A simple method for the differentiation of Listeria monocytogenes based on induction of lecithinase activity by charcoal

Sа, Ermolaeva; Карпова, Т И; Novella, Susana; Wagner, Martin; Scortti, Mariela; Tartakovskiĭ, I S; Vázquez‐Boland, José A.

doi:10.1016/s0168-1605(02)00399-9

Cited by 22 publications

(8 citation statements)

References 15 publications

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“…Hemolysis and lecithinase activity tests were performed on blood agar plates (blood agar base; Oxoid) or egg yolk agar plates supplemented with charcoal, as described previously (5). Utilization of different carbon sources was determined by the API 50 CHL method as recommended by the manufacturer (BioMérieux).…”

Section: Methodsmentioning

confidence: 99%

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

et al. 2004

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In gram-negative bacteria, the RNA-binding protein Hfq has emerged as an important regulatory factor in a variety of physiological processes, including stress resistance and virulence. In Escherichia coli, Hfq modulates the stability or the translation of mRNAs and interacts with numerous small regulatory RNAs. Here, we studied the role of Hfq in the stress tolerance and virulence of the gram-positive food-borne human pathogen Listeria monocytogenes. We present evidence that Hfq is involved in the ability of L. monocytogenes to tolerate osmotic and ethanol stress and contributes to long-term survival under amino acid-limiting conditions. However, Hfq is not required for resistance to acid and oxidative stress. Transcription of hfq is induced under various stress conditions, including osmotic and ethanol stress and at the entry into the stationary growth phase, thus supporting the view that Hfq is important for the growth and survival of L. monocytogenes in harsh environments. The stress-inducible transcription of hfq depends on the alternative sigma factor B , which controls the expression of numerous stress-and virulence-associated genes in L. monocytogenes. Infection studies showed that Hfq contributes to pathogenesis in mice, yet plays no role in the infection of cultured cell lines. This study provides, for the first time, information on the role of Hfq in the stress tolerance and virulence of a gram-positive pathogen.

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Section: Methodsmentioning

confidence: 99%

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

et al. 2004

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“…Egg yolk assay was performed essentially as described previously [16,18]. Activated charcoal powder (Hangzhou Charcoal, Hangzhou, China) was added to the base agar medium TSB-Y before autoclaving.…”

Section: Phospholipase Activity Assaymentioning

confidence: 99%

Virulence Phenotyping and Molecular Characterization of a Low-pathogenicity Isolate of Listeria <italic>monocytogenes</italic> from Cow's Milk

Jiang

Chen

et al. 2006

ABBS

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A low-pathogenicity isolate of Listeria monocytogenes from cow's milk, as screened in mouse and chicken embryonated egg models, was examined for virulence-related phenotypic traits. Corresponding virulence genes (iap, prfA, plcA, hly, mpl, actA, plcB, InlA and InlB) were compared with L. monocytogenes reference strains 10403S and EGD to elucidate the possible molecular mechanisms of low virulence. Although L. monocytogenes H4 exhibited similar patterns to strain 10403S in terms of hemolytic activity, in vitro growth and invasiveness and even had higher adhesiveness, faster intracellular growth and higher phospholipase activity in vitro, it was substantially less virulent than the strain 10403S in mouse and chicken embryo models (50% lethal dose: 10(8.14) vs. 10(5.49) and 10(6.73) vs. 10(1.9), respectively). The genes prfA, plcA and mpl were homologous among L. monocytogenes strains H4, 10403S and EGD (>98%). Genes iap, hly, plcB, InlA and InlB of L. monocytogenes 10403S had higher homology to those of strain EGD (>98%) than isolate H4. The homology of the gene hly between strain 10403S and isolate H4 was 96.9% at the nucleotide level, but 98.7% at the amino acid level. The actA gene of isolate H4 had deletions of 105 nucleotides corresponding to 35 amino acid deletions falling within the proline-rich region. Taken together, this study presents some clues as to reduced virulence to mice and chicken embryos of the isolate H4 probably as a result of deletion mutations of actA.

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“…Using charcoal-supplemented egg-yolk agar plates, PlcB acitivity was estimated as the size of a halo of precipitation around the bacterial colony, essentially as described by Ermolaeva et al (2003). The concentration of activated charcoal was 0?2 %.…”

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confidence: 99%

The Dps-like protein Fri of Listeria monocytogenes promotes stress tolerance and intracellular multiplication in macrophage-like cells

Olsen¹,

Larsen²,

Gahan

et al. 2005

Microbiology

103

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Members of the ferritin-like Dps protein family are found in a number of bacterial species, where they demonstrate the potential to bind iron, and have been implicated in tolerance to oxidative stress. In this study of the food-borne pathogen Listeria monocytogenes, the fri gene encoding a Dps homologue was deleted, and, compared to wild-type cells, it was found that the resulting mutant was less resistant to hydrogen peroxide, and demonstrated reduced survival following long-term (7–11 days) incubation in laboratory media. In view of this, it is shown that fri gene expression is controlled by the hydrogen peroxide regulator PerR, as well as the general stress sigma factor σ B. When fri mutant cells were transferred to iron-limiting conditions, growth was retarded relative to wild-type cells, indicating that Fri may be required for iron storage. This notion is supported by the observation that the L. monocytogenes genome appears not to encode other ferritin-like proteins. Given the role of Fri in resistance to oxidative stress, and growth under iron-limiting conditions, the ability of the fri mutant to infect mice was examined. When injected by the intraperitoneal route, the fri mutant demonstrated a reduced capacity to proliferate in the organs of infected mice relative to the wild-type, whereas when the bacteria were supplied intravenously this effect was mitigated. In addition, the mutant was impaired in its ability to survive and grow in J774.A1 mouse macrophage cells. Thus, the data suggest that Fri contributes to the ability of L. monocytogenes to survive in environments where oxidative stress and low iron availability may impede bacterial proliferation.

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A simple method for the differentiation of Listeria monocytogenes based on induction of lecithinase activity by charcoal

Cited by 22 publications

References 15 publications

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

Virulence Phenotyping and Molecular Characterization of a Low-pathogenicity Isolate of Listeria <italic>monocytogenes</italic> from Cow's Milk

The Dps-like protein Fri of Listeria monocytogenes promotes stress tolerance and intracellular multiplication in macrophage-like cells

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A simple method for the differentiation of Listeria monocytogenes based on induction of lecithinase activity by charcoal

Cited by 22 publications

References 15 publications

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

The RNA-Binding Protein Hfq ofListeria monocytogenes: Role in Stress Tolerance and Virulence

Virulence Phenotyping and Molecular Characterization of a Low-pathogenicity Isolate of Listeria &lt;italic&gt;monocytogenes&lt;/italic&gt; from Cow's Milk

The Dps-like protein Fri of Listeria monocytogenes promotes stress tolerance and intracellular multiplication in macrophage-like cells

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Virulence Phenotyping and Molecular Characterization of a Low-pathogenicity Isolate of Listeria <italic>monocytogenes</italic> from Cow's Milk