disk diffusion test and characterized by isoelectric point. The median incidence of E. aerogenes colonization or infection increased from 3.3 per 1,000 admissions in 1996 to 4.2 per 1000 admissions in the first half of 1997 (P < 0.01). E. aerogenes strains (n = 260) clustered in 25 AP-PCR types. Two major types, BE1 and BE2, included 36 and 38% of strains and were found in 21 and 25 hospitals, respectively. The BE1 type was indistinguishable from a previously described epidemic strain in France. Half of the strains produced an extended-spectrum beta-lactamase, either TEM-24 (in 86% of the strains) or TEM-3 (in 14% of the strains). Over 75% of the isolates were resistant to ceftazidime, piperacillin-tazobactam, and ciprofloxacin. Over 90% of the strains were susceptible to cefepime, carbapenems, and aminoglycosides. In conclusion, these data suggest a nationwide dissemination of two epidemic multiresistant E. aerogenes strains in Belgian hospitals. TEM-24 beta-lactamase was frequently harbored by one of these epidemic strains, which appeared to be genotypically related to a TEM-24-producing epidemic strain from France, suggesting international dissemination.

De Gheldre, Y.; Struelens, M. J.; Glupczynski, Y.; De Mol, P.; Maes, N.; Nonhoff, C.; Chetoui, H.; Sion, C.; Ronveaux, O.; Vaneechoutte, M.

2001-01-01

92

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

Microsoft Academic Search

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

LUC DE VUYST; ERICK J. VANDAMME

1992-01-01

93

A Deficiency in Aspartate Biosynthesis in Lactococcus lactis subsp. lactis C2 Causes Slow Milk Coagulation†  

PubMed Central

A mutant of fast milk-coagulating (Fmc+) Lactococcus lactis subsp. lactis C2, designated L. lactis KB4, was identified. Although possessing the known components essential for utilizing casein as a nitrogen source, which include functional proteinase (PrtP) activity and oligopeptide, di- and tripeptide, and amino acid transport systems, KB4 exhibited a slow milk coagulation (Fmc?) phenotype. When the amino acid requirements of L. lactis C2 were compared with those of KB4 by use of a chemically defined medium, it was found that KB4 was unable to grow in the absence of aspartic acid. This aspartic acid requirement could also be met by aspartate-containing peptides. The addition of aspartic acid to milk restored the Fmc+ phenotype of KB4. KB4 was found to be defective in pyruvate carboxylase and thus was deficient in the ability to form oxaloacetate and hence aspartic acid from pyruvate and carbon dioxide. The results suggest that when lactococci are propagated in milk, aspartate derived from casein is unable to meet fully the nutritional demands of the lactococci, and they become dependent upon aspartate biosynthesis.

Wang, Hua; Yu, Weizhu; Coolbear, Tim; O'Sullivan, Dan; McKay, Larry L.

1998-01-01

94

Cloning and characterization of the thymidylate synthase gene from Lactococcus lactis subsp. lactis.  

PubMed Central

The thymidylate synthase (thyA) gene has been isolated from Lactococcus lactis subsp. lactis. The cloned gene was strongly expressed in Escherichia coli both in vivo and in vitro (maxicells and cell-free transcription and translation systems) and complemented E. coli thyA mutants. DNA-DNA hybridizations demonstrated that the thyA gene is encoded by the chromosome of L. lactis subsp. lactis. By sequential deletion of DNA outside the complementing region, the thyA gene was localized to a 1.1-kilobase DNA fragment. The nucleotide sequence of the lactococcal thyA gene was determined by the dideoxy-chain termination technique. The derived amino acid sequence indicated a protein size of 32,580 daltons, which is in good agreement with results obtained from maxicell and in vitro transcription and translation experiments. The primary sequence is homologous to 12 other thyA proteins from a variety of other organisms. Upstream from the structural gene, -10 and -35 promoter sequences which were almost canonical sigma-70 promoter sequences were identified, which may explain the strong expression of the thyA gene observed in E. coli. An A-T-rich sequence characteristic of gram-positive promoters was also noted adjacent to the -35 region. The thyA gene has potential as a marker for plasmid maintenance and selection in food systems. Images

Ross, P; O'Gara, F; Condon, S

1990-01-01

95

Effect of fatty acids on the ?-oxidation system and thioesterase of Lactococcus lactis subspecies lactis.  

PubMed

The influence of fatty acids on the ?-oxidation system and thioesterase of Lactococcus lactis was investigated in this study. The results showed that fatty acids (C8:0-C16:0) significantly inhibited the growth of Lactococcus lactis, and laurate (C12:0) had the highest bactericidal effects. We detected the maximum activity of ?-oxidation at different incubation times (8, 12, and 18h) to be 6.460, 7.751, and 8.203, respectively, and the maximum activity of thioesterase at different incubation times (8, 12, and 18h) to be 19.498, 27.180, and 12.800, respectively. Fatty acids were seen to induce the ?-oxidation system and activity of thioesterase; decanoic acid (C10:0) and palmitic acid (C16:0) were also seen to induce the ?-oxidation system of Lactococcus lactis, but the induced ability was significantly different. Octanoic acid (C8:0) and palmitic acid (C16:0) were seen to induce thioesterase activity in Lactococcus lactis. When 1mM palmitic acid (C16:0) was added to M17 broth, the activity of thioesterase increased 5-fold after 2min; however, adding octanoic acid (C8:0) changed the activity little. Evidence showed that the ability to induce the ?-oxidation system and thioesterase activity was related to the fatty acids' chain lengths. PMID:23462166

Li, Liang; Ma, Ying

2013-02-22

96

High efficiency electrotransformation of Lactococcus lactis spp. lactis cells pretreated with lithium acetate and dithiothreitol  

Microsoft Academic Search

BACKGROUND: A goal for the food industry has always been to improve strains of Lactococcus lactis and stabilize beneficial traits. Genetic engineering is used extensively for manipulating this lactic acid bacterium, while electropolation is the most widely used technique for introducing foreign DNA into cells. The efficiency of electrotransformation depends on the level of electropermealization and pretreatment with chemicals which

Maria Papagianni; Nicholaos Avramidis; George Filioussis

2007-01-01

97

Construction of a Lactococcal Expression Vector: Expression of Hen Egg White Lysozyme in Lactococcus lactis subsp. lactis  

Microsoft Academic Search

A pair of vectors for expression of heterologous genes in Lactococcus lactis was constructed. In addition to an origin of replication that has a broad host range, these vectors contain a multiple cloning site flanked by gene expression signals originating from L. lactis subsp. cremoris Wg2. The two vectors, about 3.7 kilobase pairs in size, differ only in the type

Maarten van de Guchte; Jos M. B. M. van der Vossen; Jan Kok; Gerard Venema

1989-01-01

98

Asparagine synthetases of Klebsiella aerogenes: properties and regulation of synthesis.  

PubMed

We isolated pleiotropic mutants of Klebsiella aerogenes with the transposon Tn5 which were unable to utilize a variety of poor sources of nitrogen. The mutation responsible was shown to be in the asnB gene, one of two genes coding for an asparagine synthetase. Mutations in both asnA and asnB were necessary to produce an asparagine requirement. Assays which could distinguish the two asparagine synthetase activities were developed in strains missing a high-affinity asparaginase. The asnA and asnB genes coded for ammonia-dependent and glutamine-dependent asparagine synthetases, respectively. Asparagine repressed both enzymes. When growth was nitrogen limited, the level of the ammonia-dependent enzyme was low and that of the glutamine-dependent enzyme was high. The reverse was true in a nitrogen-rich (ammonia-containing) medium. Furthermore, mutations in the glnG protein, a regulatory component of the nitrogen assimilatory system, increased the level of the ammonia-dependent enzyme. The glutamine-dependent asparagine synthetase was purified to 95%. It was a tetramer with four equal 57,000-dalton subunits and catalyzed the stoichiometric generation of asparagine, AMP, and inorganic pyrophosphate from aspartate, ATP, and glutamine. High levels of ammonium chloride (50 mM) could replace glutamine. The purified enzyme exhibited a substrate-independent glutaminase activity which was probably an artifact of purification. The tetramer could be dissociated; the monomer possessed the high ammonia-dependent activity and the glutaminase activity, but not the glutamine-dependent activity. In contrast, the purified ammonia-dependent asparagine synthetase, about 40% pure, had a molecular weight of 80,000 and is probably a dimer of identical subunits. Asparagine inhibited both enzymes. Kinetic constants and the effect of pH, substrate, and product analogs were determined. The regulation and biochemistry of the asparagine synthetases prove the hypothesis strongly suggested by the genetic and physiological evidence that a glutamine-dependent enzyme is essential for asparagine synthesis when the nitrogen source is growth rate limiting. PMID:6125499

Reitzer, L J; Magasanik, B

1982-09-01

99

The Function of UreB in Klebsiella aerogenes Urease†  

PubMed Central

Urease from Klebsiella aerogenes is composed of three subunits (UreA, UreB, and UreC) which assemble into a (UreABC)3 quaternary structure. UreC harbors the dinuclear nickel active site, whereas the functions of UreA and UreB remain unknown. UreD and UreF accessory proteins previously were suggested to reposition UreB and increase exposure of the nascent urease active site, thus facilitating metallocenter assembly. In this study, cells were engineered to separately produce (UreAC)3 or UreB, and the purified proteins were characterized. Monomeric UreB spontaneously binds to the trimeric heterodimer of UreA plus UreC to form (UreABC*)3 apoprotein, as shown by gel filtration chromatography, integration of electrophoretic gel band intensities, and mass spectrometry. Similar to authentic urease apoprotein, active enzyme is produced by incubation of (UreABC*)3 with Ni2+ and bicarbonate. Conversely, UreB?1-19, lacking the 19 residue potential hinge and tether to UreC, does not form a complex with (UreAC)3 and yields negligible levels of active enzyme when incubated under activation conditions with (UreAC)3. Comparison of activities and nickel contents for (UreAC)3, (UreABC*)3, and (UreABC)3 samples treated with Ni2+ and bicarbonate and then desalted indicates that UreB facilitates efficient incorporation of the metal into the active site and protects the bound metal from chelation. Amylose resin pull-down studies reveal that MBP-UreD (a fusion of maltose binding protein with UreD) forms complexes with (UreABC)3, (UreAC)3, and UreB in vivo, but not in vitro. By contrast, MBP-UreD does not form an in vivo complex with UreB?1-19. The soluble MBP-UreD:UreF:UreG complex binds in vitro to (UreABC)3, but not to (UreAC)3 or UreB. Together these data demonstrate that UreB facilitates the interaction of urease with accessory proteins during metallocenter assembly, with the N-terminal hinge and tether region being specifically required for this process. In addition to its role in urease activation, UreB enhances the stability of UreC against proteolytic cleavage.

Carter, Eric L.; Boer, Jodi L.; Farrugia, Mark A.; Flugga, Nicholas; Towns, Christopher L.; Hausinger, Robert P.

2011-01-01

100

Optimization of key process variables for enhanced hydrogen production by Enterobacter aerogenes using statistical methods  

Microsoft Academic Search

The individual and mutual effects of glucose concentration, temperature and pH on the hydrogen production by Enterobacter aerogenes were investigated in a batch system. A Box–Behnken design and response surface methodology (RSM) were employed to determine the optimum condition for enhanced hydrogen production. The hydrogen production rate was investigated by simultaneously changing the three independent variables, which all had significant

Ji Hye Jo; Dae Sung Lee; Donghee Park; Woo-Seok Choe; Jong Moon Park

2008-01-01

101

Porin alteration and active efflux: two in vivo drug resistance strategies used by Enterobacter aerogenes  

Microsoft Academic Search

Entembacter aemgenes is among the five most frequently isolated nosocomial pathogens in France, and this bacterium also shows increasing multidrug resistance. In this study, various E. aerogenes strains isolated from hospital units were characterized for their outer-membrane proteins, antibiotic susceptibilities (inhibition diameters and MICs) and resistance mechanisms associated with modification of envelope permeability (porin alteration and active efflux). Diminished outer-membrane

Monique Mallea; Jacqueline Chevalier; Charleric Bornet; Annie Eyraud; Anne Davin-Regli; Claude Bollet; Jean-Marie Pages

1998-01-01

102

In Vivo Modification of Porin Activity Conferring Antibiotic Resistance to Enterobacter aerogenes  

Microsoft Academic Search

Cephalosporins are widely used in chemotherapy of bacterial infections and resistance mechanisms seriously impair their antibacterial activity. Several resistant strains of Enterobacter aerogenes, a frequently isolated nosocomial pathogen, were analyzed. One isolate exhibited a strong modification of the porin antigenic pattern, especially with an immunological probe directed against an epitope located inside the pore lumen. A strong decrease of cefepime

Jacqueline Chevalier; Jean-Marie Pagès; Monique Malléa

1999-01-01

103

Repeated cadmium biosorption by regenerated Enterobacter aerogenes biofilm attached to activated carbon  

Microsoft Academic Search

Summary The bacteriumEnterobacter aerogenes has been used to develop a biofilm over activated carbon for biosorption from various strength cadmium solutions (25–500ppm). High bacterial resistance to metal poisoning allowed biofilm regeneration to raise the net loading of cadmium over the carbon by repeated biosorption runs.

J. A. Scott; A. M. Karanjkar

1992-01-01

104

Hydrogen production of Enterobacter aerogenes altered by extracellular and intracellular redox states  

Microsoft Academic Search

Enterobacter aerogenes HU-101, tested for its hydrogen production in batch cultures on various substrates, produced the highest amount of hydrogen when the substrate was glycerol. The yield of hydrogen is a function of the degree to which the substrates are reduced. To examine the effect of intracellular redox state on hydrogen yield, glucose-limiting chemostat cultures were carried out at various

Y. Nakashimada; M. A. Rachman; T. Kakizono; N. Nishio

2002-01-01

105

An adaptive response of Enterobacter aerogenes to imipenem: regulation of porin balance in clinical isolates.  

PubMed

Imipenem (IPM) is a carbapenem antibiotic frequently used in severe hospital infections. Several reports have mentioned the emergence of resistant isolates exhibiting membrane modifications. A study was conducted between September 2005 and August 2007 to survey infections due to Enterobacter aerogenes in patients hospitalised in a French university hospital. Resistant E. aerogenes clinical isolates obtained from patients treated with IPM and collected during the 3 months following initiation of treatment were phenotypically and molecularly characterised for ?-lactamases, efflux pumps activity and outer membrane proteins. Among the 339 patients infected with E. aerogenes during the study period, 41 isolates (12.1%) were resistant to extended-spectrum cephalosporins and 17 patients (5.0%) were treated with IPM. The isolates from these 17 patients presented TEM-24 and basal efflux expression. Following IPM treatment, an IPM-intermediate-susceptible (IPM-I) isolate emerged in 11 patients and an IPM-resistant (IPM-R) isolate in 6 patients. A change in the porin balance (Omp35/Omp36) was observed in IPM-I isolates exhibiting ertapenem resistance. Finally, a porin deficiency (Omp35 and Omp36 absence) was detected in IPM-R isolates associated with efflux pump expression. This study indicates that the alteration in porin expression, including the shift of porin expression and lack of porins, contribute to the E. aerogenes adaptive response to IPM treatment. PMID:23280442

Lavigne, Jean-Philippe; Sotto, Albert; Nicolas-Chanoine, Marie-Hélène; Bouziges, Nicole; Pagès, Jean-Marie; Davin-Regli, Anne

2012-12-29

106

Hydrogen production by immobilized cells of aciduric Enterobacter aerogenes strain HO39  

Microsoft Academic Search

Cell immobilization of Enterobacter aerogenes strain HO-39 in agar gel or on porous glass beads was effective for hydrogen production in batch cultures of cells immobilized by the entrapment and adsorption methods. Stirring of the culture was indispensable for effective hydrogen production using cells immobilized in agar gel. However, relatively good hydrogen-production performance was obtained with cells immobilized on porous

Haruhiko Yokoi; Tadafumi Tokushige; Jun Hirose; Sachio Hayashi; Yoshiyuki Takasaki

1997-01-01

107

Development of Enterobacter aerogenes fuel cells: from in situ biohydrogen oxidization to direct electroactive biofilm.  

PubMed

This study described an Enterobacter aerogenes-catalyzed microbial fuel cell (MFC) with a carbon-based anode that exhibited a maximum power density of 2.51 W/m(3) in the absence of artificial electron mediators. The MFC was started up rapidly, within hours, and the current generation in the early stage was demonstrated to result from in situ oxidation of biohydrogen produced by E. aerogenes during glucose fermentation. Over periodic replacement of substrate, both planktonic biomass in the culture liquid and hydrogen productivity decreased, while increased power density and coulombic efficiency and decreased internal resistance were unexpectedly observed. Using scanning electron microscopy and cyclic voltammetry, it was found that the enhanced MFC performance was associated with the development of electroactive biofilm on the anodic surface, proposed to involve an acclimation and selection process of E. aerogenes cells under electrochemical tension. The significant advantage of rapid start-up and the ability to develop an electroactive biofilm identifies E. aerogenes as a suitable biocatalyst for MFC applications. PMID:20598528

Zhuang, Li; Zhou, Shungui; Yuan, Yong; Liu, Tinglin; Wu, Zhifeng; Cheng, Jiong

2010-07-02

108

The Interrelationship between Potassium, Magnesium and Phosphorus in Potassium-limited Chemostat Cultures of Aerobacter Aerogenes  

Microsoft Academic Search

SUMMARY The growth of Aerobacter aerogenes cultures in a chemostat under conditions of K+-limitation was investigated. At a fixed dilution rate there was a linear relationship between bacterial concentration and the K+ concentration in the culture. The extrapolated plot did not pass through the origin, however; this indicated the presence in the medium of sub- stance(s) supporting some growth in

D. W. TEMPEST; J. W. DICKS; J. R. HUNTER

1966-01-01

109

Determination of the efficiency of oxidative phosphorylation in continuous cultures of Aerobacter aerogenes  

Microsoft Academic Search

For anaerobic glucose-limited chemostat cultures of Aerobacter aerogenes a values of 14.0 g\\/mole was found for YATPmaxand a value of 6.8 mmoles ATP\\/g dry weight\\/hr for the maintenance coefficient. Both values are much lower than those previously determined for tryptophan-limited anaerobic chemostat cultures.

A. H. Stouthamer; Corry W. Bettenhaussen

1975-01-01

110

Enhanced production of acetoin and butanediol in recombinant Enterobacter aerogenes carrying Vitreoscilla hemoglobin gene  

Microsoft Academic Search

Microbial production of butanediol and acetoin has received increasing interest because of their diverse potential practical uses. Although both products are fermentative in nature, their optimal production requires a low level of oxygen. In this study, the use of a recombinant oxygen uptake system on production of these metabolites was investigated. Enterobacter aerogenes was transformed with a pUC8-based plasmid carrying

Hikmet Geckil; Ze’ev Barak; David M. Chipman; Sebnem O. Erenler; Dale A. Webster; Benjamin C. Stark

2004-01-01

111

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

Microsoft Academic Search

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

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

1989-01-01

112

Rewiring Lactococcus lactis for Ethanol Production  

PubMed Central

Lactic acid bacteria (LAB) are known for their high tolerance toward organic acids and alcohols (R. S. Gold, M. M. Meagher, R. Hutkins, and T. Conway, J. Ind. Microbiol. 10:45–54, 1992) and could potentially serve as platform organisms for production of these compounds. In this study, we attempted to redirect the metabolism of LAB model organism Lactococcus lactis toward ethanol production. Codon-optimized Zymomonas mobilis pyruvate decarboxylase (PDC) was introduced and expressed from synthetic promoters in different strain backgrounds. In the wild-type L. lactis strain MG1363 growing on glucose, only small amounts of ethanol were obtained after introducing PDC, probably due to a low native alcohol dehydrogenase activity. When the same strains were grown on maltose, ethanol was the major product and lesser amounts of lactate, formate, and acetate were formed. Inactivating the lactate dehydrogenase genes ldhX, ldhB, and ldh and introducing codon-optimized Z. mobilis alcohol dehydrogenase (ADHB) in addition to PDC resulted in high-yield ethanol formation when strains were grown on glucose, with only minor amounts of by-products formed. Finally, a strain with ethanol as the sole observed fermentation product was obtained by further inactivating the phosphotransacetylase (PTA) and the native alcohol dehydrogenase (ADHE).

Dehli, Tore; Jensen, Peter Ruhdal

2013-01-01

113

Ornithine transport and exchange in Streptococcus lactis  

SciTech Connect

Resting cells of Streptococcus lactis 133 appeared to accumulate (/sup 14/C)ornithine to a high concentration in the absence of an exogenous energy source. However, analysis of intracellular amino acid pool constituents and results of transport experiments revealed that the accumulation of ornithine represented a homoexchange between extracellular (/sup 14/C)ornithine and unlabeled ornithine in the cell. The energy-independent exchange of ornithine was not inhibited by proton-conducting uncouplers or by metabolic inhibitors. Intracellular (/sup 14/C)ornithine was retained by resting cells after suspension in a buffered medium. However, addition of unlabeled ornithine to the suspension elicited rapid exit of labeled amino acid. The initial rate of exist of (/sup 14/C)ornithine was dependent on the concentration of unlabeled ornithine in the medium, but this accelerative exchange diffusion process caused no net loss of amino acid. By contrast, the presence of a fermentable energy source caused a rapid expulsion of and new decrease in the concentration of intracellular ornithine. Kinetic analyses of amino acid transport demonstrated competitive inhibition between lysine and ornithine, and data obtained by two-dimensional thin-layer chromatography established the heteroexchange of these basic amino acids. The effects of amino acids and of ornithine analogs on both entry and exit of (/sup 14/C)ornithine have been examined. The data suggest that common carrier mediates the entry and exchange of lysine, arginine, and ornithine in cells of S. lactis.

Thompson, J.

1987-09-01

114

Antioxidant and immunomodulatory activity of selenium exopolysaccharide produced by Lactococcus lactis subsp. lactis.  

PubMed

Exopolysaccharide (EPS) was isolated and purified from Lactococcus lactis subsp. Lactis culture broth. Selenium chloride oxide (SeCl(2)O) was added to the EPS to synthesize selenium-exopolysaccharide (Se-EPS). The in vitro and in vivo antioxidant and in vivo immunomodulatory activity of EPS and Se-EPS were compared. EPS and Se-EPS scavenged superoxide anions and hydroxyl radicals. They also increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, while decreasing malondialdehyde (MDA) levels in serum and in the livers of mice. Se-EPS showed stronger in vitro and in vivo antioxidant activity than were shown by EPS. The in vivo immunoenhancement activity of EPS and Se-EPS induced by cyclophosphamide (CY) treatment in immunosuppressed mice was researched. EPS and Se-EPS treatments increased macrophage phagocytosis, spleen and thymus indices and haemolytic complement activity (HC(50)). Se-EPS showed stronger immunomodulatory activity than did EPS. PMID:23265459

Guo, Yuxing; Pan, Daodong; Li, Hua; Sun, Yangying; Zeng, Xiaoqun; Yan, Bingxiang

2012-11-02

115

Generation and Characterization of Thymidine\\/ d Alanine Auxotrophic Recombinant Lactococcus lactis subsp. lactis IL1403 Expressing BmpB  

Microsoft Academic Search

Genetic engineering of Lactococcus lactis to produce a heterologous protein may cause potential risks to the environment despite the industrial usefulness of engineered\\u000a strains. To reduce the risks, we generated three auxotrophic recombinant L. lactis subsp. lactis IL1403 strains expressing a heterologous protein, BmpB, using thyA- and alr-targeting integration vectors: ITD (thyA\\u000a ?\\u000a alr\\u000a +\\u000a bmpB\\u000a +), IAD (thyA\\u000a +

Eun Bae Kim; Jee Soo Son; Qian Kun Zhang; Nam Kyung Lee; Sung Hee Kim; Jin Huk Choi; Sang Kee Kang; Yun Jaie Choi

2010-01-01

116

Genetic transformation of intact Lactococcus lactis subsp. lactis by high-voltage electroporation  

SciTech Connect

The objective of this study was to develop a system for electroporating intact cells of Lactococcus lactis subsp. lactis LM0230 (previously designated Streptococcus lactis LM0230) with a commercially available electroporation unit. Parameters which influenced the efficiency of transformation included growth phase and final concentration of cells, ionic strength of the suspending medium, concentration of plasmid DNA, and the amplitude and duration of the pulse. Washed suspensions of intact cells suspended in deionized distilled water were subjected to one high-voltage electric pulse varying in voltage (300 to 900 V corresponding to field strengths of 5 to 17 kV/cm) and duration (100 {mu}s to 1 s). Transformation efficiencies of 10{sup 3} transformants per {mu}g of DNA were obtained when dense suspensions (final concentration, 5 {times} 10{sup 10} CFU/ml) of stationary-phase cells were subjected to one pulse with a peak voltage of 900 V (field strength, 17 kV/cm) and a pulse duration of 5 ms in the presence of plasmid DNA. Dilution of porated cells in broth medium followed by an expression period of 2 h at 30{degree}C was beneficial in enhancing transformation efficiencies. Plasmids ranging in size from 9.8 to 30.0 kilobase pairs could be transformed by this procedure.

McIntyre, D.A.; Harlander, S.K. (Univ. of Minnesota, St. Paul (USA))

1989-03-01

117

Genes but Not Genomes Reveal Bacterial Domestication of Lactococcus Lactis  

Microsoft Academic Search

BackgroundThe population structure and diversity of Lactococcus lactis subsp. lactis, a major industrial bacterium involved in milk fermentation, was determined at both gene and genome level. Seventy-six lactococcal isolates of various origins were studied by different genotyping methods and thirty-six strains displaying unique macrorestriction fingerprints were analyzed by a new multilocus sequence typing (MLST) scheme. This gene-based analysis was compared

Delphine Passerini; Charlotte Beltramo; Michele Coddeville; Yves Quentin; Paul Ritzenthaler; Marie-Line Daveran-Mingot; Pascal Le Bourgeois

2010-01-01

118

Production of Dehydroamino AcidContaining Peptides by Lactococcus lactis  

Microsoft Academic Search

Nisin is a pentacyclic peptide antibiotic produced by some Lactococcus lactis strains. Nisin contains dehydroresidues and thioether rings that are posttranslationally introduced by a membrane-associated enzyme complex, composed of a serine and threonine dehydratase NisB and the cyclase NisC. In addition, the transporter NisT is necessary for export of the modified peptide. We studied the potential of L. lactis expressing

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

2007-01-01

119

Plasmid-encoded copper resistance in Lactococcus lactis  

Microsoft Academic Search

A 54-kb plasmid (pND306) from Lactococcus lactis subsp. lactis 1252D encoded resistance to both Cu and Sn . The copper resistance determinant was subcloned on a 12.8-kb PvuII DNA fragment and mapped using a number of restriction endonucleases. Six other copper resistant lactococcal strains were also identified and all contained multiple plasmids. Plasmids in five of these strains showed strong

Vichien Leelawatcharamas; Lian G. Chia; Pilaiwan Charoenchai; Nongpanga Kunajakr; Chun-Qiang Liu; Noel W. Dunn

1997-01-01

120

Proteomic Signature of Lactococcus lactis NCDO763 Cultivated in Milk  

Microsoft Academic Search

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

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

2005-01-01

121

Increased production of folate by metabolic engineering of Lactococcus lactis  

Microsoft Academic Search

The dairy starter bacterium Lactococcus lactis is able to synthesize folate and accumulates large amounts of folate, predominantly in the polyglutamyl form. Only small amounts of the produced folate are released in the extracellular medium. Five genes involved in folate biosynthesis were identified in a folate gene cluster in L. lactis MG1363: folA, folB, folKE, folP, and folC. The gene

Wilbert Sybesma; Marjo Starrenburg; Michiel Kleerebezem; Igor Mierau; Vos de W. M; Jeroen Hugenholtz

2003-01-01

122

Production of adenine arabinoside by gel-entrapped cells of Enterobacter aerogenes in water-organic cosolvent system  

Microsoft Academic Search

Gel-entrapped whole cells of Enterobacter aerogenes, which has a transglycosylation activity, were used to produce adenine arabinoside from uracil arabinoside and adenine, in an appropriate water-organic cosolvent system. Cells of E. aerogenes entrapped with a hydrophilic photo-crosslinkable resin prepolymer, ENT-4000, or a urethane prepolymer, PU-6, had a high and stable transglycosylation activity. To improve the poor solubility in water of

Kenzo Yokozekil; Shigeru Yamanaka; Takashi Utagawa; Koichi Takinami; Yoshio Hirose; Atsuo Tanaka; Kenji Sonomoto; Saburo Fukui

1982-01-01

123

Gene cloning of the maoA gene and overproduction of a soluble monoamine oxidase from Klebsiella aerogenes  

Microsoft Academic Search

We cloned the structural gene for monoamine oxidase (maoA) from Klebsiella aerogenes into a pKI212 vector in an maoA mutant strain of K. aerogenes. Deletion analysis and complementation tests of the recombinant plasmid showed that the maoA gene was located entirely within a 4.1-kb segment. In an maoA mutant strain harbouring the cloned maoA gene, synthesis of monoamine oxidase was

Hiroyuki Sugino; Kaname Ishibashi; Masashi Sakaue; Mitsuo Yamashita; Yoshikatsu Murooka

1991-01-01

124

Transformation of Kluyveromyces lactis by Electroporation  

PubMed Central

The physical and biological parameters involved in efficient transformation of Kluyveromyces lactis by electroporation have been analyzed. By using an optimum voltage and a constant volume of cell suspension in a cuvette, the efficiency of transformation increased with increases in cell numbers and plasmid concentration. However, the most important parameter was the time of the pulse. Changes of 1 ms decreased the efficiency of transformation more than 70 to 80%. Under our best conditions, between 106 and 107 transformants per ?g of plasmid DNA could be obtained. Under certain conditions, the size of the plasmid also affected electroporation efficiency. In any case, we did not obtain integrative transformation with an autonomously replicating plasmid. Images

Sanchez, Manuel; Iglesias, Francisco J.; Santamaria, Carlos; Dominguez, Angel

1993-01-01

125

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

PubMed Central

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

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

1992-01-01

126

Influence of pH on growth and bacteriocin production by Lactococcus lactis subsp. lactis 140NWC during batch fermentation  

Microsoft Academic Search

The influence of pH?on growth, and lactic acid and bacteriocin production by Lactococcus 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 of growth and lactic acid production rate. The optimal pH?for growth

E. Parente; A. Ricciardi; G. Addario

1994-01-01

127

l(+)Lactic acid production from starch by a novel amylolytic Lactococcus lactis subsp. lactis B84  

Microsoft Academic Search

A new Lactococcus lactis subsp. lactis B84, capable of utilizing starch as a sole carbon source and producing l(+)-lactate, was isolated from spontaneously fermented rye sourdough. Aiming at maximum lactic acid productivity, the components of the media and the cultivation conditions were varied. In MRS-starch medium (with absence of yeast and meat extracts), at 33°C, agitation 200rpm and pH 6.0

Kaloyan Petrov; Zoltan Urshev; Penka Petrova

2008-01-01

128

A comparison of the properties of bacteriocins formed by Lactococcus lactis subsp. lactis strains of diverse origin  

Microsoft Academic Search

Bacteriocins formed by four strains of Lactococcus lactis subsp. lactis have been studied and compared: 729 (a natural strain isolated from milk), 1605 (a mutant of strain 729), F-116 (a recombinant\\u000a obtained by fusing of protoplasts of the two related strain 729 and 1605), and a nisin-forming strain obtained by adaptive\\u000a selection at Moscow State University. Antimicrobial activity studies revealed

L. G. Stoyanova; N. S. Egorov; G. B. Fedorova; G. S. Katrukha; A. I. Netrusov

2007-01-01

129

Isolation and Properties of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 Mutants Producing Diacetyl and Acetoin from Glucose  

Microsoft Academic Search

Following treatment with the mutagen N-methyl-N*-nitro-N-nitrosoguanidine, three mutants of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 that produced diacetyl and acetoin from glucose were isolated. The lactate dehydrogenase activity of these mutants was strongly attenuated, and the mutants produced less lactate than the parental strain. The kinetic properties of lactate dehydrogenase of strain CNRZ 483 and the mutants revealed

HASSINA BOUMERDASSI; CHRISTOPHE MONNET; MICHEL DESMAZEAUD; GEORGES CORRIEU

1997-01-01

130

Novel Exopolysaccharides Produced by Lactococcus lactis subsp. lactis, and the Diversity of epsE Genes in the Exopolysaccharide Biosynthesis Gene Clusters.  

PubMed

To characterize novel variations of exopolysaccharides (EPSs) produced by dairy strains of Lactococcus lactis subsp. lactis and subsp. cremoris, the EPSs of five dairy strains of L. lactis were purified. Sugar composition analysis showed two novel EPSs produced by strains of L. lactis subsp. lactis. One strain produced EPS lacking galactose, and the other produced EPS containing fucose. Among the eps gene clusters of these strains, the highly conserved epsD and its neighboring epsE were sequenced. Sequence and PCR analysis revealed that epsE genes were strain-specific. By Southern blot analysis using epsD, the eps gene cluster in each strain was found to locate to the chromosome or a very large plasmid. This is the first report on the identification of two novel EPSs in L. lactis subsp. lactis. The strains can be detected among other strains by using epsE genes specific to them. PMID:24096663

Suzuki, Chise; Kobayashi, Miho; Kimoto-Nira, Hiromi

2013-10-07

131

Membrane permeability, a pivotal function involved in antibiotic resistance and virulence in Enterobacter aerogenes clinical isolates.  

PubMed

Imipenem-susceptible E. aerogenes isolates exhibiting extended spectrum ?-lactamases, target mutations and a basal efflux expression, were identified in five patients. After imipenem treatment, imipenem-intermediate susceptible (IMI-I) or resistant (IMI-R) isolates emerged in these patients. Alteration in porin synthesis and increase in efflux expression were observed in the IMI-I isolates whereas complete loss of the porins, LPS alteration and efflux overexpression were observed in the IMI-R isolates. Bacterial virulence of the strains was investigated by the Caenorhabditis elegans model. The IMI-R isolates were shown to be significantly less virulent than the IMI-susceptible or IMI-I isolates. The pleiotropic membrane alteration and its associated fitness burden exhibited by E. aerogenes isolates influence their antibiotic resistance and their virulence behaviour. These findings highlight the balance between the low permeability-related resistance and virulence and their relationships with the treatment of resistant pathogens. PMID:21883663

Lavigne, J-P; Sotto, A; Nicolas-Chanoine, M-H; Bouziges, N; Bourg, G; Davin-Regli, A; Pagès, J-M

2011-08-29

132

Engineered Enterobacter aerogenes for efficient utilization of sugarcane molasses in 2,3-butanediol production.  

PubMed

Sugarcane molasses is considered to be a good carbon source for biorefinery due to its high sugar content and low price. Sucrose occupies more than half of the sugar in the molasses. Enterobacter aerogenes is a good host strain for 2,3-butanediol production, but its utilization of sucrose is not very efficient. To improve sucrose utilization in E. aerogenes, a sucrose regulator (ScrR) was disrupted from the genomic DNA. The deletion mutation increased the sucrose consumption rate significantly when sucrose or sugarcane molasses was used as a carbon source. The 2,3-butanediol production from sugarcane molasses by the mutant was enhanced by 60% in batch fermentation compared to that by the wild type strain. In fed-batch fermentation, 98.69 g/L of 2,3-butanediol production was achieved at 36 h. PMID:23644066

Jung, Moo-Young; Park, Bu-Soo; Lee, Jinwon; Oh, Min-Kyu

2013-04-08

133

21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

134

Occurrence of Efflux Mechanism and Cephalosporinase Variant in a Population of Enterobacter aerogenes and Klebsiella pneumoniae Isolates Producing Extended-Spectrum  -Lactamases  

Microsoft Academic Search

We investigated the occurrence of multidrug resistance in 44 Enterobacter aerogenes and Klebsiella pneumoniae clinical isolates. Efflux was involved in resistance in E. aerogenes isolates more frequently than in K. pneumoniae isolates (100 versus 38% of isolates) and was associated with the expression of phenylalanine arginine -naphthylamide-susceptible active efflux. AcrA-TolC overproduction in E. aerogenes isolates was noted. An analysis of

Que-Tien Tran; Myrielle Dupont; Jean-Philippe Lavigne; Jacqueline Chevalier; Jean-Marie Pages; Albert Sotto; Anne Davin-Regli

2009-01-01

135

2,3Butanediol production by Enterobacter aerogenes in continuous culture: role of oxygen supply  

Microsoft Academic Search

The influence of oxygen on growth and production of 2,3-butanediol and acetoin by Enterobacter aerogenes was studied in continuous culture. At all dilution rates (D) studied cell mass increased steadily with increasing oxygen uptake rate (OUR), hence the micro-aerobic cultivation was energy-limited. The biomass yield on oxygen increased with D which suggests that cells need more energy for maintenance functions

An-Ping Zeng; Hanno Biebl; Wolf-Dieter Deckwer

1990-01-01

136

Enterobacter aerogenes OmpX, a cation-selective channel mar- and osmo-regulated  

Microsoft Academic Search

The ompX gene of Enterobacter aerogenes was cloned. Its overexpression induced a decrease in the major porin Omp36 production and consequently a ?-lactam resistance was noted. Purified outer membrane protein X (OmpX) was reconstituted into artificial membranes and formed ion channels with a conductance of 20 pS in 1 M NaCl and a cationic selectivity. Both MarA expression and high

Myrielle Dupont; Emmanuelle Dé; Renaud Chollet; Jacqueline Chevalier; Jean-Marie Pagès

2004-01-01

137

Production of l-asparaginase in Enterobacter aerogenes expressing Vitreoscilla hemoglobin for efficient oxygen uptake  

Microsoft Academic Search

This study is the first utilizing Vitreoscilla hemoglobin in a heterologous bacterium, Enterobacter aerogenes, to determine the effect of such a highly efficient oxygen-uptake system on the production of l-asparaginase, an enzyme that has attracted considerable attention due to its anti-tumor activity. Here, we show that the Vitreoscilla hemoglobin expressing strain has from 10-fold to more than two orders of

H. Geckil; S. Gencer

2004-01-01

138

Fluorescence monitoring during cultivation of Enterobacter aerogenes at different oxygen levels  

Microsoft Academic Search

On-line monitoring of NAD(P)H fluorescence and 2D fluorescence spectroscopy was performed with Enterobacter aerogenes, a bacterium sensitive to oxygen availability. The organism was grown in a reactor under low and high dissolved oxygen concentrations\\u000a and circulated through a bypass attached to the reactor. Under low dissolved oxygen concentration in the reactor, NAD(P)H\\u000a fluorescence in the reactor and the bypass showed

J. Mukherjee; C. Lindemann; T. Scheper

1999-01-01

139

A novel bioflocculant produced by Enterobacter aerogenes and its use in defecating the trona suspension  

Microsoft Academic Search

In this paper, a bioflocculant-producing bacterium, named W-23, was isolated from soil and identified as Enterobacter aerogenes. The bioflocculant (named WF-1) produced by W-23 was an acidic polysaccharide composed mainly of uronic acid (13.2%), pyruvic acid (7.4%) and acetic acid (1.6%). The three components sugars of WF-1 were glucose, fructose and manose, and the molar ratio was 10.3:5.4:1 for glucose:fructose:manose.

Wen-Yu Lu; Tong Zhang; Dong-Yan Zhang; Cai-Hong Li; Jian-Ping Wen; Lian-Xiang Du

2005-01-01

140

Studies on nutritional and oxygen requirements for production of L-asparaginase by Enterobacter aerogenes  

Microsoft Academic Search

The carbon and nitrogen sources most suitable for L-asparaginase production by Enterobacter aerogenes were selected and their concentrations optimized in shake-flask cultures. Sodium citrate (1.0%) and diammonium hydrogen phosphate\\u000a (0.16%) proved to be the best sources of carbon and nitrogen, respectively. Nitrogen catabolite repression of enzyme formation\\u000a was absent in this bacterium. Cultivation in a reactor showed that the dissolved

J. Mukherjee; S. Majumdar; T. Scheper

2000-01-01

141

Biotransformation of ferulic acid to 4-vinylguaiacol by Enterobacter soli and E. aerogenes.  

PubMed

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 by chemical methods but biological synthesis adds market value. Ferulic acid, a relatively inexpensive component of agricultural crops, is plentiful in corn hulls, cereal bran, and sugar-beet pulp. Two Enterobacter strains, E. soli, and E. aerogenes, accumulated 550-600 ppm amounts of 4-VG when grown in media containing 1,000 ppm ferulic acid; no accumulations were observed with the other strains. Decreasing the amount of ferulic acid present in the media increased the conversion efficiency. When ferulic acid was supplied in 500, 250, or 125 ppm amounts E. aerogenes converted ~72 % of the ferulic acid present to 4-VG while E. soli converted ~100 % of the ferulic acid to 4-VG when supplied with 250 or 125 ppm amounts of ferulic acid. Also, lowering the pH improved the conversion efficiency. At pH 5.0 E. aerogenes converted ~84 % and E. soli converted ~100 % of 1,000 ppm ferulic acid to 4-VG. Only small, 1-5 ppm, accumulations of vanillin, vanillyl alcohol, and vanillic acid were observed. E. soli has a putative phenolic acid decarboxylase (PAD) that is 168 amino acids long and is similar to PADs in other enterobacteriales; this protein is likely involved in the bioconversion of ferulic acid to 4-VG. E. soli or E. aerogenes might be useful as a means of biotransforming ferulic acid to 4-VG. PMID:22986816

Hunter, William J; Manter, Daniel K; van der Lelie, Daniel

2012-09-18

142

Rapid detection of a gfp-marked Enterobacter aerogenes under anaerobic conditions by aerobic fluorescence recovery  

Microsoft Academic Search

A gfp- and kanamycin-resistance gene-containing plasmid pUCGK was successfully constructed and transformed into Enterobacter aerogenes to develop a rapid GFP-based method for quantifying the bacterial concentration under anaerobic conditions for production of biohydrogen. Since the use of GFP as a molecular reporter is restricted by its requirement for oxygen in the development of the fluorophore, fluorescence detection for the fluorescent

Chong Zhang; Xin-Hui Xing; Kai Lou

2005-01-01

143

Nucleotide Sequence of the Chromosomal ampC Gene of Enterobacter aerogenes  

Microsoft Academic Search

The AmpC b-lactamase gene and a small portion of the regulatory ampR sequence of Enterobacter aerogenes 97B were cloned and sequenced. The b-lactamase had an isoelectric point of 8 and conferred cephalosporin and cephamycin resistance on the host. The sequence of the cloned gene is most closely related to those of the ampC genes of E. cloacae and C. freundii.

KAREN E. PRESTON; CHRISTOPHER C. A. RADOMSKI; RICHARD A. VENEZIA

2000-01-01

144

Characteristics of hydrogen production by aciduric Enterobacter aerogenes strain HO39  

Microsoft Academic Search

An aciduric facultative anaerobe with a hydrogen-producing ability was isolated and identified as Enterobacter aerogenes strain HO-39. The bacterium was able to grow at acidic pH of 3.3 aerobically and at 4.0 anaerobically. Although the optimum pH for hydrogen production was 6.0 to 7.0, hydrogen could be produced at acidic pH of 4.0. The optimum temperature for hydrogen production and

Haruhiko Yokoi; Takanobu Ohkawara; Jun Hirose; Satio Hayashi; Yoshiyuki Takasaki

1995-01-01

145

H2 production from starch by a mixed culture of Clostridium butyricum and Enterobacter aerogenes  

Microsoft Academic Search

A mixed continuous culture of Clostridium butyricum and Enterobacter aerogenes removed O2 in a reactor and produced H2 from starch with yield of more than 2 mol H2\\/mol glucose without any reducing agents in the medium. Co-immobilized cells of the bacteria on porous glass beads evolved H2 from starch at 1.3 l\\/l.h, with H2 yield of 2.6 mol H2\\/ mol

Haruhiko Yokoi; Tadafumi Tokushige; Jun Hirose; Sachio Hayashi; Yoshiyuki Takasaki

1998-01-01

146

Nucleotide Sequence of the Chromosomal ampC Gene of Enterobacter aerogenes  

PubMed Central

The AmpC ?-lactamase gene and a small portion of the regulatory ampR sequence of Enterobacter aerogenes 97B were cloned and sequenced. The ?-lactamase had an isoelectric point of 8 and conferred cephalosporin and cephamycin resistance on the host. The sequence of the cloned gene is most closely related to those of the ampC genes of E. cloacae and C. freundii.

Preston, Karen E.; Radomski, Christopher C. A.; Venezia, Richard A.

2000-01-01

147

Energetic aspects of anaerobic growth of Aerobacter aerogenes in complex medium  

Microsoft Academic Search

Molar growth yields for anaerobic growth of Aerobacter aerogenes in complex medium were much higher than for growth in minimal medium. In batch cultures the molar growth yield for glucose varied from 44 to 50 and YATP from 17.1 to 18.8. For glucose-limited chemostat cultures a value of 17.5 g\\/mole was found for YATPmaxand a value of 2.3 mmoles ATP\\/g

A. H. Stouthamer; Corry W. Bettenhaussen

1976-01-01

148

Energy-dispersive X-ray analysis of the extracellular cadmium sulfide crystallites of Klebsiella aerogenes  

Microsoft Academic Search

Klebsiella aerogenes forms electron-dense partieles on the cell surface in response to the presence of cadmium ions in the growth medium. These particles ranged from 20 to 200 nm in size, and quantitative energy dispersive X-ray analysis established that they comprise cadmium and sulfur in a 1:1 ratio. This observation leads to the conclusion that the particles are cadmium sulfide

Justin D. Holmes; Peter R. Smith; Richard Evans-Gowing; David J. Richardson; David A. Russell; John R. Sodeau

1995-01-01

149

Effect of oxygen supply on growth of Klebsiella aerogenes in a multistage tower fermentor  

Microsoft Academic Search

The effect of the rate of oxygen supply on biomass growth, consumption of carbon source formation of metabolic by-products,\\u000a biomass yields referred to C-source and oxygen, respiration rate and the respiratory quotient was studied in a multistage\\u000a tower fermentor with an interstage backflow,i.e. with a continuous reinoculation of the preceding stages. Experiments were done withKlebsiella aerogenes CCM 2318 in a

J. Páca

1978-01-01

150

The regulation of carbohydrate metabolism in Klebsiella aerogenes NCTC 418 organisms, growing in chemostat culture  

Microsoft Academic Search

Klebsiella aerogenes NCTC 418 was grown in chemostat cultures (D=0.17 hr-1; pH 6.8; 35° C) that were, successively, carbon-, sulphate-, ammonia-, and phosphate-limited, and which contained as the sole carbon-substrate first glucose, then glycerol, mannitol and lactate. Quantitative analyses of carbon-substrate used and products formed allowed carbon balances to be constructed and direct comparisons to be made of the effciency

O. M. Neijssel; D. W. Tempest

1975-01-01

151

Process development of continuous hydrogen production by Enterobacter aerogenes in a packed column reactor  

Microsoft Academic Search

Hydrogen bioproduction from agro-industrial residues by Enterobacter aerogenes in a continuous packed column has been investigated and a complete reactor characterization is presented. Experimental runs carried out at different residence time, liable of interest for industrial application, showed hydrogen yields ranging from 1.36 to 3.02 mmolH2mmolуglucose or, in other words, from 37.5% to 75% of the theoretical hydrogen yield. A

E. Palazzi; B. Fabiano; P. Perego

2000-01-01

152

Isolation of poly-alpha-L-guluronate lyase from Klebsiella aerogenes.  

PubMed

The bacterium Klebsiella aerogenes type 25 produces an extracellular alginolyase which has been partly purified. The enzyme is specific for the alpha-L-guluronosyl linkages in whole alginate and fractions therefrom. The end products of its action on polyguluronic acid blocks are mainly the unsaturated di- and tri-saccharides, with a smaller proportion of the homologous tetrasaccharide. Some general properties of the enzyme are reported. PMID:332364

Boyd, J; Turvey, J R

1977-08-01

153

Deletion of lactate dehydrogenase in Enterobacter aerogenes to enhance 2,3-butanediol production.  

PubMed

2,3-Butanediol is an important bio-based chemical product, because it can be converted into several C4 industrial chemicals. In this study, a lactate dehydrogenase-deleted mutant was constructed to improve 2,3-butanediol productivity in Enterobacter aerogenes. To delete the gene encoding lactate dehydrogenase, ? Red recombination method was successfully adapted for E. aerogenes. The resulting strain produced a very small amount of lactate and 16.7% more 2,3-butanediol than that of the wild-type strain in batch fermentation. The mutant and its parental strain were then cultured with six different carbon sources, and the mutant showed higher carbon source consumption and microbial growth rates in all media. The 2,3-butanediol titer reached 69.5 g/l in 54 h during fed-batch fermentation with the mutant,which was 27.4% higher than that with the parental strain.With further optimization of the medium and aeration conditions,118.05 g/l 2,3-butanediol was produced in 54 h during fed-batch fermentation with the mutant. This is by far the highest titer of 2,3-butanediol with E. aerogenes achieved by metabolic pathway engineering. PMID:22297429

Jung, Moo-Young; Ng, Chiam Yu; Song, Hyohak; Lee, Jinwon; Oh, Min-Kyu

2012-07-01

154

Genetic transformation of intact Lactococcus lactis subsp. lactis by high-voltage electroporation.  

PubMed Central

To apply recombinant DNA techniques for genetic manipulation of the industrially important lactococci, an efficient and reliable high-frequency transformation system must be available. High-voltage electric pulses have been demonstrated to enhance uptake of DNA into protoplasts and intact cells of numerous gram-negative and gram-positive microorganisms. The objective of this study was to develop a system for electroporating intact cells of Lactococcus lactis subsp. lactis LM0230 (previously designated Streptococcus lactis LM0230) with a commercially available electroporation unit (BTX Transfector 100; BTX, Inc., San Diego, Calif.). Parameters which influenced the efficiency of transformation included growth phase and final concentration of cells, ionic strength of the suspending medium, concentration of plasmid DNA, and the amplitude and duration of the pulse. Washed suspensions of intact cells suspended in deionized distilled water were subjected to one high-voltage electric pulse varying in voltage (300 to 900 V corresponding to field strengths of 5 to 17 kV/cm) and duration (100 microseconds to 1 s). Transformation efficiencies of 10(3) transformants per microgram of DNA were obtained when dense suspensions (final concentration, 5 x 10(10) CFU/ml) of stationary-phase cells were subjected to one pulse with a peak voltage of 900 V (field strength, 17 kV/cm) and a pulse duration of 5 ms in the presence of plasmid DNA. Dilution of porated cells in broth medium followed by an expression period of 2 h at 30 degrees C was beneficial in enhancing transformation efficiencies. Plasmids ranging in size from 9.8 to 30.0 kilobase pairs could be transformed by this procedure. Images

McIntyre, D A; Harlander, S K

1989-01-01

155

Low-redundancy sequencing of the entire Lactococcus lactis IL1403 genome  

Microsoft Academic Search

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

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

1999-01-01

156

Cloning, Expression, and Characterization of the Lactococcus lactis pfl Gene, Encoding Pyruvate Formate-Lyase  

Microsoft Academic Search

The Lactococcus lactis pfl gene, encoding pyruvate formate-lyase (PFL), has been cloned and characterized. The deduced amino acid sequence of the L. lactis PFL protein showed high similarity to those of other bacterial PFL proteins and included the conserved glycine residue involved in posttranslational activation of PFL. The genetic organization of the chromosomal pfl region in L. lactis showed differences

FLEMMING JØRGENSEN; SØREN M. MADSEN; ASTRID VRANG; HANS ISRAELSEN

1997-01-01

157

Effect of ph and salt gradient on the autolysis of Lactococcus lactis strains  

PubMed Central

The aim of this work was to assess in-vitro the effect of pH and salt concentration on the rate of autolysis in L. lactis strains. Regardless autolysis variation among L. lactis strains, statistical analysis showed evidence of increase of autolysis in L. lactis under low salt concentration and acidic conditions.

Ramirez-Nunez, Jennifer; Romero-Medrano, Ruth; Nevarez-Moorillon, Guadalupe V.; Gutierrez-Mendez, Nestor

2011-01-01

158

Acanthamoeba castellanii of the T4 genotype is a potential environmental host for Enterobacter aerogenes and Aeromonas hydrophila  

PubMed Central

Background Acanthamoeba can interact with a wide range of microorganisms such as viruses, algae, yeasts, protists and bacteria including Legionella pneumophila, Pseudomonas aeruginosa, Vibrio cholerae, Helicobacter pylori, Listeria monocytogenes, Mycobacterium spp., and Escherichia coli. In this capacity, Acanthamoeba has been suggested as a vector in the transmission of bacterial pathogens to the susceptible hosts. Methods Here, we used a keratitis isolate of A. castellanii of the T4 genotype and studied its interactions with two bacterial genera which have not been tested before, Enterobacter aerogenes, and Aeromonas hydrophila, as well as E. coli. Assays were performed to determine bacterial association with and invasion of A. castellanii. Additionally, bacterial survival intracellular of A. castellanii trophozoites as well as cysts was determined. Results All three bacterial isolates tested, associated, invaded, and survived inside A. castellanii trophozoites as well as A. castellanii cysts. However, E. aerogenes and E. coli exhibited significantly reduced association with and invasion of A. castellanii as compared with A. hydrophila (P?aerogenes (3.96?±?0.7 bacteria:amoeba ratio) and E. coli (5.85?±?1.1 bacteria:amoeba ratio). A. hydrophila, E. coli, and E. aerogenes remained viable during the encystment process and exhibited higher levels of recovery from mature cysts (14.13?±?0.89 A. hydrophila:amoeba ratio, 10.13?±?1.17 E. aerogenes:amoeba ratio, and 11.95?±?0.7 E. coli:amoeba ratio). Conclusions A. hydrophila and E. aerogenes also joined the ranks of other bacteria that could benefit from A. castellanii. Because cysts can be airborne, these findings suggest that Acanthamoeba is a potential vector in the transmission of A. hydrophila and E. aerogenes to susceptible hosts.

2013-01-01

159

Expression of Plant Flavor Genes in Lactococcus lactis? †  

PubMed Central

Lactic acid bacteria, such as Lactococcus lactis, are attractive hosts for the production of plant-bioactive compounds because of their food grade status, efficient expression, and metabolic engineering tools. Two genes from strawberry (Fragaria x ananassa), encoding an alcohol acyltransferase (SAAT) and a linalool/nerolidol synthase (FaNES), were cloned in L. lactis and actively expressed using the nisin-induced expression system. The specific activity of SAAT could be improved threefold (up to 564 pmol octyl acetate h?1 mg protein?1) by increasing the concentration of tRNA1Arg, which is a rare tRNA molecule in L. lactis. Fermentation tests with GM17 medium and milk with recombinant L. lactis strains expressing SAAT or FaNES resulted in the production of octyl acetate (1.9 ?M) and linalool (85 nM) to levels above their odor thresholds in water. The results illustrate the potential of the application of L. lactis as a food grade expression platform for the recombinant production of proteins and bioactive compounds from plants.

Hernandez, Igor; Molenaar, Douwe; Beekwilder, Jules; Bouwmeester, Harro; van Hylckama Vlieg, Johan E. T.

2007-01-01

160

Expression of plant flavor genes in Lactococcus lactis.  

PubMed

Lactic acid bacteria, such as Lactococcus lactis, are attractive hosts for the production of plant-bioactive compounds because of their food grade status, efficient expression, and metabolic engineering tools. Two genes from strawberry (Fragaria x ananassa), encoding an alcohol acyltransferase (SAAT) and a linalool/nerolidol synthase (FaNES), were cloned in L. lactis and actively expressed using the nisin-induced expression system. The specific activity of SAAT could be improved threefold (up to 564 pmol octyl acetate h-1 mg protein-1) by increasing the concentration of tRNA1Arg, which is a rare tRNA molecule in L. lactis. Fermentation tests with GM17 medium and milk with recombinant L. lactis strains expressing SAAT or FaNES resulted in the production of octyl acetate (1.9 microM) and linalool (85 nM) to levels above their odor thresholds in water. The results illustrate the potential of the application of L. lactis as a food grade expression platform for the recombinant production of proteins and bioactive compounds from plants. PMID:17209074

Hernández, Igor; Molenaar, Douwe; Beekwilder, Jules; Bouwmeester, Harro; van Hylckama Vlieg, Johan E T

2007-01-05

161

The Complete Genome Sequence of the Lactic Acid Bacterium Lactococcus lactis ssp. lactis IL1403  

PubMed Central

Lactococcus lactis is a nonpathogenic AT-rich gram-positive bacterium closely related to the genus Streptococcus and is the most commonly used cheese starter. It is also the best-characterized lactic acid bacterium. We sequenced the genome of the laboratory strain IL1403, using a novel two-step strategy that comprises diagnostic sequencing of the entire genome and a shotgun polishing step. The genome contains 2,365,589 base pairs and encodes 2310 proteins, including 293 protein-coding genes belonging to six prophages and 43 insertion sequence (IS) elements. Nonrandom distribution of IS elements indicates that the chromosome of the sequenced strain may be a product of recent recombination between two closely related genomes. A complete set of late competence genes is present, indicating the ability of L. lactis to undergo DNA transformation. Genomic sequence revealed new possibilities for fermentation pathways and for aerobic respiration. It also indicated a horizontal transfer of genetic information from Lactococcus to gram-negative enteric bacteria of Salmonella-Escherichia group. [The sequence data described in this paper has been submitted to the GenBank data library under accession no. AE005176.

Bolotin, Alexander; Wincker, Patrick; Mauger, Stephane; Jaillon, Olivier; Malarme, Karine; Weissenbach, Jean; Ehrlich, S. Dusko; Sorokin, Alexei

2001-01-01

162

[Characteristics and identification of bacteriocins produced by Lactococcus lactis subsp. lactis 194-K].  

PubMed

The Lactococcus lactis subsp. lactis 194-K strain has been established to be able to produce two bacteriocins, one of which was identified as the known lantibiotic nisin A, and the other 194-D bacteriocin represents a polypeptide with a 2589-Da molecular mass and comprises 20 amino acid residues. Both bacteriocins were produced in varying proportions in all of the studied nutrient media, which support the growth of the producer. Depending on the cultivation medium, the nisin A content was 380- to 1123-fold lower in the 194-K stain culture fluid than that of the 194-D peptide. In comparision to to nisin A Bacteriocin 194-D possessed a wide range of antibacterial activity and suppressed the growth of both Gram-positive and Gram-negative bacteria. An optimal medium for 194-D bacteriocin synthesis was shown to be a fermentation medium which contained yeast extract, casein hydrolysate, and potassium phosphate. The biosynthesis ofbacteriocin 194-D by the 194-K strain in these media occurred parallel to producer growth, and its maximal accumulation in the culture fluid was observed at 14-20 h of the strain's growth. PMID:23330388

Ustiugova, E A; Timofeeva, A V; Stoianova, L G; Netrusov, A I; Katrukha, G S

163

Expression, purification, and characterization of thymidylate synthase from Lactococcus lactis.  

PubMed Central

The thymidylate synthase (TS) gene from Lactococcus lactis has been highly expressed in Escherichia coli. The TS protein was purified by sequential chromatography on Q-Sepharose and phenyl-Sepharose. Six grams of cell pellet yielded 140 mg of homogeneous TS. TS is a highly conserved enzyme, and several of the conserved amino acid residues that have been implicated in catalytic function are altered in L. lactis TS. By use of a 3-dimensional homology model, we have predicted covariant changes that might compensate for these differences. With the large amounts of L. lactis TS now available, studies can be pursued to understand the structure-function relationships of this enzyme compared to other TSs and to confirm the presumed roles of the compensatory changes predicted in the homology model.

Greene, P. J.; Yu, P. L.; Zhao, J.; Schiffer, C. A.; Santi, D.

1994-01-01

164

Genome-wide metabolic (re-) annotation of Kluyveromyces lactis  

PubMed Central

Background Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome. Results In this work, a new metabolic genome-wide functional re-annotation of the proteins encoded in the Kluyveromyces lactis genome was performed, resulting in the annotation of 1759 genes with metabolic functions, and the development of a methodology supported by merlin (software developed in-house). The new annotation includes novelties, such as the assignment of transporter superfamily numbers to genes identified as transporter proteins. Thus, the genes annotated with metabolic functions could be exclusively enzymatic (1410 genes), transporter proteins encoding genes (301 genes) or have both metabolic activities (48 genes). The new annotation produced by this work largely surpassed the Kluyveromyces lactis currently available annotations. A comparison with KEGG’s annotation revealed a match with 844 (~90%) of the genes annotated by KEGG, while adding 850 new gene annotations. Moreover, there are 32 genes with annotations different from KEGG. Conclusions The methodology developed throughout this work can be used to re-annotate any yeast or, with a little tweak of the reference organism, the proteins encoded in any sequenced genome. The new annotation provided by this study offers basic knowledge which might be useful for the scientific community working on this model yeast, because new functions have been identified for the so-called metabolic genes. Furthermore, it served as the basis for the reconstruction of a compartmentalized, genome-scale metabolic model of Kluyveromyces lactis, which is currently being finished.

2012-01-01

165

Rapid PCR-Based Method Which Can Determine Both Phenotype and Genotype of Lactococcus lactis Subspecies  

PubMed Central

A highly efficient, rapid, and reliable PCR-based method for distinguishing Lactococcus lactis subspecies (L. lactis subsp. lactis and L. lactis subsp. cremoris) is described. Primers complementary to positions in the glutamate decarboxylase gene have been constructed. PCR analysis with extracted DNA or with cells of different L. lactis strains resulted in specific fragments. The length polymorphism of the PCR fragments allowed a clear distinction of the L. lactis subspecies. The amplified fragment length polymorphism with the primers and the restriction fragment length polymorphism of the amplified products agreed perfectly with the identification based on genotypic and phenotypic analyses, respectively. Isolates from cheese starters were investigated by this method, and amplified fragments of genetic variants were found to be approximately 40 bp shorter than the typical L. lactis subsp. cremoris fragments.

Nomura, Masaru; Kobayashi, Miho; Okamoto, Takashi

2002-01-01

166

Heterologous protein production in the yeast Kluyveromyces lactis.  

PubMed

Kluyveromyces lactis is both scientifically and biotechnologically one of the most important non-Saccharomyces yeasts. Its biotechnological significance builds on its history of safe use in the food industry and its well-known ability to produce enzymes like lactase and bovine chymosin on an industrial scale. In this article, we review the various strains, genetic techniques and molecular tools currently available for the use of K. lactis as a host for protein expression. Additionally, we present data illustrating the recent use of proteomics studies to identify cellular bottlenecks that impede heterologous protein expression. PMID:16630278

van Ooyen, Albert J J; Dekker, Peter; Huang, Michael; Olsthoorn, Maurien M A; Jacobs, Denise I; Colussi, Paul A; Taron, Christopher H

2006-05-01

167

Expression of the Arxula adeninivorans glucoamylase gene in Kluyveromyces lactis.  

PubMed

The glucoamylase gene of the yeast Arxula adeninivorans was expressed in Kluyveromyces lactis by using the GAP promoter from Saccharomyces cerevisiae and a multicopy plasmid vector. The transformants secreted 90.1% of the synthesized glucoamylase into the culture medium. The secreted glucoamylase activities are about 20 times higher in comparison to those of Saccharomyces cerevisiae transformants using the same promoter. Secreted glucoamylase possesses identical N-terminal amino acid sequences to those secreted by A. adeninivorans showing that cleavage of the N-terminal signal peptide takes place at the same site. Biochemical characteristics of glucoamylase expressed by K. lactis and A. adeninivorans are very similar. PMID:8920185

Bui, D M; Kunze, I; Horstmann, C; Schmidt, T; Breunig, K D; Kunze, G

1996-03-01

168

Identification of the theta-type minimal replicon of the Lactococcus lactis subsp. lactis CNRZ270 lactose protease plasmid pUCL22  

Microsoft Academic Search

The replication region of pUCL22, the lactose-protease plasmid ofLactococcus lactis subsp.lactis (Lc. lactis) CNRZ270, was isolated on an 18-kbBamHI fragment, by cloning into pUCB300, anEscherichia coli vector encoding Emr, and selecting for Emr inLc. lactis MG1614. Subcloning and deletion analysis localized the replication region, namedRep22, on a 2.3-kb fragment. Replicons based on this region followed a theta-type mechanism of replication

Jacques Frère; Abdellah Benachour; Madeleine Novel; Georges Novel

1993-01-01

169

Gene inactivation in Lactococcus lactis: histidine biosynthesis.  

PubMed Central

Lactococcus lactis strains from dairy and nondairy sources were tested for the ability to grow in the absence of histidine. Among 60 dairy strains tested, 56 required histidine, whereas only 1 of 11 nondairy strains had this requirement. Moreover, 10 of the 56 auxotrophic strains were able to grow in the presence of histidinol (Hol+), the immediate histidine precursor. This indicates that adaptation to milk often results in histidine auxotrophy. The histidine operon was detected by Southern hybridization in eight dairy auxotrophic strains tested. A large part of the histidine operon (8 kb, containing seven histidine biosynthetic genes and three unrelated open reading frames [ORFs]) was cloned from an auxotroph, which had an inactive hisD gene, as judged by its inability to grow on histidinol. Complementation analysis of three genes, hisA, hisB, and hisG, in Escherichia coli showed that they also were inactive. Sequence analysis of the cloned histidine region, which revealed 98.6% overall homology with that of the previously analyzed prototrophic strain, showed the presence of frameshift mutations in three his genes, hisC, hisG, and hisH, and two genes unrelated to histidine biosynthesis, ORF3 and ORF6. In addition, several mutations were detected in the promoter region of the operon. Northern (RNA) hybridization analysis showed a much lower amount of the his transcript in the auxotrophic strain than in the prototrophic strain. The mutations detected account for the histidine auxotrophy of the analyzed strain. Certain other dairy auxotrophic strains carry a lower number of mutations, since they were able to revert either to a Hol+ phenotype or to histidine prototrophy. Images

Delorme, C; Godon, J J; Ehrlich, S D; Renault, P

1993-01-01

170

Towards Enhanced Galactose Utilization by Lactococcus lactis?  

PubMed Central

Accumulation of galactose in dairy products due to partial lactose fermentation by lactic acid bacteria yields poor-quality products and precludes their consumption by individuals suffering from galactosemia. This study aimed at extending our knowledge of galactose metabolism in Lactococcus lactis, with the final goal of tailoring strains for enhanced galactose consumption. We used directed genetically engineered strains to examine galactose utilization in strain NZ9000 via the chromosomal Leloir pathway (gal genes) or the plasmid-encoded tagatose 6-phosphate (Tag6P) pathway (lac genes). Galactokinase (GalK), but not galactose permease (GalP), is essential for growth on galactose. This finding led to the discovery of an alternative route, comprising a galactose phosphotransferase system (PTS) and a phosphatase, for galactose dissimilation in NZ9000. Introduction of the Tag6P pathway in a galPMK mutant restored the ability to metabolize galactose but did not sustain growth on this sugar. The latter strain was used to prove that lacFE, encoding the lactose PTS, is necessary for galactose metabolism, thus implicating this transporter in galactose uptake. Both PTS transporters have a low affinity for galactose, while GalP displays a high affinity for the sugar. Furthermore, the GalP/Leloir route supported the highest galactose consumption rate. To further increase this rate, we overexpressed galPMKT, but this led to a substantial accumulation of ?-galactose 1-phosphate and ?-glucose 1-phosphate, pointing to a bottleneck at the level of ?-phosphoglucomutase. Overexpression of a gene encoding ?-phosphoglucomutase alone or in combination with gal genes yielded strains with galactose consumption rates enhanced up to 50% relative to that of NZ9000. Approaches to further improve galactose metabolism are discussed.

Neves, Ana R.; Pool, Wietske A.; Solopova, Ana; Kok, Jan; Santos, Helena; Kuipers, Oscar P.

2010-01-01

171

[Isolation and various properties of alpha-aminocaprolactam hydrolase from Klebsiella aerogenes].  

PubMed

L-alpha-aminocaprolactam hydrolase possessing the L lysine amidase activity was isolated from Klebsiella aerogenes and purified. The procedure of enzymes purification included cell destruction on USDN-I, fractionation by ammonium sulfate, gel chromatography on G-200. The preparation of the purified enzyme possessed specific activity of 50 mumol of lysin per 1 mg of protein per hour. Km was 2.6 mM in case of phosphate buffer (ph 7.2) for I-alpha-aminocaprolactam. Besides L-alpha-aminocaprolactam the enzyme hydrolyses lysine amide, leucine amide tryptophanamide. Magnesium ions are necessary for manifestation of catalytic activity of the enzyme. PMID:1519339

Kliment'eva, T A; Brel', A K

172

Heterologous expression of a hydrogenase gene in Enterobacter aerogenes to enhance hydrogen gas production  

Microsoft Academic Search

The hydrogenase gene from Enterobacter cloacae (IIT-BT 08) was amplified and inserted into a prokaryotic expression vector to create a recombinant plasmid (pGEX-4T-2-Cat\\/hydA).\\u000a The recombinant plasmid was transformed into a hydrogen-producing strain of Enterobacter aerogenes (ATCC13408). SDS–PAGE and western blot analysis confirmed the successful expression of the GST-tagged hydA protein. Anaerobic\\u000a fermentation for the production of hydrogen from glucose was

Jin-Fang Zhao; Wen-Lu Song; Jun Cheng; Chuan-Xi Zhang

2010-01-01

173

Optimization and mechanism of diacetyl accumulation by Enterobacter aerogenes mutant UV3  

Microsoft Academic Search

A mutant designated as UV-3 was obtained from wild-type Enterobacter aerogenes 10293 through u.v. radiation. The activities of ?-acetolactate decarboxylase (Ald), lactate dehydrogenase (Ldh) and diacetyl\\u000a reductase (Dr) in UV-3 were strongly attenuated, with the lowest activities at pH 7.0–7.5, and temperature between 36 and\\u000a 39°C. Compared to the wild-type, the yield of diacetyl by UV-3 was increased 18.7-fold, up

Ling Zhao; Yongming Bao; Jingyun Wang; Boshi Liu; Lijia An

2009-01-01

174

Deformation of Lactococcus lactis surface in atomic force microscopy study  

Microsoft Academic Search

The surface of the bacterium Lactococcus lactis was investigated under water by contact mode atomic force microscopy (AFM) while varying the imaging parameters (imaging force, scanning velocity, scanning direction). Height images were three-dimensionally (3-D) reconstructed using GOCAD© software; this revealed grooves oriented along the scanning direction. Although the grooves were created by the scanning probe, they were not due to

Christophe J. P Boonaert; Valérie Toniazzo; Christian Mustin; Yves F Dufrêne; Paul G Rouxhet

2002-01-01

175

Specificity of Milk Peptide Utilization by Lactococcus lactis  

PubMed Central

To study the substrate specificity of the oligopeptide transport system of Lactococcus lactis for its natural substrates, the growth of L. lactis MG1363 was studied in a chemically defined medium containing milk peptides or a tryptic digest of ?s2-casein as the source of amino acids. Peptides were separated into acidic, neutral, and basic pools by solid-phase extraction or by cation-exchange liquid chromatography. Their ability to sustain growth and the time course of their utilization demonstrated the preferential use of hydrophobic basic peptides with molecular masses ranging between 600 and 1,100 Da by L. lactis MG1363 and the inability to use large, acidic peptides. These peptide utilization preferences reflect the substrate specificity of the oligopeptide transport system of the strain, since no significant cell lysis was inferred. Considering the free amino acid content of milk and these findings on peptide utilization, it was demonstrated that the cessation of growth of L. lactis MG1363 in milk was due to deprivation of leucine and methionine.

Juillard, Vincent; Guillot, Alain; Le Bars, Dominique; Gripon, Jean-Claude

1998-01-01

176

In situ delivery of cytokines by genetically engineered Lactococcus lactis  

Microsoft Academic Search

The development of novel approaches that allow for accurate targeting of therapeutics to the bowel mucosa is a priority in the research on inflammatory bowel disease. We have engineered Lactococcus lactis to secrete soluble, fully active, correctly processed cytokines. We have used these live, recombinant strains for the in situ delivery of mouse interleukin (mIL)-2, -6 and -10 at airway

Lothar Steidler

2002-01-01

177

[Components of fermentation medium regulate bacteriocin synthesis by the recombinant strain Lactococcus lactis subsp. lactis F-116].  

PubMed

The regulation of the synthesis of bacteriocin produced by the recombinant strain Lactococcus lactis subsp. lactis F-116 has been studied. The synthesis is regulated by the components of the fermentation medium, the content of inorganic phosphate (KH2PO4), yeast autolysate (source of amine nitrogen), and changes in carbohydrates and amino acids. The strain was obtained by fusion of protoplasts derived from two related L. lactis subsp. lactis strains, both exhibiting a weak ability to synthesize the bacteriocin nisin. Decreasing the content of KH2PO4 from 2.0 to 1.0 or 0.5% caused bacteriocin production to go down from 4100 to 2800 or 1150 IU/ml, respectively; the base fermentation medium contained 1.0% glucose, 0.2% NaCl, 0.02% MgSO4, and yeast autolysate (an amount corresponding to 35 mg % ammonium nitrogen). The substitution of sucrose for glucose (as the source of carbon) increased the antibiotic activity by 26%, and the addition of isoleucine, by 28.5%. Elevation of the concentration of yeast autolysate in the low-phosphate fermentation medium stimulated both the growth of the lactococci and the synthesis of bacteriocin. Introduction of 1% KH2PO4, yeast autolysate (in an amount corresponding to 70 mg % ammonium nitrogen), 2.0% sucrose, and 0.1% isoleucine increased the bacteriocin-producing activity of the strain by 2.4 times. PMID:16871800

Stoianova, L G; Levina, N A

178

Isolation and characterization of a bacteriophage F20 virulent to Enterobacter aerogenes.  

PubMed

An aquatic phage, designated F20, was characterized and its physico-chemical characteristics studied. F20 was specifically virulent to only two strains of Enterobacter aerogenes (ATCC 13048 and the multi-drug-resistant strain K113) among other species tested (n?=?15). It was classified in the family Siphoviridae of T1-like viruses and contained a linear dsDNA genome estimated to be 51.5 kbp enclosed by an isometric capsid of 50±2 nm in diameter and a tail of 150±3 nm in length. F20 was able to survive in a broad pH range between 4 and 11, showed potential for future animal trials using oral solution and resisted chloroform and ethanol. It exhibited remarkable stability between room temperature and 70 °C for up to 150 min, and even up to 6 months at room temperature. Knowledge of this phage belonging to the widespread T1-like viruses might be helpful for adopting therapeutic strategies against E. aerogenes. PMID:22764320

Mishra, Charitra Kumar; Choi, Tae Jin; Kang, Sun Chul

2012-07-04

179

EFFECT OF l-CYSTINE ON INITIATION OF ANAEROBIC GROWTH OF ESCHERICHIA COLI AND AEROBACTER AEROGENES  

PubMed Central

Gorini, Luigi (Harvard Medical School, Boston, Mass.). Effect of l-cystine on initiation of anaerobic growth of Escherichia coli and Aerobacter aerogenes. J. Bacteriol. 82:305–312. 1961.—Under anaerobic conditions Escherichia coli and Aerobacter aerogenes, inoculated in a mineral-citrate-glucose medium at densities up to 106 bacteria per ml, exhibit a long lag, or fail to initiate growth at all. Growth is initiated rapidly if the medium is supplemented with various SH or SS compounds. Of these the most active is l-cystine, which is fully effective at 1 to 2 ?m. In a heavily seeded semisolid medium without cystine, turbidity rapidly appears at the aerobic surface and then slowly extends throughout the anaerobic region of the culture. This finding implies that a sufficiently dense anaerobically growing culture creates conditions in the medium which eliminate the requirement for cystine. The nature of this effect on the medium has not been determined, but certain possibilities (pH, pCO2) have been eliminated. The anaerobic cystine requirement becomes more pronounced in the presence of Cu++, at concentrations far lower than those required for inhibition under aerobic conditions. While it is possible that cystine is acting by complexing the toxic metal ion, it seems more likely that l-cystine is an essential metabolite, poorly produced under anaerobic conditions, and that the marked toxicity of Cu++ under anaerobic conditions depends on its complexing of cystine.

Gorini, Luigi

1961-01-01

180

Requirement for sodium in the anaerobic growth of Aerobacter aerogenes on citrate.  

PubMed

Anaerobic growth of Aerobacter aerogenes on citrate as a carbon source required the presence of Na(+). The growth rate increased with increasing Na(+) concentration and was optimal at 0.10 m Na(+). The requirement was specific for Na(+), which could not be replaced by K(+), NH(4) (+), Li(+), Rb(+), or Cs(+). K(+) was required for growth in the presence of Na(+), the optimal K(+) concentration being 0.15 mm. Enzyme profiles were determined on cells grown in three different media: (i) intermediate Na(+), high K(+) concentration, (ii) high Na(+), high K(+) concentration, and (c) high Na(+), low K(+) concentration. All cells contained the enzymes of the citrate fermentation pathway, namely, citritase and the Na(+)-requiring oxalacetate (OAA) decarboxylase. All of the enzymes of the citric acid cycle were present, except alpha-ketoglutarate dehydrogenase which could not be detected. The incomplete citric acid cycle was, in effect, converted into two biosynthetic pathways leading to glutamate and succinate, respectively. The specific activities of citritase and OAA decarboxylase were lowest in medium (i), and under these conditions the activity of OAA decarboxylase appeared to be limited in vivo by the availability of Na(+). Failure of A. aerogenes to grow anaerobically on citrate in the absence of Na(+) can be explained at the enzymatic level by the Na(+) requirement of the OAA decarboxylase step of the citrate fermentation pathway and by the absence of an alternate pathway of citrate catabolism. PMID:5784198

O'Brien, R W; Stern, J R

1969-05-01

181

Histamine production by Enterobacter aerogenes in sailfish and milkfish at various storage temperatures.  

PubMed

Enterobacter aerogenes was studied for its growth and ability to promote the formation of total volatile base nitrogen (TVBN) and histamine in sailfish (Istiophorus platypterus) and milkfish (Chanos chanos) stored at various temperatures from -20 to 37 degrees C. The optimal temperature for bacterial growth in both fish species was 25 degrees C, whereas the optimal temperature for histamine formation was 37 degrees C. The two fish species inoculated with E. aerogenes, when not properly stored at low temperatures such as 15 degrees C for 36 h, formed histamine at above the U.S. Food and Drug Administration hazardous guideline level of 50 mg/100 g. Milkfish was a better substrate than sailfish for histamine formation by bacterial histidine decarboxylation at elevated temperatures (> 15 degrees C). Although higher contents of TVBN were detected in the spiked sailfish than milkfish during the same storage time at temperatures above 15 degrees C, the use of the 30-mg/100 g level of TVBN as a determination index for fish quality and decomposition was not a good criterion for assessing potential histamine hazard for both fish species. Bacterial growth was controlled by cold storage of the fish at 4 degrees C or below, but histamine formation was stopped only by frozen storage. Once the frozen fish samples were thawed and stored at 25 degrees C, histamine started to accumulate rapidly and reached levels greater than the hazardous action level in 36 h. PMID:21132980

Tsai, Yung-Hsiang; Chang, Shiou-Chung; Kung, Hsien-Feng; Wei, Cheng-I; Hwang, Deng-Fwu

2005-08-01

182

Modification of Outer Membrane Protein Profile and Evidence Suggesting an Active Drug Pump in Enterobacter aerogenes Clinical Strains  

Microsoft Academic Search

Two clinical strains of Enterobacter aerogenes that exhibited phenotypes of multiresistance to -lactam antibiotics, fluoroquinolones, chloramphenicol, tetracycline, and kanamycin were investigated. Both strains showed a porin pattern different from that of a susceptible strain, with a drastic reduction in the amount of the major porin but with an apparently conserved normal structure (size and immunogenicity), together with overproduction of two

Stephane Gayet; Renaud Chollet; Gerard Molle; Jean-Marie Pages

2003-01-01

183

Regulation of nitrogen metabolism in Escherichia coli and Klebsiella aerogenes: studies with the continuous-culture technique.  

PubMed Central

Ammonia-nitrogen-limited continuous cultures of Escherichia coli and Klebsiella aerogenes contain induced levels of glutamine synthetase that is deadenylyated (i.e., fully active). In the presence of excess ammonia or glutamate in glucose-limited cultures of E. coli, glutamine synthetase is repressed and adenylylated (inactive). The average state of adenylylation (n) is a linear function of the specific growth rate. At low specific growth rates, glutamine synthetase is adenylylated; as the specific growth rate increases, n decreases, approaching 0 to 2 at rapid growth rates. The average state of adenylylation correlates well with the intracellular concentrations and ratios of alpha-ketoglutarate and glutamine, which are key effectors in the adenylylation-deadenylylation systems. E. coli and K. aerogenes differ markedly in their growth yields, growth rates, and enzymatic composition during nitrogen limitation. The data suggest that, unlike K. aerogenes, E. coli W uses glutamate dehydrogenase to incorporate ammonia during nitrogen limitation. In E. coli, glutamate dehydrogenase is progressively induced during nitrogen limitation when mu (growth rate) approaches mumax. In contrast, in K. aerogenes glutamate dehydrogenase is repressed during nitrogen limitation, whereas glutamate synthase, an alternative supplier of glutamate to the cell, is induced. Data are presented that support the regulatory schemes proposed for the control of glutamine synthetase activity by induction-repression phenomena and adenylylation-deadenylylation reaction. We propose that the intracellular ratio of alpha-ketoglutarate to glutamine may be the most important physiological parameter in determining the activity of glutamine synthetase.

Senior, P J

1975-01-01

184

The Influence of Dissolved Oxygen Concentration on the Respiration and Glucose Metabolism of Klebsiella aerogenes during Growth  

Microsoft Academic Search

SUMMARY The influence of dissolved oxygen concentration on the metabolism and respiration of growing Klebsiella aerogenes NCTC 8017 was studied by means of a continuous-flow culture technique. Different dissolved oxygen tensions (equivalent partial pressures) were obtained by varying the partial pressure of oxygen in the gas phase. The respiration rate (oxygen uptake rate per unit mass organism) was independent of

D. E. F. HARRISON; S. J. PIRT

1967-01-01

185

Metabolic and energetic aspects of the growth of Klebsiella aerogenes NCTC 418 on glucose in anaerobic chemostat culture  

Microsoft Academic Search

Klebsiella aerogenes NCTC 418 was cultured anaerobically in chemostat cultures (pH 6.8; 35° C) under carbon, phosphate-, ammonia-, sulphate- and potassium-limited conditions with glucose as the sole carbon- and energy source. The rates of uptake of glucose and excretion of fermentation products were quantitatively determined and carbon, hydrogen- and oxygen balances were constructed with recoveries better than 90%.

M. J. Teixeira de Mattos; D. W. Tempest

1983-01-01

186

Expression of a chitinase gene from Serratia marcescens in Lactococcus lactis and Lactobacillus plantarum  

Microsoft Academic Search

A chitinase gene from the Gram-negative bacterium Serratia marcescens BJL200 was cloned in Lactococcus lactis subsp. lactis MG1363 and in the silage inoculum strain Lactobacillus plantarum E19b. The chitinase gene was expressed as an active enzyme at a low level in Lactococcus lactis, when cloned in the same transcriptional orientation as the gene specifying the replication protein of the vector

M. B. Brurberg; A. J. Haandrikman; K. J. Leenhouts; G. Venema; I. F. Nes

1994-01-01

187

Strains of Lactococcus lactis with a partial pyrimidine requirement show sensitivity toward aspartic acid  

Microsoft Academic Search

The growth rate of the widely used laboratory strain Lactococcus lactis subsp. cremoris LM0230 was reduced if aspartic acid were present in the growth medium. The strain LM0230 is a plasmid- and phage-cured derivative\\u000a of L. lactis subsp. cremoris C2, the ancestor of the original dairy isolate L. lactis subsp. cremoris NCDO712. The growth of both C2 and NCDO712 was

Steen Wadskov Hansen; Jan Martinussen

2009-01-01

188

Engineering of the Lactococcus lactis serine proteinase by construction of hybrid enzymes  

Microsoft Academic Search

Plasmids containing wild-type and hybrid proteinase genes were constructed from DNA fragments of the prtP genes of Lactococcus lactis strains Wg2 and SK11. These plasmids were introduced into the plasmid-free strain L. lactis MG1363. The serine proteinases produced by these L. lactis strains were isolated, and their cleavage specificity and rate towards ?s1-and ?-casein was investigated. The catalytic properties of

Pieter Vos; Ingrid J. Boerrigter; Girbe Buist; Alfred J. Haandrikman; Monique Nijhuis; Marjon B. de Reuver; Roland J. Siezen; Gerard Venema; Willem M. de Vos; Jan Kok

1991-01-01

189

Cloning in Streptococcus lactis of plasmid-mediated UV resistance and effect on prophage stability  

SciTech Connect

Plasmid pIL7 (33 kilobases) from Streptococcus lactis enhances UV resistance and prophage stability. A 5.4-kilobase pIL7 fragment carrying genes coding for both characters was cloned into S. lactis, using plasmid pHV1301 as the cloning vector. The recombinant plasmid was subsequently transferred to three other S. lactis strains by transformation or protoplast fusion. Cloned genes were expressed in all tested strains.

Chopin, M.C.; Chopin, A.; Rouault, A.; Simon, D.

1986-02-01

190

Transformation of Kluyveromyces lactis cells by plasmid DNA does not require alkaline cations  

Microsoft Academic Search

Summary A procedure for the transformation ofKluyveromyces lactis based on the Li salt method for introducing plasmid DNA into intact yeast cells is described. Contrary toSaccharomyces cerevisiae, lithium salts are dispensable for inducing competence inK. lactis. 2-Mercaptoethanol, a compound that stimulates transformation inS. cerevisiae, showed an opposite effect. inK. lactis. On the other hand, the presence of PEG 4000 and

Hilda M. Garcia; Roberto Vazquez; Julio Delgado

1985-01-01

191

Porosity of Lactococcus lactis subsp. lactis LD61 colonies immobilised in model cheese.  

PubMed

During cheese ripening, micro-organisms grow as immobilised colonies, metabolising substrates present in the matrix which generate products triggered by enzymatic reactions. Local limitation rates of diffusion, either in the matrix or within the bacterial colonies, can be responsible for modulation in the metabolic and enzymatic activities of micro-organisms during ripening. How bacterial colonies immobilised in cheese are porous to these diffusing solutes has never been explored. The objective of this study was to determine if fluorescent dextrans of different sizes (4.4, 70 and 155 kDa) are able to penetrate through colonies of Lactococcus lactis LD61 immobilised in solid media, either agar or model cheese. Confocal microscopic observations showed that lactococcus colonies immobilised in these two media were porous to dextrans from 4 kDa to 155 kDa. However, the rate of diffusion of the solutes was faster inside the colonies immobilised in ultrafiltered-cheese than in agar when large dextrans were considered (?70 kDa). The colonial shape of the lactococcus strain was also shown to be lenticular in agar and spherical in the model cheese, indicating that the physical pressure exerted on the colony by the surrounding casein network was probably isotropous in the UF-cheese but not in agar. In both cases, the fact that lactococcus colonies immobilised in solid media are porous to large dextran solutes suggests that substrates or enzymes are likely also to be able to migrate inside the colonies during cheese ripening. PMID:23558188

Floury, J; Jeanson, S; Madec, M-N; Lortal, S

2013-03-01

192

Secretion of biologically active porcine interleukin-2 by Lactococcus lactis.  

PubMed

In this study, secretion of two functional recombinant porcine interleukin-2 (rIL-2) proteins by Lactococcus lactis was studied. Two secretion cassettes were constructed in which the secretion was achieved by gene fusion between the lactococcal usp45 secretion signal, a synthetic propeptide and the sequence encoding the mature IL-2. In addition, one of the two secretion cassettes contained the H-domains of L. lactis PrtP. Both of the constructed recombinant IL-2 proteins were found to be secreted in the same quantities, approximately 0.5mg/l. According to a cell proliferative assay using CTLL-2 cell line the specific biological activities of both purified rIL-2 proteins were found to be of similar levels. PMID:16549279

Avall-Jääskeläinen, Silja; Palva, Airi

2006-03-23

193

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

PubMed Central

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.

Gueimonde, Miguel; Florez, Ana Belen; van Hoek, Angela H. A. M.; Stuer-Lauridsen, Birgitte; Str?man, Per; de los Reyes-Gavilan, Clara G.; Margolles, Abelardo

2010-01-01

194

Improvement of human interferon alpha secretion by Lactococcus lactis.  

PubMed

To improve the secretion and expression of human interferon alpha 2b (IFN) in Lactococcus lactis, a synthetic pro-peptide, LEISSTCDA (LEISS), was fused to the N-terminus of IFN. This gave a higher secretion efficiency (12% vs. 5%) and yield (approximately 2.8-fold) of IFN. The signal peptide, SP(SlpA) (SlpA, an S-layer protein of Lactobacillus brevis), was also tested to secrete IFN instead of SP(Usp45) (Usp45, the main secreted protein in L. lactis). This gave increased IFN secretion (approximately 3-fold) but lower total production. All the recombinant IFN had appropriate bioactivities in an antiviral assay. PMID:20431909

Zhang, Qiuxiang; Zhong, Jin; Liang, Xiaobo; Liu, Wenjun; Huan, Liandong

2010-04-30

195

Strain improvement of Lactobacillus lactis for d -lactic acid production  

Microsoft Academic Search

Three mutants, isolated by repeated UV mutagenesis of Lactobacillus lactis NCIM 2368, produced increased d-lactic acid concentrations. These mutants were compared with the wild type using 100 g hydrolyzed cane sugar\\/l in the fermentation\\u000a medium. One mutant, RM2-24, produced 81 g lactic acid\\/l which was over three times that of the wild type. The highest d-lactic acid (110 g\\/l) in batch fermentation was

D. S. Joshi; M. S. Singhvi; J. M. Khire; D. V. Gokhale

2010-01-01

196

Treatment of Murine Colitis by Lactococcus lactis Secreting Interleukin10  

Microsoft Academic Search

The cytokine interleukin-10 (IL-10) has shown promise in clinical trials for treatment of inflammatory bowel disease (IBD). Using two mouse models, we show that the therapeutic dose of IL-10 can be reduced by localized delivery of a bacterium genetically engineered to secrete the cytokine. Intragastric administration of IL-10-secreting Lactococcus lactis caused a 50% reduction in colitis in mice treated with

Lothar Steidler; Wolfgang Hans; Lieven Schotte; Sabine Neirynck; Florian Obermeier; Werner Falk; Walter Fiers; Erik Remaut

2000-01-01

197

Continuous nisin production with bioengineered Lactococcus lactis strains  

Microsoft Academic Search

Nisin production in continuous cultures of bioengineered Lactococcus lactis strains that incorporate additional immunity and regulation genes was studied. Highest nisin activities were observed at\\u000a 0.2 h–1 dilution rate and 12.5 g l–1 fructose concentration for all strains. Recombinant strains were able to produce greater amounts of nisin at dilution rates\\u000a below 0.3 h?1 compared to the control strain. However, this significant difference

Ö. ?im?ek; N. Akkoç; A. H. Çon; F. Özçelik; P. E. J. Saris; Mustafa Akçelik

2009-01-01

198

Modeling Lactococcus lactis using a genome-scale flux model  

Microsoft Academic Search

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)

Ana Paula Oliveira; Jens Nielsen; Jochen Förster

2005-01-01

199

Expression of the Arxula adeninivorans glucoamylase gene in Kluyveromyces lactis  

Microsoft Academic Search

The glucoamylase gene of the yeast Arxula adeninivorans was expressed in Kluyveromyces lactis by using the GAP promoter from Saccharomyces cerevisiae and a multicopy plasmid vector. The transformants secreted 90.1% of the synthesized glucoamylase into the culture medium.\\u000a The secreted glucoamylase activities are about 20 times higher in comparison to those of Saccharomyces cerevisiae transformants using the same promoter. Secreted

D. M. Bui; I. Kunze; C. Horstmann; T. Schmidt; K. D. Breunig; G. Kunze

1996-01-01

200

Mobile CRISPR/Cas-Mediated Bacteriophage Resistance in Lactococcus lactis  

PubMed Central

Lactococcus lactis is a biotechnological workhorse for food fermentations and potentially therapeutic products and is therefore widely consumed by humans. It is predominantly used as a starter microbe for fermented dairy products, and specialized strains have adapted from a plant environment through reductive evolution and horizontal gene transfer as evidenced by the association of adventitious traits with mobile elements. Specifically, L. lactis has armed itself with a myriad of plasmid-encoded bacteriophage defensive systems to protect against viral predation. This known arsenal had not included CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins), which forms a remarkable microbial immunity system against invading DNA. Although CRISPR/Cas systems are common in the genomes of closely related lactic acid bacteria (LAB), none was identified within the eight published lactococcal genomes. Furthermore, a PCR-based search of the common LAB CRISPR/Cas systems (Types I and II) in 383 industrial L. lactis strains proved unsuccessful. Here we describe a novel, Type III, self-transmissible, plasmid-encoded, phage-interfering CRISPR/Cas discovered in L. lactis. The native CRISPR spacers confer resistance based on sequence identity to corresponding lactococcal phage. The interference is directed at phages problematic to the dairy industry, indicative of a responsive system. Moreover, targeting could be modified by engineering the spacer content. The 62.8-kb plasmid was shown to be conjugally transferrable to various strains. Its mobility should facilitate dissemination within microbial communities and provide a readily applicable system to naturally introduce CRISPR/Cas to industrially relevant strains for enhanced phage resistance and prevention against acquisition of undesirable genes.

Millen, Anne M.; Horvath, Philippe; Boyaval, Patrick; Romero, Dennis A.

2012-01-01

201

Genomic Exploration of the Hemiascomycetous Yeasts: 11. Kluyveromyces lactis  

Microsoft Academic Search

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

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

202

Structure of the capsular polysaccharide of Klebsiella type 73 (Enterobacter aerogenes).  

PubMed

The capsular polysaccharide from Klebsiella Type 73 (Enterobacter aerogenes) was found to contain equimolar amounts of D-galactose, D-glucose, L-rhamnose, and D-glucuronic acid. Acid hydrolysis of the polysaccharide gave one aldobio-and one aldotrio-uronic acid, whose structures were established by acid hydrolysis and by methylation analysis. The anomeric configurations of the different sugar residues were determined from the specific rotations of the polysaccharide and the aldobio-and aldotrio-uronic acids, and also by oxidation of the native and the carboxyl-reduced polysaccharide with chromium trioxide. Methylation analysis of the polysaccharide provided information about the linkages of the different sugar residues. Based on all of these results, the structure assigned to the repeating unit of the polysaccharide is as follows. (Formula: see text). PMID:7317881

Batavyal, L; Roy, N

1981-12-01

203

Enhanced production of acetoin and butanediol in recombinant Enterobacter aerogenes carrying Vitreoscilla hemoglobin gene.  

PubMed

Microbial production of butanediol and acetoin has received increasing interest because of their diverse potential practical uses. Although both products are fermentative in nature, their optimal production requires a low level of oxygen. In this study, the use of a recombinant oxygen uptake system on production of these metabolites was investigated. Enterobacter aerogenes was transformed with a pUC8-based plasmid carrying the gene (vgb) encoding Vitreoscilla (bacterial)hemoglobin (VHb). The presence of vgb and production of VHb by this strain resulted in an increase in viability from 72 to 96 h in culture, but no overall increase in cell mass. Accumulation of the fermentation products acetoin and butanediol were enhanced (up to 83%) by the presence of vgb/VHb. This vgb/VHb related effect appears to be due to an increase of flux through the acetoin/butanediol pathway, but not at the expense of acid production. PMID:15309606

Geckil, Hikmet; Barak, Ze'ev; Chipman, David M; Erenler, Sebnem O; Webster, Dale A; Stark, Benjamin C

2004-10-01

204

Role of sodium in determining alternate pathways of aerobic citrate catabolism in Aerobacter aerogenes.  

PubMed

In contrast to the absolute Na(+) requirement for anaerobic growth of Aerobacter aerogenes on citrate as sole carbon source, aerobic growth of this microorganism did not require the presence of Na(+). However, Na(+) (optimal concentration, 10 mm) did increase the maximal amount of aerobic growth by 60%, even though it did not change the rate of growth. This increase in growth was specifically affected by Na(+), which could not be replaced by K(+), NH(4) (+), Li(+), Rb(+), or Cs(+). Enzyme profiles were determined in A. aerogenes cells grown aerobically on citrate in media of varying cationic composition. Cells grown in Na(+)-free medium possessed all the enzymes of the citric acid cycle including alpha-ketoglutarate dehydrogenase, which is repressed by anaerobic conditions of growth. The enzymes of the anaerobic citrate fermentation pathway, citritase and oxalacetate decarboxylase, were also present in these cells, but this pathway of citrate catabolism was effectively blocked by the absence of Na(+), which is essential for the activation of the oxalacetate decarboxylase step. Thus, in Na(+)-free medium, aerobic citrate catabolism proceeded solely via the citric acid cycle. Addition of 10 mm Na(+) to the aerobic citrate medium resulted in the activation of oxalacetate decarboxylase and the repression of alpha-ketoglutarate dehydrogenase, thereby diverting citrate catabolism from the (aerobic) citric acid cycle mechanism to the fermentation mechanism characteristic of anaerobic growth. The further addition of 2% potassium acetate to the medium caused repression of citritase and derepression of alpha-ketoglutarate dehydrogenase, switching citrate catabolism back into the citric acid cycle. PMID:5808070

O'Brien, R W; Stern, J R

1969-08-01

205

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

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)

Not Available

1980-11-21

206

Influence of Lipoteichoic Acid D-Alanylation on Protein Secretion in Lactococcus lactis as Revealed by Random Mutagenesis  

Microsoft Academic Search

Lactococcus lactis, a food-grade nonpathogenic lactic acid bacterium, is a good candidate for the production of heterologous proteins of therapeutic interest. We examined host factors that affect secretion of heterologous proteins in L. lactis. Random insertional mutagenesis was performed with L. lactis strain MG1363 carrying a staphylococcal nuclease (Nuc) reporter cassette in its chromosome. This cassette encodes a fusion protein

S. Nouaille; J. Commissaire; J. J. Gratadoux; P. Ravn; A. Bolotin; A. Gruss; Y. Le Loir; P. Langella

2004-01-01

207

High-level Expression of Phenylalanine Ammonialyase in Lactococcus lactis via Synthesized Sequence Based on Bias Codons  

Microsoft Academic Search

To construct a safer and more efficient gene engineering Lactococcus lactis for expressing phenylalanine ammonia lyase (PAL) which will benefit PKU therapy. A PAL cDNA of Parsly and a synthesized PAL sequence based on Lactococcus lactis bias codons (palart) were recombined into two Lactococcus lactis NICE systems. The activities of the expressed PALs were detected, and the effect of Lactococcus

Xing CHEN; Bin GAO; Xing-Yuan JIA; Chang SU; Yue-Ping LÜ; Zhan-Yong WANG; Xin-Ping FAN; Bai XIAO; Jing-Zhong LIU

2006-01-01

208

A Plasmid Selection System in Lactococcus lactis and Its Use for Gene Expression in L. lactis and Human Kidney Fibroblasts  

Microsoft Academic Search

We report the development of a nonantibiotic and nonpathogenic host-plasmid selection system based on lactococcal genes and threonine complementation. We constructed an auxotrophic Lactococcus lactis MG1363thr strain which carries deletions in two genes encoding threonine biosynthetic enzymes. To achieve plasmid-borne complementation, we then constructed the minimal cloning vector, pJAG5, based on the genes encoding homoserine dehydrogenase-homoserine kinase (the hom-thrB operon)

Jacob Glenting; Søren M. Madsen; Astrid Vrang; Anders Fomsgaard; Hans Israelsen

2002-01-01

209

The role of NADH-oxidation in acetoin and diacetyl production from glucose in Lactococcus lactis subsp. lactis MG1363  

Microsoft Academic Search

Product formation from glucose and NADH-oxidase activity from Lactococcus lactis MG1363, a non-citrate fermenter, was studied under aerobic conditions. In continuous cultures constantly aerated to 80% air saturation, the usual homolactic fermentation was almost completely replaced by acetate fermentation (80–90% of the fermented glucose) at low dilution rates. As the dilution rate was increased, the homolactic fermentation was partially restored,

Felix Lopez de Felipe; Marjo J. C Starrenburg; Jeroen Hugenholtz

1997-01-01

210

The AcrAB-TolC Pump Is Involved in Macrolide Resistance but Not in Telithromycin Efflux in Enterobacter aerogenes and Escherichia coli  

Microsoft Academic Search

The role of the AcrAB-TolC pump in macrolide and ketolide susceptibility in Escherichia coli and Enterobacter aerogenes was studied. Efflux pump inhibitor restored erythromycin, clarithromycin, and telithromycin sus- ceptibilities to multidrug-resistant isolates. No modification of telithromycin accumulation was detected in E. aerogenes acrAB or tolC derivatives compared to that in the parental strain. Two independent efflux pumps, inhibited by phenylalanine

Renaud Chollet; Jacqueline Chevalier; A. Bryskier; J.-M. Pages

2004-01-01

211

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

Microsoft Academic Search

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

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

2004-01-01

212

Vitreoscilla hemoglobin expressing Enterobacter aerogenes and Pseudomonas aeruginosa respond differently to carbon catabolite and oxygen repression for production of l-asparaginase, an enzyme used in cancer therapy  

Microsoft Academic Search

The production of antileukemic enzyme l-asparaginase in two distinctly related bacteria, Enterobacter aerogenes, Pseudomonas aeruginosa, and in their recombinants expressing the Vitresocilla hemoglobin (VHb) has been studied. Both bacteria showed a substantially different degree of carbon catabolite repression of the enzyme production. E. aerogenes grown under catabolite repression had more than 20-fold lower l-asparaginase activity than the controls. This figure

Hikmet Geckil; Salih Gencer; Mirac Uckun

2004-01-01

213

Insensitivity of 5-enolpyruvylshikimic acid-3-phosphate synthase to glyphosate confers resistance to this herbicide in a strain of Aerobacter aerogenes  

Microsoft Academic Search

The broadspectrum herbicide glyphosate (N-[phosphonomethyl]glycine), an inhibitor of the shikimate pathway enzyme 5-enolpyruvyl-shikimic acid-3-phosphate (EPSP)-synthase, inhibits the growth of Aerobacter aerogenes and causes the excretion of shikimic acid-3-phosphate. A strain of A. aerogenes, resistant to inhibition of growth by glyphosate, was isolated and found to have a glyphosate-insensitive EPSP-synthase and to no longer excrete shikimic acid-3-phosphate in the presence of

A. Schulz; D. Sost; N. Amrhein

1984-01-01

214

Identification of Plasmalogens in the Cytoplasmic Membrane of Bifidobacterium animalis subsp. lactis  

PubMed Central

Plasmalogens are ether-linked lipids that may influence oxidative stress resistance of eukaryotic cell membranes. Since bacterial membrane composition can influence environmental stress resistance, we explored the prevalence of plasmalogens in the cytoplasmic membrane of Bifidobacterium animalis subsp. lactis. Results showed plasmalogens are a major component of the B. animalis subsp. lactis membrane.

Oberg, Taylor S.; Ward, Robert E.; Steele, James L.

2012-01-01

215

Functional characterisation and transcriptional regulation of the KlHEM12 gene from Kluyveromyces lactis  

Microsoft Academic Search

Cloning, sequencing and functional analysis of the Kluyveromyces lactis KlHEM12 gene and its upstream region are reported. The gene encodes for a protein that is highly homologous to uroporphyrinogen decarboxylases from different organisms and complements its mutation in Saccharomyces cerevisiae. Secondary structure prediction allows outlining a topology diagram which is compatible with a (?\\/?) 8-barrel structure. A K. lactis haploid

Laura Núñez; Isabel González-Siso; Manuel Becerra; M. Esperanza Cerdán

2004-01-01

216

Identification of plasmalogens in the cytoplasmic membrane of Bifidobacterium animalis subsp. lactis.  

PubMed

Plasmalogens are ether-linked lipids that may influence oxidative stress resistance of eukaryotic cell membranes. Since bacterial membrane composition can influence environmental stress resistance, we explored the prevalence of plasmalogens in the cytoplasmic membrane of Bifidobacterium animalis subsp. lactis. Results showed plasmalogens are a major component of the B. animalis subsp. lactis membrane. PMID:22138986

Oberg, Taylor S; Ward, Robert E; Steele, James L; Broadbent, Jeff R

2011-12-02

217

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

Microsoft Academic Search

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

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

1998-01-01

218

Riboflavin Production in Lactococcus lactis: Potential for In Situ Production of Vitamin-Enriched Foods  

Microsoft Academic Search

This study describes the genetic analysis of the riboflavin (vitamin B2) biosynthetic (rib) operon in the lactic acid bacterium Lactococcus lactis subsp. cremoris strain NZ9000. Functional analysis of the genes of the L. lactis rib operon was performed by using complementation studies, as well as by deletion analysis. In addition, gene-specific genetic engineering was used to examine which genes of

Catherine Burgess; Mary O'Connell-Motherway; Wilbert Sybesma; Jeroen Hugenholtz; Douwe van Sinderen

2004-01-01

219

Improved Production of Heterologous Proteins by a Glucose Repression-Defective Mutant of Kluyveromyces lactis  

Microsoft Academic Search

The secreted production of heterologous proteins in Kluyveromyces lactis was studied. A glucoamylase (GAA) from the yeast Arxula adeninivorans was used as a reporter protein for the study of the secretion efficiencies of several wild-type and mutant strains of K. lactis. The expression of the reporter protein was placed under the control of the strong promoter of the glyceraldehyde-3-phosphate dehydrogenase

Claudia Donnini; Francesca Farina; Barbara Neglia; Maria Concetta Compagno; Daniela Uccelletti; Paola Goffrini; Claudio Palleschi

2004-01-01

220

Increasing the heme-dependent respiratory efficiency of Lactococcus lactis by inhibition of lactate dehydrogenase.  

PubMed

The discovery of heme-induced respiration in Lactococcus lactis has radically improved the industrial processes used for the biomass production of this species. Here, we show that inhibition of the lactate dehydrogenase activity of L. lactis during growth under respiration-permissive conditions can stimulate aerobic respiration, thereby increasing not only growth efficiency but also the robustness of this organism. PMID:23064338

Arioli, Stefania; Zambelli, Daniele; Guglielmetti, Simone; De Noni, Ivano; Pedersen, Martin B; Pedersen, Per Dedenroth; Dal Bello, Fabio; Mora, Diego

2012-10-12

221

Increasing the Heme-Dependent Respiratory Efficiency of Lactococcus lactis by Inhibition of Lactate Dehydrogenase  

PubMed Central

The discovery of heme-induced respiration in Lactococcus lactis has radically improved the industrial processes used for the biomass production of this species. Here, we show that inhibition of the lactate dehydrogenase activity of L. lactis during growth under respiration-permissive conditions can stimulate aerobic respiration, thereby increasing not only growth efficiency but also the robustness of this organism.

Arioli, Stefania; Zambelli, Daniele; Guglielmetti, Simone; De Noni, Ivano; Pedersen, Martin B.; Pedersen, Per Dedenroth; Dal Bello, Fabio

2013-01-01

222

Engineering of carbon distribution between glycolysis and sugar nucleobiosynthesis in Lactococcus lactis  

Microsoft Academic Search

We describe the effects of modulating the activities of glucokinase, phosphofructokinase, and phosphoglu- comutase on the branching point between sugar degradation and the biosynthesis of sugar nucleotides involved in the production of exopolysaccharide biosynthesis by Lactococcus lactis. This was realized by using a described isogenic L. lactis mutant with reduced enzyme activities or by controlled expression of the well-characterized genes

Ingeborg C. Boels; Michiel Kleerebezem; Vos de W. M

2003-01-01

223

A phosphoglucose isomerase gene is involved in the Rag phenotype of the yeast Kluyveromyces lactis  

Microsoft Academic Search

The rag2 mutant of Kluyveromyces lactis cannot grow on glucose when mitochondrial functions are blocked by various mitochondrial inhibitors, suggesting the presence of a defect in the fermentation pathway. The RAG2 gene has been cloned from a K. lactis genomic library by complementation of the rag2 mutation. The amino acid sequence of the RAG2 protein deduced from the nucleotide sequence

Paola Goffrini; Micheline Wésolowski-Louvel; Iliana Ferrero

1991-01-01

224

Induction of Loci Mutation during Lactococcus lactis Spontaneous Conversion to Bacteriophage-Insensitive Phenotype  

Microsoft Academic Search

The dairy industry utilizes Lactococcus lactis strains as starter cultures to manufacture fermented products. Bacteriophages specific for the cultures are an important and persistent problem for the industry. The development of phage-insensitive strains is one approach to handle the problem. We have identified loci that were spontaneously mutated in Lactococcus lactis ssp. cremoris MG1363 during its natural conversion to the

Marcin T. Schmidt; Agnieszka K. Olejnik-Schmidt; Adam Zar?ba; Marek Pezacki; Iwona Wojewoda; W?odzimierz Grajek

2010-01-01

225

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

Microsoft Academic Search

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

AMANDA FORDE; CHARLES DALY; GERALD F. FITZGERALD

226

Redirection of pyruvate catabolism in Lactococcus lactis by selection of mutants with additional growth requirements  

Microsoft Academic Search

Based on requirements for acetate or lipoic acid for aerobic (but not anaerobic) growth, Lactococcus lactis subsp. lactis mutants with impaired pyruvate catabolism were isolated following classical mutagenesis. Strains with defects in one or two of the enzymes, pyruvate formate-lyase (PFL), lactate dehydrogenase (LDH) and the pyruvate dehydrogenase complex (PDHC) were obtained. Growth and product formation of these strains were

C. M. Henriksen; D. Nilsson

2001-01-01

227

Inactivation of the panE gene in Lactococcus lactis enhances formation of cheese aroma compounds.  

PubMed

Hydroxyacid dehydrogenases limit the conversion of ?-keto acids into aroma compounds. Here we report that inactivation of the panE gene, encoding the ?-hydroxyacid dehydrogenase activity in Lactococcus lactis, enhanced the formation of 3-methylbutanal and 3-methylbutanol. L. lactis IFPL953?panE was an efficient strain producing volatile compounds related to cheese aroma. PMID:23524675

de Cadiñanos, Luz P Gómez; García-Cayuela, Tomás; Yvon, Mireille; Martinez-Cuesta, M Carmen; Peláez, Carmen; Requena, Teresa

2013-03-22

228

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

Microsoft Academic Search

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

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

2002-01-01

229

Complete Genome Sequence of Lactococcus lactis IO-1, a Lactic Acid Bacterium That Utilizes Xylose and Produces High Levels of l-Lactic Acid  

PubMed Central

We report the complete genome sequence of Lactococcus lactis IO-1 (= JCM7638). It is a nondairy lactic acid bacterium, produces nisin Z, ferments xylose, and produces predominantly l-lactic acid at high xylose concentrations. From ortholog analysis with other five L. lactis strains, IO-1 was identified as L. lactis subsp. lactis.

Kato, Hiroaki; Shiwa, Yuh; Oshima, Kenshiro; Machii, Miki; Araya-Kojima, Tomoko; Zendo, Takeshi; Shimizu-Kadota, Mariko; Hattori, Masahira; Sonomoto, Kenji

2012-01-01

230

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

Microsoft Academic Search

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.

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

2008-01-01

231

Purification and properties of pyridoxal-5'-phosphate-dependent histidine decarboxylases from Klebsiella planticola and Enterobacter aerogenes.  

PubMed Central

Histidine decarboxylases from Klebsiella planticola and Enterobacter aerogenes were purified to homogeneity and compared with the histidine decarboxylase from Morganella morganii. All three enzymes required pyridoxal 5'-phosphate as a coenzyme, showed optimal activity at pH 6.5, decarboxylated only histidine among the amino acids derived from protein, and were tetramers or dimers of identical subunits. Amino-terminal sequences of the three enzymes showed up to 81% homology through residue 33, but the enzymes differed sufficiently in amino acid composition and sequence so that no cross-reaction occurred between the K. planticola or E. aerogenes enzymes and antibodies to the decarboxylase from M. morganii. All three enzymes were inhibited by carbonyl reagents; by amino-, carboxyl-, and some methyl-substituted histidines; and by alpha-fluoromethylhistidine. These decarboxylases, all from gram-negative organisms, differed greatly in subunit structure, biogenesis, and other properties from the pyruvoyl-dependent histidine decarboxylases from gram-positive organisms described previously. Images

Guirard, B M; Snell, E E

1987-01-01

232

Studies on the formation of N6-hydroxylysine in cell-free extracts of Aerobacter aerogenes 62-1.  

PubMed

We have investigated conditions optimal for the conversion of L-lysine to its N6-hydroxy derivative by partially purified cell-free extracts of Aerobacter aerogenes 62-1. The enzyme system was highly specific to L-lysine: the D-isomer and, the N2- or N6-derivatives of lysine, and alpha-amino acids were not hydroxylated. Most of the latter compounds had little effect onthe hydroxylation of L-lysine. However, -l-glutamic acid and L-glutamine enhanced the hydroxylation, with half-maximal activation achieved at 100 micrometers concentration of the effector. The Km values for pyruvate and L-(+)-lactate (compounds known to stimulate N-hydroxylysine formation) were found to be approx. 100 micrometers. The data show that N-hydroxylation of the amino acid precedes acylation in the biosynthesis of hydroxamic acid in A. aerogenes 62-1. PMID:465510

Parniak, M A; Jackson, G E; Murray, G J; Viswanatha, T

1979-07-11

233

Cholate Resistance in Lactococcus lactis Is Mediated by an ATP-Dependent Multispecific Organic Anion Transporter  

PubMed Central

The cholate-resistant Lactococcus lactis strain C41-2, derived from wild-type L. lactis MG1363 through selection for growth on cholate-containing medium, displayed a reduced accumulation of cholate due to an enhanced active efflux. However, L. lactis C41-2 was not cross resistant to deoxycholate or cationic drugs, such as ethidium and rhodamine 6G, which are typical substrates of the multidrug transporters LmrP and LmrA in L. lactis MG1363. The cholate efflux activity in L. lactis C41-2 was not affected by the presence of valinomycin plus nigericin, which dissipated the proton motive force. In contrast, cholate efflux in L. lactis C41-2 was inhibited by ortho-vanadate, an inhibitor of P-type ATPases and ATP-binding cassette transporters. Besides ATP-dependent drug extrusion by LmrA, two other ATP-dependent efflux activities have previously been detected in L. lactis, one for the artificial pH probe 2?,7?-bis-(2-carboxyethyl)-5(and 6)-carboxyfluorescein (BCECF) and the other for the artificial pH probe N-(fluorescein thio-ureanyl)-glutamate (FTUG). Surprisingly, the efflux rate of BCECF, but not that of FTUG, was significantly enhanced in L. lactis C41-2. Further experiments with L. lactis C41-2 cells and inside out membrane vesicles revealed that cholate and BCECF inhibit the transport of each other. These data demonstrate the role of an ATP-dependent multispecific organic anion transporter in cholate resistance in L. lactis.

Yokota, Atsushi; Veenstra, Marloes; Kurdi, Peter; van Veen, Hendrik W.; Konings, Wil N.

2000-01-01

234

Generalized model of the effect of pH on lactate fermentation and citrate bioconversion in Lactococcus lactis ssp. Lactis biovar. diacetylactis  

Microsoft Academic Search

An aroma-imparting mesophilic lactic starter (Lactococcus lactis ssp. lactis biovar. diacetylactis) was studied in batch culture in medium with 50 g·l-1 lactose and 2 g·l-1 citrate. The effect of pH on the physiology of growth and the production of flavour compounds was investigated with a mathematical model. The specific rates of growth and of lactose fermentation obeyed a law of

R. Cachon; C. Diviés

1994-01-01

235

Generalized model of the effect of pH on lactate fermentation and citrate bioconversion in Lactococcus lactis ssp. lactis biovar. diacetylactis  

Microsoft Academic Search

An aroma-imparting mesophilic lactic starter ( Lactococcus lactis ssp. lactis biovar. diacetylactis) was studied in batch culture in medium with 50?g·l –-1 lactose and 2?g·l –-1 citrate. The effect of pH on the physiology of growth and the production of flavour compounds was investigated with a mathematical model. The specific rates of growth and of lactose fermentation obeyed a law

R. Cachon; C. Diviès

1994-01-01

236

Characterization of an insertion sequence-like element identified in plasmid pCIT264 from Lactococcus lactis subsp. lactis biovar diacetylactis  

Microsoft Academic Search

Plasmid pCIT264 from Lactococcus lactis subsp. lactis biovar diacetylactis (L. diacetylactis) contains an insertion sequence (IS)-like element located in the citrate utilization (citQRP) cluster. This 967-nucleotide long element is bounded by 17 bp perfect inverted repeats and contains an open reading frame (ORF1) composed of 296 codons, which could encode a transposase. Expression of the IS from pCIT264 generates two

Christian Magni; Félix López de Felipe; Paloma López; Diego de Mendoza

1996-01-01

237

Use of a Genetically Enhanced, Pediocin-Producing Starter Culture, Lactococcus lactis subsp. lactis MM217, To Control Listeria monocytogenes in Cheddar Cheese  

Microsoft Academic Search

Cheddar cheese was prepared with Lactococcus lactis subsp. lactis MM217, a starter culture which contains pMC117 coding for pediocin PA-1. About 75 liters of pasteurized milk (containing ca. 3.6% fat) was inoculated with strain MM217 (ca. 10^6 CFU per ml) and a mixture of three Listeria monocytogenes strains (ca. 10^3 CFU per ml). The viability of the pathogen and the

Nurliza Buyong; Jan Kok; John B. Luchansky

1998-01-01

238

Influence of growth conditions on the production of a nisin-like bacteriocin by Lactococcus lactis subsp. lactis A164 isolated from kimchi  

Microsoft Academic Search

The influence of growth parameters on the fermentative production of a nisin-like bacteriocin by Lactococcus lactis subsp. lactis A164 isolated from kimchi was studied. The bacteriocin production was greatly affected by carbon and nitrogen sources. Strain A164 produced at least 4-fold greater bacteriocin in M17 broth supplemented with lactose than other carbon sources. The amount of 3% yeast extract was

Chan-Ick Cheigh; Hak-Jong Choi; Hoon Park; Seong-Bo Kim; Moo-Chang Kook; Tae-Seok Kim; Jae-Kwan Hwang; Yu-Ryang Pyun

2002-01-01

239

Influence of cryoprotectants on the viability and acidifying activity of frozen and freeze-dried cells of the novel starter strain Lactococcus lactis ssp. lactis CECT 5180  

Microsoft Academic Search

Lactococcus lactis ssp. lactis CECT 5180 is a novel starter strain with highly desirable technological properties, selected to be used a starter culture\\u000a for the manufacture of Afuega'l Pitu cheese, a farmhouse cheese very popular in Asturias (Northern Spain). In order to optimise\\u000a biomass preservation of this strain the effect of different substances on the viability and acidifying activity of

R. Cárcoba; A. Rodríguez

2000-01-01

240

Involvement of the LlaKR2I Methylase in Expression of the AbiR Bacteriophage Defense System in Lactococcus lactis subsp. lactis biovar diacetylactis KR2  

Microsoft Academic Search

The native lactococcal plasmid, pKR223, from Lactococcus lactis subsp. lactis biovar diacetylactis KR2 encodes two distinct bacteriophage-resistant mechanisms, the LlaKR2I restriction and modification (R\\/M) system and the abortive infection (Abi) mechanism, AbiR, that impedes bacteriophage DNA replication. This study completed the characterization of AbiR, revealing that it is the first Abi system to be encoded by three genes, abiRa, abiRb,

Julie M. Yang; Patricio J. DeUrraza; Nadya Matvienko; Daniel J. O'Sullivan

2006-01-01

241

Cloning and sequencing of the novel abortive infection gene abiH of Lactococcus lactis ssp. lactis biovar. diacetylactis S94  

Microsoft Academic Search

A gene which encodes resistance by abortive infection (Abi+) to bacteriophage was cloned from Lactococcus lactis ssp. lactis biovar. diacetylactis S94. This gene was found to confer a reduction in efficiency of plating and plaque size for prolate-headed bacteriophage ?53 (group I of homology) and total resistance to the small isometric-headed bacteriophage ?59 (group III of homology). The cloned gene

Fabien Prévots; Marlène Daloyau; Odile Bonin; Xavier Dumont; Sandrine Tolou

1996-01-01

242

Enhancement of Diacetyl Production by a Diacetyl-Resistant Mutant of Citrate-Positive Lactococcus lactis ssp. lactis 3022 and by Aerobic Conditions of Growth  

Microsoft Academic Search

Addition of Cu2+ and Fe3+ inhibited citrate uptake by citrate-positive Lacto- coccus lacris ssp. lads 3022 and stimu- lated the production of diacetyl, probably because citrate uptake activity of the cells is lowered by diacetyl. A diacetyl-resis- tant mutant, HK-7, derived from citrate- positive L. lactis ssp. lactis 3022, in which diacetyl production was deregulat- ed, produced a larger amount

Tsutomu Kaneko; Yukari Watanabe; Hideki Suzuki

1990-01-01

243

Influence of the phosphorus and nitrogen source on nisin production in Lactococcus lactis subsp. lactis batch fermentations using a complex medium  

Microsoft Academic Search

The influence of different phosphorus and nitrogen sources on Lactococcus lactis subsp. lactis NIZO 22186 growth and nisin production was studied in batch fermentations using a complex medium. KH2PO4 was found to be the best phosphorus source for nisin production. Increasing initial phosphate concentrations from 0 to 5% KH2PO4 exerted a double effect, creating favourable pH conditions and particularly stimulating

Luc De Vuyst; Erick J. Vandamme

1993-01-01

244

Detection of Extended-Spectrum b-Lactamases in Clinical Isolates of Enterobacter cloacae and Enterobacter aerogenes  

Microsoft Academic Search

The aim of the present study was to investigate the frequency of extended-spectrum b-lactamases (ESBLs) in a consecutive collection of clinical isolates of Enterobacter spp. The abilities of various screening methods to detect ESBLs in enterobacters were simultaneously tested. Among the 68 consecutive isolates (56 Enterobacter cloacae and 12 Enterobacter aerogenes isolates) that were analyzed for b-lactamase content, 21 (25

EVA TZELEPI; PANAGIOTA GIAKKOUPI; DANAI SOFIANOU; VENETA LOUKOVA; ANASTASSIA KEMEROGLOU; ATHANASSIOS TSAKRIS

2000-01-01

245

Isolation of Enterobacter aerogenes susceptible to beta-lactam antibiotics despite high level beta-lactamase production  

Microsoft Academic Search

This report describes a patient with nosocomial meningitis from whom four distinct isolates ofEnterobacter aerogenes were recovered over a complicated course of chemotherapy. The initial isolate was susceptible to expanded spectrum ?-lactams despite constitutive production of high levels of ?-lactamase. Resistant isolates recovered during antibiotic therapy had lost a 42,000 outer membrane protein. These data suggest that b-lactam susceptibility in

M. A. Mellencamp; J. S. Roccaforte; L. C. Preheim; C. C. Sanders; C. A. Anene; M. J. Bittner

1990-01-01

246

2,3Butanediol production by Enterobacter aerogenes : selection of the optimal conditions and application to food industry residues  

Microsoft Academic Search

Optimum values of temperature, pH, and starting substrate concentration are experimentally determined for 2,3-butanediol production by Enterobacter aerogenes through three set of batch fermentations of synthetic glucose solutions. The results of tests carried out at variable temperature show an optimum of 39 °C and are used to estimate, for both fermentation and thermal inactivation, the activation enthalpies (7.19 and 23.6

P. Perego; A. Converti; A. Del Borghi; P. Canepa

2000-01-01

247

Successive Emergence of Extended-Spectrum  -Lactamase-Producing and Carbapenemase-Producing Enterobacter aerogenes Isolates in a University Hospital  

Microsoft Academic Search

Sixty-two clinical isolates of Enterobacter aerogenes resistant to expanded-spectrum cephalosporins were collected between July 2003 and May 2005. Among these isolates, 23 (37.1%) were imipenem (IPM) susceptible, and 39 (62.9%) were IPM insusceptible, of which 89.7% (35\\/39) were resistant and 10.3% (4\\/39) were inter- mediate. Isolate genotypes were compared by pulsed-field gel electrophoresis. Of 62 isolates, 48 belonged to epidemic

M. Biendo; B. Canarelli; D. Thomas; F. Rousseau; F. Hamdad; C. Adjide; G. Laurans; F. Eb

2008-01-01

248

Bioenergetic aspects of aerobic growth of Klebsiella aerogenes NCTC 418 in carbon-limited and carbon-sufficient chemostat culture  

Microsoft Academic Search

Carbon-limited chemostat cultures of Klebsiella aerogenes NCTC 418 consumed more oxygen per unit of cell synthesis when growing on mannitol or glycerol than when growing on glucose; and since the “maintenance” requirements were similar, this suggested that the extra reducing equivalents present in these compounds were oxidized wastefully. By comparison with carbon-limited cultures, carbon-sufficient cultures that were ammonia-, sulphate- or

O. M. Neijssel; D. W. Tempest

1976-01-01

249

Energy requirement for maintenance of the transmembrane potassium gradient in Klebsiella aerogenes NCTC 418: A continuous culture study  

Microsoft Academic Search

With a glucose-limited culture of Klebsiella aerogenes, growing at a fixed dilution rate (0.4 h-1), the specific respiration rate varied progressively as a function of the transmembrane K+ gradient. The latter was varied by changing the input K+ concentration and, under these conditions, the specific respiration rate was linearly related to the electrochemical potential of the K+ gradient. Increasing or

S. Hueting; Titia Lange; D. W. Tempest

1979-01-01

250

The role of energy-spilling reactions in the growth of Klebsiella aerogenes NCTC 418 in aerobic chemostat culture  

Microsoft Academic Search

When cell-saturating amounts of glucose and phosphate were added to steady state cultures ofKlebsiella aerogenes that were, respectively, glucose-and phosphate-limited, the organisms responded immediately with an increased oxygen consumption rate. This suggested that in neither case was glucose transport the rate-limiting process, and also that organisms must posses effective mechanisms for spilling the excess energy initially generated when a growth-limitation

O. M. Neijssel; D. W. Tempest

1976-01-01

251

Overflow metabolism during anaerobic growth of Klebsiella aerogenes NCTC 418 on glycerol and dihydroxyacetone in chemostat culture  

Microsoft Academic Search

Klebsiella aerogenes NCTC 418 was grown anaerobically in chemostat culture with glycerol as source of carbon and energy. Glycerol-limited cultures did not ferment the carbon source with maximal efficiency but produced considerable amounts of 1,3-propanediol. The fraction of glycerol converted to this product depended on the growth rate and on the limitation: faster growing cells produced relatively more of this

H. Streekstra; M. J. Teixeira de Mattos; O. M. Neijssel; D. W. Tempest

1987-01-01

252

Alteration of hydrogen metabolism of ldh- deleted Enterobacter aerogenes by overexpression of NAD(+)-dependent formate dehydrogenase  

Microsoft Academic Search

The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate\\u000a in the ldh-deleted mutant. The knockout of NADH-consuming

Yuan Lu; Hongxin Zhao; Chong Zhang; Qiheng Lai; Xi Wu; Xin-Hui Xing

2010-01-01

253

Expression of NAD + -dependent formate dehydrogenase in Enterobacter aerogenes and its involvement in anaerobic metabolism and H 2 production  

Microsoft Academic Search

An expression system for NAD+-dependent formate dehydrogenase gene (fdh1), from Candida boidinii, was constructed and cloned into Enterobacter aerogenes IAM1183. With the fdh1 expression, the total H2 yield was attributed to a decrease in activity of the lactate pathway and an increase of the formate pathway flux due to\\u000a the NADH regeneration. Analysis of the redox state balance and ethanol-to-acetate

Yuan Lu; Hongxin Zhao; Chong Zhang; Qiheng Lai; Xi Wu; Xin-Hui Xing

2009-01-01

254

CTP Limitation Increases Expression of CTP Synthase in Lactococcus lactis  

PubMed Central

CTP synthase is encoded by the pyrG gene and catalyzes the conversion of UTP to CTP. A Lactococcus lactis pyrG mutant with a cytidine requirement was constructed, in which ?-galactosidase activity in a pyrG-lacLM transcriptional fusion was used to monitor gene expression of pyrG. A 10-fold decrease in the CTP pool induced by cytidine limitation was found to immediately increase expression of the L. lactis pyrG gene. The final level of expression of pyrG is 37-fold higher than the uninduced level. CTP limitation has pronounced effects on central cellular metabolism, and both RNA and protein syntheses are inhibited. Expression of pyrG responds only to the cellular level of CTP, since expression of pyrG has no correlation to alterations in UTP, GTP, and ATP pool sizes. In the untranslated pyrG leader sequence a potential terminator structure can be identified, and this structure is required for regulation of the pyrG gene. It is possible to fold the pyrG leader in an alternative structure that would prevent the formation of the terminator. We suggest a model for pyrG regulation in L. lactis, and probably in other gram-positive bacteria as well, in which pyrG expression is directly dependent on the CTP concentration through an attenuator mechanism. At normal CTP concentrations a terminator is preferentially formed in the pyrG leader, thereby reducing expression of CTP synthase. At low CTP concentrations the RNA polymerase pauses at a stretch of C residues in the pyrG leader, thereby allowing an antiterminator to form and transcription to proceed. This model therefore does not include any trans-acting protein for sensing the CTP concentration as previously proposed for Bacillus subtilis.

J?rgensen, Casper M?ller; Hammer, Karin; Martinussen, Jan

2003-01-01

255

Engineering Trehalose Synthesis in Lactococcus lactis for Improved Stress Tolerance ? †  

PubMed Central

Trehalose accumulation is a common cell defense strategy against a variety of stressful conditions. In particular, our team detected high levels of trehalose in Propionibacterium freudenreichii in response to acid stress, a result that led to the idea that endowing Lactococcus lactis with the capacity to synthesize trehalose could improve the acid tolerance of this organism. To this end, we took advantage of the endogenous genes involved in the trehalose catabolic pathway of L. lactis, i.e., trePP and pgmB, encoding trehalose 6-phosphate phosphorylase and ?-phosphoglucomutase, respectively, which enabled the synthesis of trehalose 6-phosphate. Given that L. lactis lacks trehalose 6-phosphate phosphatase, the respective gene, otsB, from the food-grade organism P. freudenreichii was used to provide the required activity. The trehalose yield was approximately 15% in resting cells and in mid-exponential-phase cells grown without pH control. The intracellular concentration of trehalose reached maximal values of approximately 170 mM, but at least 67% of the trehalose produced was found in the growth medium. The viability of mutant and control strains was examined after exposure to heat, cold or acid shock, and freeze-drying. The trehalose-producing strains showed improved tolerance (5- to 10-fold-higher survivability) to acid (pH 3) and cold shock (4°C); there was also a strong improvement in cell survival in response to heat shock (45°C), and no protection was rendered against dehydration. The insight provided by this work may help the design of food-grade strains optimized for the dairy industry as well as for oral drug delivery.

Carvalho, Ana Lucia; Cardoso, Filipa S.; Bohn, Andreas; Neves, Ana Rute; Santos, Helena

2011-01-01

256

Production and separation of dipeptidyl peptidase IV from Lactococcus lactis: scale up for industrial production.  

PubMed

Lactococcus lactis spp. lactis and Lactococcus lactis spp. cremoris are widely used in the manufacture of fermented milk. These strains were compared for production of Dipeptidyl Peptidase IV (DPP IV) enzyme in terms of enzyme activity, specific growth rates and productivity. Lactococcus lactis spp. lactis was produced in 3 L bioreactor and scaled up to 30 and 150 L stirred tank bioreactors, and the enzyme activities were found as 110, 110 and 122 mU mL(-1), respectively. After 8 h of production, separation steps were performed. While purification fold was 127 and yield was 2.69 %, the molecular weight of the enzyme was estimated as 68 kDa. Partially purified enzyme was enteric coated with capsules and a 95.5 % of DPP IV enzyme passed into the artificial intestine. Results show that production of DPP IV enzyme by Lactococcus lactis spp. lactis strain in submerged culture is comparable with the productions by commercial strains, mostly Aspergillus, in solid state fermentations based on productivity. PMID:22847360

Ustün, Ozlem; Ongen, Gaye

2012-07-31

257

Interaction between Streptococcus lactis and Aspergillus flavus on production of aflatoxin.  

PubMed Central

The inoculation of Aspergillus flavus spores into a culture of Streptococcus lactis in Lablemco tryptone broth medium resulted in little or no aflatoxin accumulation even though the growth of the fungus was not hindered. The drop in pH and reduced nutrient levels in the medium as a result of the S. lactis growth were not the cause of the observed inhibition. The inhibition was not eliminated by the addition of carbohydrate equal to the amount used by the bacterium before the inoculation with the fungus. Aflatoxin levels were also markedly reduced when S. lactis was inoculated into a growing A. flavus culture. In addition to inhibiting the synthesis of aflatoxin, S. lactis also degraded preformed toxin. A. flavus, on the other hand, not only reduced the growth of S. lactis but also affected the morphology of the bacterial cell; the cells became elongated and formed long chains. S. lactis produced and excreted the inhibitor into the medium late in its growth phase. The inhibitor was a heat-stable low-molecular-weight compound. Chloroform extracts of A. flavus grown in the presence of S. lactis were toxic to Bacillus megaterium but did not exhibit mutagenic or carcinogenic activity in the Salmonella/mammalian microsome mutagenicity test.

Coallier-Ascah, J; Idziak, E S

1985-01-01

258

Genetically Modified Lactococcus lactis for Delivery of Human Interleukin-10 to Dendritic Cells  

PubMed Central

Interleukin-10 (IL-10) plays an indispensable role in mucosal tolerance by programming dendritic cells (DCs) to induce suppressor Th-cells. We have tested the modulating effect of L. lactis secreting human IL-10 (L.??lactisIL-10) on DC function in vitro. Monocyte-derived DC incubated with L.??lactisIL-10 induced effector Th-cells that markedly suppressed the proliferation of allogenic Th-cells as compared to L. lactis. This suppressive effect was only seen when DC showed increased CD83 and CD86 expression. Furthermore, enhanced production of IL-10 was measured in both L.??lactisIL-10-derived DC and Th-cells compared to L. lactis-derived DC and Th-cells. Neutralizing IL-10 during DC-Th-cell interaction and coculturing L.??lactisIL-10-derived suppressor Th-cells with allogenic Th-cells in a transwell system prevented the induction of suppressor Th-cells. Only 130?pg/mL of bacterial-derived IL-10 and 40 times more exogenously added recombinant human IL-10 were needed during DC priming for the generation of suppressor Th-cells. The spatially restricted delivery of IL-10 by food-grade bacteria is a promising strategy to induce suppressor Th-cells in vivo and to treat inflammatory diseases.

Huibregtse, Inge L.; Zaat, Sebatian A.; Kapsenberg, Martien L.; Sartori da Silva, Maria A.; Peppelenbosch, Maikel P.; van Deventer, Sander J. H.; Braat, Henri

2012-01-01

259

Genetically Modified Lactococcus lactis for Delivery of Human Interleukin-10 to Dendritic Cells.  

PubMed

Interleukin-10 (IL-10) plays an indispensable role in mucosal tolerance by programming dendritic cells (DCs) to induce suppressor Th-cells. We have tested the modulating effect of L. lactis secreting human IL-10 (L.??lactis(IL-10)) on DC function in vitro. Monocyte-derived DC incubated with L.??lactis(IL-10) induced effector Th-cells that markedly suppressed the proliferation of allogenic Th-cells as compared to L. lactis. This suppressive effect was only seen when DC showed increased CD83 and CD86 expression. Furthermore, enhanced production of IL-10 was measured in both L.??lactis(IL-10)-derived DC and Th-cells compared to L. lactis-derived DC and Th-cells. Neutralizing IL-10 during DC-Th-cell interaction and coculturing L.??lactis(IL-10)-derived suppressor Th-cells with allogenic Th-cells in a transwell system prevented the induction of suppressor Th-cells. Only 130?pg/mL of bacterial-derived IL-10 and 40 times more exogenously added recombinant human IL-10 were needed during DC priming for the generation of suppressor Th-cells. The spatially restricted delivery of IL-10 by food-grade bacteria is a promising strategy to induce suppressor Th-cells in vivo and to treat inflammatory diseases. PMID:21811497

Huibregtse, Inge L; Zaat, Sebatian A; Kapsenberg, Martien L; Sartori da Silva, Maria A; Peppelenbosch, Maikel P; van Deventer, Sander J H; Braat, Henri

2011-07-27

260

Bifidobacterium lactis attenuates onset of inflammation in a murine model of colitis  

PubMed Central

AIM: To assess the anti-inflammatory effect of the probiotic Bifidobacterium lactis (B. lactis) in an adoptive transfer model of colitis. METHODS: Donor and recipient mice received either B. lactis or bacterial culture medium as control (deMan Rogosa Sharpe) in drinking water for one week prior to transfer of a mix of naive and regulatory T cells until sacrifice. RESULTS: All recipient mice developed signs of colonic inflammation, but a significant reduction of weight loss was observed in B. lactis-fed recipient mice compared to control mice. Moreover, a trend toward a diminution of mucosal thickness and attenuated epithelial damage was revealed. Colonic expression of pro-inflammatory and T cell markers was significantly reduced in B. lactis-fed recipient mice compared to controls. Concomitantly, forkhead box protein 3, a marker of regulatory T cells, was significantly up-regulated by B. lactis. CONCLUSION: Daily oral administration of B. lactis was able to reduce inflammatory and T cells mediators and to promote regulatory T cells specific markers in a mouse model of colitis.

Philippe, David; Favre, Laurent; Foata, Francis; Adolfsson, Oskar; Perruisseau-Carrier, Genevieve; Vidal, Karine; Reuteler, Gloria; Dayer-Schneider, Johanna; Mueller, Christoph; Blum, Stephanie

2011-01-01

261

Complete Genome Sequence of the Prototype Lactic Acid Bacterium Lactococcus lactis subsp. cremoris MG1363?  

PubMed Central

Lactococcus lactis is of great importance for the nutrition of hundreds of millions of people worldwide. This paper describes the genome sequence of Lactococcus lactis subsp. cremoris MG1363, the lactococcal strain most intensively studied throughout the world. The 2,529,478-bp genome contains 81 pseudogenes and encodes 2,436 proteins. Of the 530 unique proteins, 47 belong to the COG (clusters of orthologous groups) functional category “carbohydrate metabolism and transport,” by far the largest category of novel proteins in comparison with L. lactis subsp. lactis IL1403. Nearly one-fifth of the 71 insertion elements are concentrated in a specific 56-kb region. This integration hot-spot region carries genes that are typically associated with lactococcal plasmids and a repeat sequence specifically found on plasmids and in the “lateral gene transfer hot spot” in the genome of Streptococcus thermophilus. Although the parent of L. lactis MG1363 was used to demonstrate lysogeny in Lactococcus, L. lactis MG1363 carries four remnant/satellite phages and two apparently complete prophages. The availability of the L. lactis MG1363 genome sequence will reinforce its status as the prototype among lactic acid bacteria through facilitation of further applied and fundamental research.

Wegmann, Udo; O'Connell-Motherway, Mary; Zomer, Aldert; Buist, Girbe; Shearman, Claire; Canchaya, Carlos; Ventura, Marco; Goesmann, Alexander; Gasson, Michael J.; Kuipers, Oscar P.; van Sinderen, Douwe; Kok, Jan

2007-01-01

262

Adhesion and immunomodulatory effects of Bifidobacterium lactis HN019 on intestinal epithelial cells INT-407  

PubMed Central

AIM: To elucidate the adherence and immunomodulatory properties of a probiotic strain Bifidobacterium lactis (B. lactis) HN019. METHODS: Adhesion assays of B. lactis HN019 and Salmonella typhimurium (S. typhimurium) ATCC 14028 to INT-407 cells were carried out by detecting copies of species-specific genes with real-time polymerase chain reaction. Morphological study was further conducted by transmission electron microscopy. Interleukin-1? (IL-1?), interleukin-8, and tumor necrosis factor-? (TNF-?) gene expression were assessed while enzyme linked immunosorbent assay was used to detect IL-8 protein secretion. RESULTS: The attachment of S. typhimurium ATCC 14028 to INT407 intestinal epithelial cells was inhibited significantly by B. lactis HN019. B. lactis HN019 could be internalized into the INT-407 cells and attenuated IL-8 mRNA level at both baseline and S. typhimurium-induced pro-inflammatory responses. IL-8 secretion was reduced while IL-1? and TNF-? mRNA expression level remained unchanged at baseline after treated with B. lactis HN019. CONCLUSION: B. lactis HN019 does not up-regulate the intestinal epithelium expressed pro-inflammatory cytokine, it showed the potential to protect enterocytes from an acute inflammatory response induced by enteropathogen.

Liu, Chang; Zhang, Zhuo-Yang; Dong, Ke; Guo, Xiao-Kui

2010-01-01

263

Optimization of cultural conditions for conversion of glycerol to ethanol by Enterobacter aerogenes S012.  

PubMed

The aim of this research is to optimize the cultural conditions for the conversion of glycerol to ethanol by Enterobacter aerogenes S012. Taguchi method was used to screen the cultural conditions based on their signal to noise ratio (SN). Temperature (°C), agitation speed (rpm) and time (h) were found to have the highest influence on both glycerol utilization and ethanol production by the organism while pH had the lowest. Full factorial design, statistical analysis, and regression model equation were used to optimize the selected cultural parameters for maximum ethanol production. The result showed that fermentation at 38°C and 200 rpm for 48 h would be ideal for the bacteria to produce maximum amount of ethanol from glycerol. At these optimum conditions, ethanol production, yield and productivity were 25.4 g/l, 0.53 g/l/h, and 1.12 mol/mol-glycerol, repectively. Ethanol production increased to 26.5 g/l while yield and productivity decreased to 1.04 mol/mol-glycerol and 0.37 g/l/h, respectively, after 72 h. Analysis of the fermentation products was performed using HPLC, while anaerobic condition was created by purging the fermentation vessel with nitrogen gas. PMID:23388539

Nwachukwu, Raymond E S; Shahbazi, Abolghasem; Wang, Lijun; Worku, Mulumebet; Ibrahim, Salam; Schimmel, Keith

2013-02-06

264

The synthesis of exopolysaccharide by Klebsiella aerogenes membrane preparations and the involvement of lipid intermediates  

PubMed Central

1. Membrane preparations from Klebsiella aerogenes type 8 were shown to transfer glucose and galactose from their uridine diphosphate derivatives to a lipid and to polymer. The ratio of glucose to galactose transfer in both cases was 1:2. This is the same ratio in which these sugars occur in native polysaccharide. Galactose transfer was dependent on prior glucosylation of the lipid. Mutants were obtained lacking (a) glucosyltransferase and (b) galactosyltransferase. The transferase activities in a number of non-mucoid mutants was examined. 2. Glucose transfer was partially inhibited by uridine monophosphate, and incorporation of either glucose or galactose into lipid was decreased in the presence of uridine diphosphate. The sugars are thought to be linked to a lipid through a pyrophosphate bond, and treatment of the lipid intermediates with phenol yielded water-soluble compounds. These could be dephosphorylated with alkaline phosphatase. Transfer of glucuronic acid to lipid or polymer from uridine diphosphate glucuronic acid was much lower than that of the other two sugars. 3. The fate of sugars incorporated into polymer was also followed. Some conversion of glucose into galactose and glucuronic acid occurred. Mutants unable to transfer glucose or galactose to lipid were unable to form polymer. Other mutants capable of lipid glycosylation were in some cases unable to form polymer. A model for capsular polysaccharide synthesis is proposed and its similarity to the formation of other polymers outside the cell membrane is discussed.

Sutherland, I. W.; Norval, Mary

1970-01-01

265

Optimization of cultural conditions for conversion of glycerol to ethanol by Enterobacter aerogenes S012  

PubMed Central

The aim of this research is to optimize the cultural conditions for the conversion of glycerol to ethanol by Enterobacter aerogenes S012. Taguchi method was used to screen the cultural conditions based on their signal to noise ratio (SN). Temperature (°C), agitation speed (rpm) and time (h) were found to have the highest influence on both glycerol utilization and ethanol production by the organism while pH had the lowest. Full factorial design, statistical analysis, and regression model equation were used to optimize the selected cultural parameters for maximum ethanol production. The result showed that fermentation at 38°C and 200 rpm for 48 h would be ideal for the bacteria to produce maximum amount of ethanol from glycerol. At these optimum conditions, ethanol production, yield and productivity were 25.4 g/l, 0.53 g/l/h, and 1.12 mol/mol-glycerol, repectively. Ethanol production increased to 26.5 g/l while yield and productivity decreased to 1.04 mol/mol-glycerol and 0.37 g/l/h, respectively, after 72 h. Analysis of the fermentation products was performed using HPLC, while anaerobic condition was created by purging the fermentation vessel with nitrogen gas.

2013-01-01

266

Effect of crude glycerol-derived inhibitors on ethanol production by Enterobacter aerogenes.  

PubMed

In this study, ethanol production from pure and crude glycerol using Enterobacter aerogenes ATCC 29007 was evaluated under anaerobic culture conditions. Inhibitory effects of substrate concentrations, pH, and salt concentrations were investigated based on crude glycerol components. Ethanol production was performed with pure glycerol concentrations ranging from 5 to 30 g/L to evaluate the effects of substrate concentration and osmotic pressure. The consumed glycerol was 5-14.33 g/L, and the yield of ethanol was higher than 0.75 mol ethanol/mol glycerol after 24 h of cultivation. To evaluate the inhibitory effects of salts (NaCl and KCl), experiments were performed with 0-20 g/L of each salt. Inhibitory effects of salts were strongest at high salt concentrations. The inhibitory effect of pH was performed in the pH range 4-10, and cell growth and ethanol production were highest at pH 5-6. Also, ethanol production was slightly inhibited at low concentration of crude glycerol comparison with pure glycerol. However, significant inhibitory effects were not observed at 1.5 and 2% crude glycerol which showed higher ethanol production compared to pure glycerol. PMID:21909938

Lee, Sang Jun; Kim, Sung Bong; Kang, Seong Woo; Han, Sung Ok; Park, Chulhwan; Kim, Seung Wook

2011-09-11

267

Mutants of Aerobacter aerogenes Capable of Utilizing Xylitol as a Novel Carbon1  

PubMed Central

Wild-type Aerobacter aerogenes 1033 is unable to utilize xylitol. A succession of mutants was isolated capable of growth on this compound (0.2%) at progressively faster rates. Whereas the ability to utilize xylitol was achieved in the first-stage mutant (X1) by constitutive production of ribitol dehydrogenase (for which xylitol is a substrate but not an inducer), the basis for enhanced utilization of xylitol in the second-stage mutant (X2) was an alteration of ribitol dehydrogenase. This enzyme was purified from the various mutants. The apparent Km for xylitol was 0.12 m with X2 enzyme and 0.29 m with X1 enzyme. The X2 enzyme was also less heat stable and, at 0.05 m substrate concentration, had a higher ratio of activity with xylitol compared to ribitol than did the X1 enzyme. The third mutant (X3), with an even faster growth rate on xylitol, produced a ribitol dehydrogenase indistinguishable physically or kinetically from that of X2. However, X3 produced constitutively an active transport system which accepts xylitol. The usual function of this system is apparently for the transport of d-arabitol since the latter is not only a substrate but also an inducer of the transport system in parental strains of X3. The sequence of mutations described herein illustrates how genes belonging to different metabolic systems can be mobilized to serve a new biochemical pathway. Images

Wu, T. T.; Lin, E. C. C.; Tanaka, S.

1968-01-01

268

Nucleotide sequence and expression of the Enterobacter aerogenes alpha-acetolactate decarboxylase gene in brewer's yeast.  

PubMed Central

The nucleotide sequence of a 1.4-kilobase DNA fragment containing the alpha-acetolactate decarboxylase gene of Enterobacter aerogenes was determined. The sequence contains an entire protein-coding region of 780 nucleotides which encodes an alpha-acetolactate decarboxylase of 260 amino acids. The DNA sequence coding for alpha-acetolactate decarboxylase was placed under the control of the alcohol dehydrogenase I promoter of the yeast Saccharomyces cerevisiae in a plasmid capable of autonomous replication in both S. cerevisiae and Escherichia coli. Brewer's yeast cells transformed by this plasmid showed alpha-acetolactate decarboxylase activity and were used in laboratory-scale fermentation experiments. These experiments revealed that the diacetyl concentration in wort fermented by the plasmid-containing yeast strain was significantly lower than that in wort fermented by the parental strain. These results indicated that the alpha-acetolactate decarboxylase activity produced by brewer's yeast cells degraded alpha-acetolactate and that this degradation caused a decrease in diacetyl production.

Sone, H; Fujii, T; Kondo, K; Shimizu, F; Tanaka, J; Inoue, T

1988-01-01

269

Relevance of Bifidobacterium animalis subsp. lactis Plasminogen Binding Activity in the Human Gastrointestinal Microenvironment ?  

PubMed Central

Human plasmin(ogen) is regarded as a component of the molecular cross talk between the probiotic species Bifidobacterium animalis subsp. lactis and the human host. However, up to now, only in vitro studies have been reported. Here, we demonstrate that the probiotic strain B. animalis subsp. lactis BI07 is capable of recruiting plasmin(ogen) present at physiological concentrations in crude extracts from human feces. Our results provide evidence that supports the significance of the B. lactis-plasmin(ogen) interaction in the human gastrointestinal tract.

Candela, Marco; Turroni, Silvia; Centanni, Manuela; Fiori, Jessica; Bergmann, Simone; Hammerschmidt, Sven; Brigidi, Patrizia

2011-01-01

270

Functional Expression of an Orchid Fragrance Gene in Lactococcus lactis  

PubMed Central

Vanda Mimi Palmer (VMP), an orchid hybrid of Vanda tesselata and Vanda Tan Chay Yan is a highly scented tropical orchid which blooms all year round. Previous studies revealed that VMP produces a variety of isoprenoid volatiles during daylight. Isoprenoids are well known to contribute significantly to the scent of most fragrant plants. They are a large group of secondary metabolites which may possess valuable characteristics such as flavor, fragrance and toxicity and are produced via two pathways, the mevalonate (MVA) pathway or/and the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. In this study, a sesquiterpene synthase gene denoted VMPSTS, previously isolated from a floral cDNA library of VMP was cloned and expressed in Lactococcus lactis to characterize the functionality of the protein. L. lactis, a food grade bacterium which utilizes the mevalonate pathway for isoprenoid production was found to be a suitable host for the characterization of plant terpene synthases. Through recombinant expression of VMPSTS, it was revealed that VMPSTS produced multiple sesquiterpenes and germacrene D dominates its profile.

Song, Adelene Ai Lian; Abdullah, Janna O.; Abdullah, Mohd Puad; Shafee, Norazizah; Rahim, Raha A.

2012-01-01

271

The Response of Lactococcus lactis to Membrane Protein Production  

PubMed Central

Background The biogenesis of membrane proteins is more complex than that of water-soluble proteins, and recombinant expression of membrane proteins in functional form and in amounts high enough for structural and functional studies is often problematic. To better engineer cells towards efficient protein production, we set out to understand and compare the cellular consequences of the overproduction of both classes of proteins in Lactococcus lactis, employing a combined proteomics and transcriptomics approach. Methodology and Findings Highly overproduced and poorly expressed membrane proteins both resulted in severe growth defects, whereas amplified levels of a soluble substrate receptor had no effect. In addition, membrane protein overproduction evoked a general stress response (upregulation of various chaperones and proteases), which is probably due to accumulation of misfolded protein. Notably, upon the expression of membrane proteins a cell envelope stress response, controlled by the two-component regulatory CesSR system, was observed. Conclusions The physiological response of L. lactis to the overproduction of several membrane proteins was determined and compared to that of a soluble protein, thus offering better understanding of the bottlenecks related to membrane protein production and valuable knowledge for subsequent strain engineering.

Geertsma, Eric R.; Fusetti, Fabrizia; Permentier, Hjalmar P.; Kuipers, Oscar P.; Kok, Jan; Poolman, Bert

2011-01-01

272

Functional Expression of an Orchid Fragrance Gene in Lactococcus lactis.  

PubMed

Vanda Mimi Palmer (VMP), an orchid hybrid of Vanda tesselata and Vanda Tan Chay Yan is a highly scented tropical orchid which blooms all year round. Previous studies revealed that VMP produces a variety of isoprenoid volatiles during daylight. Isoprenoids are well known to contribute significantly to the scent of most fragrant plants. They are a large group of secondary metabolites which may possess valuable characteristics such as flavor, fragrance and toxicity and are produced via two pathways, the mevalonate (MVA) pathway or/and the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. In this study, a sesquiterpene synthase gene denoted VMPSTS, previously isolated from a floral cDNA library of VMP was cloned and expressed in Lactococcus lactis to characterize the functionality of the protein. L. lactis, a food grade bacterium which utilizes the mevalonate pathway for isoprenoid production was found to be a suitable host for the characterization of plant terpene synthases. Through recombinant expression of VMPSTS, it was revealed that VMPSTS produced multiple sesquiterpenes and germacrene D dominates its profile. PMID:22408409

Song, Adelene Ai Lian; Abdullah, Janna O; Abdullah, Mohd Puad; Shafee, Norazizah; Rahim, Raha A

2012-02-02

273

Decarboxylation of ?-Keto Acids by Streptococcus lactis var. maltigenes1  

PubMed Central

Decarboxylation rates for a series of C-3 to C-6 ?-keto acids were determined in the presence of resting cells and cell-free extracts of Streptococcus lactis var. maltigenes. The C-5 and C-6 acids branched at the penultimate carbon atom were converted most rapidly to the respective aldehydes in the manner described for ?-carboxylases. Pyruvate and ?-ketobutyrate did not behave as ?-carboxylase substrates, in that O2 was absorbed when they were reacted with resting cells. The same effect with pyruvate was noted in a nonmalty S. lactis, accounting for CO2 produced by some “homofermentative” streptococci. Mixed substrate reactions indicated that the same enzyme was responsible for decarboxylation of ?-ketoisocaproate and ?-ketoisovalerate, but it appeared unlikely that this enzyme was responsible for the decarboxylation of pyruvate. Ultrasonic disruption of cells of the malty culture resulted in an extract inactive for decarboxylation of pyruvate in the absence of ferricyanide. Dialyzed cell-free extracts were inactive against all keto acids and could not be reactivated.

Tucker, J. S.; Morgan, M. E.

1967-01-01

274

Micrococcus lactis sp. nov., isolated from dairy industry waste.  

PubMed

A Gram-positive, yellow-pigmented, actinobacterial strain, DW152(T), was isolated from a dairy industry effluent treatment plant. 16S rRNA gene sequence analysis indicated that strain DW152(T) exhibited low similarity with many species with validly published names belonging to the genera Micrococcus and Arthrobacter. However, phenotypic properties including chemotaxonomic markers affiliated strain DW152(T) to the genus Micrococcus. Strain DW152(T) had ai-C(15:0) and i-C(15:0) as major cellular fatty acids, and MK-8(H(2)) as the major menaquinone. The cell-wall peptidoglycan of strain DW152(T) had l-lysine as the diagnostic amino acid and the type was A4?. The DNA G+C content of strain DW152(T) was 68.0 mol%. In 16S rRNA gene sequence analysis, strain DW152(T) exhibited significant similarity with Micrococcus terreus NBRC 104258(T), but the mean value of DNA-DNA relatedness between these strains was only 42.3%. Moreover, strain DW152(T) differed in biochemical and chemotaxonomic characteristics from M. terreus and other species of the genus Micrococcus. Based on the above differences, we conclude that strain DW152(T) should be treated as a novel species of the genus Micrococcus, for which the name Micrococcus lactis sp. nov. is proposed. The type strain of Micrococcus lactis sp. nov. is DW152(T) (=MTCC10523(T) =DSM 23694(T)). PMID:21239567

Chittpurna; Singh, Pradip K; Verma, Dipti; Pinnaka, Anil Kumar; Mayilraj, Shanmugam; Korpole, Suresh

2011-01-14

275

Study of the Citrate Metabolism of Lactococcus lactis subsp. lactis Biovar Diacetylactis by Means of 13C Nuclear Magnetic Resonance  

PubMed Central

The metabolic fate of citrate and pyruvate in four strains of Lactococcus lactis subsp. lactis biovar diacetylactis has been studied by means of 13C nuclear magnetic resonance, using as a substrate either [3-13C]pyruvic acid or custom-synthesized citric acid that is 13C labeled either at carbons 2 and 4 or at carbon 3. The fermentations were carried out batchwise in modified M17 broth. For the actual conversions of the 13C-labeled substrates, cells at the end of their logarithmic growth phase were used to minimize the conversion to lactic acid. A mass balance of the main citric acid metabolites was obtained; the four strains produced from 50 to 70% (on a molar basis) lactic acid from either citrate or pyruvate. The remaining 50 to 30% was converted mainly to either ?-acetolactic acid (for one strain) or acetoin (for the other three strains). One of the strains produced an exceptionally high concentration of the diacetyl precursor ?-acetolactic acid. Another strain (SDC6) also produced ?-acetolactic acid, but this was decarboxylated to acetoin at a high rate. The 13C nuclear magnetic resonance method confirmed that the biosynthesis of ?-acetolactic acid occurs via condensation of pyruvate and “active” acetaldehyde. Diacetyl was not found as a direct metabolite of citrate or pyruvate metabolism.

Verhue, Walter M.; Tjan, Frans S. B.

1991-01-01

276

Effect of selenium-enriched exopolysaccharide produced by Lactococcus lactis subsp. lactis on signaling molecules in mouse spleen lymphocytes.  

PubMed

Selenium-enriched exopolysaccharides (Se-EPS) produced by Lactococcus lactis subsp. lactis can be used as a safe and effective selenium (Se) supplement. Analysis of the Se content and monosaccharide components of Se-EPS demonstrated that it consisted of mannose, fucose, ribose, glucose, galactose, and arabinose with a molar ratio of 5.48?:?0.39?:?9.77?:?4.03?:?1.00?:?1.92, and an Se content of 183.263 ?g g(-1). The differing effects of Se-EPS and EPS on calcium channels and certain key secondary messengers in spleen lymphocytes were examined and compared. Results showed that low-dose Se-EPS, but not EPS, increased the intracellular calcium ([Ca(2+)]i) levels of mouse spleen lymphocytes. Se-EPS also increased the expression and phosphorylation of Ca(2+)-calmodulin-dependent kinase (CaMK) II in lymphocytes. In addition, increased intracellular Ca(2+) levels were also found in the cells with blocked Ca(2+) channels. We speculated that Se-EPS enhanced the activation and proliferation of lymphocytes through calcium signaling by drawing from extracellular and intracellular stores. Low-dose Se-EPS also enhanced NO production, cAMP levels and PKA activity. We speculated that low-dose Se-EPS may activate certain pathways, including the calcium channel, NO, cAMP, and PKA related pathways. PMID:24056684

Liu, Lu; Pan, Daodong; Zeng, Xiaoqun; Li, Hua

2013-10-25

277

An evaluation and partial characterization of a bacteriocin produced by Lactococcus lactis subsp lactis ST1 isolated from goat milk  

PubMed Central

A bacteriocin-like inhibitory substance producing Lactococcus lactis subsp lactis strain, ST1, isolated from goat milk of Iranian origin and with broad spectrum of activity and desirable technical properties was used for evaluating some futures of bacteriocin inhibitory activity. Cell growth and bacteriocin production studies were carried out in MRS medium incubated statically under uncontrolled pH condition. The antibacterial activity presented a primary metabolite pattern and showed a rapid decrease at the stationary phase. Microaerobiosis and capnophily growth conditions resulted in higher bacteriocin production while aerobiosis showed negative effect on both cell growth and bacteriocin production. Bacteriocin production, on the other hand, was favored in MRS broth (pH; 6.5) inoculated with 0.1 ml l-1 fresh culture when incubation was carried out at 30 °C. This indicated that the conditions resulted in higher levels of growth were frequently favoring bacteriocin production by ST1 as well. Decrease in activity, at the stationary growth phase, was much pronounced in favored growth condition. Nutrient depletion, deferent effect of low pH on bacteriocin production and/or protein degradation seemed more responsible for this phenomenon. The study also provided further data on new method for bacteriocin release from the cell wall of producer. It was clearly shown that both heating and ultrasound shock for 5 min at pH 2 could increase bacteriocin activity significantly. The release was more pronounced in the presence of 0.5% Tween80.

Taheri, Parinaz; Samadi?, Nasrin; Ehsani, Mohammad Reza; Khoshayand, Mohammad Reza; Jamalifar, Hossein

2012-01-01

278

Antilisterial Activity of Nisin-Like Bacteriocin-Producing Lactococcus lactis subsp. lactis Isolated from Traditional Sardinian Dairy Products  

PubMed Central

With the aim of selecting LAB strains with antilisterial activity to be used as protective cultures to enhance the safety of dairy products, the antimicrobial properties of 117 Lactococcus lactis subsp. lactis isolated from artisanal Sardinian dairy products were evaluated, and six strains were found to produce bacteriocin-like substances. The capacity of these strains to antagonize Listeria monocytogenes during cocultivation in skimmed milk was evaluated, showing a reduction of L. monocytogenes counts of approximately 4 log units compared to the positive control after 24?h of incubation. In order for a strain to be used as bioprotective culture, it should be carefully evaluated for the presence of virulence factors, to determine what potential risks might be involved in its use. None of the strains tested was found to produce biogenic amines or to possess haemolytic activity. In addition, all strains were sensitive to clinically important antibiotics such as ampicillin, tetracycline, and vancomycin. Our results suggest that these bac+ strains could be potentially applied in cheese manufacturing to control the growth of L. monocytogenes.

Cosentino, Sofia; Fadda, Maria Elisabetta; Deplano, Maura; Melis, Roberta; Pomata, Rita; Pisano, Maria Barbara

2012-01-01

279

The transcriptional and gene regulatory network of Lactococcus lactis MG1363 during growth in milk.  

PubMed

In the present study we examine the changes in the expression of genes of Lactococcus lactis subspecies cremoris MG1363 during growth in milk. To reveal which specific classes of genes (pathways, operons, regulons, COGs) are important, we performed a transcriptome time series experiment. Global analysis of gene expression over time showed that L. lactis adapted quickly to the environmental changes. Using upstream sequences of genes with correlated gene expression profiles, we uncovered a substantial number of putative DNA binding motifs that may be relevant for L. lactis fermentative growth in milk. All available novel and literature-derived data were integrated into network reconstruction building blocks, which were used to reconstruct and visualize the L. lactis gene regulatory network. This network enables easy mining in the chrono-transcriptomics data. A freely available website at http://milkts.molgenrug.nl gives full access to all transcriptome data, to the reconstructed network and to the individual network building blocks. PMID:23349698

de Jong, Anne; Hansen, Morten E; Kuipers, Oscar P; Kilstrup, Mogens; Kok, Jan

2013-01-17

280

The Autoproteolysis of Lactococcus lactis Lactocepin III Affects Its Specificity towards ?-Casein  

PubMed Central

The effect of autoproteolysis of Lactococcus lactis lactocepin III on its specificity towards ?-casein was investigated. ?-Casein degradation was performed by using either an autolysin-defective derivative of L. lactis MG1363 carrying the proteinase genes of L. lactis SK11, which was unable to transport oligopeptides, or autoproteolyzed enzyme purified from L. lactis SK11. Comparison of the peptide pools by high-performance liquid chromatography analysis revealed significant differences. To analyze these differences in more detail, the peptides released by the cell-anchored proteinase were identified by on-line coupling of liquid chromatography to mass spectrometry. More than 100 oligopeptides were released from ?-casein by the cell-anchored proteinase. Analysis of the cleavage sites indicated that the specificity of peptide bond cleavage by the cell-anchored proteinase differed significantly from that of the autoproteolyzed enzyme.

Flambard, Benedicte; Juillard, Vincent

2000-01-01

281

The Transcriptional and Gene Regulatory Network of Lactococcus lactis MG1363 during Growth in Milk  

PubMed Central

In the present study we examine the changes in the expression of genes of Lactococcus lactis subspecies cremoris MG1363 during growth in milk. To reveal which specific classes of genes (pathways, operons, regulons, COGs) are important, we performed a transcriptome time series experiment. Global analysis of gene expression over time showed that L. lactis adapted quickly to the environmental changes. Using upstream sequences of genes with correlated gene expression profiles, we uncovered a substantial number of putative DNA binding motifs that may be relevant for L. lactis fermentative growth in milk. All available novel and literature-derived data were integrated into network reconstruction building blocks, which were used to reconstruct and visualize the L. lactis gene regulatory network. This network enables easy mining in the chrono-transcriptomics data. A freely available website at http://milkts.molgenrug.nl gives full access to all transcriptome data, to the reconstructed network and to the individual network building blocks.

de Jong, Anne; Hansen, Morten E.; Kuipers, Oscar P.; Kilstrup, Mogens; Kok, Jan

2013-01-01

282

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

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

283

Innate inflammatory responses to the Gram-positive bacterium Lactococcus lactis.  

PubMed

Lactococcus lactis is a non-pathogenic and non-colonizing Gram-positive bacterium commonly used in the dairy industry. To support the potential applications of this bacterium, such as use as an oral live vaccine, it is of interest to investigate the adjuvant properties of L. lactis. We compared the proinflammatory effects of L. lactis with two non-pathogenic Gram-negative bacteria: Escherichia coli and Salmonella typhi, a widely studied live vaccine. The gene expression profiles of chemokines induced by the three bacteria were examined in macrophages in vitro and in cells recruited into murine air-pouches in vivo. In addition, we studied the effect of co-incubating bacteria with dendritic cells (DCs) generated from mice bone marrow. We demonstrate that L. lactis exhibits proinflammatory effects, which indicates a capacity for adjuvanticity by this bacterium. PMID:18436352

Yam, Karen K; Pouliot, Philippe; N'diaye, Marie M; Fournier, Sylvie; Olivier, Martin; Cousineau, Benoit

2008-04-03

284

21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.  

Code of Federal Regulations, 2010 CFR

...nonpathogenic, nontoxicogenic yeast Kluyveromyces lactis (previously...which converts lactose to glucose and galactose. It is prepared from yeast that has been grown in a...chapter to convert lactose to glucose and galactose. (2)...

2009-04-01

285

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

Code of Federal Regulations, 2010 CFR

...1985 Aminopeptidase enzyme preparation derived...a) Aminopeptidase enzyme preparation is derived...nonpathogenic and nontoxicogenic bacterium Lactococcus lactis...preparation contains the enzyme aminopeptidase...produced by pure culture fermentation. (b) The...

2009-04-01

286

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

Code of Federal Regulations, 2010 CFR

...1985 Aminopeptidase enzyme preparation derived...a) Aminopeptidase enzyme preparation is derived...nonpathogenic and nontoxicogenic bacterium Lactococcus lactis...preparation contains the enzyme aminopeptidase...produced by pure culture fermentation. (b) The...

2010-01-01

287

Heterologous leaky production of transglutaminase in Lactococcus lactis significantly enhances the growth performance of the host.  

PubMed

This study describes a novel strategy to improve the growth performance of Lactococcus lactis by heterologous production of food-grade transglutaminase. The mtg gene from Streptoverticillium mobaraense that encodes the transglutaminase mature protein was cloned into a nisin-inducible expression vector and transformed into L. lactis subsp. cremoris NZ9000. The leaky expression of the mtg gene from the nisA promoter resulted in ammonia formation and carbon flux redistribution at the pyruvate branch. As a consequence, medium acidification was lessened and energy utilization was improved. This led to significantly higher biomass production under aerobic conditions and particularly under non-pH-controlled conditions (up to a 12-fold increase). The results presented here provide a novel way to enhance the growth yield of L. lactis, which is an important step for the purposes of producing proteins of commercial interest using L. lactis as a host. PMID:16332889

Fu, Rui-Yan; Chen, Jian; Li, Yin

2005-12-01

288

Codon optimization of the calf prochymosin gene and its expression in Kluyveromyces lactis  

Microsoft Academic Search

Chymosin as an important industrial enzyme widely used in cheese manufacture. The yeast Kluyveromyces lactis is a promising host strain for expression of the chymosin gene. However, low yields (80 U\\/ml in shake flask cultures) were\\u000a obtained when the K. lactis strain GG799 was used to express chymosin. We hypothesized that the codon-usage bias of the host may have resulted in

Zhen FengLanwei; Lanwei Zhang; Xue Han; Yanhe Zhang

2010-01-01

289

Expanding the molecular toolbox for Lactococcus lactis: construction of an inducible thioredoxin gene fusion expression system  

PubMed Central

Background The development of the Nisin Inducible Controlled Expression (NICE) system in the food-grade bacterium Lactococcus lactis subsp. cremoris represents a cornerstone in the use of Gram-positive bacterial expression systems for biotechnological purposes. However, proteins that are subjected to such over-expression in L. lactis may suffer from improper folding, inclusion body formation and/or protein degradation, thereby significantly reducing the yield of soluble target protein. Although such drawbacks are not specific to L. lactis, no molecular tools have been developed to prevent or circumvent these recurrent problems of protein expression in L. lactis. Results Mimicking thioredoxin gene fusion systems available for E. coli, two nisin-inducible expression vectors were constructed to over-produce various proteins in L. lactis as thioredoxin fusion proteins. In this study, we demonstrate that our novel L. lactis fusion partner expression vectors allow high-level expression of soluble heterologous proteins Tuc2009 ORF40, Bbr_0140 and Tuc2009 BppU/BppL that were previously insoluble or not expressed using existing L. lactis expression vectors. Over-expressed proteins were subsequently purified by Ni-TED affinity chromatography. Intact heterologous proteins were detected by immunoblotting analyses. We also show that the thioredoxin moiety of the purified fusion protein was specifically and efficiently cleaved off by enterokinase treatment. Conclusions This study is the first description of a thioredoxin gene fusion expression system, purposely developed to circumvent problems associated with protein over-expression in L. lactis. It was shown to prevent protein insolubility and degradation, allowing sufficient production of soluble proteins for further structural and functional characterization.

2011-01-01

290

Continuous nisin production in laboratory media and whey permeate by immobilized Lactococcus lactis  

Microsoft Academic Search

Continuous production of nisin in laboratory media and whey permeate was investigated using a packed-bed bioreactor. Lactococcus lactis subsp. lactis ATCC 11454 was immobilized by natural attachment to fibre surfaces and entrapment in the void volume within spiral wound fibrous matrix. The inoculated bioreactor was fed M17 medium and effect of pH, temperature, dilution rate, and substrate concentrations on nisin

Xia Liu; Yoon-Kyung Chung; Shang-Tian Yang; Ahmed E. Yousef

2005-01-01

291

Mutations in MGI Genes Convert Kluyueromyces lactis Into a Petite-Positive Yeast  

Microsoft Academic Search

Following targeted disruption of the unique CYCl gene, the petite-negative yeast, Kluyveromyces lactis, was found to grow fermentatively in the absence of cytochrome c-mediated respiration. This observation encouraged us to seek mitochondrial mutants by treatment of K. lactis with ethidium bromide at the highest concentration permitting survival. By this technique, we isolated four mtDNA mutants, three lacking mtDNA and one

Xin Jie Chen; G. Desmond Clark-Walker

292

Characterization of the Role of para-Aminobenzoic Acid Biosynthesis in Folate Production by Lactococcus lactis  

Microsoft Academic Search

The pab genes for para-aminobenzoic acid (pABA) biosynthesis in Lactococcus lactis were identified and characterized. In L. lactis NZ9000, only two of the three genes needed for pABA production were initially found. No gene coding for 4-amino-4-deoxychorismate lyase (pabC) was initially annotated, but detailed analysis revealed that pabC was fused with the 3 end of the gene coding for chorismate

Arno Wegkamp; Wietske van Oorschot; Willem M. de Vos; Eddy J. Smid

2007-01-01

293

Lactococcin Q, a Novel Two-Peptide Bacteriocin Produced by Lactococcus lactis QU 4  

Microsoft Academic Search

A bacteriocin-producing strain, Lactococcus lactis QU 4, was isolated from corn. The bacteriocin, termed lactococcin Q, showed antibacterial activity only against L. lactis strains among a wide range of gram-positive indicator strains tested. Lactococcin Q was purified by acetone precipitation, cation exchange chromatography, and reverse-phase chromatography. Lactococcin Q consisted of two peptides, and , whose molecular masses were determined to

Takeshi Zendo; Shoko Koga; Yasushi Shigeri; Jiro Nakayama; Kenji Sonomoto

2006-01-01

294

Genetic and transcriptional analysis of a novel plasmid-encoded copper resistance operon from Lactococcus lactis  

Microsoft Academic Search

A plasmid-borne copper resistance operon (lco) was identified from Lactococcus lactis subsp. lactis LL58-1. The lco operon consists of three structural genes lcoABC. The predicted products of lcoA and lcoB were homologous to chromosomally encoded prolipoprotein diacylglyceral transferases and two uncharacterized proteins respectively, and the product of lcoC is similar to several multicopper oxidases, which are generally plasmid-encoded. This genetic

Chun-Qiang Liu; Pilaiwan Charoechai; Nongpanga Khunajakr; Yi-Mo Deng; Widodo; Noel W. Dunn

2002-01-01

295

Complete Genome Sequence of the Prototype Lactic Acid Bacterium Lactococcus lactis subsp. cremoris MG1363  

Microsoft Academic Search

Lactococcus lactis is of great importance for the nutrition of hundreds of millions of people worldwide. This paper describes the genome sequence of Lactococcus lactis subsp. cremoris MG1363, the lactococcal strain most intensively studied throughout the world. The 2,529,478-bp genome contains 81 pseudogenes and encodes 2,436 proteins. Of the 530 unique proteins, 47 belong to the COG (clusters of orthologous

Udo Wegmann; Mary O’Connell-Motherway; Aldert Zomer; Girbe Buist; Claire Shearman; Carlos Canchaya; Marco Ventura; Alexander Goesmann; Michael J. Gasson; Oscar P. Kuipers; Douwe van Sinderen; Jan Kok

2007-01-01

296

Transcriptome Analysis of the Lactococcus lactis ArgR and AhrC Regulons?  

PubMed Central

In previous studies, we have shown that direct protein-protein interaction between the two regulators ArgR and AhrC in Lactococcus lactis is required for arginine-dependent repression of the biosynthetic argC promoter and the activation of the catabolic arcA promoter. Here, we establish the global ArgR and AhrC regulons by transcriptome analyses and show that both regulators are dedicated to the control of arginine metabolism in L. lactis.

Larsen, Rasmus; van Hijum, Sacha A. F. T.; Martinussen, Jan; Kuipers, Oscar P.; Kok, Jan

2008-01-01

297

Generation of a membrane potential by Lactococcus lactis through aerobic electron transport  

Microsoft Academic Search

Lactococcus lactis, a facultative anaerobic lactic acid bacterium, is known to have an increased growth yield when grown aerobically in the presence of heme. We have now established the presence of a functional, proton motive force-generating electron transfer chain (ETC) in L. lactis under these conditions. Proton motive force generation in whole cells was measured using a fluorescent probe (3',3'-dipropylthiadicarbocyanine),

R. J. W. Brooijmans; B. Poolman; G. K. Schuurman-Wolters; W. M. de Vos; J. Hugenholtz

2007-01-01

298

Quantitative analysis of the growth of Salmonella stanley during alfalfa sprouting and evaluation of Enterobacter aerogenes as its surrogate.  

PubMed

Raw seed sprouts have been implicated in several food poisoning outbreaks in the last 10 years. Few studies have included investigations of factors influencing the effectiveness of testing spent irrigation water, and in no studies to date has a nonpathogenic surrogate been identified as suitable for large-scale irrigation water testing trials. Alfalfa seeds were inoculated with Salmonella Stanley or its presumptive surrogate (nalidixic acid-resistant Enterobacter aerogenes) at three concentrations (-3, -30, and -300 CFU/g) and were then transferred into either flasks or a bench top-scale sprouting chamber. Microbial concentrations were determined in seeds, sprouts, and irrigation water at various times during a 4-day sprouting process. Data were fit to logistic regression models, and growth rates and maximum concentrations were compared using the generalized linear model procedure of SAS. No significant differences in growth rates were observed among samples taken from flasks or the chamber. Microbial concentrations in irrigation water were not significantly different from concentrations in sprout samples obtaihed at the same time. E. aerogenes concentrations were similar to those of Salmonella Stanley at corresponding time points for all three inoculum concentrations. Growth rates were also constant regardless of inoculum concentration or strain, except that lower inoculum concentrations resulted in lower final concentrations proportional to their initial concentrations. This research demonstrated that a nonpathogenic easy-to-isolate surrogate (nalidixic acid-resistant E. aerogenes) provides results similar to those obtained with Salmonella Stanley, supporting the use of this surrogate in future large-scale experiments. PMID:17340864

Liu, Bin; Schaffner, Donald W

2007-02-01

299

Magnesium starvation of Aerobacter aerogenes. I. Changes in nucleic acid composition.  

PubMed

Aerobacter aerogenes incubated in a medium containing all factors necessary for exponential growth except Mg(++) continued to synthesize nucleic acids and proteins for more than 70 hr, provided the major carbon source was in excess at all times. After 24 hr of Mg(++) starvation, deoxyribonucleic acid content in the culture had increased 10-fold. In contrast, the viable-cell count increased only about threefold during the first few hours and then remained approximately constant for the subsequent 70 hr. After specified intervals of Mg(++) starvation, extracts of the bacteria, or ribonucleic acid (RNA) purified from them, was centrifuged through gradients of sucrose to separate transfer RNA from ribosomal components. After correcting for losses, we obtained the following results. (i) There was a progressive rise in the content of transfer RNA competent to accept amino acids and during starvation it remained completely stable. (ii) In contrast, the contents of normally sedimenting ribosomal RNA and ribosomal subunits (30 and 50S) remained approximately constant for more than 24 hr. This did not result from stability of ribosomes made prior to starvation together with an inhibition of synthesis of new particles. Rather, ribosomes were continually breaking down and being replaced by an equivalent number of new ones. (iii) The breakdown of ribosomes appeared to be sequentially ordered; polysomes yielded 70S monomers, which then gave 30 and 50S particles, and these disintegrated to smaller units and finally to acid-soluble products. (iv) Furthermore, the particles derived from breakdown do not appear to exchange with subparticles on the path of assembly. Thus, ribosome decay was age-dependent and ribosomal RNA molecules had a minimal life expectancy of 90 min; however, some survived much longer. PMID:6020411

Kennell, D; Kotoulas, A

1967-01-01

300

Magnesium starvation of Aerobacter aerogenes. II. Rates of nucleic acid synthesis and methods for their measurement.  

PubMed

The rates of synthesis of Aerobacter aerogenes nucleic acids were estimated during incubation of the bacteria in a Mg(++)-free medium. Deoxyribonucleic acid (DNA) synthesized during Mg(++) starvation, or in the preceding exponential growth, remained acid-precipitable for 2.5 hr before breaking down to acid-soluble products during a period of many hours. Rates of DNA synthesis were calculated by correcting the net amounts of DNA per milliliter to values that would have appeared had there been no decay. After the first few hours, this rate was constant, the amount of DNA present at the start of Mg(++) starvation being synthesized every 130 min. Rates of synthesis of total ribonucleic acid (RNA) were established in two ways: (i) by measurements of the incorporation of exogeneous uracil and glucose carbon into RNA, and (ii) by the accumulation of transfer RNA (tRNA), since this component is stable during Mg(++) starvation. After the first few hours, this rate was constant, the amount of RNA present at the start of Mg(++) starvation being synthesized about every 120 min. Fractionation by gradient centrifugation revealed that at all times of starvation the ratio of newly synthesized tRNA-rRNA was the same as it was during exponential growth. Furthermore, newly synthesized ribosomal RNA (rRNA) became a part of polysomal structures. Thus, in the absence of Mg(++), DNA, tRNA, and rRNA were synthesized in the same relative proportions as during exponential growth, at rates close to one-half the instantaneous rates of synthesis in the bacteria growing exponentially at the start of starvation. PMID:6021070

Kennell, D; Kotoulas, A

1967-01-01

301

Magnesium Starvation of Aerobacter aerogenes II. Rates of Nucleic Acid Synthesis and Methods for Their Measurement  

PubMed Central

The rates of synthesis of Aerobacter aerogenes nucleic acids were estimated during incubation of the bacteria in a Mg++-free medium. Deoxyribonucleic acid (DNA) synthesized during Mg++ starvation, or in the preceding exponential growth, remained acid-precipitable for 2.5 hr before breaking down to acid-soluble products during a period of many hours. Rates of DNA synthesis were calculated by correcting the net amounts of DNA per milliliter to values that would have appeared had there been no decay. After the first few hours, this rate was constant, the amount of DNA present at the start of Mg++ starvation being synthesized every 130 min. Rates of synthesis of total ribonucleic acid (RNA) were established in two ways: (i) by measurements of the incorporation of exogeneous uracil and glucose carbon into RNA, and (ii) by the accumulation of transfer RNA (tRNA), since this component is stable during Mg++ starvation. After the first few hours, this rate was constant, the amount of RNA present at the start of Mg++ starvation being synthesized about every 120 min. Fractionation by gradient centrifugation revealed that at all times of starvation the ratio of newly synthesized tRNA-rRNA was the same as it was during exponential growth. Furthermore, newly synthesized ribosomal RNA (rRNA) became a part of polysomal structures. Thus, in the absence of Mg++, DNA, tRNA, and rRNA were synthesized in the same relative proportions as during exponential growth, at rates close to one-half the instantaneous rates of synthesis in the bacteria growing exponentially at the start of starvation.

Kennell, David; Kotoulas, Angeliki

1967-01-01

302

Expression of NAD+-dependent formate dehydrogenase in Enterobacter aerogenes and its involvement in anaerobic metabolism and H2 production.  

PubMed

An expression system for NAD(+)-dependent formate dehydrogenase gene (fdh1), from Candida boidinii, was constructed and cloned into Enterobacter aerogenes IAM1183. With the fdh1 expression, the total H(2) yield was attributed to a decrease in activity of the lactate pathway and an increase of the formate pathway flux due to the NADH regeneration. Analysis of the redox state balance and ethanol-to-acetate ratio in the fdhl-expressed strain showed that increased reducing power arose from the reconstruction of NADH regeneration pathway from formate thereby contributing to the improved H(2) production. PMID:19533026

Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

2009-06-16

303

Nasal Immunization with Lactococcus lactis Expressing the Pneumococcal Protective Protein A Induces Protective Immunity in Mice?  

PubMed Central

Nisin-controlled gene expression was used to develop a recombinant strain of Lactococcus lactis that is able to express the pneumococcal protective protein A (PppA) on its surface. Immunodetection assays confirmed that after the induction with nisin, the PppA antigen was predictably and efficiently displayed on the cell surface of the recombinant strain, which was termed L. lactis PppA. The production of mucosal and systemically specific antibodies in adult and young mice was evaluated after mice were nasally immunized with L. lactis PppA. Immunoglobulin M (IgM), IgG, and IgA anti-PppA antibodies were detected in the serum and bronchoalveolar lavage fluid of adult and young mice, which showed that PppA expressed in L. lactis was able to induce a strong mucosal and systemic immune response. Challenge survival experiments demonstrated that immunization with L. lactis PppA was able to increase resistance to systemic and respiratory infection with different pneumococcal serotypes, and passive immunization assays of naïve young mice demonstrated a direct correlation between anti-PppA antibodies and protection. The results presented in this study demonstrate three major characteristics of the effectiveness of nasal immunization with PppA expressed as a protein anchored to the cell wall of L. lactis: it elicited cross-protective immunity against different pneumococcal serotypes, it afforded protection against both systemic and respiratory challenges, and it induced protective immunity in mice of different ages.

Medina, Marcela; Villena, Julio; Vintini, Elisa; Hebert, Elvira Maria; Raya, Raul; Alvarez, Susana

2008-01-01

304

Relationship between utilization of proline and proline-containing peptides and growth of Lactococcus lactis.  

PubMed Central

Proline, which is the most abundant residue in beta-casein, stimulates growth of Lactococcus lactis in a proline-requiring strain (Lactococcus lactis subsp. cremoris Wg2) and in a proline-prototrophic strain (Lactococcus lactis subsp. lactis ML3). Both strains lack a proline-specific uptake system, and free proline can enter the cell only by passive diffusion across the cytoplasmic membrane. On the other hand, lactococci can actively take up proline-containing peptides via the lactococcal di- and tripeptide transport system, and these peptides are the major source of proline. Consequently, lactococcal growth on amino acid-based media is highly stimulated by the addition of proline-containing di- and tripeptides. Growth of L. lactis subsp. lactis ML3 on chemically defined media supplemented with casein does not appear proline limited. Addition of dipeptides (including proline-containing peptides) severely inhibits growth on a casein-containing medium, which indicates that the specific growth rate is determined by the balanced supply of different di- or tripeptides which compete for the same di- and tripeptide transport system.

Smid, E J; Konings, W N

1990-01-01

305

Adaptation and Response of Bifidobacterium animalis subsp. lactis to Bile: a Proteomic and Physiological Approach?  

PubMed Central

Bile salts are natural detergents that facilitate the digestion and absorption of the hydrophobic components of the diet. However, their amphiphilic nature makes them very inhibitory for bacteria and strongly influences bacterial survival in the gastrointestinal tract. Adaptation to and tolerance of bile stress is therefore crucial for the persistence of bacteria in the human colonic niche. Bifidobacterium animalis subsp. lactis, a probiotic bacterium with documented health benefits, is applied largely in fermented dairy products. In this study, the effect of bile salts on proteomes of B. animalis subsp. lactis IPLA 4549 and its bile-resistant derivative B. animalis subsp. lactis 4549dOx was analyzed, leading to the identification of proteins which may represent the targets of bile salt response and adaptation in B. animalis subsp. lactis. The comparison of the wild-type and the bile-resistant strain responses allowed us to hypothesize about the resistance mechanisms acquired by the derivative resistant strain and about the bile salt response in B. animalis subsp. lactis. In addition, significant differences in the levels of metabolic end products of the bifid shunt and in the redox status of the cells were also detected, which correlate with some differences observed between the proteomes. These results indicate that adaptation and response to bile in B. animalis subsp. lactis involve several physiological mechanisms that are jointly dedicated to reduce the deleterious impact of bile on the cell's physiology.

Sanchez, Borja; Champomier-Verges, Marie-Christine; Stuer-Lauridsen, Birgitte; Ruas-Madiedo, Patricia; Anglade, Patricia; Baraige, Fabienne; de los Reyes-Gavilan, Clara G.; Johansen, Eric; Zagorec, Monique; Margolles, Abelardo

2007-01-01

306

Antigenicity and Immunogenicity of Rotavirus VP6 Protein Expressed on the Surface of Lactococcus lactis  

PubMed Central

Group A rotaviruses are the major etiologic agents of acute gastroenteritis worldwide in children and young animals. Among its structural proteins, VP6 is the most immunogenic and is highly conserved within this group. Lactococcus lactis is a food-grade, Gram-positive, and nonpathogenic lactic acid bacteria that has already been explored as a mucosal delivery system of heterologous antigens. In this work, the nisin-controlled expression system was used to display the VP6 protein at the cell surface of L. lactis. Conditions for optimal gene expression were established by testing different nisin concentrations, cell density at induction, and incubation times after induction. Cytoplasmic and cell wall protein extracts were analyzed by Western blot and surface expression was confirmed by flow cytometry. Both analysis provided evidence that VP6 was efficiently expressed and displayed on the cell surface of L. lactis. Furthermore, the humoral response of mice immunized with recombinant L. lactis was evaluated and the displayed recombinant VP6 protein proved to be immunogenic. In conclusion, this is the first report of displaying VP6 protein on the surface of L. lactis to induce a specific immune response against rotavirus. These results provide the basis for further evaluation of this VP6-displaying L. lactis as a mucosal delivery vector in a mouse model of rotavirus infection.

Esteban, L. E.; Temprana, C. F.; Arguelles, M. H.; Glikmann, G.; Castello, A. A.

2013-01-01

307

Purification and characterization of pullulanase from Lactococcus lactis.  

PubMed

This paper describes a simple and efficient method of isolation of a plullulanase type I from amylolytic lactic acid bacteria (ALAB). Extracellular pullulanase type I was purified from a cell-free culture supernatant of Lactococcus lactis IBB 500 by using ammonium sulfate fractionation and dialysis (instead of ultrafiltration), and ion-exchange chromatography with CM Sepharose FF followed by gel filtration chromatography with Sephadex G-150 as the final step. A final purification factor of 14.36 was achieved. The molecular mass of the enzyme was estimated as 73.9 kD. The optimum temperature for the enzyme activity was 45°C and the optimum pH was 4.5. Pullulanase activity was increased by addition Co(2+) and completely inhibited by Hg(2+). The enzyme activity was specifically directed toward ?-1,6 glycosidic linkages of pullulan giving maltotriose units. Enzymatic hydrolysis of starch and amylose produced a mixture of maltose and maltotriose. PMID:21660865

Wa?ko, Adam; Polak-Berecka, Magdalena; Targonski, Zdzis?aw

2011-01-01

308

A membrane protein is required for bacteriophage c2 infection of Lactococcus lactis subsp. lactis C2.  

PubMed Central

Phage-resistant mutants, isolated from cultures of Lactococcus lactis subsp. lactis C2 infected with phage c2, did not form plaques but bound phage normally. The mutants were sensitive to another phage, sk1, although the number of plaques was reduced approximately 56% and the plaques were four times smaller. Binding to phage sk1 was reduced about 10%. Another group of phage-resistant mutants, isolated from cultures infected with phage sk1, bound normally to both phages c2 and sk1 but did not form plaques with either phage. Carbohydrate analyses by gas chromatography of the cell walls showed no significant differences in saccharide compositions between the wild-type and phage-resistant cells. However, a difference was observed in the interactions of the phage with the cytoplasmic membranes. Membranes from the wild-type cells, but not mutant cells, inactivated phage c2. Phage sk1 was not inactivated by membrane from either strain. Treatment of wild-type membranes with proteinase K eliminated the ability of the membrane to inactivate the phage, whereas treatment with mutanolysin had no effect. On the basis of this ability to inactivate the phage, a membrane protein was partially purified by gel filtration and ion-exchange chromatography. Under nondenaturing conditions, the phage-inactivating protein has an apparent Mr of approximately 350,000. The protein has an apparent subunit size of 32 kDa, which suggests that it normally exists as a multimer with 10 to 12 subunits or in association with other membrane components. It is proposed that this protein is required for phage c2 infection. Images

Valyasevi, R; Sandine, W E; Geller, B L

1991-01-01

309

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

PubMed

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

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

2010-08-04

310

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

PubMed

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

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

2013-08-30

311

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

SciTech Connect

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.

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

1985-04-01

312

Casitone-mediated expression of the prtP and prtM genes in Lactococcus lactis subsp. lactis BGIS29.  

PubMed

Casitone added to chemically defined medium (CDM) specifically influenced the regulation of the proteinase activity in the natural isolate Lactococcus lactis subsp. lactis BGIS29. Comparative analysis of the influence of casitone present in CDM on the proteolytic activity of strain BGIS29 and of L. lactis subsp. cremoris strains SK11 and Wg2 indicated that the proteolytic activity of strains BGIS29 and SK11 is casitone-dependent, whereas that of strain Wg2 is not. The regulatory region of the prt genes of strain BGIS29 was cloned and sequenced. The nucleotide sequence of the prt regulatory region of strain BGIS29 was distinctly different from that of L. lactis subsp. cremoris strains SK11 and Wg2. Transcriptional gene fusions with the Escherichia coli beta-glucuronidase gene ( gusA) were used to study medium-dependent expression of two divergent prtP and prtM promoters of strain BGIS29 (designated P (prtP) and P (prtM), respectively). beta-Glucuronidase assays and Northern blot analysis showed that the activities of P (prtP) and P (prtM) are controlled by casitone at the transcriptional level. PMID:11797045

Miladinov, N; Kuipers, O P; Topisirovic, L

2001-10-19

313

Use of carbon and energy balances in the study of the anaerobic metabolism of Enterobacter aerogenes at variable starting glucose concentrations  

Microsoft Academic Search

The anaerobic metabolism of Enterobacter aerogenes was studied in batch culture at increasing initial glucose levels (9.0So -1). The ultimate concentrations of fermentation products were utilized to check a metabolic flux analysis based on simple carbon mass and energy balances that promise to be suitable for the study of different fermentation processes, either under aerobic or anaerobic conditions. The stoichiometric

A. Converti; P. Perego

2002-01-01

314

Similar Effects of Various Neutral Solutes on the Survival of Aerobacter aerogenes and of Red Blood Cells after Freezing and Thawing  

Microsoft Academic Search

Aerobacter aerogenes from continuous culture is killed by slow freezing in buffer or by freeze-drying. Rapid freezing in liquid nitrogen results in 50 per cent survival if the organisms are suspended in distilled water, and almost complete survival if they are suspended in 10 per cent glycerol. Ten per cent solutions of some other polyhydroxy-compounds, sugars or of polyethylene glycol

T. Nash; J. R. POSTGATE; J. R. HUNTER

1963-01-01

315

The Influence of Temperature and pH Value on the Macromolecular Composition of Magnesium-limited and Glycerol-limited Aerobacter aerogenes Growing in a Chemostat  

Microsoft Academic Search

SUMMARY Progressive alteration of the incubation temperature of Aerobacter aerogenes cultures, growing in a chemostat at a fixed dilution rate, caused a progressive change in bacterial concentration and in bacterial RNA, carbohydrate and protein contents; the DNA content did not vary significantly. The change in bacterial RNA concentration was associated with a variation in bacterial ribosome content, similar to that

D. W. Tempest; J. R. Hunter

1965-01-01

316

Complete Genome of Lactococcus lactis subsp. cremoris UC509.9, Host for a Model Lactococcal P335 Bacteriophage  

PubMed Central

Here, we report the complete genome of Lactococcus lactis subsp. cremoris UC509.9, an Irish dairy starter. The circular chromosome of L. lactis UC509.9 represents the smallest among those of the sequenced lactococcal strains, while its large complement of eight plasmids appears to be a reflection of its adaptation to the dairy environment.

Ainsworth, Stuart; Zomer, Aldert; de Jager, Victor; Bottacini, Francesca; van Hijum, Sacha A. F. T.; Mahony, Jennifer

2013-01-01

317

Expression of Staphylococcus aureus Clumping Factor A in Lactococcus lactis subsp. cremoris Using a New Shuttle Vector  

Microsoft Academic Search

Staphylococcus aureus harbors redundant adhesins mediating tissue colonization and infection. To evaluate their intrinsic role outside of the staphylococcal background, a system was designed to express them in Lactococcus lactis subsp. cremoris 1363. This bacterium is devoid of virulence factors and has a known genetic background. A new Escherichia coli-L. lactis shuttle and expression vector was constructed for this purpose.

YOK-AI QUE; JACQUES-ANTOINE HAEFLIGER; PATRICK FRANCIOLI; P. Moreillon

2000-01-01

318

Complete Genome of Lactococcus lactis subsp. cremoris UC509.9, Host for a Model Lactococcal P335 Bacteriophage.  

PubMed

Here, we report the complete genome of Lactococcus lactis subsp. cremoris UC509.9, an Irish dairy starter. The circular chromosome of L. lactis UC509.9 represents the smallest among those of the sequenced lactococcal strains, while its large complement of eight plasmids appears to be a reflection of its adaptation to the dairy environment. PMID:23405300

Ainsworth, Stuart; Zomer, Aldert; de Jager, Victor; Bottacini, Francesca; van Hijum, Sacha A F T; Mahony, Jennifer; van Sinderen, Douwe

2013-01-31

319

Improved membrane protein expression in Lactococcus lactis by fusion to Mistic.  

PubMed

Difficulty overexpressing (eukaryotic) membrane proteins is generally considered as the major impediment in their structural and functional research. Lactococcus lactis possesses many properties ideal for membrane protein expression. In order to investigate membrane protein expression in L. lactis, we created a novel expression system by introducing Mistic, a short peptide previously identified in Bacillus subtilis, into L. lactis. The potential of this system was demonstrated in the overexpression of a eukaryotic membrane protein (pkjDes4) and a prokaryotic membrane protein (pkjLi), a newly isolated linoleate isomerase from Lactobacillus acidophilus. The expression levels reached up to 4.4?% and 45.2?% for pkjDes4 and pkjLi, respectively, which represented an exceptionally robust ability to overproduce membrane proteins. Moreover, the expressed pkjLi was functional, with its catalysing nature characterized for the first time in this species. Up to 0.852 mg ml(-1) conjugated linoleic acid was obtained during the linoleic acid conversion catalysed by the recombinant lactococcal strains. In summary, we established a membrane protein expression system in L. lactis and examined its functionality. Our results demonstrate that the Mistic chaperoning strategy can be efficiently applied to L. lactis hosts and show its extraordinary capacity to facilitate the high-yield production of intractable membrane proteins. PMID:23519161

Xu, Yi; Kong, Jian; Kong, Wentao

2013-03-21

320

Dynamic modeling of lactic acid fermentation metabolism with Lactococcus lactis.  

PubMed

A dynamic model of lactic acid fermentation using Lactococcus lactis was constructed, and a metabolic flux analysis (MFA) and metabolic control analysis (MCA) were performed to reveal an intensive metabolic understanding of lactic acid bacteria (LAB). The parameter estimation was conducted with COPASI software to construct a more accurate metabolic model. The experimental data used in the parameter estimation were obtained from an LC-MS/ MS analysis and time-course simulation study. The MFA results were a reasonable explanation of the experimental data. Through the parameter estimation, the metabolic system of lactic acid bacteria can be thoroughly understood through comparisons with the original parameters. The coefficients derived from the MCA indicated that the reaction rate of L-lactate dehydrogenase was activated by fructose 1,6-bisphosphate and pyruvate, and pyruvate appeared to be a stronger activator of L-lactate dehydrogenase than fructose 1,6-bisphosphate. Additionally, pyruvate acted as an inhibitor to pyruvate kinase and the phosphotransferase system. Glucose 6-phosphate and phosphoenolpyruvate showed activation effects on pyruvate kinase. Hexose transporter was the strongest effector on the flux through L-lactate dehydrogenase. The concentration control coefficient (CCC) showed similar results to the flux control coefficient (FCC). PMID:21364298

Oh, Euhlim; Lu, Mingshou; Park, Changhun; Park, Changhun; Oh, Han Bin; Lee, Sang Yup; Lee, Jinwon

2011-02-01

321

Controlled Release of Protein from Viable Lactococcus lactis Cells ?  

PubMed Central

Overexpression of the lactococcal CsiA protein affects the cell wall integrity of growing cells and leads to leakage of intracellular material. This property was optimized and exploited for the targeted release of biologically active compounds into the extracellular environment, thereby providing a new delivery system for bacterial proteins and peptides. The effects of different levels of CsiA expression on the leakage of endogenous lactate dehydrogenase and nucleic acids were measured and related to the impact of CsiA expression on Lactococcus lactis cell viability and growth. A leakage phenotype was obtained from cells expressing both recombinant and nonrecombinant forms of CsiA. As proof of principle, we demonstrated that CsiA promotes the efficient release of the heterologous Listeria bacteriophage endolysin LM4 in its active form. Under optimized conditions, native and heterologous active-molecule release is possible without affecting cell viability. The ability of CsiA to release intracellular material by controlled lysis without the requirement for an external lytic agent provides a technology for the control of both the extent of lysis and its timing. Taken together, these results demonstrate the potential of this novel approach for applications including product recovery in industrial fermentations, food processing, and medical therapy.

Stentz, Regis; Bongaerts, Roy J.; Gunning, A. Patrick; Gasson, Mike; Shearman, Claire

2010-01-01

322

Continuous nisin production with bioengineered Lactococcus lactis strains.  

PubMed

Nisin production in continuous cultures of bioengineered Lactococcus lactis strains that incorporate additional immunity and regulation genes was studied. Highest nisin activities were observed at 0.2 h(-1) dilution rate and 12.5 g l(-1) fructose concentration for all strains. Recombinant strains were able to produce greater amounts of nisin at dilution rates below 0.3 h(-1) compared to the control strain. However, this significant difference disappeared at dilution rates of 0.4 and 0.5 h(-1). For the strains LL27, LAC338, LAC339, and LAC340, optimum conditions for nisin production were determined to be at 0.29, 0.26, 0.27, and 0.27 h(-1) dilution rates and 11.95, 12.01, 11.63, and 12.50 g l(-1) fructose concentrations, respectively. The highest nisin productivity, 496 IU ml(-1) h(-1), was achieved with LAC339. The results of this study suggest that low dilution rates stabilize the high specific nisin productivity of the bioengineered strains in continuous fermentation. Moreover, response surface methodology analysis showed that regulation genes yielded high nisin productivity at wide ranges of dilution rates and fructose concentrations. PMID:19337764

Sim?ek, O; Akkoç, N; Con, A H; Ozçelik, F; Saris, P E J; Akçelik, Mustafa

2009-04-01

323

Geraniol dehydrogenase, the key enzyme in biosynthesis of the alarm pheromone, from the astigmatid mite Carpoglyphus lactis (Acari: Carpoglyphidae).  

PubMed

Geraniol dehydrogenase (GeDH), which plays an important role in the biosynthesis of neral, an alarm pheromone, was purified from the astigmatid mite Carpoglyphus lactis. The enzyme was obtained in an apparently homogeneous and active form after 1879-fold purification through seven steps of chromatography. Car. lactis GeDH was determined to be a monomer in its active form with a relative molecular mass of 42 800, which is a unique subunit structure in comparison with already established alcohol dehydrogenases. Car. lactis GeDH oxidized geraniol into geranial in the presence of NAD+. NADP+ was ineffective as a cofactor, suggesting that Car. lactis GeDH is an NAD+-dependent alcohol dehydrogenase. The optimal pH and temperature for geraniol oxidation were determined to be pH 9.0 and 25 degrees C, respectively. The Km values for geraniol and NAD+ were 51.0 microm and 59.5 microm, respectively. Car. lactis GeDH was shown to selectively oxidize geraniol, whereas its geometrical isomer, nerol, was inert as a substrate. The high specificity for geraniol suggests that Car. lactis GeDH specializes in the alarm pheromone biosynthesis of Car. lactis. Car. lactis GeDH is composed of 378 amino acids. Structurally, Car. lactis GeDH showed homology with zinc-dependent alcohol dehydrogenases found in mammals and a mosquito (36.6-37.6% identical), and the enzyme was considered to be a member of the medium-chain dehydrogenase/reductase family, in view of the highly conserved sequences of zinc-binding and NAD+-binding sites. Phylogenetic analyses indicate that Car. lactis GeDH could be categorized as a new class, different from other established alcohol dehydrogenases. PMID:18422649

Noge, Koji; Kato, Makiko; Mori, Naoki; Kataoka, Michihiko; Tanaka, Chihiro; Yamasue, Yuji; Nishida, Ritsuo; Kuwahara, Yasumasa

2008-04-17

324

Genome Sequences of Lactococcus lactis MG1363 (Revised) and NZ9000 and Comparative Physiological Studies ?  

PubMed Central

Lactococcus lactis NZ9000 and its parent MG1363 are the most commonly used lactic acid bacteria for expression and physiological studies. We noted unexpected but significant differences in the growth behaviors of both strains. We sequenced the entire genomes of the original NZ9000 and MG1363 strains using an ultradeep sequencing strategy. The analysis of the L. lactis NZ9000 genome yielded 79 differences, mostly point mutations, with the annotated genome sequence of L. lactis MG1363. Resequencing of the MG1363 strain revealed that 73 out of the 79 differences were due to errors in the published sequence. Comparative transcriptomic studies revealed several differences in the regulation of genes involved in sugar fermentation, which can be explained by two specific mutations in a region of the ptcC promoter with a key role in the regulation of cellobiose and glucose uptake.

Linares, Daniel M.; Kok, Jan; Poolman, Bert

2010-01-01

325

A new protein of alpha-amylase activity from Lactococcus lactis.  

PubMed

An extracellular alpha-amylase from Lactococcus lactis IBB500 was purified and characterized. The optimum conditions for the enzyme activity were pH 4.5, temperature of 35 degrees C, enzyme molecular mass of 121 kDa. The genome analysis and a plasmid curing experiment indicated that amy+ genes were located in a plasmid of 30 kb. An analysis of phylogenetic relationships strongly supported a hypothesis of horizontal gene transfer. A strong homology was found for the peptides with the sequence of alpha-amylases from Ralstonia pikettii and Ralstonia solanacearum. The protein of alpha-amylase activity purified in this study is the first one described for the Lactococcus lactis species, and this paper is the first report on Lactococcus lactis strain as a microorganism belonging to amylolytic lactic acid bacteria (ALAB). PMID:20890096

Wasko, Adam; Polak-Berecka, Magdalena; Targonski, Zdzislaw

2010-09-01

326

Extracellular Expression of a Functional Recombinant Ganoderma lucidium Immunomodulatory Protein by Bacillus subtilis and Lactococcus lactis? †  

PubMed Central

Bacillus subtilis and Lactococcus lactis are ideal hosts for the production of extracellular heterologous proteins of major commercial importance. A recombinant gene for the novel Ganoderma lucidium immunomodulatory protein LZ-8, recombinant LZ-8, was designed encoding the same amino acid sequence but using the preferred codons for both strains and was synthesized by overlapping extension PCR. Using the signal peptide (SP) from subtilisin YaB (SPYaB), recombinant LZ-8 was expressed extracellularly in Bacillus subtilis and Lactococcus lactis. In the absence of SPYaB, recombinant LZ-8 was expressed extracellularly in B. subtilis, but not in L. lactis. The three expressed recombinant LZ-8s showed different capacities for modulating the production of Th1 and Th2 cytokines by peripheral blood mononuclear cells and of tumor necrosis factor alpha by a macrophage cell line.

Yeh, Chuan M.; Yeh, Chun K.; Hsu, Xun Y.; Luo, Qiu M.; Lin, Ming Y.

2008-01-01

327

Function of Ubiquinone in Electron Transport from Reduced Nicotinamide Adenine Dinucleotide to Nitrate and Oxygen in Aerobacter aerogenes  

PubMed Central

The possible role of quinones in the electron transport system of Aerobacter aerogenes was investigated. The only quinone found in measurable amounts in bacteria grown in minimal media under both aerobic and anaerobic conditions was ubiquinone-8. Membrane-bound ubiquinone-8 could be removed by extraction with pentane, or destroyed by ultraviolet irradiation, with a concomitant loss of both reduced nicotinamide adenine dinucleotide (NADH) oxidase and NADH-linked respiratory nitrate reductase activity. In the extracted membrane preparations, these enzymatic activities could be restored, both to the same degree, by incorporation of ubiquinone-6, -8, or -10, but not by incorporation of menaquinones. The NADH oxidation and the nitrate reduction were sensitive to the respiratory inhibitors dicoumarol, lapachol, and cyanide. The results obtained indicate that ubiquinone-8 mediates the electron transport between NADH and oxygen as well as between NADH and nitrate. Branching of the electron transport chain to oxygen and nitrate occurs after an initial common pathway.

Knook, D. L.; Planta, R. J.

1971-01-01

328

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

PubMed

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

Loquasto, Joseph R; Barrangou, Rodolphe; Dudley, Edward G; Stahl, Buffy; Chen, Chun; Roberts, Robert F

2013-08-30

329

Vibrio furnissii (formerly aerogenic biogroup of Vibrio fluvialis), a new species isolated from human feces and the environment.  

PubMed Central

Strains formerly classified as the aerogenic (gas-producing) biogroup of Vibrio fluvialis were shown by DNA relatedness to be a separate species. The species was named Vibrio furnissii sp. nov. (type strain ATCC 35016 = CDC B3215). Three strains of V. furnissii were 79% or more related to the type strain of V. furnissii and about 50% related to the type strain of V. fluvialis. V. fluvialis strains were 40 to 64% related to the type strain of V. furnissii. Divergence in related sequences was only 0.0 to 1.5% among strains of V. furnissii and among strains of V. fluvialis but was 5.0 to 8.0% in interspecific reactions between V. fluvialis and V. furnissii. V. furnissii was aerogenic (produced gas from the fermentation of carbohydrates), whereas V. fluvialis was anaerogenic (did not produce gas from the fermentation of carbohydrates). Another test of some help in differentiating the two species was fermentation of L-rhamnose (57% positive for V. furnissii and negative for V. fluvialis). In addition to the reactions above, V. furnissii is distinguished from other salt-requiring vibrios on the basis of its positive reactions in tests for Møller L-arginine, L-arabinose, maltose, and D-mannitol and its negative reactions for Møller L-lysine and L-ornithine, lactose, and Voges-Proskauer. V. furnissii has been isolated from patients with acute gastroenteritis in at least two outbreaks of food poisoning; its role as a cause of diarrhea needs further study.

Brenner, D J; Hickman-Brenner, F W; Lee, J V; Steigerwalt, A G; Fanning, G R; Hollis, D G; Farmer, J J; Weaver, R E; Joseph, S W; Seidler, R J

1983-01-01

330

METABOLISM OF PENTOSES AND PENTITOLS BY AEROBACTER AEROGENES. II. MECHANISM OF ACQUISITION OF KINASE, ISOMERASE, AND DEHYDROGENASE ACTIVITY.  

PubMed

Mortlock, R. P. (Michigan State University, East Lansing), and W. A. Wood. Metabolism of pentoses by Aerobacter aerogenes. II. Mechanism of acquisition of kinase, isomerase, and dehydrogenase activity. J. Bacteriol. 88:845-849. 1964.-Aerobacter aerogenes PRL-R3 possesses the genetic information to synthesize, in the presence of the appropriate inducer, at least three members of the family of ketopentokinases, two members of the family of pentitol dehydrogenases, and two members of the family of aldopentose isomerases. That is, d-xylulokinase, d-ribulokinase, l-ribulokinase, ribitol dehydrogenase, d-arabitol dehydrogenase, d-xylose (--> d-xylulose) isomerase, and l-arabinose (--> l-ribulose) isomerase activities were detectable within 4 hr after addition of inducer. The possibility that mutation and selection are involved in the formation of l-xylulokinase, l-arabitol dehydrogenase, d-arabinose (--> d-ribulose) isomerase and d-lyxose (--> d-xylulose) isomerase could not be eliminated, because 11 hr or more of incubation after the addition of inducer were required before the appearance of these enzyme activities. d-Xylulokinase activity was induced in less than 2 hr when d-xylose or d-arabitol were inducers, but 45 hr were required for the appearance of activity when xylitol was the inducer, and 83 hr were required when d-lyxose was the inducer. Likewise, the time required for induction of ribitol dehydrogenase was 2 hr for ribitol, 12 hr for d-arabinose, and 45 hr for xylitol. The time required for the appearance of enzyme activity correlated with the time required for the beginning of cell growth and substrate utilization. PMID:14219045

MORTLOCK, R P; WOOD, W A

1964-10-01

331

Nisin-selectable food-grade secretion vector for Lactococcus lactis.  

PubMed

A nisin-resistant Lactococcus lactis strain TML01 was isolated from crude milk. A gene with 99% homology to the nisin-resistance gene, nsr, was identified. The food-grade secretion plasmid, pLEB690 (3746 bp), was constructed based on this novel nsr gene enabling primary selection with up to 5 ?g nisin/ml. The functionality of pLEB690 as a secretion vector was shown by expressing and secreting the pediocin AcH gene papA in L. lactis. pLEB690 is therefore, a functional food-grade secretion vector potentially useful for the food industry. PMID:21184135

Li, Ruiqing; Takala, Timo M; Qiao, Mingqiang; Xu, Haijin; Saris, Per E J

2010-12-24

332

DNA Sequence Analysis of Three Lactococcus lactis Plasmids Encoding Phage Resistance Mechanisms  

Microsoft Academic Search

The three Lactococcus lactis plasmids pSRQ700, pSRQ800, and pSRQ900 encode the previously de- scribed anti-phage resistance mechanisms LlaDCHI, AbiK, and AbiQ, respectively. Since these plasmids are likely to be introduced into industrial Lactococcus lactis strains used to manufacture commercial fermented dairy products, their complete DNA sequences were determined and analyzed. The plasmids pSRQ700 (7784 bp), pSRQ800 (7858 bp), and pSRQ900

I. Boucher; É. Émond; M. Parrot; S. Moineau

2001-01-01

333

Secretion of biologically active interferon-gamma inducible protein-10 (IP-10) by Lactococcus lactis  

PubMed Central

Background Chemokines are a large group of chemotactic cytokines that regulate and direct migration of leukocytes, activate inflammatory responses, and are involved in many other functions including regulation of tumor development. Interferon-gamma inducible-protein-10 (IP-10) is a member of the C-X-C subfamily of the chemokine family of cytokines. IP-10 specifically chemoattracts activated T lymphocytes, monocytes, and NK cells. IP-10 has been described also as a modulator of other antitumor cytokines. These properties make IP-10 a novel therapeutic molecule for the treatment of chronic and infectious diseases. Currently there are no suitable live biological systems to produce and secrete IP-10. Lactococcus lactis has been well-characterized over the years as a safe microorganism to produce heterologous proteins and to be used as a safe, live vaccine to deliver antigens and cytokines of interest. Here we report a recombinant strain of L. lactis genetically modified to produce and secrete biologically active IP-10. Results The IP-10 coding region was isolated from human cDNA and cloned into an L. lactis expression plasmid under the regulation of the pNis promoter. By fusion to the usp45 secretion signal, IP-10 was addressed out of the cell. Western blot analysis demonstrated that recombinant strains of L. lactis secrete IP-10 into the culture medium. Neither degradation nor incomplete forms of IP-10 were detected in the cell or supernatant fractions of L. lactis. In addition, we demonstrated that the NICE (nisin-controlled gene expression) system was able to express IP-10 "de novo" even two hours after nisin removal. This human IP-10 protein secreted by L. lactis was biological active as demonstrated by Chemotaxis assay over human CD3+T lymphocytes. Conclusion Expression and secretion of mature IP-10 was efficiently achieved by L. lactis forming an effective system to produce IP-10. This recombinant IP-10 is biologically active as demonstrated by its ability to chemoattract human CD3+ T lymphocytes. This strain of recombinant L. lactis represents a potentially useful tool to be used as a live vaccine in vivo.

Villatoro-Hernandez, Julio; Loera-Arias, Maria J; Gamez-Escobedo, Anali; Franco-Molina, Moises; Gomez-Gutierrez, Jorge G; Rodriguez-Rocha, Humberto; Gutierrez-Puente, Yolanda; Saucedo-Cardenas, Odila; Valdes-Flores, Jesus; Montes-de-Oca-Luna, Roberto

2008-01-01

334

Mycotoxin production by isolates of Fusarium lactis from greenhouse sweet pepper (Capsicum annuum).  

PubMed

Internal fruit rot, caused by Fusarium lactis, is an important disease of sweet pepper (Capsicum annuum) in Canadian greenhouses. Production of the mycotoxins fumonisin B? (FB?), moniliformin (MON) and beauvericin (BEA) by F. lactis (17 isolates) and the related species F. proliferatum (three isolates) and F. verticillioides (one isolate), which are also associated with internal fruit rot, was evaluated on rice medium. All 21 isolates examined were found to produce BEA, at concentrations ranging from 13.28 to 1674.60 ppm, while 13 of 17 F. lactis isolates and two of three F. proliferatum isolates produced MON (0.23 to 181.85 ppm). Only one isolate of F. lactis produced detectable levels of FB? in culture, whereas all three F. proliferatum isolates and the F. verticilloides isolate produced this mycotoxin (0.28 to 314 ppm). Production of FB?, MON and BEA was also evaluated in inoculated pepper fruits showing mild or severe symptoms of infection. FB? could be detected in both lightly and heavily diseased fruit tissue after inoculation with F. lactis, F. proliferatum or F. verticilloides, at concentrations ranging from 0.61 to 8.04 ppm. BEA was also detected in lightly and heavily diseased fruit tissue inoculated with F. lactis, as well as in heavily diseased tissue inoculated with F. proliferatum (3.00 to 19.43 ppm), but not in tissue inoculated with F. verticilloides. MON was detected in all tissues inoculated with F. proliferatum or F. verticilloides, and in heavily diseased tissue inoculated with F. lactis (0.03 to 0.27 ppm). The three mycotoxins were also found in naturally infected sweet pepper fruits exhibiting symptoms of internal fruit rot and collected from a commercial greenhouse. The production of MON, BEA and FB? alone or in combination by isolates of F. lactis suggests that development of internal fruit rot of sweet pepper is an important food safety concern, and that every effort should be made to cull infected fruit before it makes it to market. PMID:21903288

Yang, Y; Bouras, N; Yang, J; Howard, R J; Strelkov, S E

2011-08-22

335

Comparison of sequences from the malB regions of Salmonella typhimurium and Enterobacter aerogenes with Escherichia coli K12: A potential new regulatory site in the interoperonic region  

Microsoft Academic Search

The malE and malK genes from Salmonella typhimurium, and the MalEFG operon and a portion of malK from Enterobacter aerogenes were cloned and sequenced. Plasmid-borne malE genes from both species and the malF and malG genes from E. aerogenes were expressed normally in Escherichia coli, and their products function in maltose transport. This shows that the malB products from the

Michael K. Dahl; Eric Francoz; William Saurin; Winfried Boos; Michael D. Manson; Maurice Hofnung

1989-01-01

336

Comparative In Vitro Activities of Ciprofloxacin, Clinafloxacin, Gatifloxacin, Levofloxacin, Moxifloxacin, and Trovafloxacin against Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, and Enterobacter aerogenes Clinical Isolates with Alterations in GyrA and ParC Proteins  

Microsoft Academic Search

The in vitro activities of ciprofloxacin, clinafloxacin, gatifloxacin, levofloxacin, moxifloxacin, and trovafloxa- cin were tested against 72 ciprofloxacin-resistant and 28 ciprofloxacin-susceptible isolates of Klebsiella pneu- moniae, Klebsiella oxytoca, Enterobacter cloacae, and Enterobacter aerogenes. Irrespective of the alterations in GyrA and ParC proteins, clinafloxacin exhibited greater activity than all other fluoroquinolones tested against K. pneumoniae and E. aerogenes.

SYLVAIN BRISSE; DANA MILATOVIC; AD C. FLUIT; JAN VERHOEF; NELE MARTIN; SYBILLE SCHEURING; KARL KOHRER; FRANZ-JOSEF SCHMITZ

1999-01-01

337

BACT/LAER (Best Available Control Technology/Lowest Achievable Emission Rate) Clearinghouse: a compilation of control-technology determinations. First supplement to 1985 edition. Summary tables and Appendices A-G. Final report  

SciTech Connect

The volume explains the history of the BACT/LAER Clearinghouse, the background of the report format development, and acknowledges the continued support and effort of STAPPA and ALAPCO members. The volume contains three summary tables consisting of: a list of new control technology determinations received since May 1985, a list of all control-technology determinations that have been submitted, and a list of control-technology determinations for external combustion sources (boilers). A detailed listing of source type codes and abbreviations for process and emission limits are also shown. The volume contains the detailed source listing for the determinations submitted since May 1985. The detailed source listing normally contains the following information: source type and size; company name and location; whether determination was BACT or LAER for new or modified source; the person, agency and phone number that made the determination; permit issue date; estimated date of start-up; processes subject to this permit; through-put capacity; pollutant(s) emitted; emission limits; control equipment or process modification; a section for notes; and review status dates.

Dunbar, D.; Rust, G.

1986-05-01

338

BACT/LAER (best available control technology/lowest achievable emission rate) Clearinghouse: a compilation of control technology determinations. Second supplement to 1985 edition. Summary tables and appendices A-H. Final report  

SciTech Connect

This report explains the history of the BACT/LAER Clearinghouse, the background of the report format development, and acknowledges the continued support and effort of STAPPA and ALAPCO members. The report contains three summary tables consisting of: a list of new control-technology determinations received since May 1986, a list of all control-technology determinations that have been submitted, and a list of control-technology determinations for external combustion sources (boilers). A detailed listing of source-type codes and abbreviations for process and emission limits are also shown. The report contains the detailed source listings for the determinations submitted in source type code 1.0 through source type code 12.0. The detailed source listing normally contains the following information: source type and size; company name and location; whether determination was BACT or LAER for new or modified source; the person, agency, and phone number that made the determination; permit issue date; estimated date of start-up; processes subject to the permit; through-put capacity; pollutant(s) emitted; emission limits; control equipment or process modification; a section for notes; and review status dates.

Dunbar, D.; Sorrell, C.

1987-06-01

339

Conjugative transfer of the Lactococcus lactis chromosomal sex factor promotes dissemination of the Ll.LtrB group II intron.  

PubMed

The Ll.LtrB group II intron from the low-G+C gram-positive bacterium Lactococcus lactis was the first bacterial group II intron shown to splice and mobilize in vivo. This retroelement interrupts the relaxase gene (ltrB) of three L. lactis conjugative elements: plasmids pRS01 and pAH90 and the chromosomal sex factor. Conjugative transfer of a plasmid harboring a segment of the pRS01 conjugative plasmid including the Ll.LtrB intron allows dissemination of Ll.LtrB among L. lactis strains and lateral transfer of this retroelement from L. lactis to Enterococcus faecalis. Here we report the dissemination of the Ll.LtrB group II intron among L. lactis strains following conjugative transfer of the native chromosomally embedded L. lactis sex factor. We demonstrated that Ll.LtrB dissemination is highly variable and often more efficient from this integrative and conjugative element than from an engineered conjugative plasmid. Cotransfer among L. lactis strains of both Ll.LtrB-containing elements, the conjugative plasmid and the sex factor, was detected and shown to be synergistic. Moreover, following their concurrent transfer, both mobilizable elements supported the spread of their respective copies of the Ll.LtrB intron. Our findings explain the unusually high efficiency of Ll.LtrB mobility observed following conjugation of intron-containing plasmids. PMID:15659671

Belhocine, Kamila; Yam, Karen K; Cousineau, Benoit

2005-02-01

340

Use of a Genetically Enhanced, Pediocin-Producing Starter Culture, Lactococcus lactis subsp. lactis MM217, To Control Listeria monocytogenes in Cheddar Cheese  

PubMed Central

Cheddar cheese was prepared with Lactococcus lactis subsp. lactis MM217, a starter culture which contains pMC117 coding for pediocin PA-1. About 75 liters of pasteurized milk (containing ca. 3.6% fat) was inoculated with strain MM217 (ca. 106 CFU per ml) and a mixture of three Listeria monocytogenes strains (ca. 103 CFU per ml). The viability of the pathogen and the activity of pediocin in the cheese were monitored at appropriate intervals throughout the manufacturing process and during ripening at 8°C for 6 months. In control cheese made with the isogenic, non-pediocin-producing starter culture L. lactis subsp. lactis MM210, the counts of the pathogen increased to about 107 CFU per g after 2 weeks of ripening and then gradually decreased to about 103 CFU per g after 6 months. In the experimental cheese made with strain MM217, the counts of L. monocytogenes decreased to 102 CFU per g within 1 week of ripening and then decreased to about 10 CFU per g within 3 months. The average titer of pediocin in the experimental cheese decreased from approximately 64,000 arbitrary units (AU) per g after 1 day to 2,000 AU per g after 6 months. No pediocin activity (<200 AU per g) was detected in the control cheese. Also, the presence of pMC117 in strain MM217 did not alter the cheese-making quality of the starter culture, as the rates of acid production, the pH values, and the levels of moisture, NaCl, and fat of the control cheese and the experimental cheese were similar. Our data revealed that pediocin-producing starter cultures have significant potential for protecting natural cheese against L. monocytogenes.

Buyong, Nurliza; Kok, Jan; Luchansky, John B.

1998-01-01

341

Comparison of the nucleoside sequence of trpA and sequences immediately beyond the trp operon of Klebsiella aerogenes. Salmonella typhimurium and Escherichia coli.  

PubMed Central

The nucleotide sequence of trpA of Klebsiella aerogenes is presented and compared with the trpA sequences of Salmonella typhimurium and Escherichia coli. The majority of the approximately 200 differences between each pair of trpA's are single nucleotide pair changes that do not alter the amino acid sequence. Codon usage conforms to the general patterns revealed by examination of other prokaryotic gene sequences. However, codon usage in K. aerogenes trpA reflects the high G+C content of the genome of this organism. The DNA sequences just beyond trpA, the presumed transcription termination region, are also compared for the three species. Perusal of these sequences indicates that the secondary structure of the transcript segment just beyond trpA has been preserved, while the primary sequence has diverged appreciably.

Nichols, B P; Blumenberg, M; Yanofsky, C

1981-01-01

342

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

Microsoft Academic Search

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

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

1999-01-01

343

The cmbT gene encodes a novel major facilitator multidrug resistance transporter in Lactococcus lactis.  

PubMed

Functional characterization of the multidrug resistance CmbT transporter was performed in Lactococcus lactis. The cmbT gene is predicted to encode an efflux protein homologous to the multidrug resistance major facilitator superfamily. The cmbT gene (1377 bp) was cloned and overexpressed in L. lactis NZ9000. Results from cell growth studies revealed that the CmbT protein has an effect on host cell resistance to lincomycin, cholate, sulbactam, ethidium bromide, Hoechst 33342, sulfadiazine, streptomycin, rifampicin, puromycin and sulfametoxazole. Moreover, in vivo transport assays showed that overexpressed CmbT-mediated extrusion of ethidium bromide and Hoechst 33342 was higher than in the control L. lactis NZ9000 strain. CmbT-mediated extrusion of Hoechst 33342 was inhibited by the ionophores nigericin and valinomycin known to dissipate proton motive force. This indicates that CmbT-mediated extrusion is based on a drug-proton antiport mechanism. Taking together results obtained in this study, it can be concluded that CmbT is a novel major facilitator multidrug resistance transporter candidate in L. lactis, with a possible signaling role in sulfur metabolism. PMID:22985829

Filipic, Brankica; Golic, Natasa; Jovcic, Branko; Tolinacki, Maja; Bay, Denice C; Turner, Raymond J; Antic-Stankovic, Jelena; Kojic, Milan; Topisirovic, Ljubisa

2012-09-14

344

Sec-Mediated Secretion of Bacteriocin Enterocin P by Lactococcus lactis  

PubMed Central

Most lactic acid bacterium bacteriocins utilize specific leader peptides and dedicated machineries for secretion. In contrast, the enterococcal bacteriocin enterocin P (EntP) contains a typical signal peptide that directs its secretion when heterologously expressed in Lactococcus lactis. Signal peptide mutations and the SecA inhibitor azide blocked secretion. These observations demonstrate that EntP is secreted by the Sec translocase.

Herranz, Carmen; Driessen, Arnold J. M.

2005-01-01

345

Genome Sequence of the Cheese-Starter Strain Lactobacillus delbrueckii subsp. lactis CRL 581.  

PubMed

We report the genome sequence of Lactobacillus delbrueckii subsp. lactis CRL 581 (1,911,137 bp, GC 49.7%), a proteolytic strain isolated from a homemade Argentinian hard cheese which has a key role in bacterial nutrition and releases bioactive health-beneficial peptides from milk proteins. PMID:23929489

Hebert, Elvira María; Raya, Raúl R; Brown, Lucía; Font de Valdez, Graciela; Savoy de Giori, Graciela; Taranto, María Pía

2013-08-08

346

Carbon catabolite repression and global control of the carbohydrate metabolism in Lactococcus lactis  

Microsoft Academic Search

In view of the economic importance of fermented dairy products considerable scientific attention has been given to various steps of fermentation processes, including the L-lactate formation of lactic acid bacteria (de Vos, 1996). In particular, the carbohydrate metabolism of L. lactis has been the subject of extensive research and several genes encoding proteins involved in the central carbohydrate metabolism have

E. J. Luesink

1998-01-01

347

Lactococcus lactis as a live vector: Heterologous protein production and DNA delivery systems  

Microsoft Academic Search

Lactic acid bacteria (LAB), widely used in the food industry, are present in the intestine of most animals, including humans. The potential use of these bacteria as mucosal delivery vehicles for vaccinal, medical or technological use has been extensively investigated. Lactococcus lactis, a LAB species, is a potential candidate for the production of biologically useful proteins and for plasmid DNA

Daniela Santos Pontes; Marcela Santiago Pacheco de Azevedo; Jean-Marc Chatel; Philippe Langella; Vasco Azevedo; Anderson Miyoshi

2011-01-01

348

The role of microbial surface properties and extracellular polymer in Lactococcus Lactis aggregation  

Microsoft Academic Search

Microbial adhesion to an interface is known to have an important role in a wide variety of situations. In this study, we examine the effect of the surface physicochemical properties and extracellular polymers (ECP) of a lactic bacterium on microbial aggregation. Lactococcus lactis JCM 5805 was used in the current experiments to investigate the factors that control microbial aggregation. To

Toshiyuki Nomura; Hisaya Narahara; Hayato Tokumoto; Yasuhiro Konishi

2009-01-01

349

Progress in the development of mucosal vaccines based on Lactococcus lactis  

Microsoft Academic Search

This paper reviews recent work on the construction and characterisation of recombinant strains of Lactococcus lactis which are able to express immunogens derived from e.g. Clostridium tetani, H.I.V. — 1 and Schistosoma mansoni. The immunogenicity of these constructs has been tested in mice. In some instances it has been possible to elicit protective level systemic immune responses as well as

Jeremy M. Wells; Pamela M. Norton; Richard W. F. Le Page

1995-01-01

350

Extracellular Expression of a Functional Recombinant Ganoderma lucidium Immunomodulatory Protein by Bacillus subtilis and Lactococcus lactis  

Microsoft Academic Search

Bacillus subtilis and Lactococcus lactis are ideal hosts for the production of extracellular heterologous proteins of major commercial importance. A recombinant gene for the novel Ganoderma lucidium immunomodulatory protein LZ-8, recombinant LZ-8, was designed encoding the same amino acid sequence but using the preferred codons for both strains and was synthesized by overlapping extension PCR. Using the signal peptide (SP)

Chuan M. Yeh; Chun K. Yeh; Xun Y. Hsu; Qiu M. Luo; Ming Y. Lin

2008-01-01

351

Analysis of heat shock gene expression in Lactococcus lactis MG1363  

Microsoft Academic Search

The induction of the heat shock response in Lactococcus lactis subsp. cremoris strain MG1363 was analysed at the RNA level using a novel RNA isolation procedure to prevent degradation. Cloning of the dnal and gmÄL homologues was carried out. Northern blot analysis showed a similar induction pattern for dnaK, dnal and gmÄLS after transfer from 30 \\

Jose Arnau; K. I. Sorensen; Karen F. Appel; F. K. Vogensen; K. Hammer

1996-01-01

352

Heterologous Expression of an Immunogenic Pneumococcal Type 3 Capsular Polysaccharide in Lactococcus lactis  

Microsoft Academic Search

In order to develop a new system for the analysis of capsular biosynthetic pathways we have explored the possibility of expressing type 3 capsular polysaccharide (CPS) from the pathogen Streptococcus pneumoniae in Lactococcus lactis, an unencapsulated lactic acid bacterium being developed as a vaccine delivery vehicle for mucosal immunization. Only three of the four type 3 CPS biosynthesis genes were

CHRISTOPHE GILBERT; KAREN ROBINSON; RICHARD W. F. LE PAGE; JEREMY M. WELLS

2000-01-01

353

Fine Tuning of the Lactate and Diacetyl Production through Promoter Engineering in Lactococcus lactis  

Microsoft Academic Search

Lactococcus lactis is a well-studied bacterium widely used in dairy fermentation and capable of producing metabolites with organoleptic and nutritional characteristics. For fine tuning of the distribution of glycolytic flux at the pyruvate branch from lactate to diacetyl and balancing the production of the two metabolites under aerobic conditions, a constitutive promoter library was constructed by randomizing the promoter sequence

Tingting Guo; Jian Kong; Li Zhang; Chenchen Zhang; Shumin Hu

2012-01-01

354

Characterization of the Two-Component Abortive Phage Infection Mechanism AbiT from Lactococcus lactis  

Microsoft Academic Search

During the production of fermented dairy products, virulent bacteriophages infecting Lactococcus lactis can delay or stop the milk acidification process. A solution to this biological problem consists of introducing natural phage barriers into the strains used by the dairy industry. One such hurdle is called abortive infection (Abi) and causes premature cell death with no or little phage progeny. Here,

Julie D. Bouchard; Eric Dion; Frederic Bissonnette; Sylvain Moineau

2002-01-01

355

Effects of Lactococcus lactis on Composition of Intestinal Microbiota: Role of Nisin  

PubMed Central

This study examined the ability of (i) pure nisin, (ii) nisin-producing Lactococcus lactis strain CHCC5826, and (iii) the non-nisin-producing L. lactis strain CHCH2862 to affect the composition of the intestinal microbiota of human flora-associated rats. The presence of both the nisin-producing and the non-nisin-producing L. lactis strains significantly increased the number of Bifidobacterium cells in fecal samples during the first 8 days but decreased the number of enterococci/streptococci in duodenum, ileum, cecum, and colon samples as detected by selective cultivation. No significant changes in the rat fecal microbiota were observed after dosage with nisin. Pearson cluster analysis of denaturing gradient gel electrophoresis profiles of the 16S rRNA genes present in the fecal microbial population revealed that the microbiota of animals dosed with either of the two L. lactis strains were different from that of control animals dosed with saline. However, profiles of the microbiota from animals dosed with nisin did not differ from the controls. The concentrations of nisin estimated by competitive enzyme-linked immunosorbent assay (ELISA) were approximately 10-fold higher in the small intestine and 200-fold higher in feces than the corresponding concentrations estimated by a biological assay. This indicates that nisin was degraded or inactivated in the gastrointestinal tract, since fragments of this bacteriocin are detected by ELISA while an intact molecule is needed to retain biological activity.

Bernbom, Nete; Licht, Tine Rask; Brogren, Carl-Henrik; Jelle, Birthe; Johansen, Anette H.; Badiola, Iker; Vogensen, Finn K.; N?rrung, Birgit

2006-01-01

356

Preferential localization of Lactococcus lactis cells entrapped in a caseinate/alginate phase separated system.  

PubMed

This study aimed to entrap bioprotective lactic acid bacteria in a sodium caseinate/sodium alginate aqueous two-phase system. Phase diagram at pH=7 showed that sodium alginate and sodium caseinate were not miscible when their concentrations exceeded 1% (w/w) and 6% (w/w), respectively. The stability of the caseinate/alginate two-phase system was also checked at pH values of 6.0 and 5.5. Lactococcus lactis subsp. lactis LAB3 cells were added in a 4% (w/w) caseinate/1.5% (w/w) alginate two-phase system at pH=7. Fluorescence microscopy allowed to observe that the caseinate-rich phase formed droplets dispersed in a continuous alginate-rich phase. The distribution of bacteria in such a system was observed by epifluorescence microscopy: Lc. lactis LAB3 cells stained with Live/Dead(®) Baclight kit™ were located exclusively in the protein phase. Since zeta-potential measurements indicated that alginate, caseinate and bacterial cells all had an overall negative charge at pH 7, the preferential adhesion of LAB cells was assumed to be driven by hydrophobic effect or by depletion phenomena in such biopolymeric systems. Moreover, LAB cells viability was significantly higher in the ternary mixture obtained in the presence of both caseinate and alginate than in single alginate solution. Caseinate/alginate phase separated systems appeared thus well suited for Lc. lactis LAB3 cells entrapment. PMID:23665092

Léonard, Lucie; Gharsallaoui, Adem; Ouaali, Fahima; Degraeve, Pascal; Waché, Yves; Saurel, Rémi; Oulahal, Nadia

2013-04-08

357

Comparative Analyses of Prophage-Like Elements Present in Two Lactococcus lactis Strains? †  

PubMed Central

In this study, we describe the genetic organizations of six and five apparent prophage-like elements present in the genomes of the Lactococcus lactis subsp. cremoris strains MG1363 and SK11, respectively. Phylogenetic investigation as well bioinformatic analyses indicates that all 11 prophages belong to subdivisions of the lactococcal P335 group of temperate bacteriophages.

Ventura, Marco; Zomer, Aldert; Canchaya, Carlos; O'Connell-Motherway, Mary; Kuipers, Oscar; Turroni, Francesca; Ribbera, Angela; Foroni, Elena; Buist, Girbe; Wegmann, Udo; Shearman, Claire; Gasson, Michael J.; Fitzgerald, Gerald F.; Kok, Jan; van Sinderen, Douwe

2007-01-01

358

Cloning, Characterization, Controlled Overexpression, and Inactivation of the Major Tributyrin Esterase Gene of Lactococcus lactis  

Microsoft Academic Search

The gene encoding the major intracellular tributyrin esterase of Lactococcus lactis was cloned using degenerate DNA probes based on 19 known N-terminal amino acid residues of the purified enzyme. The gene, named estA, was sequenced and found to encode a protein of 258 amino acid residues. The transcription start site was mapped 233 nucleotides upstream of the start codon, and

Leonides Fernández; Marke M. Beerthuyzen; Julie Brown; Roland J. Siezen; Tim Coolbear; Ross Holland; Oscar P. Kuipers

2000-01-01

359

How physiological and cultural conditions influence heterologous protein production in Kluyveromyces lactis  

Microsoft Academic Search

The optimization and scale-up of a specific protein production process have to take into account cultural conditions as well as cell physiology of growth and influence of foreign protein expression on host cell metabolism. Growth on cheap substrates, efficient secretion ability and a weaker tendency to hypermannosilate proteins than S. cerevisiae, make K. lactis an excellent and well-accepted host for

Annamaria Merico; Daniele Capitanio; Ileana Vigentini; Bianca Maria Ranzi; Concetta Compagno

2004-01-01

360

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403  

Microsoft Academic Search

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 experi- mentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food.

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

2005-01-01

361

Bifidobacterium animalis ssp. lactis 420 Protects against Indomethacin-Induced Gastric Permeability in Rats  

PubMed Central

Gastrointestinal (GI) adverse effects such as erosion and increased permeability are common during the use of nonsteroidal anti-inflammatory drugs (NSAIDs). Our objective was to assess whether Bifidobacterium animalis ssp. lactis 420 protects against NSAID-induced GI side effects in a rat model. A total of 120 male Wistar rats were allocated into groups designated as control, NSAID, and probiotic. The NSAID and probiotic groups were challenged with indomethacin (10?mg/kg?1; single dose). The probiotic group was also supplemented daily with 1010?CFU of B. lactis 420 for seven days prior to the indomethacin administration. The control group rats received no indomethacin or probiotic. The permeability of the rat intestine was analysed using carbohydrate probes and the visual damage of the rat stomach mucosa was graded according to severity. B. lactis 420 significantly reduced the indomethacin-induced increase in stomach permeability. However, the protective effect on the visual mucosal damage was not significant. The incidence of severe NSAID-induced lesions was, nevertheless, reduced from 50% to 33% with the probiotic treatment. To conclude, the B. lactis 420 supplementation protected the rats from an NSAID-induced increase in stomach permeability and may reduce the formation of more serious GI mucosal damage and/or enhance the recovery rate of the stomach mucosa.

Lyra, Anna; Saarinen, Markku; Putaala, Heli; Olli, Kaisa; Lahtinen, Sampo J.; Ouwehand, Arthur C.; Madetoja, Mari; Tiihonen, Kirsti

2012-01-01

362

Effect of Exopolysaccharides on Phage-Host Interactions in Lactococcus lactis  

Microsoft Academic Search

In this study, we report that Lactococcus lactis strains producing exopolysaccharides (EPS) are sensitive to virulent phages. Eight distinct lytic phages (Q61 to Q68) specifically infecting Eps strains were isolated in 47 buttermilk samples obtained from 13 North American factories. The eight phages were classified within the 936 species by the multiplex PCR method, indicating that these phages are not

Helene Deveau; Marie-Rose Van Calsteren; Sylvain Moineau

2002-01-01

363

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

PubMed Central

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.

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

2011-01-01

364

Transcriptomic Analysis of Extensive Changes in Metabolic Regulation in Kluyveromyces lactis Strains  

Microsoft Academic Search

Genome-wide analysis of transcriptional regulation is generally carried out on well-characterized reference laboratory strains; hence, the characteristics of industrial isolates are therefore overlooked. In a previous study on the major cheese yeast Kluyveromyces lactis, we have shown that the reference strain and an industrial strain used in cheese making display a differential gene expression when grown on a single carbon

Audrey Suleau; Pierre Gourdon; Joelle Reitz-Ausseur; Serge Casaregola

2006-01-01

365

Coexistence of SHV-4- and TEM24-Producing Enterobacter aerogenes Strains before a Large Outbreak of TEM24-Producing Strains in a French Hospital  

Microsoft Academic Search

In 1996, a monitoring program was initiated at the teaching hospital of Amiens, France, and carried out for 3 years. All extended-spectrum b-lactamase (ESBL)-producing Enterobacter aerogenes isolates recovered from clinical specimens were collected for investigation of their epidemiological relatedness by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) and determination of the type of ESBL harbored by isoelectric

H. Mammeri; G. Laurans; M. Eveillard; S. Castelain; F. Eb

2001-01-01

366

Reactor comparison and scale-up for the microaerobic production of 2,3-butanediol by Enterobacter aerogenes at constant oxygen transfer rate  

Microsoft Academic Search

Stirred tank (STR), bubble column (BCR) and airlift (ALR) bioreactors of 0.05 and 1.5 m3 total volume were compared for the production of 2,3-butanediol using Enterobacter aerogenes under microaerobic conditions. Batch fermentations were carried out at constant oxygen transfer rate (OTR=35 mmol\\/lh). At 0.05 m3 scale, the STR reactor achieved much higher biomass and product concentrations than the BCR and

T.-G. Byun; A.-P. Zeng; W.-D. Deckwer

1994-01-01

367

Hydrogen production with high yield and high evolution rate by self-flocculated cells of Enterobacter aerogenes in a packed-bed reactor  

Microsoft Academic Search

Continuous hydrogen gas evolution by self-flocculated cells of Enterobacter aerogenes, a natural isolate HU-101 and its mutant AY-2, was performed in a packed-bed reactor under glucose-limiting conditions in\\u000a a minimal medium. The flocs that formed during the continuous culture were retained even when the dilution rate was increased\\u000a to 0.9?h?1. The H2 production rate increased linearly with increases in the

M. A. Rachman; Y. Nakashimada; T. Kakizono; N. Nishio

1998-01-01

368

Treatment of a meningitis due to an Enterobacter aerogenes producing a derepressed cephalosporinase and a klebsiella pneumoniae producing an extended-spectrum ?-lactamase  

Microsoft Academic Search

Summary A case of nosocomial meningitis due to aKlebsiella pneumoniae producing a CAZ-5 extendedspectrum ß-lactamase and anEnterobacter aerogenes producing a derepressed cephalosporinase is reported. The intrathecal catheter incriminated was removed and a treatment with ceftazidime (4 g\\/24 h) and amikacin (1.5 g\\/24 h) was started. After 24 h ceftazidime was replaced by imipenem (2 then 4 g\\/24 h). This treatment

C. de Champs; D. Sirot; M. Chanal; J. Sirot; D. Guelon; D. Joyon

1991-01-01

369

Effect of pH and acetic acid on growth and 2,3-butanediol production of Enterobacter aerogenes in continuous culture  

Microsoft Academic Search

The effect of pH and acetic acid on growth and 2,3-butanediol production of Enterobacter aerogenes from glucose was investigated in a microaerobic continuous culture. At a dilution rate of 0.20 h-1 and a fixed oxygen uptake rate (OUR) of 31.5 mmol l-1 h-1 the biomass concentration increased with pH ranging from 5.0 to 7.0, while the specific ATP requirement of

An-Ping Zeng; Hanno Biebl; Wolf-Dieter Deckwer

1990-01-01

370

Short-chain organic acids produced on glucose, lactose, and citrate media by Enterococcus faecalis, Lactobacillus casei, and Enterobacter aerogenes strains  

Microsoft Academic Search

Three strains of Enterococcus faecalis, three of Lactobacillus casei and two of Enterobacter aerogenes, isolated from commercial Palmita-type cheese were cultured in peptone-yeast extract broth with glucose (PYG), lactose (PYL), or citrate (PYC) added as the main carbon sources. The short-chain volatile and non-volatile organic acids were extracted and their concentration determined by GC with a FID detector. The identity

D. Urdaneta; D. Raffe; A. Ferrer; B. Sulbarán de Ferrer; L. Cabrera; M. Pérez

1995-01-01

371

Bioproduction of a novel sugar 1-deoxy- l-fructose by Enterobacter aerogenes IK7; isomerization of a 6-deoxyhexose to a 1-deoxyhexose  

Microsoft Academic Search

1-Deoxy-l-fructose, a very rare monosaccharide, was produced by hydrogenation of 6-deoxy-l-mannose (l-rhamnose)—the only cheaply available deoxy sugar—to 1-deoxy-l-mannitol (l-rhamnitol) followed by oxidation with Enterobacter aerogenes IK7. The entire procedure was conducted in water and shows the power of green environmentally friendly chemistry combined with biotechnology in the preparation of new monosaccharides with potential for novel bioactive properties or alternative foodstuffs;

Pushpakiran Gullapalli; Takayuki Shiji; Devendar Rao; Akihide Yoshihara; Kenji Morimoto; Goro Takata; George W. J. Fleet; Ken Izumori

2007-01-01

372

Carbapenem Resistance in a Clinical Isolate of Enterobacter aerogenes Is Associated with Decreased Expression of OmpF and OmpC Porin Analogs  

Microsoft Academic Search

We investigated the mechanism of imipenem resistance in Enterobacter aerogenes strain 810, a clinical isolate from the United States for which the imipenem MIC was 16 g\\/ml and the meropenem MIC was 8 g\\/ml. An imipenem-susceptible revertant, strain 810-REV, was obtained after multiple passages of the strain on non- selective media. For the revertant, the imipenem MIC was <1 g\\/ml

Hesna Yigit; Gregory J. Anderson; James W. Biddle; Christine D. Steward; J. Kamile Rasheed; Lourdes L. Valera; John E. McGowan; F. C. Tenover

2002-01-01

373

Changes in ciprofloxacin resistance levels in Enterobacter aerogenes isolates associated with variable expression of the aac(6')-Ib-cr gene.  

PubMed

Two closely related Enterobacter aerogenes isolates presented a new identical aac(6')-Ib-cr genetic environment, including IS26. One isolate showed lower MICs of ciprofloxacin, norfloxacin, tobramycin, and amikacin and decreased expression of aac(6')-Ib-cr, which might be related to a 12-bp deletion causing a displacement of the -10 box upstream of the aac(6')-Ib-cr gene. PMID:22106222

Ruiz, Elena; Ocampo-Sosa, Alain A; Alcoba-Flórez, Julia; Román, Elena; Arlet, Guillaume; Torres, Carmen; Martínez-Martínez, Luis

2011-11-21

374

Exopolysaccharide Expression in Lactococcus lactis subsp. cremoris Ropy352: Evidence for Novel Gene Organization?  

PubMed Central

Lactococcus lactis subsp. cremoris Ropy352 produces two distinct heteropolysaccharides, phenotypically described as ropy and mucoid, when cultured in nonfat milk. One exopolysaccharide precipitated with 50% ethanol as a series of elongated threads and was composed of glucose and galactose in a molar ratio of 3:2. The second exopolysaccharide precipitated with 75% ethanol as a fine flocculant and consisted of galactose, glucose, and mannose with a molar ratio of 67:21:12. A mutant strain, L. lactis subsp. cremoris EK240, lacking the ropy phenotype did not produce the exopolysaccharide that precipitated with 50% ethanol; however, it produced the exopolysaccharide that precipitated with 75% ethanol, indicating that the former exopolysaccharide is essential for the ropy phenotype. Cultures of L. lactis subsp. cremoris Ropy352 in 10% nonfat milk reached a viscosity of 25 Pa-s after 24 h, while those of the nonropy L. lactis subsp. cremoris EK240 mutant did not change. A mutation abolishing ropy exopolysaccharide expression mapped to a region on a plasmid containing two open reading frames, epsM and epsN, encoding novel glycosyltransferases bordered by ISS1 elements oriented in the same direction. Sequencing of this plasmid revealed two other regions involved in exopolysaccharide expression, an operon located between partial IS981 and IS982 elements, and an independent gene, epsU. Two and possibly three of these regions are involved in L. lactis subsp. cremoris Ropy352 exopolysaccharide expression and are arranged in a novel fashion different from that of typical lactococcal exopolysaccharide loci, and this provides genetic evidence for exopolysaccharide gene reorganization and evolution in Lactococcus.

Knoshaug, Eric P.; Ahlgren, Jeff A.; Trempy, Janine E.

2007-01-01

375

Vanadium and Experimental Caries. VII. Action of Vanadium on the Development of Lactobacillus Acidophilus and Streptococcus Lactis (Vanadio E Carie Sperimentale. VII. Azione del Vanadio sullo Sviluppo del Lactobacillus Acidophilus e dello Streptococcus Lactis).  

National Technical Information Service (NTIS)

The action of solutions with different contents of vanadium on the development and on the production of lactic acid of cultures of lactobacillus acidophilus and streptococcus lactis was investigated by the authors. The authors have established that there ...

G. Santacatterina G. Grippaudo F. Valfre G. Cecchetti

1972-01-01

376

Lactococcus lactis Expressing either Staphylococcus aureus Fibronectin-Binding Protein A or Listeria monocytogenes Internalin A Can Efficiently Internalize and Deliver DNA in Human Epithelial Cells?  

PubMed Central

Lactococci are noninvasive bacteria frequently used as protein delivery vectors and, more recently, as in vitro and in vivo DNA delivery vehicles. We previously showed that a functional eukaryotic enhanced green fluorescent protein (eGFP) expression plasmid vector was delivered in epithelial cells by Lactococcus lactis producing Listeria monocytogenes internalin A (L. lactis InlA+), but this strategy is limited in vivo to transgenic mice and guinea pigs. In this study, we compare the internalization ability of L. lactis InlA+ and L. lactis producing either the fibronectin-binding protein A of Staphylococcus aureus (L. lactis FnBPA+) or its fibronectin binding domains C and D (L. lactis CD+). L. lactis FnBPA+ and L. lactis InlA+ showed comparable internalization rates in Caco-2 cells, while the internalization rate observed with L. lactis CD+ was lower. As visualized by conventional and confocal fluorescence microscopy, large clusters of L. lactis FnBPA+, L. lactis CD+, and L. lactis InlA+ were present in the cytoplasm of Caco-2 cells after internalization. Moreover, the internalization rates of Lactobacillus acidophilus NCFM and of an NCFM mutant strain with the gene coding for the fibronectin-binding protein (fbpA) inactivated were also evaluated in Caco-2 cells. Similar low internalization rates were observed for both wild-type L. acidophilus NCFM and the fbpA mutant, suggesting that commensal fibronectin binding proteins have a role in adhesion but not in invasion. L. lactis FnBPA+, L. lactis CD+, and L. lactis InlA+ were then used to deliver a eukaryotic eGFP expression plasmid in Caco-2 cells: flow cytometry analysis showed that the highest percentage of green fluorescent Caco-2 cells was observed after coculture with either L. lactis FnBPA+ or L. lactis InlA+. Analysis of the in vivo efficiency of these invasive recombinant strains is currently in progress to validate their potential as DNA vaccine delivery vehicles.

Innocentin, Silvia; Guimaraes, Valeria; Miyoshi, Anderson; Azevedo, Vasco; Langella, Philippe; Chatel, Jean-Marc; Lefevre, Francois

2009-01-01

377

Conjugative transfer of the Lactococcus lactis sex factor and pRS01 plasmid to Enterococcus faecalis.  

PubMed

The low G+C gram-positive bacterium Lactococcus lactis harbours two highly similar conjugative elements: an integrative and conjugative element called sex factor and the pRS01 plasmid. Originally, it was believed that the host range of the sex factor was limited to L. lactis subspecies. Here, it is reported that pTRK28 cointegrates of a spectinomycin-marked L. lactis sex factor and of the pRS01 conjugative plasmid can be transferred from L. lactis to Enterococcus faecalis. These results demonstrate the conjugative transfer of these elements to other bacterial species. Furthermore, it is reported that Ll.LtrB, a mobile group II intron carried by both elements, can invade its recognition site upon pRS01 conjugative transfer to E. faecalis. PMID:17263841

Belhocine, Kamila; Mandilaras, Victoria; Yeung, Bonnie; Cousineau, Benoit

2007-01-30

378

Contribution of Citrate Metabolism to the Growth of Lactococcus lactis CRL264 at Low pH  

Microsoft Academic Search

Lactococcus lactis subsp. lactis biovar diacetylactis CRL264 is a natural strain isolated from cheese (F. Sesma, D. Gardiol, A. P. de Ruiz Holgado, and D. de Mendoza, Appl. Environ. Microbiol. 56:2099-2103, 1990). The effect of citrate on the growth parameters at a very acidic pH value was studied with this strain and with derivatives whose citrate uptake capacity was genetically

Claudia Sanchez; Ana Rute Neves; Joao Cavalheiro; Margarida Moreira dos Santos; N. Garcia-Quintans; Paloma Lopez; Helena Santos

2008-01-01

379

Proton Motive Force-Driven and ATP-Dependent Drug Extrusion Systems in Multidrug-Resistant Lactococcus lactis  

Microsoft Academic Search

Three mutants of Lactococcus lactis subsp. lactis MG1363, termed EthR, DauR, and RhoR, were selected for resistance to high concentrations of ethidium bromide, daunomycin, and rhodamine 6G, respectively. These mutants were found to be cross resistant to a number of structurally and functionally unrelated drugs, among which were typical substrates of the mammalian multidrug transporter (P-glycoprotein) such as daunomycin, quinine,

Hendrik W. van Veen; Gerrit Poelarends; Douwe Molenaar; Henk Bolhuis; Bert Poolman; Arnold J. M. Driessen; Wil N. Konings

1994-01-01

380

Induction by glucose of an antimycin-insensitive, azide-sensitive respiration in the yeast Kluyveromyces lactis  

Microsoft Academic Search

Increasing the glucose concentration from 0.1 to 10% in exponentially growing cultures of Kluyveromyces lactis CBS 2359 does not repress the antimycin-sensitive respiration (QO2 of 80 µl O2·h-1·mg-1 dry weight) but raises the antimycin-insensitive respiration from 3 to 12 µl O2·h-1·mg-1 dry weight. Antimycin A inhibits the growth of K. lactis on a variety of substrates with the exception of

Iliana Ferrero; Anna-Maria Viola; A. Goffeau

1981-01-01

381

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

Microsoft Academic Search

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

MICHAELJ. GASSON

382

Characterization and Genomic Analysis of Phage ascc 28, a Phage of the Family Podoviridae Infecting Lactococcus lactis  

Microsoft Academic Search

Bacteriophage ascc28 infects dairy fermentation strains of Lactococcus lactis. This report describes char- acterization of ascc28 and its full genome sequence. Phage ascc28 has a prolate head, whiskers, and a short tail (C2 morphotype). This morphology and DNA hybridization to L. lactis phage P369 DNA showed that ascc28 belongs to the P034 phage species, a group rarely encountered in the

Steven E. Kotsonis; Ian B. Powell; Christopher J. Pillidge; Gaetan K. Y. Limsowtin; Alan J. Hillier; Barrie E. Davidson

2008-01-01

383

Identification and Molecular Characterization of the Chromosomal Exopolysaccharide Biosynthesis Gene Cluster from Lactococcus lactis subsp. cremoris SMQ-461  

Microsoft Academic Search

The exopolysaccharide (EPS) capsule-forming strain SMQ-461 of Lactococcus lactis subsp. cremoris, isolated from raw milk, produces EPS with an apparent molecular mass of >1.6 106 Da. The EPS biosynthetic genes are located on the chromosome in a 13.2-kb region consisting of 15 open reading frames. This region is flanked by three IS1077-related tnp genes (L. lactis) at the 5 end

N. Dabour; G. LaPointe

2005-01-01

384

The development of Tn Nuc and its use for the isolation of novel secretion signals in Lactococcus lactis  

Microsoft Academic Search

We have previously used Tn917 for the identification and characterization of regulated promoters from Lactococcus lactis [Israelsen et al., Appl. Environ. Microbiol. 61 (1995) 2540–2547]. We describe here the construction of a new Tn917-transposon derivative, termed TnNuc, which includes the Staphylococcus aureus nuclease gene (nuc) as a reporter for secretion. Transposition of TnNuc into the L. lactis chromosome allows the

Peter Ravn; José Arnau; Søren M. Madsen; Astrid Vrang; Hans Israelsen

2000-01-01

385

A General Method for Selection of a-Acetolactate Decarboxylase-Deficient Lactococcus lactis Mutants To Improve Diacetyl Formation  

Microsoft Academic Search

The enzyme acetolactate decarboxylase (Ald) plays a key role in the regulation of the a-acetolactate pool in both pyruvate catabolism and the biosynthesis of the branched-chain amino acids, isoleucine, leucine, and valine (ILV). This dual role of Ald, due to allosteric activation by leucine, was used as a strategy for the isolation of Ald-deficient mutants of Lactococcus lactis subsp. lactis

MIRJANA CURIC; BIRGITTE STUER-LAURIDSEN; PIERRE RENAULT; DAN NILSSON

1999-01-01

386

Conjugative Transfer of the Lactococcus lactis Chromosomal Sex Factor Promotes Dissemination of the Ll.LtrB Group II Intron  

Microsoft Academic Search

The Ll.LtrB group II intron from the low-GC gram-positive bacterium Lactococcus lactis was the first bacterial group II intron shown to splice and mobilize in vivo. This retroelement interrupts the relaxase gene (ltrB) of three L. lactis conjugative elements: plasmids pRS01 and pAH90 and the chromosomal sex factor. Conjugative transfer of a plasmid harboring a segment of the pRS01 conjugative

Kamila Belhocine; Karen K. Yam; Benoit Cousineau

2005-01-01

387

KlPMR1 inactivation and calcium addition enhance secretion of non-hyperglycosylated heterologous proteins in Kluyveromyces lactis  

Microsoft Academic Search

The Kluyveromyces lactis KlPMR1 gene is the functional homologue of Saccharomyces cerevisiae PMR1 which encodes a Ca2+-ATPase localized in the Golgi apparatus. We studied the effects of KlPMR1 inactivation on the glycosylation and secretion of native and heterologous proteins in K. lactis. We used acid phosphatase, recombinant human serum albumin and ?-glucoamylase from Arxula adeninivorans as reporter proteins. The Klpmr1?

D. Uccelletti; F. Farina; P. Mancini; C. Palleschi

2004-01-01

388

Mdt(A), a New Efflux Protein Conferring Multiple Antibiotic Resistance in Lactococcus lactis and Escherichia coli  

Microsoft Academic Search

The mdt(A) gene, previously designated mef214, from Lactococcus lactis subsp. lactis plasmid pK214 encodes a protein (Mdt(A) (multiple drug transporter)) with 12 putative transmembrane segments (TMS) that contain typical motifs conserved among the efflux proteins of the major facilitator superfamily. However, it also has two C-motifs (conserved in the fifth TMS of the antiporters) and a putative ATP-binding site. Expression

VINCENT PERRETEN; FRANZISKA V. SCHWARZ; MICHAEL TEUBER; STUART B. LEVY

2001-01-01

389

Genome-scale diversity and niche adaptation analysis of Lactococcus lactis by comparative genome hybridization using multi-strain arrays.  

PubMed

Lactococcus lactis produces lactic acid and is widely used in the manufacturing of various fermented dairy products. However, the species is also frequently isolated from non-dairy niches, such as fermented plant material. Recently, these non-dairy strains have gained increasing interest, as they have been described to possess flavour-forming activities that are rarely found in dairy isolates and have diverse metabolic properties. We performed an extensive whole-genome diversity analysis on 39 L. lactis strains, isolated from dairy and plant sources. Comparative genome hybridization analysis with multi-strain microarrays was used to assess presence or absence of genes and gene clusters in these strains, relative to all L. lactis sequences in public databases, whereby chromosomal and plasmid-encoded genes were computationally analysed separately. Nearly 3900 chromosomal orthologous groups (chrOGs) were defined on basis of four sequenced chromosomes of L. lactis strains (IL1403, KF147, SK11, MG1363). Of these, 1268 chrOGs are present in at least 35 strains and represent the presently known core genome of L. lactis, and 72 chrOGs appear to be unique for L. lactis. Nearly 600 and 400 chrOGs were found to be specific for either the subspecies lactis or subspecies cremoris respectively. Strain variability was found in presence or absence of gene clusters related to growth on plant substrates, such as genes involved in the consumption of arabinose, xylan, ?-galactosides and galacturonate. Further niche-specific differences were found in gene clusters for exopolysaccharides biosynthesis, stress response (iron transport, osmotolerance) and bacterial defence mechanisms (nisin biosynthesis). Strain variability of functions encoded on known plasmids included proteolysis, lactose fermentation, citrate uptake, metal ion resistance and exopolysaccharides biosynthesis. The present study supports the view of L. lactis as a species with a very flexible genome. PMID:21338475

Siezen, Roland J; Bayjanov, Jumamurat R; Felis, Giovanna E; van der Sijde, Marijke R; Starrenburg, Marjo; Molenaar, Douwe; Wels, Michiel; van Hijum, Sacha A F T; van Hylckama Vlieg, Johan E T

2011-02-21

390

The ldh phylogeny for environmental isolates of Lactococcus lactis is consistent with rRNA genotypes but not with phenotypes.  

PubMed Central

Lactate dehydrogenase (ldh) gene sequences, levels of 16S rRNA group-specific probe binding, and phenotypic characteristics were compared for 45 environmental isolates and four commercial starter strains of Lactococcus lactis to identify evolutionary groups best suited to cheddar cheese manufacture, ldh sequences from the environmental isolates showed high similarity to those from two groups of L. lactis used for industrial fermentations, L. lactis subsp. cremoris and subsp. lactis. Within each phylogenetically defined subspecies, ldh sequence similarities were greater than 99.1%. Strains with phenotypic traits formerly diagnostic for both subspecies were found in each ldh similarity group, but only strains belonging to L. lactis subsp. cremoris by both the newer, genetic and the older, superseded phenotypic criteria were judged potentially suitable for the commercial production of cheddar cheese. Identical evolutionary relationships were inferred from ldh sequences and from binding of subspecies-specific, 16S rRNA-directed oligonucleotide probes. However, groups defined according to these chromosomal traits bore no relationship to patterns of arginine deamination, carbon substrate utilization, or bacteriophage sensitivity, which may be encoded by cryptic genes or sexually transmissible genetic elements. Fourteen new L. lactis subsp. cremoris isolates were identified as suitable candidates for cheddar cheese manufacture, and 10 of these were completely resistant to three different batteries of commercial bacteriophages known to reduce starter activity.

Urbach, E; Daniels, B; Salama, M S; Sandine, W E; Giovannoni, S J

1997-01-01

391

Generation and evaluation of A2-expressing Lactococcus lactis live vaccines against Leishmania donovani in BALB/c mice.  

PubMed

Leishmaniasis is a parasitic disease affecting over 12 million individuals worldwide. As current treatments are insufficient, the development of an effective vaccine is a priority. This study generated and assessed the efficacy of Leishmania vaccines engineered from the non-colonizing, non-pathogenic Gram-positive bacterium Lactococcus lactis. A truncated, codon-optimized version of the A2 antigen from Leishmania donovani was engineered for expression in Lactococcus lactis in three different subcellular compartments: in the cytoplasm, secreted outside the cell or anchored to the cell wall. These three A2-expressing Lactococcus lactis strains were tested for their ability to generate A2-specific immune responses and as live vaccines against visceral Leishmania donovani infection in BALB/c mice. Subcutaneous immunization with live Lactococcus lactis expressing A2 anchored to the cell wall effectively induced high levels of antigen-specific serum antibodies. It was demonstrated that Lactococcus lactis-based vaccines are a feasible approach in the generation of live vaccines against leishmaniasis. The Lactococcus lactis strains generated in this study provide an excellent foundation for further studies on live bacterial vaccines against leishmaniasis and other pathogens. PMID:21527547

Yam, Karen K; Hugentobler, Felix; Pouliot, Philippe; Stern, Andrew M; Lalande, Jean-Daniel; Matlashewski, Greg; Olivier, Martin; Cousineau, Benoit

2011-04-28

392

Molecular cloning and expression of a proteinase gene from Lactococcus lactis subsp. cremoris H2 and construction of a new lactococcal vector pFX1  

Microsoft Academic Search

The 6.5 kb HindIII DNA fragment of the Lactococcus lactis subsp. cremoris H2 plasmid pDI21 was cloned into Escherichia coli POP13 with ?NM1149, and also directly into Lactococcus lactis subsp. lactis 4125 using a newly-constructed broad host-range vector pFX1. Proteinase was experessed in both transformed organisms. The proteinase resembles a PI type since it preferentially degraded ?-casein. The restriction map

Feng-Feng Xu; Lindsay E. Pearce; Pak-Lam Yu

1990-01-01

393

Expression of Helicobacter pylori urease subunit B gene in Lactococcus lactis MG1363 and its use as a vaccine delivery system against H. pylori infection in mice  

Microsoft Academic Search

The use of Lactococcus lactis as an antigen delivery vehicle for mucosal immunisation has been proposed. To determine whether L. lactis could effectively deliver Helicobacterpylori antigens to the immune system, a recombinant L. lactis expressing H. pylori urease subunit B (UreB) was constructed. Constitutive expression of UreB by a pTREX1 vector resulted in the intracellular accumulation of UreB to ?6.25%

Ming Hsun Lee; Yvonne Roussel; Mark Wilks; Soad Tabaqchali

2001-01-01

394

Alteration of hydrogen metabolism of ldh-deleted Enterobacter aerogenes by overexpression of NAD+-dependent formate dehydrogenase.  

PubMed

The NAD+-dependent formate dehydrogenase FDH1 gene (fdh1), cloned from Candida boidinii, was expressed in the ldh-deleted mutant of Enterobacter aerogenes IAM1183 strain. The plasmid of pCom10 driven by the PalkB promoter was used to construct the fdh1 expression system and thus introduce a new dihydronicotinamide adenine dinucleotide (NADH) regeneration pathway from formate in the ldh-deleted mutant. The knockout of NADH-consuming lactate pathway affected the whole cellular metabolism, and the hydrogen yield increased by 11.4% compared with the wild strain. Expression of fdh1 in the ldh-deleted mutant caused lower final cell concentration and final pH after 16 h cultivation, and finally resulted in 86.8% of increase in hydrogen yield per mole consumed glucose. The analysis of cellular metabolites and estimated redox state balance in the fdhl-expressed strain showed that more excess of reducing power was formed by the rewired NADH regeneration pathway, changing the metabolic distribution and promoting the hydrogen production. PMID:19830418

Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Wu, Xi; Xing, Xin-Hui

2009-10-15

395

Repression of Glutamate Dehydrogenase Formation in Klebsiella aerogenes Requires Two Binding Sites for the Nitrogen Assimilation Control Protein, NAC  

PubMed Central

In Klebsiella aerogenes, the gdhA gene codes for glutamate dehydrogenase, one of the enzymes responsible for assimilating ammonia into glutamate. Expression of a gdhAp-lacZ transcriptional fusion was strongly repressed by the nitrogen assimilation control protein, NAC. This strong repression (>50-fold under conditions of severe nitrogen limitation) required the presence of two separate NAC binding sites centered at ?89 and +57 relative to the start of gdhA transcription. Mutants lacking either or both of these sites lost the strong repression. The distance between the two sites was less important than the face of the helix on which they lay. Insertion or deletion of 10 bp between the sites had little effect on the strong repression, but insertion of 5 bp or deletion of either 5 or 15 bp decreased the repression significantly. We propose that the strong repression of gdhAp-lacZ expression requires an interaction between the NAC molecules bound at the two sites. A weaker repression of gdhAp-lacZ expression (about threefold) required only the NAC site centered at ?89. This weaker repression appears to result from NAC's ability to prevent the action of a positive effector the target of which overlaps the NAC binding site centered at ?89. Point mutations and deletions of this region result in the same threefold reduction in gdhAp-lacZ expression as the presence of NAC at this site.

Goss, Thomas J.; Janes, Brian K.; Bender, Robert A.

2002-01-01

396

Alginate lyase from Klebsiella pneumoniae, subsp. aerogenes: gene cloning, sequence analysis and high-level production in Escherichia coli.  

PubMed

The alyA gene, encoding a secreted guluronate-specific alginate lyase (Aly) from Klebsiella pneumoniae subsp. aerogenes type 25, has been cloned. DNA sequence analysis reveals two possible translation start sites for the precursor form of Aly and a long open reading frame (ORF) predicted to encode a 287-amino-acid (aa) mature form of Aly, in agreement with N-terminal aa sequence analysis of the protein. Aly has a calculated molecular mass of 31.4 kDa, in good agreement with SDS-PAGE analysis, and a calculated pI of 9.39. Comparison of the deduced aa sequence with a mannuronate-specific lyase from a marine bacterium reveals 19.3% identity and 28.8% similarity with a 9-aa conserved region close to the C terminus, probably of functional or structural significance. There is no obvious sequence similarity with pectate lyases which also catalyse a beta-elimination reaction. Heterologous expression of K. pneumoniae alyA in Escherichia coli yields 10 mg of Aly per litre of culture supernatant, apparently due to non-specific release from the periplasm. PMID:8200539

Baron, A J; Wong, T Y; Hicks, S J; Gacesa, P; Willcock, D; McPherson, M J

1994-05-27

397

Evolution of the alcohol dehydrogenase (ADH) genes in yeast: characterization of a fourth ADH in Kluyveromyces lactis.  

PubMed

Three alcohol dehydrogenase (ADH) genes have recently been characterized in the yeast Kluyveromyces lactis. We report on a fourth ADH in K. lactis (KADH II: KADH2* gene) which is highly similar to other ADHs in K. lactis and Saccharomyces cerevisiae. KADH II appears to be a cytoplasmic enzyme, and after expression of KADH2 in S. cerevisiae enzyme activity comigrated with a K. lactis ADH present in cells grown in glucose or in ethanol. KADH I was also expressed in S. cerevisiae and it comigrated with a major ADH species expressed under glucose growth conditions in K. lactis. The substrate specificities for KADH I and KADH II were shown to be more similar to that of SADH II than to SADH I. SADH I cannot efficiently utilize long chain alcohols, in contrast to other cytoplasmic yeast ADHs, presumably because of the presence of a methionine (residue 271) in its substrate binding cleft. A comparison of the DNA sequences of ADHs among K. lactis, S. cerevisiae and Schizosaccharomyces pombe suggests that the ancestral yeast species contained one cytoplasmic ADH. After divergence from S. pombe, the ADH in the ancestor to K. lactis and S. cerevisiae was duplicated, and one ADH became localized to the mitochondrion, presumably for the oxidative use of ethanol. Following the speciation of S. cerevisiae and K. lactis, the gene encoding the cytoplasmic ADH in S. cerevisiae duplicated, which resulted in the development of the SADH II protein as the primary oxidative enzyme in place of SADH III. In contrast, the K. lactis mitochondrial ADH duplicated to give rise to the highly expressed KADH3 and KADH4 genes, both of which may still play primary roles in oxidative metabolism. These data suggest that K. lactis and S. cerevisiae use different compartments for their metabolism of ethanol. Our results also indicate that the complex regulatory circuits controlling the glucose-repressible SADH2 in S. cerevisiae are a recent acquisition from regulatory networks used for the control of genes other than SADH2. PMID:1588917

Shain, D H; Salvadore, C; Denis, C L

1992-04-01

398

Absence of anionic phospholipids in Kluyveromyces lactis cells is fatal without F1-catalysed ATP hydrolysis.  

PubMed

We have shown in previous research that the loss of phosphatidylglycerol and cardiolipin caused by disruption of the PGS1 gene is lethal for the petite-negative yeast Kluyveromyces lactis . This present study demonstrates the role and mechanism of atp2.1 in the suppression of pgs1 lethality in K. lactis cells. Phenotypic characterization has shown that a strain lacking the phosphatidylglycerolphosphate synthase (atp2.1pgs1?) possessed a markedly impaired respiratory chain, very low endogenous respiration, and uncoupled mitochondria. As a result the mutant strain was unable to generate a sufficient mitochondrial membrane potential via respiration. The atp2.1 suppressor mutation enabled an increase in the affinity of F(1)-ATPase for ATP in the hydrolytic reaction, resulting in the maintenance of sufficient membrane potential for the biogenesis of mitochondria and survival of cells lacking anionic phospholipid biosynthesis. PMID:22582877

Palovicova, Viktoria; Bardelcikova, Annamaria; Obernauerova, Margita

2012-05-14

399

Tight controlled expression and secretion of Lactobacillus brevis SlpA in Lactococcus lactis.  

PubMed

Prokaryotes commonly present outer cell wall structures composed of a crystalline array of proteinaceous subunits, known as surface layers (S-layers). The ORF encoding the S-layer protein (SlpA) of Lactobacillus brevis was cloned into Lactococcus lactis under the transcriptional control of the xylose-inducible expression system (XIES). SlpA was secreted into the extracellular medium, as determined by immunoblotting, and assays on the kinetics of SlpA production revealed that repression of the system with glucose did not require the depletion of xylose from the medium that allows transitory ORF expression. The successful use of XIES to express S-layer proteins in the versatile and generally recognized as safe species L. lactis opens new possibilities for an efficient production and isolation of SlpA S-layer protein for its various applications in biotechnology and importantly as an antigen-carrying vehicle. PMID:22391736

Hollmann, Axel; Saviello, Mariano; Delfederico, Lucrecia; Saraiva, Tessália Diniz Luerce; Barh, Debmalya; Jain, Neha; Tiwari, Sandeep; Chandra, Sudha; Gupta, Krishnakant; Zambare, Vasudeo; Kumar, Anil; Christopher, Lew; Misra, Amarendra Narayan; Kumavath, Ranjith N; Azevedo, Vasco; Semorile, Liliana; Miyoshi, Anderson

2012-03-04

400

Modelling the production of nisin by Lactococcus lactis in fed-batch culture.  

PubMed

Nisin production in batch culture and fed-batch cultures (sucrose feeding rates were 6, 7, 8, and 10 g l(-1) h(-1), respectively) by Lactococcus lactis subsp. lactis ATCC 11454 was investigated. Nisin production showed primary metabolite kinetics, and could be improved apparently by altering the feeding strategy. The nisin titer reached its maximum, 4,185 IU ml(-1), by constant addition of sucrose at a feeding rate of 7 g l(-1) h(-1); an increase in 58% over that of the batch culture (2,658 IU ml(-1)). Nisin biosynthesis was affected strongly by the residual sucrose concentration during the feeding. Finally, a mathematical model was developed to simulate the cell growth, sucrose consumption, lactic acid production and nisin production. The model was able to describe the fermentation process in all cases. PMID:15692804

Lv, Wenhua; Zhang, Xiaoyan; Cong, Wei

2005-02-04

401

Production of S -adenosyl- L-methionine by a mutant strain of Kluyveromyces lactis  

Microsoft Academic Search

S-Adenosyl-l-methionine (AdoMet) was produced by a mutant strain Kluyveromyces lactis AM-65 grown on whey. A full factorial design method of three factors – (NH4)2SO4 (factor x1), corn steep liquor (factor x2) and l-methionine (factor x3) on three levels – was used to determine the optimal medium conditions for the production of AdoMet. A time course shake-flask experiment in optimal whey

Kremena Mincheva; Veselka Kamburova; Venelin Balutzov

2002-01-01

402

Genetic Marking ofLactococcus lactisShows Its Survival in the Human Gastrointestinal Tract  

Microsoft Academic Search

A human feeding study was performed with Lactococcus lactis TC165.5, which is genetically marked by insertion of the sucrose-nisin conjugative transposon Tn5276 and chromosomal resistance to rifampin and streptomycin. The fate of strain TC165.5 and its nucleic acids was monitored by conventional plating methods and by molecular detection techniques based on specific PCR amplification of the nisin (nisA) gene from

NICOLETTE KLIJN; ANTON H. WEERKAMP; ANDWILLEM M. DEVOS

1995-01-01

403

Immunogenicity of a malaria parasite antigen displayed by Lactococcus lactis in oral immunisations  

Microsoft Academic Search

A putative protective protein from Plasmodium falciparum merozoites, MSA2, was expressed in two different ways on the cell surface of the Gram-positive food-grade bacterium, Lactococcus lactis. The first display format exploits an LPXTG-type anchoring motif of the lactococcal proteinase PrtP to covalently anchor MSA2 to the genetically modified producer cells. In a second display format, MSA2 was fused to the

R. Ramasamy; S. Yasawardena; A. Zomer; G. Venema; J. Kok; K. Leenhouts

2006-01-01

404

Citrate utilization gene cluster of the Lactococcus lactis biovar diacetylactis : organization and regulation of expression  

Microsoft Academic Search

The transport of citrate in Lactococcus lactis biovar diacetylactis is mediated by the citrate permease P. This polypeptide is encoded by the citP gene carried by plasmid pCIT264. In this report, we characterize the citP transcript, identify a cluster of two genes cotranscribed with citP and describe their post-transcriptional regulation. The transcriptional promoter is located 1500 nucleotides upstream of the

Felix López Felipe; Christian Magni; Diego Mendoza; Paloma López

1995-01-01

405

Signal Peptide and Propeptide Optimization for Heterologous Protein Secretion in Lactococcus lactis  

PubMed Central

Lactic acid bacteria are food-grade microorganisms that are potentially good candidates for production of heterologous proteins of therapeutical or technological interest. We developed a model for heterologous protein secretion in Lactococcus lactis using the staphylococcal nuclease (Nuc). The effects on protein secretion of alterations in either (i) signal peptide or (ii) propeptide sequences were examined. (i) Replacement of the native Nuc signal peptide (SPNuc) by that of L. lactis protein Usp45 (SPUsp) resulted in greatly improved secretion efficiency (SE). Pulse-chase experiments showed that Nuc secretion kinetics was better when directed by SPUsp than when directed by SPNuc. This SPUsp effect on Nuc secretion is not due to a better antifolding activity, since SPUsp:Nuc precursor proteins display enzymatic activity in vitro, while SPNuc:Nuc precursor proteins do not. (ii) Deletion of the native Nuc propeptide dramatically reduces Nuc SE, regardless of which SP is used. We previously reported that a synthetic propeptide, LEISSTCDA, could efficiently replace the native Nuc propeptide to promote heterologous protein secretion in L. lactis (Y. Le Loir, A. Gruss, S. D. Ehrlich, and P. Langella, J. Bacteriol. 180:1895–1903, 1998). To determine whether the LEISSTCDA effect is due to its acidic residues, specific substitutions were introduced, resulting in neutral or basic propeptides. Effects of these two new propeptides and of a different acidic synthetic propeptide were tested. Acidic and neutral propeptides were equally effective in enhancing Nuc SE and also increased Nuc yields. In contrast, the basic propeptide strongly reduced both SE and the quantity of secreted Nuc. We have shown that the combination of the native SPUsp and a neutral or acidic synthetic propeptide leads to a significant improvement in SE and in the quantity of synthesized Nuc. These observations will be valuable in the production of heterologous proteins in L. lactis.

Le Loir, Y.; Nouaille, S.; Commissaire, J.; Bretigny, L.; Gruss, A.; Langella, P.

2001-01-01

406

Characterization of the Lactococcus lactis lactose genes and regulation of their expression  

Microsoft Academic Search

An important trait of the lactic acid bacterium Lactococcus lactis , that is used in industrial dairy fermentations, is the conversion of lactose into lactic acid. The enzymatic steps involved in the breakdown of lactose, that is transported into the cell via a phosphoenolpyruvate-dependent lactose phosphotransferase system (PEP-PTS lac<\\/SUP>), have been well established (Fig. 1). However, except for the molecular

Rooijen van R. J

1993-01-01

407

Two mitochondrial alcohol dehydrogenase activities of Kluyveromyces lactis are differently expressed during respiration and fermentation  

Microsoft Academic Search

The lactose-utilizing yeast Kluyveromyces lactis is an essentially aerobic organism in which both respiration and fermentation can coexist depending on the sugar concentration. Despite a low fermentative capacity as compared to Saccharomyces cerevisiae, four structural genes encoding alcohol dehydrogenase (ADH) activities are present in this yeast. Two of these activities, namely KlADH III and KlADH IV, are located within mitochondria

Michele Saliola; Claudio Falcone

1995-01-01

408

PepR1, a CcpA-like transcription regulator of Lactobacillus delbrueckii subsp. lactis  

Microsoft Academic Search

The PepR1 protein from Lactobacillus delbrueckii subsp. lactis DSM 7290 shares extensive homology with catabolite-control proteins from various Gram- positive bacteria. Expression of the subcloned pepR1 gene allowed for partial complementation of a ccpA defect in Staphylococcus xylosus. The influence of PepR1 on transcription of the prolidase gene pepQ, which is located adjacent to pepR1, was examined by use of

Joachim Schick; Beate Weber; R. Klein; Bernhard Henrich; Fachbereich Biologie

409

Genotype-phenotype matching analysis of 38 Lactococcus lactis strains using random forest methods  

PubMed Central

Background Lactococcus lactis is used in dairy food fermentation and for the efficient production of industrially relevant enzymes. The genome content and different phenotypes have been determined for multiple L. lactis strains in order to understand intra-species genotype and phenotype diversity and annotate gene functions. In this study, we identified relations between gene presence and a collection of 207 phenotypes across 38 L. lactis strains of dairy and plant origin. Gene occurrence and phenotype data were used in an iterative gene selection procedure, based on the Random Forest algorithm, to identify genotype-phenotype relations. Results A total of 1388 gene-phenotype relations were found, of which some confirmed known gene-phenotype relations, such as the importance of arabinose utilization genes only for strains of plant origin. We also identified a gene cluster related to growth on melibiose, a plant disaccharide; this cluster is present only in melibiose-positive strains and can be used as a genetic marker in trait improvement. Additionally, several novel gene-phenotype relations were uncovered, for instance, genes related to arsenite resistance or arginine metabolism. Conclusions Our results indicate that genotype-phenotype matching by integrating large data sets provides the possibility to identify gene-phenotype relations, possibly improve gene function annotation and identified relations can be used for screening bacterial culture collections for desired phenotypes. In addition to all gene-phenotype relations, we also provide coherent phenotype data for 38 Lactococcus strains assessed in 207 different phenotyping experiments, which to our knowledge is the largest to date for the Lactococcus lactis species.

2013-01-01

410

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

PubMed

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

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

1998-01-01

411

Production of a Particulate Hepatitis C Vaccine Candidate by an Engineered Lactococcus lactis Strain?  

PubMed Central

Vaccine delivery systems based on display of antigens on bioengineered bacterial polyester inclusions can stimulate cellular immune responses. The food-grade Gram-positive bacterium Lactococcus lactis was engineered to produce spherical polyhydroxybutyrate (PHB) inclusions which abundantly displayed the hepatitis C virus core (HCc) antigen. In mice, the immune response induced by this antigen delivery system was compared to that induced by vaccination with HCc antigen displayed on PHB beads produced in Escherichia coli, to PHB beads without antigen produced in L. lactis or E. coli, or directly to the recombinant HCc protein. Vaccination site lesions were minimal in all mice vaccinated with HCc PHB beads or recombinant protein, all mixed in the oil-in-water adjuvant Emulsigen, while vaccination with the recombinant protein in complete Freund's adjuvant produced a marked inflammatory reaction at the vaccination site. Vaccination with the PHB beads produced in L. lactis and displaying HCc antigen produced antigen-specific cellular immune responses with significant release of gamma interferon (IFN-?) and interleukin-17A (IL-17A) from splenocyte cultures and no significant antigen-specific serum antibody, while the PHB beads displaying HCc but produced in E. coli released IFN-? and IL-17A as well as the proinflammatory cytokines tumor necrosis factor alpha (TNF-?) and IL-6 and low levels of IgG2c antibody. In contrast, recombinant HCc antigen in Emulsigen produced a diverse cytokine response and a strong IgG1 antibody response. Overall it was shown that L. lactis can be used to produce immunogenic PHB beads displaying viral antigens, making the beads suitable for vaccination against viral infections.

Parlane, Natalie A.; Grage, Katrin; Lee, Jason W.; Buddle, Bryce M.; Denis, Michel; Rehm, Bernd H. A.

2011-01-01

412

Characterization of the Highly Autolytic Lactococcus lactis subsp. cremoris Strains CO and 2250  

PubMed Central

Two highly autolytic Lactococcus lactis subsp. cremoris strains (CO and 2250) were selected and analyzed for their autolytic properties. Both strains showed maximum lysis when grown in M17 broth containing a limiting concentration of glucose (0.4 to 0.5%) as the carbohydrate source. Lysis did not vary greatly with pH or temperature but was reduced when strains were grown on lactose or galactose. Growth in M17 containing excess glucose (1%) prevented autolysis, although rapid lysis of L. lactis subsp. cremoris CO did occur in the presence of 1% glucose if sodium fluoride (an inhibitor of glycolysis) was added to the medium. Maximum cell lysis in a buffer system was observed early in the stationary phase, and for CO, two pH optima were observed for log-phase and stationary-phase cells (6.5 and 8.5, respectively). Autolysins were extracted from the cell wall fraction of each strain by using either 4% sodium dodecyl sulfate (SDS), 6 M guanidine hydrochloride, or 4 M lithium chloride, and their activities were analyzed by renaturing SDS-polyacrylamide gel electrophoresis on gels containing Micrococcus luteus or L. lactis subsp. cremoris CO cells as the substrate. More than one lytic band was observed on each substrate, with the major band having an apparent molecular mass of 48 kDa for CO. Each lytic band was present throughout growth and lysis. These results suggest that at least two different autolytic enzymes are present in the autolytic L. lactis subsp. cremoris strains. The presence of the lactococcal cell wall hydrolase gene, acmA (G. Buist, J. Kok, K. J. Leenhouts, M. Dabrowska, G. Venema, and A. J. Haandrikman, J. Bacteriol. 177:1554-1563, 1995), in strains 2250 and CO was confirmed by Southern hybridization. Analysis of an acmA deletion mutant of 2250 confirmed that the gene was involved in cell separation and had a role in cell lysis.

Riepe, H. R.; Pillidge, C. J.; Gopal, P. K.; Mckay, L. L.

1997-01-01

413

Glucose Uptake inKluyveromyces lactis: Role of theHGT1Gene in Glucose Transport  

Microsoft Academic Search

A gene for high-affinity glucose transport, HGT1, has been isolated from the lactose-assimilating yeast Kluyveromyces lactis. Disruption strains showed much-reduced uptake of glucose at low concentrations and growthwasparticularlyaffectedinlow-glucosemedium.TheHGT1nucleotidesequenceimpliesthatitencodes a typical transmembrane protein with 12 hydrophobic domains and with 26 to 31% amino acid identity with the Hxtp family of glucose transport elements in Saccharomyces cerevisiae. Expression is constitutive (in contrast

PATRICK BILLARD; SANDRINE MENART; JOEL BLAISONNEAU; MONIQUE BOLOTIN-FUKUHARA; HIROSHI FUKUHARA; ANDMICHELINE WESOLOWSKI-LOUVEL

1996-01-01

414

Changes in glycolytic activity of Lactococcus lactis induced by low temperature  

Microsoft Academic Search

The effects of low-temperature stress on the glycolytic activity of the lactic acid bacterium Lactococcus lactis were studied. The maximal glycolytic activity measured at 30°C increased approximately 2.5-fold following a shift from 30 to 10°C for 4 h in a process that required protein synthesis. Analysis of cold adaptation of strains with genes involved in sugar metabolism disrupted showed that

Jeroen A. Wouters; Henrike H. Kamphuis; Jeroen Hugenholtz; Oscar P. Kuipers; Willem M. de Vos; Tjakko Abee

2000-01-01

415

Nisin-selectable food-grade secretion vector for Lactococcus lactis  

Microsoft Academic Search

A nisin-resistant Lactococcus lactis strain TML01 was isolated from crude milk. A gene with 99% homology to the nisin-resistance gene, nsr, was identified. The food-grade secretion plasmid, pLEB690 (3746 bp), was constructed based on this novel nsr gene enabling primary selection with up to 5 ?g nisin\\/ml. The functionality of pLEB690 as a secretion vector was shown by\\u000a expressing and secreting the

Ruiqing Li; Timo M. Takala; Mingqiang Qiao; Haijin Xu; Per E. J. Saris

2011-01-01

416

Role of Calcium in Activity and Stability of the Lactococcus lactis Cell Envelope Proteinase  

Microsoft Academic Search

Removal of weakly bound Ca 21 from the native cell-bound CEP of Lactococcus lactis SK11 (type III specificity) is coupled with a significant reversible decrease in specific activity and a dramatic reversible reduction in ther- mal stability, as a result of which no activity at 25°C (pH 6.5) can be measured. The consequences of Ca 21 removal are less dramatic

FRED A. EXTERKATE; ARNO C. ALTING

1999-01-01

417

The Membrane-Bound H+ATPase Complex Is Essential for Growth of Lactococcus lactis  

Microsoft Academic Search

The eight genes which encode the (F1Fo) H+-ATPase in Lactococcus lactis subsp. cremoris MG1363 were cloned and sequenced. The genes were organized in an operon with the gene order atpEBFHAGDC; i.e., the order of atpE and atpB is reversed with respect to the more typical bacterial organization. The deduced amino acid sequences of the corresponding H+-ATPase subunits showed significant homology

Brian J. Koebmann; Dan Nilsson; Oscar P. Kuipers; Peter R. Jensen

2000-01-01

418

Cell surface display system for Lactococcus lactis : a novel development for oral vaccine  

Microsoft Academic Search

The food-grade Lactococcus lactis is a potential vector to be used as a live vehicle for the delivery of heterologous proteins for vaccine and pharmaceutical purposes. We constructed a plasmid vector pSVac that harbors a 255-bp single-repeat sequence of the cell wall-binding protein region of the AcmA protein. The recombinant plasmid was transformed into Escherichia coli and expression of the

A. R. Raha; N. R. S. Varma; K. Yusoff; E. Ross; H. L. Foo

2005-01-01

419

Characterization of the Highly Autolytic Lactococcus lactis subsp. cremoris Strains CO and 2250  

Microsoft Academic Search

Two highly autolytic Lactococcus lactis subsp. cremoris strains (CO and 2250) were selected and analyzed for their autolytic properties. Both strains showed maximum lysis when grown in M17 broth containing a limiting concentration of glucose (0.4 to 0.5%) as the carbohydrate source. Lysis did not vary greatly with pH or temperature but was reduced when strains were grown on lactose

HEIDI R. RIEPE; CHRISTOPHER J. PILLIDGE; PRAMOD K. GOPAL; LARRY L. MCKAY

420

Autolysis of Lactococcus lactis Caused by Induced Overproduction of Its Major Autolysin, AcmA  

Microsoft Academic Search

The optical density of a culture of Lactococcus lactis MG1363 was reduced more than 60% during prolonged stationary phase. Reduction in optical density (autolysis) was almost absent in a culture of an isogenic mutant containing a deletion in the major autolysin gene, acmA. An acmA mutant carrying multiple copies of a plasmid encoding AcmA lysed to a greater extent than

Girbe Buist; Harma Karsens; Arjen Nauta; Douwe van Sinderen; Gerard Venema; Jan Kok

1997-01-01

421

Expression of fungal cellulase gene in Lactococcus lactis to construct novel recombinant silage inoculants  

Microsoft Academic Search

The facultative anaerobic bacterium Lactococcus lactis has been used as a host for expression of a gene isolated from the anaerobic rumen fungus Neocallimastix sp. The coding region of the cellulase gene was obtained from the fungus with the aid of polymerase chain reaction amplification.\\u000a The gene was then transformed into pCT vector system and the constructed recombinant plasmid was

E. Ozkose; I. Akyol; B. Kar; U. Comlekcioglu; M. S. Ekinci

2009-01-01

422

Effect of ilvBN -encoded ?-acetolactate synthase expression on diacetyl production in Lactococcus lactis  

Microsoft Academic Search

Conversion of pyruvate to ?-acetolactate, which is broken down to diacetyl and acetoin, can be catalysed by two ?-acetolactate\\u000a synthases in Lactococcus lactis. The enzyme encoded by the als gene (Als) has previously been shown to have a low affinity for pyruvate, which limits the formation of diacetyl. In this\\u000a study we have expressed from a plasmid the ilvBN genes,

K. H. Benson; J.-J. Godon; P. Renault; H. G. Griffin; M. J. Gasson

1996-01-01

423

Characterization of the CopR Regulon of Lactococcus lactis IL1403  

Microsoft Academic Search

To identify components of the copper homeostatic mechanism of Lactococcus lactis, we employed two- dimensional gel electrophoresis to detect changes in the proteome in response to copper. Three proteins upregulated by copper were identified: glyoxylase I (YaiA), a nitroreductase (YtjD), and lactate oxidase (LctO). The promoter regions of these genes feature cop boxes of consensus TACAnnTGTA, which are the binding

David Magnani; Olivier Barre; Simon D. Gerber; Marc Solioz

2008-01-01

424

Production of kefir like product from mixed cultures of Saccharomyces cerevisiae, Streptococcus cremoris and Streptococcus lactis  

Microsoft Academic Search

Various ratios of Streptococcus cremoris to Streptococcus lactis, 0.5 : 1.5, 1 : 1 and 1.5 : 0.5% were added to milk supplemented with 5% (w\\/v) sucrose. Fermentation temperature was kept constant at 30oC. For the first 15 h of fermentation, the milk was fermented by 5% (v\\/v) Saccharomyces cerevisiae, followed by lactic acid bacteria. The total fermentation time was

Pongpakorn Kaewprasert; Naiyatat Poosaran

425

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

Microsoft Academic Search

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.

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

1998-01-01

426

Inducible Amplification of Gene Copy Number and Heterologous Protein Production in the Yeast Kluyveromyces lactis  

Microsoft Academic Search

Heterologous protein production can be doubled by increasing the copy number of the corresponding heterologous gene. We constructed a host-vector system in the yeast Kluyveromyces lactis that was able to induce copy number amplification of pKD1 plasmid-based vectors upon expression of an integrated copy of the plasmid recombinase gene. We increased the production and secretion of two heterologous proteins, glucoamy-

GIOVANNI B. MORLINO; LORENZA TIZZANI; REINHARD FLEER; LAURA FRONTALI; MICHELE M. BIANCHI

1999-01-01

427

Phenotypic and genetic characterization of the bacteriophage abortive infection mechanism AbiK from Lactococcus lactis.  

PubMed Central

The natural plasmid pSRQ800 isolated from Lactococcus lactis subsp. lactis W1 conferred strong phage resistance against small isometric phages of the 936 and P335 species when introduced into phage-sensitive L. lactis strains. It had very limited effect on prolate phages of the c2 species. The phage resistance mechanism encoded on pSRQ800 is a temperature-sensitive abortive infection system (Abi). Plasmid pSRQ800 was mapped, and the Abi genetic determinant was localized on a 4.5-kb EcoRI fragment. Cloning and sequencing of the 4.5-kb fragment allowed the identification of two large open reading frames. Deletion mutants showed that only orf1 was needed to produce the Abi phenotype. orf1 (renamed abiK) coded for a predicted protein of 599 amino acids (AbiK) with an estimated molecular size of 71.4 kDa and a pI of 7.98. DNA and protein sequence alignment programs found no significant homology with databases. However, a database query based on amino acid composition suggested that AbiK might be in the same protein family as AbiA. No phage DNA replication nor phage structural protein production was detected in infected AbiK+ L. lactis cells. This system is believed to act at or prior to phage DNA replication. WHen cloned into a high-copy vector, AbiK efficiency increased 100-fold. AbiK provides another powerful tool that can be useful in controlling phages during lactococcal fermentations.

Emond, E; Holler, B J; Boucher, I; Vandenbergh, P A; Vedamuthu, E R; Kondo, J K; Moineau, S

1997-01-01

428

Kinetics and Substrate Specificity of Membrane-Reconstituted Peptide Transporter DtpT of Lactococcus lactis  

Microsoft Academic Search

The peptide transport protein DtpT of Lactococcus lactis was purified and reconstituted into detergent-destabilized liposomes. The kinetics and substrate specificity of the transporter in the proteoliposomal system were determined, using Pro-[14C]Ala as a reporter peptide in the presence of various peptides or peptide mimetics. The DtpT protein appears to be specific for di- and tripeptides, with the highest affinities for

Bert Poolman; Wil N. Konings; Gang Fang

2000-01-01

429

Optimization of a cultural medium for bacteriocin production by Lactococcus lactis using response surface methodology  

Microsoft Academic Search

The medium composition for bacteriocin production by Lactococcus lactis ATCC 11454 was optimized using response surface methodology. The selected six factors based on CM medium were sucrose, soybean peptone, yeast extract, KH2PO4, NaCl, and MgSO4·7H2O. Fractional factorial designs (FFD) and the path of steepest ascent were effective in searching for the main factors and approaching the optimum region of the

Chan Li; Jinghua Bai; Zhaoling Cai; Fan Ouyang

2002-01-01

430

Experimental and steady-state analysis of the GAL regulatory system in Kluyveromyces lactis.  

PubMed

The galactose uptake mechanism in yeast is a well-studied regulatory network. The regulatory players in the galactose regulatory mechanism (GAL system) are conserved in Saccharomyces cerevisiae and Kluyveromyces lactis, but the molecular mechanisms that occur as a result of the molecular interactions between them are different. The key differences in the GAL system of K. lactis relative to that of S. cerevisiae are: (a) the autoregulation of KlGAL4; (b) the dual role of KlGal1p as a metabolizing enzyme as well as a galactose-sensing protein; (c) the shuttling of KlGal1p between nucleus and cytoplasm; and (d) the nuclear confinement of KlGal80p. A steady-state model was used to elucidate the roles of these molecular mechanisms in the transcriptional response of the GAL system. The steady-state results were validated experimentally using measurements of beta-galactosidase to represent the expression for genes having two binding sites. The results showed that the autoregulation of the synthesis of activator KlGal4p is responsible for the leaky expression of GAL genes, even at high glucose concentrations. Furthermore, GAL gene expression in K. lactis shows low expression levels because of the limiting function of the bifunctional protein KlGal1p towards the induction process in order to cope with the need for the metabolism of lactose/galactose. The steady-state model of the GAL system of K. lactis provides an opportunity to compare with the design prevailing in S. cerevisiae. The comparison indicates that the existence of a protein, Gal3p, dedicated to the sensing of galactose in S. cerevisiae as a result of genome duplication has resulted in a system which metabolizes galactose efficiently. PMID:20528923

Pannala, Venkat R; Bhartiya, Sharad; Venkatesh, Kareenhalli V

2010-06-07

431

Investigation of the adaptation of Lactococcus lactis to isoleucine starvation integrating dynamic transcriptome and proteome information  

PubMed Central

Background Amino acid assimilation is crucial for bacteria and this is particularly true for Lactic Acid Bacteria (LAB) that are generally auxotroph for amino acids. The global response of the LAB model Lactococcus lactis ssp. lactis was characterized during progressive isoleucine starvation in batch culture using a chemically defined medium in which isoleucine concentration was fixed so as to become the sole limiting nutriment. Dynamic analyses were performed using transcriptomic and proteomic approaches and the results were analysed conjointly with fermentation kinetic data. Results The response was first deduced from transcriptomic analysis and corroborated by proteomic results. It occurred progressively and could be divided into three major mechanisms: (i) a global down-regulation of processes linked to bacterial growth and catabolism (transcription, translation, carbon metabolism and transport, pyrimidine and fatty acid metabolism), (ii) a specific positive response related to the limiting nutrient (activation of pathways of carbon or nitrogen metabolism and leading to isoleucine supply) and (iii) an unexpected oxidative stress response (positive regulation of aerobic metabolism, electron transport, thioredoxin metabolism and pyruvate dehydrogenase). The involvement of various regulatory mechanisms during this adaptation was analysed on the basis of transcriptomic data comparisons. The global regulator CodY seemed specifically dedicated to the regulation of isoleucine supply. Other regulations were massively related to growth rate and stringent response. Conclusion This integrative biology approach provided an overview of the metabolic pathways involved during isoleucine starvation and their regulations. It has extended significantly the physiological understanding of the metabolism of L. lactis ssp. lactis. The approach can be generalised to other conditions and will contribute significantly to the identification of the biological processes involved in complex regulatory networks of micro-organisms.

2011-01-01

432

Trans-splicing of the Ll.LtrB group II intron in Lactococcus lactis  

PubMed Central

The Ll.LtrB intron from the Gram-positive bacterium Lactococcus lactis is one of the most studied bacterial group II introns. Ll.LtrB interrupts the relaxase gene of three L. lactis conjugative elements. The relaxase enzyme recognizes the origin of transfer (oriT?) and initiates the intercellular transfer of its conjugative element. The splicing efficiency of Ll.LtrB from the relaxase transcript thus controls the conjugation level of its host element. Here, we used the level of sex factor conjugation as a read-out for Ll.LtrB splicing efficiency. Using this highly sensitive splicing/conjugation assay (107-fold detection range), we demonstrate that Ll.LtrB can trans-splice in L. lactis when fragmented at various positions such as: three different locations within domain IV, within domain I and within domain III. We also demonstrate that the intron-encoded protein, LtrA, is absolutely required for Ll.LtrB trans-splicing. Characteristic Y-branched trans-spliced introns and ligated exons are detected by RT-PCR from total RNA extracts of cells harbouring fragmented Ll.LtrB. The splicing/conjugation assay we developed constitutes the first model system to study group II intron trans-splicing in vivo. Although only previously observed in bacterial-derived organelles, we demonstrate that assembly and trans-splicing of a fragmented group II intron can take place efficiently in bacterial cells.

Belhocine, Kamila; Mak, Anthony B.; Cousineau, Benoit

2007-01-01

433

Flavins contained in yeast extract are exploited for anodic electron transfer by Lactococcus lactis.  

PubMed

Cyclic voltammograms of yeast extract-containing medium exhibit a clear redox peak around -0.4V vs. Ag|AgCl. Fermentative bacterium Lactococcus lactis was hereby shown to exploit this redox compound for extracellular electron transfer towards a graphite anode using glucose as an electron donor. High performance liquid chromatography revealed that this may be a flavin-type compound. The ability of L. lactis to exploit exogenous flavins for anodic glucose oxidation was confirmed by tests where flavin-type compounds were supplied to the bacterium in well defined media. Based on its mid-point potential, riboflavin can be regarded as a near-optimal mediator for microbially catalyzed anodic electron transfer. Riboflavin derivative flavin mononucleotide (FMN) was also exploited by L. lactis as a redox shuttle, unlike flavin adenine dinucleotide (FAD), possibly due to the absence of a specific transporter for the latter. The use of yeast extract in microbial fuel cell media is herein discouraged based on the related unwanted artificial addition of redox mediators which may distort experimental results. PMID:19717350

Masuda, Masaki; Freguia, Stefano; Wang, Yung-Fu; Tsujimura, Seiya; Kano, Kenji

2009-08-20

434

Bovine Rotavirus Nonstructural Protein 4 Produced by Lactococcus lactis Is Antigenic and Immunogenic  

PubMed Central

Rotavirus nonstructural protein 4 (NSP4) can induce diarrhea in mice. To get insight into the biological effects of NSP4, production of large quantities of this protein is necessary. We first tried to produce the protein in Escherichia coli, but the nsp4 gene proved to be unstable. The capacity of the generally regarded as safe organism Lactococcus lactis to produce NSP4 either intra- or extracellularly was then investigated by using the nisin-controlled expression system. Production of recombinant NSP4 (rNSP4) was observed in L. lactis for both locations. In spite of a very low secretion efficiency, the highest level of production was obtained with the fusion between a lactococcal signal peptide and rNSP4. Cultures of the rNSP4-secreting strain were injected into rabbits, and a specific immune response was elicited. The anti-rNSP4 antibodies produced in these rabbits recognized NSP4 in MA104 cells infected by rotavirus. We showed that L. lactis is able to produce antigenic and immunogenic rNSP4 and thus is a good organism for producing viral antigens.

Enouf, Vincent; Langella, Philippe; Commissaire, Jacqueline; Cohen, Jean; Corthier, Gerard

2001-01-01

435

A systematic study of the cell wall composition of Kluyveromyces lactis.  

PubMed

In many ascomycetous yeasts, the cell wall is composed of two main types of macromolecules: (a) polysaccharides, with a high content of beta-1,6- and beta-1,3-linked glucan chains and minor amounts of chitin; and (b) cell wall proteins of different types. Synthesis and maintenance of these macromolecules respond to environmental changes, which are sensed by the cell wall integrity (CWI) signal transduction pathway. We here present a first systematic analysis of the cell wall composition of the milk yeast, Kluyveromyces lactis. Electron microscopic analyses revealed that exponentially growing cells of K. lactis supplied with glucose as a carbon source have a wall thickness of 64 nm, as compared to 105 nm when growing on 3% ethanol. Despite their increased wall thickness, ethanol-grown cells were more sensitive to the presence of zymolyase in the growth medium. Mass spectrometric analysis identified 22 covalently linked cell wall proteins, including 19 GPI-modified proteins and two Pir wall proteins. Importantly, the composition of the cell wall glycoproteome depended on carbon source and growth phase. Our results clearly illustrate the dynamic nature of the cell wall of K. lactis and provide a firm base for studying its regulation. PMID:20641021

Backhaus, Katja; Heilmann, Clemens J; Sorgo, Alice G; Purschke, Günter; de Koster, Chris G; Klis, Frans M; Heinisch, Jürgen J

2010-08-01

436

Mode of Action of Lactococcin B, a Thiol-Activated Bacteriocin from Lactococcus lactis  

PubMed Central

Lactococcin B (LcnB) is a small, hydrophobic, positively charged bacteriocin produced by Lactococcus lactis subsp. cremoris 9B4. Purified LcnB has a bactericidal effect on sensitive L. lactis cells by dissipating the proton motive force and causing leakage of intracellular substrates. The activity of LcnB depends on the reduced state of the Cys-24 residue. Uptake and efflux studies of different solutes suggest that LcnB forms pores in the cytoplasmic membrane of sensitive L. lactis cells in the absence of a proton motive force. At low concentrations of LcnB, efflux of those ions and amino acids which are taken up by proton motive force-driven systems was observed. However, a 150-fold higher LcnB concentration was required for efflux of glutamate, previously taken up via a unidirectional ATP-driven transport system. Strains carrying the genetic information for the immunity protein against LcnB were not affected by LcnB. The proton motive force of immune cells was not dissipated, and no leakage of intracellular substrates could be detected.

Venema, K.; Abee, T.; Haandrikman, A. J.; Leenhouts, K. J.; Kok, J.; Konings, W. N.; Venema, G.

1993-01-01

437

Measuring Kinetic Dissociation/Association Constants Between Lactococcus lactis Bacteria and Mucins Using Living Cell Probes  

PubMed Central

In this work we focused on quantifying adhesion between Lactococcus lactis, the model for lactic acid bacteria (LAB) and mucins. Interactions between two strains of L. lactis (IBB477 and MG1820 as control) and pig gastric mucin–based coating were measured and compared with the use of atomic force microscopy. Analysis of retraction force-distance curves shed light on the differential contributions of nonspecific and specific forces. An increased proportion of specific adhesive events was obtained for IBB477 (20% vs. 5% for the control). Blocking assays with free pig gastric mucin and its O-glycan moiety showed that oligosaccharides play a major (but not exclusive) role in L. lactis-mucins interactions. Specific interactions were analyzed in terms of kinetic constants. An increase in the loading rate of atomic force microscope tip led to a higher force between interacting biological entities, which was directly linked to the kinetic dissociation constant (Koff). Enhancing the contact time between the tip and the sample allowed an increase in the interaction probability, which can be related to the kinetic association constant (Kon). Variations in the loading rate and contact time enabled us to determine Kon (3.3 × 102 M?1·s?1) and Koff (0.46 s?1), and the latter was consistent with values given in the literature for sugar-protein interactions.

Le, Doan Thanh Lam; Guerardel, Yann; Loubiere, Pascal; Mercier-Bonin, Muriel; Dague, Etienne

2011-01-01

438

Heterologous protein secretion in Lactococcus lactis: a novel antigen delivery system.  

PubMed

Lactic acid bacteria (LAB) are Gram-positive bacteria and are generally regarded as safe (GRAS) organisms. Therefore, LAB could be used for heterologous protein secretion and they are good potential candidates as antigen delivery vehicles. To develop such live vaccines, a better control of protein secretion is required. We developed an efficient secretion system in the model LAB, Lactococcus lactis. Staphylococcal nuclease (Nuc) was used as the reporter protein. We first observed that the quantity of secreted Nuc correlated with the copy number of the cloning vector. The nuc gene was cloned on a high-copy number cloning vector and no perturbation of the metabolism of the secreting strain was observed. Replacement of nuc native promoter by a strong lactococcal one led to a significant increase of nuc expression. Secretion efficiency (SE) of Nuc in L. lactis was low, i.e., only 60% of the synthesized Nuc was secreted. Insertion of a synthetic propeptide between the signal peptide and the mature moiety of Nuc increased the SE of Nuc. On the basis of these results, we developed a secretion system and we applied it to the construction of an L. lactis strain which secretes a bovine coronavirus (BCV) epitopeprotein fusion (BCV-Nuc). BCV-Nuc was recognized by both anti-BCV and anti-Nuc antibodies. Secretion of this antigenic fusion is the first step towards the development of a novel antigen delivery system based on LAB-secreting strains. PMID:10347754

Langella, P; Le Loir, Y

1999-02-01

439

Trans-splicing of the Ll.LtrB group II intron in Lactococcus lactis.  

PubMed

The Ll.LtrB intron from the Gram-positive bacterium Lactococcus lactis is one of the most studied bacterial group II introns. Ll.LtrB interrupts the relaxase gene of three L. lactis conjugative elements. The relaxase enzyme recognizes the origin of transfer (oriT ) and initiates the intercellular transfer of its conjugative element. The splicing efficiency of Ll.LtrB from the relaxase transcript thus controls the conjugation level of its host element. Here, we used the level of sex factor conjugation as a read-out for Ll.LtrB splicing efficiency. Using this highly sensitive splicing/conjugation assay (10(7)-fold detection range), we demonstrate that Ll.LtrB can trans-splice in L. lactis when fragmented at various positions such as: three different locations within domain IV, within domain I and within domain III. We also demonstrate that the intron-encoded protein, LtrA, is absolutely required for Ll.LtrB trans-splicing. Characteristic Y-branched trans-spliced introns and ligated exons are detected by RT-PCR from total RNA extracts of cells harbouring fragmented Ll.LtrB. The splicing/conjugation assay we developed constitutes the first model system to study group II intron trans-splicing in vivo. Although only previously observed in bacterial-derived organelles, we demonstrate that assembly and trans-splicing of a fragmented group II intron can take place efficiently in bacterial cells. PMID:17389638

Belhocine, Kamila; Mak, Anthony B; Cousineau, Benoit

2007-03-27

440

Generation of a Membrane Potential by Lactococcus lactis through Aerobic Electron Transport?  

PubMed Central

Lactococcus lactis, a facultative anaerobic lactic acid bacterium, is known to have an increased growth yield when grown aerobically in the presence of heme. We have now established the presence of a functional, proton motive force-generating electron transfer chain (ETC) in L. lactis under these conditions. Proton motive force generation in whole cells was measured using a fluorescent probe (3?,3?-dipropylthiadicarbocyanine), which is sensitive to changes in membrane potential (??). Wild-type cells, grown aerobically in the presence of heme, generated a ?? even in the presence of the F1-Fo ATPase inhibitor N,N?-dicyclohexylcarbodiimide, while a cytochrome bd-negative mutant strain (CydA?) did not. We also observed high oxygen consumption rates by membrane vesicles prepared from heme-grown cells, compared to CydA? cells, upon the addition of NADH. This demonstrates that NADH is an electron donor for the L. lactis ETC and demonstrates the presence of a membrane-bound NADH-dehydrogenase. Furthermore, we show that the functional respiratory chain is present throughout the exponential and late phases of growth.

Brooijmans, R. J. W.; Poolman, B.; Schuurman-Wolters, G. K.; de Vos, W. M.; Hugenholtz, J.

2007-01-01

441

Construction of two Lactococcus lactis expression vectors combining the Gateway and the NIsin Controlled Expression systems.  

PubMed

Over the last 10 years, the NIsin Controlled Expression (NICE) system has been extensively used in the food-grade bacterium Lactococcus lactis subsp. cremoris to produce homologous and heterologous proteins for academic and biotechnological purposes. Although various L. lactis molecular tools have been developed, no expression vectors harboring the popular Gateway recombination system are currently available for this widely used cloning host. In this study, we constructed two expression vectors that combine the NICE and the Gateway recombination systems and we tested their applicability by recombining and over-expressing genes encoding structural proteins of lactococcal phages Tuc2009 and TP901-1. Over-expressed phage proteins were analyzed by immunoblotting and purified by His-tag affinity chromatography with protein productions yielding 2.8-3.7 mg/l of culture. This therefore is the first description of L. lactis NICE expression vectors which integrate the Gateway cloning technology and which are suitable for the production of sufficient amounts of proteins to facilitate subsequent structural and functional analyses. PMID:21807023

Douillard, François P; Mahony, Jennifer; Campanacci, Valérie; Cambillau, Christian; van Sinderen, Douwe

2011-07-23

442

Oxidative Stress at High Temperatures in Lactococcus lactis Due to an Insufficient Supply of Riboflavin.  

PubMed

Lactococcus lactis MG1363 was found to be unable to grow at temperatures above 37°C in a defined medium without riboflavin, and the cause was identified to be dissolved oxygen introduced during preparation of the medium. At 30°C, growth was unaffected by dissolved oxygen and oxygen was consumed quickly. Raising the temperature to 37°C resulted in severe growth inhibition and only slow removal of dissolved oxygen. Under these conditions, an abnormally low intracellular ratio of [ATP] to [ADP] (1.4) was found (normally around 5), which indicates that the cells are energy limited. By adding riboflavin to the medium, it was possible to improve growth and oxygen consumption at 37°C, and this also normalized the [ATP]-to-[ADP] ratio. A codon-optimized redox-sensitive green fluorescent protein (GFP) was introduced into L. lactis and revealed a more oxidized cytoplasm at 37°C than at 30°C. These results indicate that L. lactis suffers from heat-induced oxidative stress at increased temperatures. A decrease in intracellular flavin adenine dinucleotide (FAD), which is derived from riboflavin, was observed with increasing growth temperature, but the presence of riboflavin made the decrease smaller. The drop was accompanied by a decrease in NADH oxidase and pyruvate dehydrogenase activities, both of which depend on FAD as a cofactor. By overexpressing the riboflavin transporter, it was possible to improve FAD biosynthesis, which resulted in increased NADH oxidase and pyruvate dehydrogenase activities and improved fitness at high temperatures in the presence of oxygen. PMID:23913422

Chen, Jun; Shen, Jing; Solem, Christian; Jensen, Peter Ruhdal

2013-08-02

443

Improved Production of Heterologous Proteins by a Glucose Repression-Defective Mutant of Kluyveromyces lactis  

PubMed Central

The secreted production of heterologous proteins in Kluyveromyces lactis was studied. A glucoamylase (GAA) from the yeast Arxula adeninivorans was used as a reporter protein for the study of the secretion efficiencies of several wild-type and mutant strains of K. lactis. The expression of the reporter protein was placed under the control of the strong promoter of the glyceraldehyde-3-phosphate dehydrogenase of Saccharomyces cerevisiae. Among the laboratory strains tested, strain JA6 was the best producer of GAA. Since this strain is known to be highly sensitive to glucose repression and since this is an undesired trait for biomass-oriented applications, we examined heterologous protein production by using glucose repression-defective mutants isolated from this strain. One of them, a mutant carrying a dgr151-1 mutation, showed a significantly improved capability of producing heterologous proteins such as GAA, human serum albumin, and human interleukin-1? compared to the parent strain. dgr151-1 is an allele of RAG5, the gene encoding the only hexokinase present in K. lactis (a homologue of S. cerevisiae HXK2). The mutation in this strain was mapped to nucleotide position +527, resulting in a change from glycine to aspartic acid within the highly conserved kinase domain. Cells carrying the dgr151-1 allele also showed a reduction in N- and O-glycosylation. Therefore, the dgr151 strain may be a promising host for the production of heterologous proteins, especially when the hyperglycosylation of recombinant proteins must be avoided.

Donnini, Claudia; Farina, Francesca; Neglia, Barbara; Compagno, Maria Concetta; Uccelletti, Daniela; Goffrini, Paola; Palleschi, Claudio

2004-01-01

444

Non-enzymic copper reduction by menaquinone enhances copper toxicity in Lactococcus lactis IL1403.  

PubMed

Lactococcus lactis possesses a pronounced extracellular Cu(2+)-reduction activity which leads to the accumulation of Cu(+) in the medium. The kinetics of this reaction were not saturable by increasing copper concentrations, suggesting a non-enzymic reaction. A copper-reductase-deficient mutant, isolated by random transposon mutagenesis, had an insertion in the menE gene, which encodes O-succinylbenzoic acid CoA ligase. This is a key enzyme in menaquinone biosynthesis. The ?menE mutant was deficient in short-chain menaquinones, and exogenously added menaquinone complemented the copper-reductase-deficient phenotype. Haem-induced respiration of wild-type L. lactis efficiently suppressed copper reduction, presumably by competition by the bd-type quinol oxidase for menaquinone. As expected, the ?menE mutant was respiration-deficient, but could be made respiration-proficient by supplementation with menaquinone. Growth of wild-type cells was more copper-sensitive than that of the ?menE mutant, due to the production of Cu(+) ions by the wild-type. This growth inhibition of the wild-type was strongly attenuated if Cu(+) was scavenged with the Cu(I) chelator bicinchoninic acid. These findings support a model whereby copper is non-enzymically reduced at the membrane by menaquinones. Respiration effectively competes for reduced quinones, which suppresses copper reduction. These findings highlight novel links between copper reduction, respiration and Cu(+) toxicity in L. lactis. PMID:23579688

Abicht, Helge K; Gonskikh, Yulia; Gerber, Simon D; Solioz, Marc

2013-04-11

445

Characterization of the CysB protein of Klebsiella aerogenes: direct evidence that N-acetylserine rather than O-acetylserine serves as the inducer of the cysteine regulon.  

PubMed Central

The cysB gene of Klebsiella aerogenes has been cloned, sequenced and shown to complement the cysteine auxotrophic phenotype of Escherichia coli cysB mutants. The K. aerogenes cysB gene is predicted to encode a protein of 324 amino acid residues that shares approx. 95% sequence similarity with the Salmonella typhimurium and E. coli CysB proteins. Gel-retardation assays demonstrate that the purified protein binds to DNA fragments containing either the K. aerogenes cysb promoter or the S. typhimurium cysJIH promoter. Acetylserine enhances CysB binding to the cysJIH promoter fragment while diminishing its binding to the cysB promoter fragment. Fluorescence-emission-spectroscopy measurements suggest strongly that N-acetylserine binds to CysB apoprotein but that O-acetylserine does not, and support the notion that N-acetylserine is the physiological inducer of cysteine biosynthesis. Images Figure 3

Lynch, A S; Tyrrell, R; Smerdon, S J; Briggs, G S; Wilkinson, A J

1994-01-01

446

Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from Enterobacter aerogenes.  

PubMed

The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. GpdQ has attracted recent attention as a promising enzymatic bioremediator. Here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. An improved crystal structure (1.9 A resolution) illustrates the presence of (i) an extended hydrogen bond network in the active site, and (ii) two possible nucleophiles, i.e., water/hydroxide ligands, coordinated to one or both metal ions. While it is at present not possible to unambiguously distinguish between these two possibilities, a reaction mechanism is proposed whereby the terminally bound H2O/OH(-) acts as the nucleophile, activated via hydrogen bonding by the bridging water molecule. Furthermore, the presence of substrate promotes the formation of a catalytically competent binuclear center by significantly enhancing the binding affinity of one of the metal ions in the active site. Asn80 appears to display coordination flexibility that may modulate enzyme activity. Kinetic data suggest that the rate-limiting step occurs after hydrolysis, i.e., the release of the phosphate moiety and the concomitant dissociation of one of the metal ions and/or associated conformational changes. Thus, it is proposed that GpdQ employs an intricate regulatory mechanism for catalysis, where coordination flexibility in one of the two metal binding sites is essential for optimal activity. PMID:18831553

Hadler, Kieran S; Tanifum, Eric A; Yip, Sylvia Hsu-Chen; Miti?, Natasa; Guddat, Luke W; Jackson, Colin J; Gahan, Lawrence R; Nguyen, Kelly; Carr, Paul D; Ollis, David L; Hengge, Alvan C; Larrabee, James A; Schenk, Gerhard

2008-10-03

447

[Protein engineering of uridine phosphorylase from Escherichia coli K-12. I. Cloning and expression of uridine phosphorylase genes from Klebsiella aerogenes and Salmonella typhimurium in E. coli].  

PubMed

Genes of uridine phosphorylases (udp) from Klebsiella aerogenes and Salmonella typhimurium were cloned and expressed. Highly effective producer strains of the corresponding proteins were constructed. Enzymic properties of the UPases obtained were studied and compared with those from the Escherichia coli enzyme. Mutant forms of UPase from E. coli (D5E, D5N, D5A) were prepared by site-directed mutagenesis techniques. It was shown that the Asp5 residue plays an insignificant role in the formation of the active form of the protein. PMID:9661793

Ve?ko, V P; Chebotaev, D V; Ovcharova, I V; Gul'ko, L B

1998-05-01

448

Prevalence and diversity of qnr alleles in AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii and Serratia marcescens: a multicentre study from Korea  

Microsoft Academic Search

Methods: A total of 644 consecutive, non-duplicate isolates of Enterobacter cloacae (186), Enterobacter aerogenes (154), Citrobacter freundii (138) and Serratia marcescens (166) were examined. We performed antimicrobial susceptibility testing and PCR for qnr determinants (qnrA, qnrB and qnrS), extended-spectrum b-lactamase (ESBL) (blaTEM, blaSHV and blaCTX-M), orf513, orf1005 and blaDHA-1. To differentiate qnr subtypes, restriction enzyme analysis and sequencing was performed.

Yeon-Joon Park; Jin Kyung Yu; Seungok Lee; Eun-Jee Oh; Gun-Jo Woo

2007-01-01

449

Mucosal Delivery of Murine Interleukin2 (IL2) and IL6 by Recombinant Strains of Lactococcus lactis Coexpressing Antigen and Cytokine  

Microsoft Academic Search

Lactococcus lactis is a nonpathogenic and noncolonizing bacterium which is being developed as a vaccine delivery vehicle for immunization by mucosal routes. To determine whether lactococci can also deliver cyto- kines to the immune system, we have constructed novel constitutive expression strains of L. lactis which accumulate a test antigen, tetanus toxin fragment C (TTFC), within the cytoplasmic compartment and

LOTHAR STEIDLER; KAREN ROBINSON; LISA CHAMBERLAIN; KARIN M. SCHOFIELD; ERIK REMAUT; RICHARD W. F. LE PAGE; JEREMY M. WELLS

1998-01-01

450

Lactococcin A, a new bacteriocin from Lactococcus lactis subsp. cremoris: isolation and characterization of the protein and its gene.  

PubMed Central

A new bacteriocin, termed lactococcin A (LCN-A), from Lactococcus lactis subsp. cremoris LMG 2130 was purified and sequenced. The polypeptide contained no unusual amino acids and showed no significant sequence similarity to other known proteins. Only lactococci were killed by the bacteriocin. Of more than 120 L. lactis strains tested, only 1 was found resistant to LCN-A. The most sensitive strain tested, L. lactis subsp. cremoris NCDO 1198, was inhibited by 7 pM LCN-A. By use of a synthetic DNA probe, lcnA was found to be located on a 55-kb plasmid. The lcnA gene was cloned and sequenced. The sequence data revealed that LCN-A is ribosomally synthesized as a 75-amino-acid precursor including a 21-amino-acid N-terminal extension. An open reading frame encoding a 98-amino-acid polypeptide was found downstream of and in the same operon as lcnA. We propose that this open reading frame encodes an immunity function for LCN-A. In Escherichia coli lcnA did not cause an LCN-A+ phenotype. L. lactis subsp. lactis IL 1403 produced small amounts of the bacteriocin and became resistant to LCN-A after transformation with a recombinant plasmid carrying lcnA. The other lactococcal strains transformed with the same recombinant plasmid became resistant to LCN-A but did not produce any detectable amount of the bacteriocin. Images

Holo, H; Nilssen, O; Nes, I F

1991-01-01

451

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

PubMed Central

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.

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

2012-01-01

452

Use of murine models to detect the allergenicity of genetically modified Lactococcus lactis NZ9000/pNZPNK.  

PubMed

By introducing aprN into Lactococcus lactis NZ9000, the genetically modified L. lactis NZ9000/pNZPNK successfully expressed the nattokinase. The safety assessment of this novel strain was based on allergenicity of pepsin digestion stability and murine model serologic identity. Subjecting to the GM strain and host to pepsin digestion, the soluble fractions and cell debris were fast degraded completely. Feeding with ovalbumin resulted in significantly higher production of IgG1 and IgE as compared to that of L. lactis NZ9000/pNZPNK or L. lactis NZ9000. Further, the serum IgG2a level increased dose-dependently at week 2 and induced immune reaction toward Th1 pathway. Secretion of cytokines IL-4 and IL-10 fed with lactococci was significantly lower than that of the OVA group. L. lactis NZ9000/pNZPNK did not increase the proliferation of type 2 helper T cells in spleen or induce allergenicity in BALB/c mice. On the basis of the results, the new GM lactic acid bacterium is regarded as safe to use. PMID:21410287

Chiang, Shen-Shih; Liu, Chin-Feng; Ku, Ting-Wei; Mau, Jeng-Leun; Lin, Hsin-Tang; Pan, Tzu-Ming

2011-03-29

453

Display of the Viral Epitopes on Lactococcus lactis: A Model for Food Grade Vaccine against EV71  

PubMed Central

In this study, we have developed a system for display of antigens of Enterovirus type 71 (EV71) on the cell surface of L. lactis. The viral capsid protein (VP1) gene from a local viral isolate was utilized as the candidate vaccine for the development of oral live vaccines against EV71 using L. lactis as a carrier. We expressed fusion proteins in E. coli and purified fusion proteins were incubated with L. lactis. We confirmed that mice orally fed with L. lactis displaying these fusion proteins on its surface were able to mount an immune response against the epitopes of EV71. This is the first example of an EV71 antigen displayed on the surface of a food grade organism and opens a new perspective for alternative vaccine strategies against the EV71. We believe that the method of protein docking utilized in this study will allow for more flexible presentations of short peptides and proteins on the surface of L. lactis to be useful as a delivery vehicle.

Varma, Nadimpalli Ravi S.; Toosa, Haryanti; Foo, Hooi Ling; Alitheen, Noorjahan Banu Mohamed; Nor Shamsudin, Mariana; Arbab, Ali S.; Yusoff, Khatijah; Abdul Rahim, Raha

2013-01-01

454

Induction of specific immune responses in piglets by intramuscular immunization with fimbrial adhesin FaeG expressed in Lactococcus lactis.  

PubMed

Fimbrial adhesin plays a critical role in the pathogenesis of enterotoxigenic Escherichia coli (ETEC)-induced piglet diarrhoea. Lactococcus lactis is an attractive food-grade host for the production of heterologous antigens. We previously demonstrated that fimbrial adhesin FaeG was expressed in L. lactis and that oral immunization in mice with recombinant L. lactis expressing FaeG induced F4-specific mucosal and systemic immune responses. In the present study, we explored the immune responses of piglets induced by intramuscular vaccination with recombinant L. lactis expressing rFaeG. Intramuscular vaccination resulted in significantly elevated serum IgG level and modest increases in serum IgA and IgM levels. In addition, IgG, IgA, and IgM antibody secreting cells were induced in the spleen, mesenteric lymph nodes, and jejunum. The growth performance of piglets was not influenced by intramuscular vaccination. The results suggest that L. lactis expressing FaeG is a promising candidate vaccine against ETEC. PMID:23540979

Liu, Shujie; Li, Yongming; Xu, Ziwei

2013-03-27

455

Study of the influence of yeast inoculum concentration (Yarrowia lipolytica and Kluyveromyces lactis) on blue cheese aroma development using microbiological models.  

PubMed

Yarrowia lipolytica and Kluyveromyces lactis occur as part of Stilton cheese microflora yet are not controlled during production. This study investigated the influence of their inoculum concentration on aroma production. Models of Y. lipolytica and K. lactis, with Penicillium roqueforti, were analysed using instrumental and sensory analysis. Different concentrations of Y. lipolytica produced important changes in the aroma profiles of microbiological models, analysed by solid-phase microextraction (SPME GC-MS). Sensory analysis with discrimination tests showed differences were detectable via human perception but did not concern the similarity to blue cheese odour. Increasing the inoculum concentration of K. lactis resulted in decreased variation between replicates. Partial least squares (PLS) regression on Flash profile data showed models inoculated with low concentrations of K. lactis exhibited blue cheese-related attributes, associated with increased ketone production. Results suggest that controlling the amount of Y. lipolytica and K. lactis during production offers potential to manipulate blue cheese aroma development. PMID:24128502

Price, Elliott J; Linforth, Robert S T; Dodd, Christine E R; Phillips, Carol A; Hewson, Louise; Hort, Joanne; Gkatzionis, Konstantinos

2013-08-29

456

Assymetry of the myo-inositol transport system in Klebsiella aerogenes. Energy is necessary to create the assymetry of the transport system.  

PubMed

1. In Klebsiella aerogenes the influx of myo-inositol proceeds during the steady state at a rate equal to that of efflux. 2. The kinetic parameters of influx during the steady state are similar to those observed at the initial time of uptake. 3. Efflux and influx processes share the same transport system. 4. The ability of other cyclitols to chase the accumulated scyllo-inositol is dependent on their affinity for the transport system. 5. A counter transport can be observed in preloaded cells only in poisoned cells and under anaerobiosis. 6. The efflux process is not temperature-dependent. 7. The KT of influx in poisoned cells is larger than that in normal cells. 8. Although no saturation kinetics of efflux could be observed, it can be inferred that the KT of efflux is at least 50-fold larger than the KT of influx; 9. The results suggest that in the transport of myo-inositol by K. aerogenes energy coupling enhances the affinity of the carrier for the substrate at the outer side of the cytolplasmic membrane by lowering the KT. PMID:318995

Deshusses, J; Reber, G

1977-01-01

457

Expression of citrate permease gene of plasmid pCM1 isolated from Lactococcus lactis subsp. lactis biovar diacetylactis NIAI N-7 in Lactobacillus casei L-49-4  

Microsoft Academic Search

Recombinant vector pJLECit (8,232 bp) was constructed using citrate permease gene contained in the 3,919-bp fragment of plasmid\\u000a pCM1 (8,280 bp) isolated from Lactococcus lactis subsp. lactis biovar diacetylactis NIAI N-7, repA and ori from pLU1, and pMB1 ori and the erythromycin resistance gene from pJIR418. Lactobacillus casei L-49-4 (plasmid-free mutant of strain L-49) harboring the constructed pJLECit converted citrate into diacetyl\\/acetoin.

Hwa-Yong An; Harutoshi Tsuda; Taku Miyamoto

2007-01-01

458

Characterization of the Klebsiella aerogenes urease accessory protein UreD in fusion with the maltose binding protein.  

PubMed

Assembly of the Klebsiella aerogenes urease metallocenter requires four accessory proteins, UreD, UreE, UreF, and UreG, to effectively deliver and incorporate two Ni2+ ions into the nascent active site of the urease apoprotein (UreABC). Each accessory protein has been purified and characterized with the exception of UreD due to its insolubility when it is overproduced in recombinant cells. In this study, a translational fusion was made between the maltose binding protein (MBP) and UreD, with the resulting MBP-UreD found to be soluble in Escherichia coli cell extracts and able to complement a DeltaureD-urease cluster in this host microorganism. MBP-UreD was purified as a large multimer (> 670 kDa) that bound approximately 2.5 Ni2+ ions (K(d) of approximately 50 microM, where K(d) is the dissociation constant) per UreD protomer according to equilibrium dialysis measurements. Zn2+ directly competes with 10-fold higher affinity (approximately 4 Zn2+ ions per protomer; K(d) of 5 microM) for the Ni2+ binding sites. MBP pulldown experiments demonstrated that the UreD domain of MBP-UreD formed in vivo complexes with UreF, UreG, UreF plus UreG, or UreABC when these proteins were overproduced in the same E. coli cells. In addition, a UreABC-(MBP-UreD)-UreFG complex was observed in cells producing all urease components. Comparative in vitro binding experiments with purified proteins demonstrated an approximate 1:1 binding ratio between the UreD domain of MBP-UreD and the UreF domain of the UreEF fusion, only weak or transient interaction between MBP-UreD and UreG, and no binding with UreABC. These studies are the first to describe the properties of purified UreD, and they extend our understanding of its binding partners both in vitro and in the cell. PMID:20207756

Carter, Eric L; Hausinger, Robert P

2010-03-05

459

Peptidoglycan Structure Analysis of Lactococcus lactis Reveals the Presence of an l,d-Carboxypeptidase Involved in Peptidoglycan Maturation  

PubMed Central

Detailed structural analysis of Lactococcus lactis peptidoglycan was achieved by identification of its constituent muropeptides separated by reverse phase high-performance liquid chromatography. Modification of the classical elution buffer allowed direct and sensitive analysis of the purified muropeptides by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The structures of 45 muropeptides were assigned for L. lactis strain MG1363. Analysis of the muropeptide composition of an MG1363 dacB mutant showed that the dacB-encoded protein has l,d-carboxypeptidase activity and is involved in peptidoglycan maturation.

Courtin, Pascal; Miranda, Guy; Guillot, Alain; Wessner, Francoise; Mezange, Christine; Domakova, Elena; Kulakauskas, Saulius; Chapot-Chartier, Marie-Pierre

2006-01-01

460

Proteinase PI and lactococcin A genes are located on the largest plasmid in Lactococcus lactis subsp. lactis bv. diacetylactis S50.  

PubMed

Lactococcus lactis subsp. lactis bv. diacetylactis S50 produces a lactococcin A-like bacteriocin named bacteriocin S50, and cell envelope-associated PI-type proteinase activity. This strain harbours 3 small size plasmids: pS6 (6.3 kb), pS7a (7.31 kb), and pS7b (7.27 kb). Plasmid curing using a combination of novobiocin treatment (10 microg.mL-1) and sublethal temperature (40 degrees C) resulted in a very low yield (0.17%) of Prt-, Bac-, Bacs derivatives, which retained all 3 small size resident plasmids. Pulsed-field gel electrophoresis of DNA isolated from the strain S50 and cured derivatives in combination with restriction enzyme analysis and DNA-DNA hybridization revealed that S50 contains 2 additional large plasmids: pS140 (140 kb) and pS80 (80 kb). Conjugation experiments using strain S50 as a donor and various lactococcal recipients resulted in Prt+, Bac+, Bacr transconjugants. Analysis of these transconjugants strongly indicated that plasmid pS140 harbours the prt and bac genes encoding proteinase and bacteriocin production, and immunity to bacteriocin, since each Prt+, Bac+, Bacr tranconjugant contained pS140. Accordingly, none of the Prt-,Bac-, Bacs transconjugants contained this plasmid. pS140 was a self-transmissible conjugative plasmid regardless of the host lactococcal recipient used in the test. Frequency of conjugation of plasmid pS140 did not depend on either the donor or recipient strain. PMID:15980892

Kojic, Milan; Strahinic, Ivana; Topisirovic, Ljubisa

2005-04-01

461

Restriction for gene insertion within the Lactococcus lactis Ll.LtrB group II intron.  

PubMed

The Ll.LtrB intron, from the low G+C gram-positive bacterium Lactococcus lactis, was the first bacterial group II intron shown to splice and mobilize in vivo. The detailed retrohoming and retrotransposition pathways of Ll.LtrB were studied in both L. lactis and Escherichia coli. This bacterial retroelement has many features that would make it a good gene delivery vector. Here we report that the mobility efficiency of Ll.LtrB expressing LtrA in trans is only slightly affected by the insertion of fragments <100 nucleotides within the loop region of domain IV. In contrast, Ll.LtrB mobility efficiency is drastically decreased by the insertion of foreign sequences >1 kb. We demonstrate that the inhibitory effect caused by the addition of expression cassettes on Ll.LtrB mobility efficiency is not sequence specific, and not due to the expression, or the toxicity, of the cargo genes. Using genetic screens, we demonstrate that in order to maintain intron mobility, the loop region of domain IV, more specifically domain IVb, is by far the best region to insert foreign sequences within Ll.LtrB. Poisoned primer extension and Northern blot analyses reveal that Ll.LtrB constructs harboring cargo sequences splice less efficiently, and show a significant reduction in lariat accumulation in L. lactis. This suggests that cargo-containing Ll.LtrB variants are less stable. These results reveal the potential, yet limitations, of the Ll.LtrB group II intron to be used as a gene delivery vector, and validate the random insertion approach described in this study to create cargo-containing Ll.LtrB variants that are mobile. PMID:16973892

Plante, Isabelle; Cousineau, Benoit

2006-09-14

462

Nisin inducible production of listeriolysin O in Lactococcus lactis NZ9000  

PubMed Central

Background Listeria monocytogenes is a well-characterized food-borne pathogen that infects pregnant women and immunocompromised individuals. Listeriolysin O (LLO) is the major virulence factor of the pathogen and is often used as a diagnostic marker for detection of L. monocytogenes. In addition, LLO represents a potent antigen driving T cell-mediated immunity during infection. In the present work, Lactococcus lactis NZ9000 was used as an expression host to hyper-produce LLO under inducible conditions using the NICE (NIsin Controlled Expression) system. We created a modified pNZ8048 vector encoding a six-His-tagged LLO downstream of the strong inducible PnisA promoter. Results The constructed vector (pNZPnisA:CYTO-LLO) was expressed in L. lactis NZ9000 and was best induced at mid-log phase with 0.2% v/v nisin for 4 h statically at 30°C. Purification of the His-tagged LLO was accomplished by Ni-NTA affinity chromatography and functionality was confirmed through haemolytic assays. Total LLO yield (measured as total protein content) was 4.43–5.9 mg per litre culture and the haemolytic activity was still detectable after 8 months of storage at 4°C. Conclusion The LLO production method described in this work provides an approach to efficient LLO production in the Gram-positive Lactococcus bacterium to yield a significant source of the protein for research and diagnostic applications. Expression of LLO in L. lactis has a number of benefits over E. coli which may facilitate both in vivo and in vitro applications of this system.

Bahey-El-Din, Mohammed; Griffin, Brendan T; Gahan, Cormac GM

2008-01-01

463

Improved production of heterologous proteins by a glucose repression-defective mutant of Kluyveromyces lactis.  

PubMed

The secreted production of heterologous proteins in Kluyveromyces lactis was studied. A glucoamylase (GAA) from the yeast Arxula adeninivorans was used as a reporter protein for the study of the secretion efficiencies of several wild-type and mutant strains of K. lactis. The expression of the reporter protein was placed under the control of the strong promoter of the glyceraldehyde-3-phosphate dehydrogenase of Saccharomyces cerevisiae. Among the laboratory strains tested, strain JA6 was the best producer of GAA. Since this strain is known to be highly sensitive to glucose repression and since this is an undesired trait for biomass-oriented applications, we examined heterologous protein production by using glucose repression-defective mutants isolated from this strain. One of them, a mutant carrying a dgr151-1 mutation, showed a significantly improved capability of producing heterologous proteins such as GAA, human serum albumin, and human interleukin-1beta compared to the parent strain. dgr151-1 is an allele of RAG5, the gene encoding the only hexokinase present in K. lactis (a homologue of S. cerevisiae HXK2). The mutation in this strain was mapped to nucleotide position +527, resulting in a change from glycine to aspartic acid within the highly conserved kinase domain. Cells carrying the dgr151-1 allele also showed a reduction in N- and O-glycosylation. Therefore, the dgr151 strain may be a promising host for the production of heterologous proteins, especially when the hyperglycosylation of recombinant proteins must be avoided. PMID:15128512

Donnini, Claudia; Farina, Francesca; Neglia, Barbara; Compagno, Maria Concetta; Uccelletti, Daniela; Goffrini, Paola; Palleschi, Claudio

2004-05-01

464

Cloning, Characterization, Controlled Overexpression, and Inactivation of the Major Tributyrin Esterase Gene of Lactococcus lactis  

PubMed Central

The gene encoding the major intracellular tributyrin esterase of Lactococcus lactis was cloned using degenerate DNA probes based on 19 known N-terminal amino acid residues of the purified enzyme. The gene, named estA, was sequenced and found to encode a protein of 258 amino acid residues. The transcription start site was mapped 233 nucleotides upstream of the start codon, and a canonical promoter sequence was identified. The deduced amino acid sequence of the estA product contained the typical GXSXG motif found in most lipases and esterases. The protein was overproduced up to 170-fold in L. lactis by use of the nisin-controlled expression system recently developed for lactic acid bacteria. The estA gene was inactivated by chromosomal integration of a temperature-sensitive integration vector. This resulted in the complete loss of esterase activity, which could then be recovered after complementation of the constructed esterase-deficient strain with the wild-type estA gene. This confirms that EstA is the main enzyme responsible for esterase activity in L. lactis. Purified recombinant enzyme showed a preference for short-chain acyl esters, surprisingly also including phospholipids. Medium- and long-