scholarly journals pH-, Lactic Acid-, and Non-Lactic Acid-Dependent Activities of Probiotic Lactobacilli against Salmonella enterica Serovar Typhimurium

2005 ◽  
Vol 71 (10) ◽  
pp. 6008-6013 ◽  
Author(s):  
Domitille Fayol-Messaoudi ◽  
Cédric N. Berger ◽  
Marie-Hélène Coconnier-Polter ◽  
Vanessa Liévin-Le Moal ◽  
Alain L. Servin
Keyword(s):  
Lactic Acid ◽  
Growth Phase ◽  
Salmonella Enterica ◽  
Lactobacillus Rhamnosus ◽  
Stationary Growth Phase ◽  
Exponential Growth Phase ◽  
Killing Activity ◽  
Serovar Typhimurium ◽  
Probiotic Strains ◽  
Probiotic Lactobacilli

ABSTRACT The mechanism(s) underlying the antibacterial activity of probiotic Lactobacillus strains appears to be multifactorial and includes lowering of the pH and the production of lactic acid and of antibacterial compounds, including bacteriocins and nonbacteriocin, non-lactic acid molecules. Addition of Dulbecco's modified Eagle's minimum essential medium to the incubating medium delays the killing activity of lactic acid. We found that the probiotic strains Lactobacillus johnsonii La1, Lactobacillus rhamnosus GG, Lactobacillus casei Shirota YIT9029, L. casei DN-114 001, and L. rhamnosus GR1 induced a dramatic decrease in the viability of Salmonella enterica serovar Typhimurium SL1344 mainly attributable to non-lactic acid molecule(s) present in the cell-free culture supernatant (CFCS). These molecules were more active against serovar Typhimurium SL1344 in the exponential growth phase than in the stationary growth phase. We also showed that the production of the non-lactic acid substance(s) responsible for the killing activity was dependent on growth temperature and that both unstable and stable substances with killing activity were present in the CFCSs. We found that the complete inhibition of serovar Typhimurium SL1344 growth results from a pH-lowering effect.

scholarly journals Salmonella enterica Serovar Gallinarum Requires ppGpp for Internalization and Survival in Animal Cells

2008 ◽  
Vol 190 (19) ◽  
pp. 6340-6350 ◽  
Author(s):  
Jae-Ho Jeong ◽  
Miryoung Song ◽  
Sang-Ik Park ◽  
Kyoung-Oh Cho ◽  
Joon Haeng Rhee ◽  
...  
Keyword(s):  
Growth Phase ◽  
Salmonella Enterica ◽  
Animal Cell ◽  
Growth Conditions ◽  
Exponential Growth Phase ◽  
Low Oxygen ◽  
Intracellular Growth ◽  
Animal Cells ◽  
Cell Internalization ◽  
Serovar Typhimurium

ABSTRACT To elucidate the pathogenic mechanism of Salmonella enterica serovar Gallinarum, we examined the expression of the genes encoded primarily in Salmonella pathogenicity island 1 (SPI-1) and SPI-2. These genes were found to be induced as cultures entered stationary phase under high- and low-oxygen growth conditions, as also observed for Salmonella serovar Typhimurium. In contrast, Salmonella serovar Gallinarum in the exponential growth phase most efficiently internalized cultured animal cells. Analysis of mutants defective in SPI-1 genes, SPI-2 genes, and others implicated in early stages of infection revealed that SPI-1 genes were not involved in the internalization of animal cells by Salmonella serovar Gallinarum. Following entry, however, Salmonella serovar Gallinarum was found to reside in LAMP1-positive vacuoles in both phagocytic and nonphagocytic cells, although internalization was independent of SPI-1. A mutation that conferred defects in ppGpp synthesis was the only one found to affect animal cell internalization by Salmonella serovar Gallinarum. It was concluded that Salmonella serovar Gallinarum internalizes animal cells by a mechanism independent of SPI-1 genes but dependent on ppGpp. Intracellular growth also required ppGpp for the transcription of genes encoded in SPI-2.

scholarly journals Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

2000 ◽  
Vol 66 (6) ◽  
pp. 2548-2554 ◽  
Author(s):  
Christophe J. P. Boonaert ◽  
Paul G. Rouxhet
Keyword(s):  
Lactic Acid ◽  
Chemical Composition ◽  
Lactic Acid Bacteria ◽  
Physicochemical Properties ◽  
Growth Phase ◽  
Surface Composition ◽  
Stationary Growth Phase ◽  
Contact Angles ◽  
Exponential Growth Phase ◽  
Stationary Growth

ABSTRACT The surface chemical composition and physicochemical properties (hydrophobicity and zeta potential) of two lactic acid bacteria,Lactococcus lactis subsp. lactis bv. diacetilactis and Lactobacillus helveticus, have been investigated using cells harvested in exponential or stationary growth phase. The surface composition determined by X-ray photoelectron spectroscopy (XPS) was converted into a molecular composition in terms of proteins, polysaccharides, and hydrocarbonlike compounds. The concentration of the last was always below 15% (wt/wt), which is related to the hydrophilic character revealed by water contact angles of less than 30°. The surfaces of L. lactis cells had a polysaccharide concentration about twice that of proteins. The S-layer of L. helveticus was either interrupted or crossed by polysaccharide-rich compounds; the concentration of the latter was higher in the stationary growth phase than in the exponential growth phase. Further progress was made in the interpretation of XPS data in terms of chemical functions by showing that the oxygen component at 531.2 eV contains a contribution of phosphate in addition to the main contribution of the peptide link. The isoelectric points were around 2 and 3, and the electrophoretic mobilities above pH 5 (ionic strength, 1 mM) were about −3.0 × 10−8 and −0.6 × 10−8 m2 s−1 V−1 forL. lactis and L. helveticus, respectively. The electrokinetic properties of the latter reveal the influence of carboxyl groups, while the difference between the two strains is related to a difference between N/P surface concentration ratios, reflecting the relative exposure of proteins and phosphate groups at the surface.

scholarly journals Sanitation of fresh green asparagus and green onions inoculated with Salmonella

2009 ◽  
Vol 27 (No. 6) ◽  
pp. 454-462 ◽  
Author(s):  
M.A. Martínez-Téllez ◽  
F.J. Rodríguez-Leyva ◽  
I.E. Espinoza-Medina ◽  
I. Vargas-Arispuro ◽  
A.A. Gardea ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Exposure Time ◽  
Salmonella Enterica ◽  
Fresh Produce ◽  
Clean Water ◽  
Effective Agent ◽  
Serovar Typhimurium ◽  
Postharvest Handling ◽  
Green Asparagus

The absence of good agricultural and manufacturing practices in the production and postharvest handling of fresh produce, such as green asparagus or green onions increase the contamination risk by biological hazards like Salmonella. The objective of this work was to investigate the efficacy of chlorine (200 and 250 ppm), hydrogen peroxide (1.5% and 2%), and lactic acid (1.5% and 2%) sanitisers during different exposure times (40, 60, and 90 s) on the reduction of <i>Salmonella enterica</i> subspecie <i>enterica</i> serovar Typhimurium in inoculated fresh green asparagus and green onions. Washing with clean water only reduced < 1 log10 CFU/g in both vegetables. The most effective sanitiser evaluated for fresh green asparagus and green onions disinfection appeared to be 2% lactic acid reducing <i>Salmonella</i> growth close to 3 log<sub>10</sub> CFU/g. Hydrogen peroxide was the least effective agent for <i>Salmonella</i> Typhimurium reduction. No effect was observed of the exposure time of inoculated product to sanitiser up to 90 seconds. These results confirm that lactic acid could be used as an alternative for fresh green asparagus and green onions sanitation.

scholarly journals H-NS Represses Salmonella enterica Serovar Typhimurium dsbA Expression during Exponential Growth

2004 ◽  
Vol 186 (4) ◽  
pp. 910-918 ◽  
Author(s):  
C. V. Gallant ◽  
T. Ponnampalam ◽  
H. Spencer ◽  
J. C. D. Hinton ◽  
N. L. Martin
Keyword(s):  
Exponential Growth ◽  
Salmonella Enterica ◽  
Immunoblot Analysis ◽  
Exponential Phase ◽  
Exponential Growth Phase ◽  
Mobility Shift ◽  
Altered Expression ◽  
Serovar Typhimurium ◽  
In The Wild ◽  
Maximal Expression

ABSTRACT Disulfide bond formation catalyzed by disulfide oxidoreductases occurs in the periplasm and plays a major role in the proper folding and integrity of many proteins. In this study, we were interested in elucidating factors that influence the regulation of dsbA, a gene coding for the primary disulfide oxidoreductase found in Salmonella enterica serovar Typhimurium. Strains with mutations created by transposon mutagenesis were screened for strains with altered expression of dsbA. A mutant (NLM2173) was found where maximal expression of a dsbA::lacZ transcriptional fusion occurred in the exponential growth phase in contrast to that observed in the wild type where maximal expression occurs in stationary phase. Sequence analysis of NLM2173 demonstrated that the transposon had inserted upstream of the gene encoding H-NS. Western immunoblot analysis using H-NS and StpA antibodies showed decreased amounts of H-NS protein in NLM2173, and this reduction in H-NS correlated with an increase of StpA protein. Northern blot analysis with a dsbA-specific probe showed an increase in dsbA transcript during exponential phase of growth. Direct binding of H-NS to the dsbA promoter region was verified using purified H-NS in electrophoretic mobility shift assays. Thus, a reduction in H-NS protein is correlated with a derepression of dsbA in NLM2173, suggesting that H-NS normally plays a role in suppressing the expression of dsbA during exponential phase growth.

High Hydrostatic Pressure Come-Up Time and Yeast Viability

1998 ◽  
Vol 61 (12) ◽  
pp. 1657-1660 ◽  
Author(s):  
E. PALOU ◽  
A. LÓPEZ-MALO ◽  
G. V. BARBOSA-CÁNOVAS ◽  
J. WELTI-CHANES ◽  
P. M. DAVIDSON ◽  
...  
Keyword(s):  
Growth Phase ◽  
Growth Cycle ◽  
Stationary Growth Phase ◽  
Yeast Cells ◽  
Exponential Growth Phase ◽  
Stationary Growth ◽  
Survival Fraction ◽  
Zygosaccharomyces Bailii ◽  
Yeast Viability ◽  
Increased Sensitivity

The effects of the come-up time at selected pressures (50 to 689 MPa) on Saccharomyces cerevisiae and Zygosaccharomyces bailii viability were evaluated at 21°C. For Z. bailii the effects of the water activity (aw) of the suspension media and the stage of the growth cycle were also investigated. Pressure come-up times exerted an important effect on the yeast survival fraction, decreasing counts as pressure increased. An increased sensitivity to pressure treatments was observed with yeast cells from the exponential growth phase. Lethality increased as aw of the suspension media increased. For an aw of 0.98 and cells from the stationary growth phase, pressure treatments at less than 200 MPa had no effect on Z. bailii viability; however, no survivors (&lt;10 CFU/ml) were observed in treatments applied only for the time needed to reach pressures greater than 517 MPa. Yeast survivor curves showed an excellent fit (r &gt; 0.996) when described by a phenomenological model based on the Fermi equation, S(P) = 1/|1 + exp[(P − Pc)/k]|, where S(P) is the survival fraction, P is the pressure, Pc is a critical pressure corresponding to 50% survival, and k is a constant representing the steepness of the curve.

scholarly journals Effects of Physical Properties of Feed on Microbial Ecology and Survival of Salmonella enterica Serovar Typhimurium in the Pig Gastrointestinal Tract

2004 ◽  
Vol 70 (6) ◽  
pp. 3485-3492 ◽  
Author(s):  
Lene Lind Mikkelsen ◽  
Patrick J. Naughton ◽  
Mette S. Hedemann ◽  
Bent Borg Jensen
Keyword(s):  
Lactic Acid ◽  
Gastrointestinal Tract ◽  
Salmonella Enterica ◽  
Death Rate ◽  
Gastric Content ◽  
The Other ◽  
Coliform Bacteria ◽  
Dry Matter Content ◽  
Distal Small Intestine ◽  
Serovar Typhimurium

ABSTRACT A two-by-two factorial experiment with pigs was conducted to study the effect of feed grinding (fine and coarse) and feed processing (pelleted and nonpelleted) on physicochemical properties, microbial populations, and survival of Salmonella enterica serovar Typhimurium DT12 in the gastrointestinal tracts of pigs. Results demonstrated a strong effect of diet on parameters measured in the stomachs of the pigs, whereas the effect was less in the other parts of the gastrointestinal tract. Pigs fed the coarse nonpelleted (C-NP) diet showed more solid gastric content with higher dry matter content than pigs fed the fine nonpelleted (F-NP), coarse pelleted (C-P), or fine pelleted (F-P) diet. Pigs fed the C-NP diet also showed significantly increased number of anaerobic bacteria (P < 0.05), increased concentrations of organic acids, and reduced pH in the stomach. In addition, pigs fed the C-NP diet showed increased in vitro death rate of S. enterica serovar Typhimurium DT12 in content from the stomach (P < 0.001). Pigs fed the C-NP diet had a significantly higher concentration of undissociated lactic acid in gastric content than pigs fed the other diets (P < 0.001). A strong correlation between the concentration of undissociated lactic acid and the death rate of S. enterica serovar Typhimurium DT12 was found. In the distal small intestine, cecum, and midcolon, significantly lower numbers of coliform bacteria were observed in pigs fed the coarse diets than in pigs fed the fine diets (P < 0.01). Pigs fed the C-NP diet showed the lowest number of coliform bacteria in these segments of the gastrointestinal tract. Pigs fed the coarse diets showed increased concentration of butyric acid in the cecum (P < 0.05) and colon (P < 0.10) compared with pigs fed the fine diets. It was concluded that feeding a coarsely ground meal feed to pigs changes the physicochemical and microbial properties of content in the stomach, which decreases the survival of Salmonella during passage through the stomach. In this way the stomach acts as a barrier preventing harmful bacteria from entering and proliferating in the lower part of the gastrointestinal tract.

scholarly journals Adherence of Staphylococcus aureus to Endothelial Cells: Influence of Capsular Polysaccharide, Global Regulatoragr, and Bacterial Growth Phase

2000 ◽  
Vol 68 (9) ◽  
pp. 4865-4871 ◽  
Author(s):  
Petra Pöhlmann-Dietze ◽  
Martina Ulrich ◽  
Kevin B. Kiser ◽  
Gerd Döring ◽  
Jean C. Lee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Endothelial Cells ◽  
Bacterial Growth ◽  
Growth Phase ◽  
Parental Strain ◽  
Double Mutant ◽  
Capsular Polysaccharide ◽  
Stationary Growth Phase ◽  
Exponential Growth Phase ◽  
Logarithmic Phase

ABSTRACT The adherence of Staphylococcus aureus to human endothelial cells (EC) is probably an important step in the pathogenesis of systemic staphylococcal infections. We examined the influence of type 5 capsular polysaccharide (CP5) production, the global regulator agr, and the bacterial growth phase onS. aureus adherence to EC. Whereas S. aureusNewman showed maximal adherence to EC in the logarithmic phase of growth, an isogenic agr mutant showed maximal adherence in the stationary growth phase. S. aureus adherence to EC and CP5 expression were negatively correlated: a mutation in theagr locus diminished CP5 production and led to increased adherence. Likewise, induction of CP5 expression by addition of NaCl to the growth medium resulted in reduced staphylococcal adherence to EC.S. aureus Newman cells that adhered to EC did not express CP5. A Newman cap5O mutant was acapsular and showed significantly greater adherence to EC than the parental strain did (P < 0.005). Complementation of the cap5Omutation in trans restored CP5 expression and reduced EC adherence to a level similar to that of the parental strain. The enhanced adherence shown by the cap5O mutant was similar in magnitude to that of the agr mutant or the cap5O agr double mutant. Cells of the cap5O mutant andcap5O agr double mutant harvested from stationary-phase cultures adhered significantly better than did cells harvested in the exponential growth phase. These data are consistent with the postexponential and agr-independent expression by S. aureus of at least one putative EC adhesin, whose binding domain may be masked by CP5.

scholarly journals Involvement of the Detoxifying Enzyme Lactoylglutathione Lyase in Streptococcus mutans Aciduricity

2007 ◽  
Vol 189 (21) ◽  
pp. 7586-7592 ◽  
Author(s):  
Bryan Korithoski ◽  
Céline M. Lévesque ◽  
Dennis G. Cvitkovitch
Keyword(s):  
Streptococcus Mutans ◽  
Growth Phase ◽  
Proteome Analysis ◽  
Stationary Growth Phase ◽  
Low Ph ◽  
Transcriptional Analysis ◽  
Exponential Growth Phase ◽  
Expression Studies ◽  
Insertional Inactivation ◽  
Gene Expression Studies

ABSTRACT Streptococcus mutans, a normal inhabitant of dental plaque, is considered a primary etiological agent of dental caries. Its main virulence factors are acidogenicity and aciduricity, the abilities to produce acid and to survive and grow at low pH, respectively. Metabolic processes are finely regulated following acid exposure in S. mutans. Proteome analysis of S. mutans demonstrated that lactoylglutathione lyase (LGL) was up-regulated during acid challenge. The LGL enzyme catalyzes the conversion of toxic methylglyoxal, derived from glycolysis, to S-d-lactoylglutathione. Methylglyoxal inhibits the growth of cells in all types of organisms. The current study aimed to investigate the relationship between LGL and aciduricity and acidogenicity in S. mutans. An S. mutans isogenic mutant defective in lgl (LGLKO) was created, and its growth kinetics were characterized. Insertional inactivation of lgl resulted in an acid-sensitive phenotype. However, the glycolytic rate at pH 5.0 was greater for LGLKO than for S. mutans UA159 wild-type cells. LGL was involved in the detoxification of methylglyoxal, illustrated by the absence of enzyme activity in LGLKO and the hypersensitivity of LGLKO to methylglyoxal, compared with UA159 (MIC of 3.9 and 15.6 mM, respectively). Transcriptional analysis of lgl conducted by quantitative real-time PCR revealed that lgl was up-regulated (approximately sevenfold) during the exponential growth phase compared with that in the stationary growth phase. Gene expression studies conducted at low pH demonstrated that lgl was induced during acidic growth (∼3.5-fold) and following acid adaptation (∼2-fold).This study demonstrates that in S. mutans, LGL functions in the detoxification of methylglyoxal, resulting in increased aciduricity.

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