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Identification of a predicted trimeric autotransporter adhesin required for biofilm formation of Burkholderia pseudomallei.

Lazar Adler NR, Dean RE, Saint RJ, Stevens MP, Prior JL, Atkins TP, Galyov EE - PLoS ONE (2013)

Bottom Line: The bpss1439 mutant demonstrated a significant reduction in biofilm formation at 48 hours in comparison to its parent 10276 wild-type strain.Additionally, it was observed that this phenotype was due to low levels of bacterial adhesion to the abiotic surface as well as reduced microcolony formation.Taken together, these studies indicate that BPSS1439 is a novel predicted autotransporter involved in biofilm formation of B. pseudomallei; hence, this factor was named BbfA, Burkholderia biofilm factor A.

View Article: PubMed Central - PubMed

Affiliation: Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom.

ABSTRACT
The autotransporters are a large and diverse family of bacterial secreted and outer membrane proteins, which are present in many Gram-negative bacterial pathogens and play a role in numerous environmental and virulence-associated interactions. As part of a larger systematic study on the autotransporters of Burkholderia pseudomallei, the causative agent of the severe tropical disease melioidosis, we have constructed an insertion mutant in the bpss1439 gene encoding an unstudied predicted trimeric autotransporter adhesin. The bpss1439 mutant demonstrated a significant reduction in biofilm formation at 48 hours in comparison to its parent 10276 wild-type strain. This phenotype was complemented to wild-type levels by the introduction of a full-length copy of the bpss1439 gene in trans. Examination of the wild-type and bpss1439 mutant strains under biofilm-inducing conditions by microscopy after 48 hours confirmed that the bpss1439 mutant produced less biofilm compared to wild-type. Additionally, it was observed that this phenotype was due to low levels of bacterial adhesion to the abiotic surface as well as reduced microcolony formation. In a murine melioidosis model, the bpss1439 mutant strain demonstrated a moderate attenuation for virulence compared to the wild-type strain. This attenuation was abrogated by in trans complementation, suggesting that bpss1439 plays a subtle role in the pathogenesis of B. pseudomallei. Taken together, these studies indicate that BPSS1439 is a novel predicted autotransporter involved in biofilm formation of B. pseudomallei; hence, this factor was named BbfA, Burkholderia biofilm factor A.

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Related in: MedlinePlus

The bpss1439 mutant displayed reduced biofilm formation which was complemented by in trans bpss1439 expression.a. The wild-type and bpss1439 mutant were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained with 1% w/v crystal violet, solubilised and quantified using an optimal density reading at 595 nm. Results are plotted with standard deviation error bars from triplicate experiments each consisting of eight experimental replicates; the p value was calculated using a paired Student's T test. b. The trans-complemented bpss1439 mutant (pME-1439), as well as the wild-type and bpss1439 pME strain, were also assessed for biofilm production as described previously.
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pone-0079461-g002: The bpss1439 mutant displayed reduced biofilm formation which was complemented by in trans bpss1439 expression.a. The wild-type and bpss1439 mutant were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained with 1% w/v crystal violet, solubilised and quantified using an optimal density reading at 595 nm. Results are plotted with standard deviation error bars from triplicate experiments each consisting of eight experimental replicates; the p value was calculated using a paired Student's T test. b. The trans-complemented bpss1439 mutant (pME-1439), as well as the wild-type and bpss1439 pME strain, were also assessed for biofilm production as described previously.

Mentions: The reported functions of TAAs includes roles in both autoagglutination and biofilm formation [29]. To assess if the unstudied predicted TAA encoded by bpss1439 has a role in either of these phenotypes, a comparative analysis of the bpss1439 mutant and its parent wild-type 10276 strain was performed. The strains were incubated for 48 hours in LB at 37°C under static conditions and monitored for altered autoagglutination by the measurement of the optical density of the growth media; the bpss1439 mutant and wild-type strains demonstrated the same level of autoagglutination (data not shown). However, when these cultures were assessed for their ability to form biofilms, the bpss1439 mutant demonstrated a significant (p<0.001) reduction in biofilm formation at 48 hours in LB at 37°C compared to the wild-type strain (Figure 2a°). This same phenotypic profile was found to occur at temperatures of 27C and 30°C, as well as in minimal media and LB enriched with 50 mM glucose (data not shown).


Identification of a predicted trimeric autotransporter adhesin required for biofilm formation of Burkholderia pseudomallei.

Lazar Adler NR, Dean RE, Saint RJ, Stevens MP, Prior JL, Atkins TP, Galyov EE - PLoS ONE (2013)

The bpss1439 mutant displayed reduced biofilm formation which was complemented by in trans bpss1439 expression.a. The wild-type and bpss1439 mutant were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained with 1% w/v crystal violet, solubilised and quantified using an optimal density reading at 595 nm. Results are plotted with standard deviation error bars from triplicate experiments each consisting of eight experimental replicates; the p value was calculated using a paired Student's T test. b. The trans-complemented bpss1439 mutant (pME-1439), as well as the wild-type and bpss1439 pME strain, were also assessed for biofilm production as described previously.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3818227&req=5

pone-0079461-g002: The bpss1439 mutant displayed reduced biofilm formation which was complemented by in trans bpss1439 expression.a. The wild-type and bpss1439 mutant were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained with 1% w/v crystal violet, solubilised and quantified using an optimal density reading at 595 nm. Results are plotted with standard deviation error bars from triplicate experiments each consisting of eight experimental replicates; the p value was calculated using a paired Student's T test. b. The trans-complemented bpss1439 mutant (pME-1439), as well as the wild-type and bpss1439 pME strain, were also assessed for biofilm production as described previously.
Mentions: The reported functions of TAAs includes roles in both autoagglutination and biofilm formation [29]. To assess if the unstudied predicted TAA encoded by bpss1439 has a role in either of these phenotypes, a comparative analysis of the bpss1439 mutant and its parent wild-type 10276 strain was performed. The strains were incubated for 48 hours in LB at 37°C under static conditions and monitored for altered autoagglutination by the measurement of the optical density of the growth media; the bpss1439 mutant and wild-type strains demonstrated the same level of autoagglutination (data not shown). However, when these cultures were assessed for their ability to form biofilms, the bpss1439 mutant demonstrated a significant (p<0.001) reduction in biofilm formation at 48 hours in LB at 37°C compared to the wild-type strain (Figure 2a°). This same phenotypic profile was found to occur at temperatures of 27C and 30°C, as well as in minimal media and LB enriched with 50 mM glucose (data not shown).

Bottom Line: The bpss1439 mutant demonstrated a significant reduction in biofilm formation at 48 hours in comparison to its parent 10276 wild-type strain.Additionally, it was observed that this phenotype was due to low levels of bacterial adhesion to the abiotic surface as well as reduced microcolony formation.Taken together, these studies indicate that BPSS1439 is a novel predicted autotransporter involved in biofilm formation of B. pseudomallei; hence, this factor was named BbfA, Burkholderia biofilm factor A.

View Article: PubMed Central - PubMed

Affiliation: Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom.

ABSTRACT
The autotransporters are a large and diverse family of bacterial secreted and outer membrane proteins, which are present in many Gram-negative bacterial pathogens and play a role in numerous environmental and virulence-associated interactions. As part of a larger systematic study on the autotransporters of Burkholderia pseudomallei, the causative agent of the severe tropical disease melioidosis, we have constructed an insertion mutant in the bpss1439 gene encoding an unstudied predicted trimeric autotransporter adhesin. The bpss1439 mutant demonstrated a significant reduction in biofilm formation at 48 hours in comparison to its parent 10276 wild-type strain. This phenotype was complemented to wild-type levels by the introduction of a full-length copy of the bpss1439 gene in trans. Examination of the wild-type and bpss1439 mutant strains under biofilm-inducing conditions by microscopy after 48 hours confirmed that the bpss1439 mutant produced less biofilm compared to wild-type. Additionally, it was observed that this phenotype was due to low levels of bacterial adhesion to the abiotic surface as well as reduced microcolony formation. In a murine melioidosis model, the bpss1439 mutant strain demonstrated a moderate attenuation for virulence compared to the wild-type strain. This attenuation was abrogated by in trans complementation, suggesting that bpss1439 plays a subtle role in the pathogenesis of B. pseudomallei. Taken together, these studies indicate that BPSS1439 is a novel predicted autotransporter involved in biofilm formation of B. pseudomallei; hence, this factor was named BbfA, Burkholderia biofilm factor A.

Show MeSH
Related in: MedlinePlus