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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 bbfA mutant demonstrated reduced adhesion and microcolony formation.A. The wild-type, bbfA mutant and trans-complemented bbfA mutant (pME-1439), along with the control wild-type and bbfA mutant strains harbouring pME, were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol and examined by light microscopy. B. The wild-type and bbfA mutant biofilms were also fixed with 2.5% v/v glutaldehyde and examined by scanning electron microscopy.
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pone-0079461-g003: The bbfA mutant demonstrated reduced adhesion and microcolony formation.A. The wild-type, bbfA mutant and trans-complemented bbfA mutant (pME-1439), along with the control wild-type and bbfA mutant strains harbouring pME, were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol and examined by light microscopy. B. The wild-type and bbfA mutant biofilms were also fixed with 2.5% v/v glutaldehyde and examined by scanning electron microscopy.

Mentions: Microscopy was used to confirm and examine the defect in biofilm production by the bbfA mutant. The wild-type and bbfA mutant, along with the control strains harbouring pME or pME-1439, were grown on glass coverslips under static conditions in LB at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol. When grown under biofilm-inducing conditions, the bbfA mutant demonstrated reduced adhesion as seen by lower total bacterial numbers, as well as reduced microcolony formation as noted by the lack of clumping or autoagglutination of bacterial cells in comparison with the wild-type (Figure 3a). As previously found with the crystal violet biofilm assay, the wild-type (pME) and the complemented bbfA (pME-1439) strains demonstrated wild-type levels of biofilm production with extensive microcolony formation while the bbfA mutant and bbfA (pME) strains displayed reduced adhesion and microcolony formation (Figure 3a).


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 bbfA mutant demonstrated reduced adhesion and microcolony formation.A. The wild-type, bbfA mutant and trans-complemented bbfA mutant (pME-1439), along with the control wild-type and bbfA mutant strains harbouring pME, were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol and examined by light microscopy. B. The wild-type and bbfA mutant biofilms were also fixed with 2.5% v/v glutaldehyde and examined by scanning electron microscopy.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818227&req=5

pone-0079461-g003: The bbfA mutant demonstrated reduced adhesion and microcolony formation.A. The wild-type, bbfA mutant and trans-complemented bbfA mutant (pME-1439), along with the control wild-type and bbfA mutant strains harbouring pME, were grown in LB under static conditions at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol and examined by light microscopy. B. The wild-type and bbfA mutant biofilms were also fixed with 2.5% v/v glutaldehyde and examined by scanning electron microscopy.
Mentions: Microscopy was used to confirm and examine the defect in biofilm production by the bbfA mutant. The wild-type and bbfA mutant, along with the control strains harbouring pME or pME-1439, were grown on glass coverslips under static conditions in LB at 37°C for 48 hours. Biofilms were stained for exopolysaccharide using the periodic acid-Schiff protocol. When grown under biofilm-inducing conditions, the bbfA mutant demonstrated reduced adhesion as seen by lower total bacterial numbers, as well as reduced microcolony formation as noted by the lack of clumping or autoagglutination of bacterial cells in comparison with the wild-type (Figure 3a). As previously found with the crystal violet biofilm assay, the wild-type (pME) and the complemented bbfA (pME-1439) strains demonstrated wild-type levels of biofilm production with extensive microcolony formation while the bbfA mutant and bbfA (pME) strains displayed reduced adhesion and microcolony formation (Figure 3a).

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