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

2014 ◽  
Vol 99 (2) ◽  
pp. 897-905 ◽  
Author(s):  
Beatriz del Rio ◽  
Daniel M. Linares ◽  
Victor Ladero ◽  
Begoña Redruello ◽  
Maria Fernández ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Culture Medium ◽  
Agmatine Deiminase

scholarly journals The effects of Lactococcus lactis subsp. lactis and its supernatant on some bacteriological and sensory values in Rainbow trout (Onchorhynchus mykiss) fillets

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Asad Abbaspour Anbi ◽  
Vadood Razavilar ◽  
Moslem Neyriz Naghadehi ◽  
Masoud Seidgar ◽  
Ali Nekuiefard ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Lactococcus Lactis ◽  
Storage Time ◽  
Culture Medium ◽  
Live Cells ◽  
Human Consumption ◽  
Lactococcus Lactis Subsp ◽  
Live Bacteria ◽  
And Control ◽  
Control Samples

Lactic Acid Bacteria (LAB) have a great potential as bio-preservatives. The live cells and supernatant Lactococcus lactis subsp. lactis induced bacteriological changes in Onchorhynchus mykiss fillet by spray and immersion methods was studied during vacuum- packaged storage at 4 °C for 15 days. 40 kg of O. mykiss were prepared from a culture farm in Oshnavieh (Northwest Iran) and 112 fillet samples (100g) were prepared by aseptic method. L. lactis subsp. lactis (PTCC1336) bacteria was cultured in MRS culture medium. Its supernatant (2%, 4%) was extracted and 106 CFUml-1 dilutions of LAB were prepared and tested on the fillets to enhance their shelf life. All samples were evaluated regarding to growth of psychrotrophic, psychrophilic, mesophilic bacteria, molds and yeasts. Four characteristics including of odor, flavor, texture and color of fillets after and before cooking were evaluated for sensory analysis on days 1, 5, 10 and 15 and compared with control samples. The 4% supernatant and live bacteria were more effective than that of 2% and control (P<0.05). The amounts of corrosive bacteria in 4% and live cells in storage time were less than human consumption limits (7log CFUg-1), whereas in control and 2% supernatant treatments were more than that limits. The results showed that increasing the percentage of supernatant was more effective on bacteriologic factors and enhanced sensory characteristics of rainbow trout fillets (P<0.05).

scholarly journals Lactococcus lactis SpOx Spontaneous Mutants: a Family of Oxidative-Stress-Resistant Dairy Strains

2005 ◽  
Vol 71 (5) ◽  
pp. 2782-2788 ◽  
Author(s):  
Tatiana Rochat ◽  
Jean-Jacques Gratadoux ◽  
Gérard Corthier ◽  
Bérard Coqueran ◽  
Maria-Elena Nader-Macias ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Lactococcus Lactis ◽  
Culture Medium ◽  
Selection Method ◽  
Lactobacillus Delbrueckii ◽  
Term Survival ◽  
Human Flora ◽  
Spontaneous Mutants ◽  
Kinetics Of

ABSTRACT Numerous industrial bacteria generate hydrogen peroxide (H2O2), which may inhibit the growth of other bacteria in mixed ecosystems. We isolated spontaneous oxidative-stress-resistant (SpOx) Lactococcus lactis mutants by using a natural selection method with milk-adapted strains on dairy culture medium containing H2O2. Three SpOx mutants displayed greater H2O2 resistance. One of them, SpOx3, demonstrated better behavior in different oxidative-stress situations: (i) higher long-term survival upon aeration in LM17 and milk and (ii) the ability to grow with H2O2-producing Lactobacillus delbrueckii subsp. delbrueckii strains. Furthermore, the transit kinetics of the SpOx3 mutant in the digestive tract of a human flora-associated mouse model was not affected.

scholarly journals Growth of Nonproteolytic Lactococcus lactis in Culture Medium Supplemented with Different Casein Hydrolyzates

1993 ◽  
Vol 76 (11) ◽  
pp. 3327-3337 ◽  
Author(s):  
Daniel St-Gelais ◽  
Denis Roy ◽  
Sylvie Haché ◽  
Marie-Line Desjardins ◽  
Sylvie F. Gauthier
Keyword(s):  
Lactococcus Lactis ◽  
Culture Medium

scholarly journals Determination of the Domain of the Lactobacillus delbrueckii subsp. bulgaricus Cell Surface Proteinase PrtB Involved in Attachment to the Cell Wall after Heterologous Expression of the prtB Gene in Lactococcus lactis

2003 ◽  
Vol 69 (6) ◽  
pp. 3377-3384 ◽  
Author(s):  
Jacques-Edouard Germond ◽  
Mich�le Delley ◽  
Christophe Gilbert ◽  
Dani�le Atlan
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Cell Surface ◽  
Lactococcus Lactis ◽  
Culture Medium ◽  
Surface Display ◽  
Cell Surface Display ◽  
Lactobacillus Delbrueckii ◽  
Heterologous Proteins

ABSTRACT Belonging to the subtilase family, the cell surface proteinase (CSP) PrtB of Lactobacillus delbrueckii subsp. bulgaricus differs from other CSPs synthesized by lactic acid bacteria. Expression of the prtB gene under its own promoter was shown to complement the proteinase-deficient strain MG1363 (PrtP− PrtM−) of Lactococcus lactis subsp. cremoris. Surprisingly, the maturation process of PrtB, unlike that of lactococcal CSP PrtPs, does not require a specific PrtM-like chaperone. The carboxy end of PrtB was previously shown to be different from the consensus anchoring region of other CSPs and exhibits an imperfect duplication of 59 amino acids with a high lysine content. By using a deletion strategy, the removal of the last 99 amino acids, including the degenerated anchoring signal (LPKKT), was found to be sufficient to release a part of the truncated PrtB into the culture medium and led to an increase in PrtB activity. This truncated PrtB is still active and enables L. lactis MG1363 to grow in milk supplemented with glucose. By contrast, deletion of the last 806 amino acids of PrtB led to the secretion of an inactive proteinase. Thus, the utmost carboxy end of PrtB is involved in attachment to the bacterial cell wall. Proteinase PrtB constitutes a powerful tool for cell surface display of heterologous proteins like antigens.

scholarly journals AguR, a Transmembrane Transcription Activator of the Putrescine Biosynthesis Operon in Lactococcus lactis, Acts in Response to the Agmatine Concentration

2015 ◽  
Vol 81 (18) ◽  
pp. 6145-6157 ◽  
Author(s):  
Daniel M. Linares ◽  
Beatriz del Rio ◽  
Begoña Redruello ◽  
Victor Ladero ◽  
M. Cruz Martin ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Transmembrane Protein ◽  
Transcription Activator ◽  
Signal Transduction System ◽  
Content Type ◽  
Polycistronic Mrna ◽  
Catabolic Genes ◽  
Cytoplasmic Dna ◽  
Agmatine Deiminase

ABSTRACTDairy industry fermentative processes mostly useLactococcus lactisas a starter. However, some dairyL. lactisstrains produce putrescine, a biogenic amine that raises food safety and spoilage concerns, via the agmatine deiminase (AGDI) pathway. The enzymatic activities responsible for putrescine biosynthesis in this bacterium are encoded by the AGDI gene cluster. The role of the catabolic genesaguB,aguD,aguA, andaguChas been studied, but knowledge regarding the role ofaguR(the first gene in the cluster) remains limited. In the present work,aguRwas found to be a very low level constitutively expressed gene that is essential for putrescine biosynthesis and is transcribed independently of the polycistronic mRNA encoding the catabolic genes (aguBDAC). In response to agmatine, AguR acts as a transcriptional activator of theaguBpromoter (PaguB), which drives the transcription of theaguBDACoperon. Inverted sequences required for PaguBactivity were identified by deletion analysis. Further work indicated that AguR is a transmembrane protein which might function as a one-component signal transduction system that senses the agmatine concentration of the medium and, accordingly, regulates the transcription of theaguBDACoperon through a C-terminal cytoplasmic DNA-binding domain typically found in LuxR-like proteins.

Optimization of Nisin Production by Lactococcus lactis UQ2 Using Supplemented Whey as Alternative Culture Medium

2010 ◽  
Vol 75 (6) ◽  
pp. M347-M353 ◽  
Author(s):  
S.Y. González-Toledo ◽  
J. Domínguez-Domínguez ◽  
B.E. García-Almendárez ◽  
L.A. Prado-Barragán ◽  
C. Regalado-González
Keyword(s):  
Lactococcus Lactis ◽  
Culture Medium ◽  
Nisin Production ◽  
Alternative Culture

scholarly journals Production of a Heterologous Nonheme Catalase by Lactobacillus casei: an Efficient Tool for Removal of H2O2 and Protection of Lactobacillus bulgaricus from Oxidative Stress in Milk

2006 ◽  
Vol 72 (8) ◽  
pp. 5143-5149 ◽  
Author(s):  
Tatiana Rochat ◽  
Jean-Jacques Gratadoux ◽  
Alexandra Gruss ◽  
Gérard Corthier ◽  
Emmanuelle Maguin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Enzyme Activity ◽  
Lactococcus Lactis ◽  
Stress Resistance ◽  
Lactobacillus Casei ◽  
Culture Medium ◽  
Lactobacillus Bulgaricus ◽  
Efficient Tool ◽  
Term Survival

ABSTRACT Lactic acid bacteria (LAB) are generally sensitive to H2O2, a compound that they can paradoxically produce themselves, as is the case for Lactobacillus bulgaricus. Lactobacillus plantarum ATCC 14431 is one of the very few LAB strains able to degrade H2O2 through the action of a nonheme, manganese-dependent catalase (hereafter called MnKat). The MnKat gene was expressed in three catalase-deficient LAB species: L. bulgaricus ATCC 11842, Lactobacillus casei BL23, and Lactococcus lactis MG1363. While the protein could be detected in all heterologous hosts, enzyme activity was observed only in L. casei. This is probably due to the differences in the Mn contents of the cells, which are reportedly similar in L. plantarum and L. casei but at least 10- and 100-fold lower in Lactococcus lactis and L. bulgaricus, respectively. The expression of the MnKat gene in L. casei conferred enhanced oxidative stress resistance, as measured by an increase in the survival rate after exposure to H2O2, and improved long-term survival in aerated cultures. In mixtures of L. casei producing MnKat and L. bulgaricus, L. casei can eliminate H2O2 from the culture medium, thereby protecting both L. casei and L. bulgaricus from its deleterious effects.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

Structural aspects of osmoregulation in porphyra

1978 ◽  
Vol 36 (2) ◽  
pp. 412-413
Author(s):  
C. Wiencke ◽  
A. Lauchli
Keyword(s):  
Culture Medium ◽  
Point Of View ◽  
Chemical Fixation ◽  
Cellular Organization ◽  
Osmotic Adaptation ◽  
Osmotic Balance ◽  
Activity Of Enzymes ◽  
Osmotic Agents ◽  
Vacuolar System ◽  
Structural Aspects

Osmoregulatory mechanisms in algae were investigated mainly from a physiological point of view (KAUSS 1977, HELLEBUST 1976). In Porphyra two osmotic agents, i. e. floridoside/isofloridoside (KAUSS 1968) and certain ions, such as K+ and Na+(EPPLEY et al. 1960) are considered for osmotic balance. Accumulations of ions (particularly Na+) in the cytoplasm during osmotic adaptation is improbable, because the activity of enzymes is generally inhibited by high ionic concentrations (FLOWERS et al. 1977).The cellular organization of Porphyra was studied with special emphasis on the development of the vacuolar system under different hyperosmotic conditions. Porphyra was cultivated at various strengths of the culture medium ASP 12 (PROVASOLI 1961) ranging from normal to 6 times concentrated (6x) culture medium. Por electron microscopy freeze fracturing was used (specimens fixed in 2% glutaraldehyde and incubated in 30% glycerol, preparation in a BALZERS BA 360 M apparatus), because chemical fixation gave poor results.

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