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Atomic force microscopy reveals a morphological differentiation of chromobacterium violaceum cells associated with biofilm development and directed by N-hexanoyl-L-homoserine lactone.

Kamaeva AA, Vasilchenko AS, Deryabin DG - PLoS ONE (2014)

Bottom Line: We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer.With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance.Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Orenburg State University, Orenburg, Russia; RSE «Republican Collection of Microorganisms», Astana, Republic of Kazakhstan.

ABSTRACT
Chromobacterium violaceum abounds in soil and water ecosystems in tropical and subtropical regions and occasionally causes severe and often fatal human and animal infections. The quorum sensing (QS) system and biofilm formation are essential for C. violaceum's adaptability and pathogenicity, however, their interrelation is still unknown. C. violaceum's cell and biofilm morphology were examined by atomic force microscopy (AFM) in comparison with growth rates, QS-dependent violacein biosynthesis and biofilm biomass quantification. To evaluate QS regulation of these processes, the wild-type strain C. violaceum ATCC 31532 and its mini-Tn5 mutant C. violaceum NCTC 13274, cultivated with and without the QS autoinducer N-hexanoyl-L-homoserine lactone (C6-HSL), were used. We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer. AFM revealed numerous invaginations of the external cytoplasmic membrane of wild-type cells, which were repressed in the mutant strain and restored by exogenous C6-HSL. With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance. Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

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Time course (a) of the cell density (OD 450) for violacein (OD 575) and biofilm (OD 540) production by wild-type strain C. violaceum ATCC 31532, growing in LB broth for 24, 48 and 72 h.
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pone-0103741-g001: Time course (a) of the cell density (OD 450) for violacein (OD 575) and biofilm (OD 540) production by wild-type strain C. violaceum ATCC 31532, growing in LB broth for 24, 48 and 72 h.

Mentions: In order to evaluate if violacein production and biofilm formation were dependent on cell density, C. violaceum ATCC 31532 was grown in LB broth for 24, 48 and 72 h (Fig. 1). This experiment showed a typical growth (OD450) curve with maximal progression in 24 h followed by a gradual increase to the late stationary phase. Production of violacein was detected at 24 h, but the most growth of characteristic OD575 was established at high cell density between 48 and 72 h where this value increased 3.4-fold. On the other hand, the biofilm production was quite similar to the growth rate, and the OD540 after crystal violet staining increased proportionally to an OD450. Thus, violacein and biofilm in the wild-type strain C. violaceum ATCC 31532 differentially corresponded to cell density and only the first developed in a fashion similar to a quorum-dependent parameter.


Atomic force microscopy reveals a morphological differentiation of chromobacterium violaceum cells associated with biofilm development and directed by N-hexanoyl-L-homoserine lactone.

Kamaeva AA, Vasilchenko AS, Deryabin DG - PLoS ONE (2014)

Time course (a) of the cell density (OD 450) for violacein (OD 575) and biofilm (OD 540) production by wild-type strain C. violaceum ATCC 31532, growing in LB broth for 24, 48 and 72 h.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128650&req=5

pone-0103741-g001: Time course (a) of the cell density (OD 450) for violacein (OD 575) and biofilm (OD 540) production by wild-type strain C. violaceum ATCC 31532, growing in LB broth for 24, 48 and 72 h.
Mentions: In order to evaluate if violacein production and biofilm formation were dependent on cell density, C. violaceum ATCC 31532 was grown in LB broth for 24, 48 and 72 h (Fig. 1). This experiment showed a typical growth (OD450) curve with maximal progression in 24 h followed by a gradual increase to the late stationary phase. Production of violacein was detected at 24 h, but the most growth of characteristic OD575 was established at high cell density between 48 and 72 h where this value increased 3.4-fold. On the other hand, the biofilm production was quite similar to the growth rate, and the OD540 after crystal violet staining increased proportionally to an OD450. Thus, violacein and biofilm in the wild-type strain C. violaceum ATCC 31532 differentially corresponded to cell density and only the first developed in a fashion similar to a quorum-dependent parameter.

Bottom Line: We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer.With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance.Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Orenburg State University, Orenburg, Russia; RSE «Republican Collection of Microorganisms», Astana, Republic of Kazakhstan.

ABSTRACT
Chromobacterium violaceum abounds in soil and water ecosystems in tropical and subtropical regions and occasionally causes severe and often fatal human and animal infections. The quorum sensing (QS) system and biofilm formation are essential for C. violaceum's adaptability and pathogenicity, however, their interrelation is still unknown. C. violaceum's cell and biofilm morphology were examined by atomic force microscopy (AFM) in comparison with growth rates, QS-dependent violacein biosynthesis and biofilm biomass quantification. To evaluate QS regulation of these processes, the wild-type strain C. violaceum ATCC 31532 and its mini-Tn5 mutant C. violaceum NCTC 13274, cultivated with and without the QS autoinducer N-hexanoyl-L-homoserine lactone (C6-HSL), were used. We report for the first time the unusual morphological differentiation of C. violaceum cells, associated with biofilm development and directed by the QS autoinducer. AFM revealed numerous invaginations of the external cytoplasmic membrane of wild-type cells, which were repressed in the mutant strain and restored by exogenous C6-HSL. With increasing bacterial growth, polymer matrix extrusions formed in place of invaginations, whereas mutant cells were covered with a diffusely distributed extracellular substance. Thus, quorum sensing in C. violaceum involves a morphological differentiation that organises biofilm formation and leads to a highly differentiated matrix structure.

Show MeSH
Related in: MedlinePlus