Influence of temperature on growth of Legionella pneumophila biofilm determined by precise temperature gradient incubator

Konishi, Tadashi; Yamashiro, Tetsu; Koide, Michio; Nishizono, Akira

doi:10.1263/jbb.101.478

Cited by 26 publications

(34 citation statements)

References 27 publications

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“…In vitro , at 37–42 °C, monospecies biofilms are mycelial mat-like and are composed of filamentous bacteria whereas biofilms produced at 25 °C are thinner and made up of rod shaped cells [81]. These findings coincide with other studies demonstrating that the filamentation of L. pneumophila is regulated by temperature [82]. Filamentous growth occurs in other bacterial species to increase fitness against adverse environmental conditions [83].…”

Section: Regulation Of L Pneumophila Endogenous Factors That May Infsupporting

confidence: 62%

Biofilms: The Stronghold of Legionella pneumophila

Abdel-Nour

Duncan²,

Low

et al. 2013

IJMS

124

115

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Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.

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Section: Regulation Of L Pneumophila Endogenous Factors That May Infsupporting

confidence: 62%

Biofilms: The Stronghold of Legionella pneumophila

Abdel-Nour

Duncan²,

Low

et al. 2013

IJMS

124

115

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“…L. pneumophila SG1 multiplied at 42°C in a batch test with Vermamoeba vermiformis, previously named Hartmannella vermiformis (29), but not at 43°C (24). Konoshi et al (30) observed growth of pure cultures of L. pneumophila SG1 strains at 43°C and not at 44°C, but growth of L. pneumophila SG1 (Philadelphia strain 1) has been observed in a chemostat at 44°C (31). Clinical isolates of L. pneumophila SG1 and SG6, respectively, showed more growth in pure culture at 44°C and 45°C than two environmental isolates of these SGs although they showed clearly less growth than at 37°C (32).…”

mentioning

confidence: 99%

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Kooij

Brouwer-Hanzens

Veenendaal

et al. 2016

Appl Environ Microbiol

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Legionella pneumophila proliferates in freshwater environments at temperatures ranging from 25 to 45°C. To investigate the preference of different sequence types (ST) for a specific temperature range, growth of L. pneumophila serogroup 1 (SG1) ST1 (environmental strains), ST47, and ST62 (disease-associated strains) was measured in buffered yeast extract broth (BYEB) and biofilms grown on plasticized polyvinyl chloride in flowing heated drinking water originating from a groundwater supply. The optimum growth temperatures in BYEB were approximately 37°C (ST1), 39°C (ST47), and 41°C (ST62), with maximum growth temperatures of 42°C (ST1) and 43°C (ST47 and ST62). In the biofilm at 38°C, the ST47 and ST62 strains multiplied equally well compared to growth of the environmental ST1 strain and an indigenous L. pneumophila non-SG1 strain, all attaining a concentration of approximately 10 7 CFU/cm ؊2 . Raising the temperature to 41°C did not impact these levels within 4 weeks, but the colony counts of all strains tested declined (at a specific decline rate of 0.14 to 0.41 day ؊1 ) when the temperature was raised to 42°C. At this temperature, the concentration of Vermamoeba vermiformis in the biofilm, determined with quantitative PCR (qPCR), was about 2 log units lower than the concentration at 38°C. In columns operated at a constant temperature, ranging from 38 to 41°C, none of the tested strains multiplied in the biofilm at 41°C, in which also V. vermiformis was not detected. These observations suggest that strains of ST47 and ST62 did not multiply in the biofilm at a temperature of >41°C because of the absence of a thermotolerant host. IMPORTANCEGrowth of Legionella pneumophila in tap water installations is a serious public health concern. The organism includes more than 2,100 varieties (sequence types). More than 50% of the reported cases of Legionnaires' disease are caused by a few sequence types which are very rarely detected in the environment. Strains of selected virulent sequence types proliferated in biofilms on surfaces exposed to warm (38°C) tap water to the same level as environmental varieties and multiplied well as pure culture in a nutrient-rich medium at temperatures of 42 and 43°C. However, these organisms did not grow in the biofilms at temperatures of >41°C. Typical host amoebae also did not multiply at these temperatures. Apparently, proliferation of thermotolerant host amoebae is needed to enable multiplication of the virulent L. pneumophila strains in the environment at elevated temperatures. The detection of these amoebae in water installations therefore is a scientific challenge with practical implications. T he genus Legionella currently includes ca. 63 (sub)species (https://www.dsmz.de), at least 20 of which have been implicated in legionellosis (1). Legionella pneumophila is responsible for more than 90% of the reported cases of Legionnaires' disease (LD) in Europe (2), the United States (3), Canada (4), and Japan (5). This species includes 15 polyclonal serogroups (SGs). Most of the cli...

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“…Interestingly, L. pneumophila shows an optimal temperature around 35–37°C but lives at 4–63°C [3]. In fact, L. pneumophila tolerates well high temperatures, but cell multiplication and CO 2 production decrease markedly at temperatures >44–45°C, while cell multiplication generally stops at around 48.4–50.0°C [73], [74]. It therefore appears that the temperature dependence of the activity of lpPAH (Fig.…”

Section: Discussionmentioning

confidence: 99%

Phenylalanine Hydroxylase from Legionella pneumophila Is a Thermostable Enzyme with a Major Functional Role in Pyomelanin Synthesis

et al. 2012

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Background Legionella pneumophila is a pathogenic bacterium that can cause Legionnaires’ disease and other non-pneumonic infections in humans. This bacterium produces a pyomelanin pigment, a potential virulence factor with ferric reductase activity. In this work, we have investigated the role of phenylalanine hydroxylase from L. pneumophila (lpPAH), the product of the phhA gene, in the synthesis of the pyomelanin pigment and the growth of the bacterium in defined compositions.Methodology/Principal FindingsComparative studies of wild-type and phhA mutant corroborate that lpPAH provides the excess tyrosine for pigment synthesis. phhA and letA (gacA) appear transcriptionally linked when bacteria were grown in buffered yeast extract medium at 37°C. phhA is expressed in L. pneumophila growing in macrophages. We also cloned and characterized lpPAH, which showed many characteristics of other PAHs studied so far, including Fe(II) requirement for activity. However, it also showed many particular properties such as dimerization, a high conformational thermal stability, with a midpoint denaturation temperature (T m) = 79±0.5°C, a high specific activity at 37°C (10.2±0.3 µmol L-Tyr/mg/min) and low affinity for the substrate (K m (L-Phe) = 735±50 µM.Conclusions/SignificancelpPAH has a major functional role in the synthesis of pyomelanin and promotes growth in low-tyrosine media. The high thermal stability of lpPAH might reflect the adaptation of the enzyme to withstand relatively high survival temperatures.

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Influence of temperature on growth of Legionella pneumophila biofilm determined by precise temperature gradient incubator

Cited by 26 publications

References 27 publications

Biofilms: The Stronghold of Legionella pneumophila

Biofilms: The Stronghold of Legionella pneumophila

Multiplication of Legionella pneumophila Sequence Types 1, 47, and 62 in Buffered Yeast Extract Broth and Biofilms Exposed to Flowing Tap Water at Temperatures of 38°C to 42°C

Phenylalanine Hydroxylase from Legionella pneumophila Is a Thermostable Enzyme with a Major Functional Role in Pyomelanin Synthesis

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