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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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Dimensional specifications of morphological features on the surface of cells (invagination and extrusion) were assessed on the basis of AFM profile data carried out through two adjoined invaginations or extrusion.Distance was defined as a spacing between points located: in center of two adjoined invaginations (a) or on the top of two adjoined extrusions (b). Diameter of invaginations and extrusions is defined as a distance between two points that are located on two crossing lines (solid line and dotted line). Precise morphometry of C. violaceum ATCC 31532 cells surfaces (in biofilm conditions), revealed: diameters of invaginations (c) and extrusions (d); distances between centres of two adjoined invaginations (e) and two adjoined extrusions (f) (histograms and average value).
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pone-0103741-g003: Dimensional specifications of morphological features on the surface of cells (invagination and extrusion) were assessed on the basis of AFM profile data carried out through two adjoined invaginations or extrusion.Distance was defined as a spacing between points located: in center of two adjoined invaginations (a) or on the top of two adjoined extrusions (b). Diameter of invaginations and extrusions is defined as a distance between two points that are located on two crossing lines (solid line and dotted line). Precise morphometry of C. violaceum ATCC 31532 cells surfaces (in biofilm conditions), revealed: diameters of invaginations (c) and extrusions (d); distances between centres of two adjoined invaginations (e) and two adjoined extrusions (f) (histograms and average value).

Mentions: The 24-h individual C. violaceum cells had a characteristic elongated shape, and based on AFM, the cells were 2.45±0.31 µm length, 0.85±0.09 µm wide and 0.34±0.07 µm high and without distinctions between planktonic and biofilm-forming bacteria. However, the surface topography of these cells was significantly different, and unusual invaginations (about 30–40 per cell taking into consideration 50% cell surface visibility) of the external membrane in biofilm-forming bacteria were observed (fig. 2 a). Based on AFM profiles, the invaginations had a 171±43 nm diameter (Fig. 3 c).and a 31.1±7.5 nm depth, whereas the distance from their centres were nearly 288±80 nm (Fig. 3 e).


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)

Dimensional specifications of morphological features on the surface of cells (invagination and extrusion) were assessed on the basis of AFM profile data carried out through two adjoined invaginations or extrusion.Distance was defined as a spacing between points located: in center of two adjoined invaginations (a) or on the top of two adjoined extrusions (b). Diameter of invaginations and extrusions is defined as a distance between two points that are located on two crossing lines (solid line and dotted line). Precise morphometry of C. violaceum ATCC 31532 cells surfaces (in biofilm conditions), revealed: diameters of invaginations (c) and extrusions (d); distances between centres of two adjoined invaginations (e) and two adjoined extrusions (f) (histograms and average value).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0103741-g003: Dimensional specifications of morphological features on the surface of cells (invagination and extrusion) were assessed on the basis of AFM profile data carried out through two adjoined invaginations or extrusion.Distance was defined as a spacing between points located: in center of two adjoined invaginations (a) or on the top of two adjoined extrusions (b). Diameter of invaginations and extrusions is defined as a distance between two points that are located on two crossing lines (solid line and dotted line). Precise morphometry of C. violaceum ATCC 31532 cells surfaces (in biofilm conditions), revealed: diameters of invaginations (c) and extrusions (d); distances between centres of two adjoined invaginations (e) and two adjoined extrusions (f) (histograms and average value).
Mentions: The 24-h individual C. violaceum cells had a characteristic elongated shape, and based on AFM, the cells were 2.45±0.31 µm length, 0.85±0.09 µm wide and 0.34±0.07 µm high and without distinctions between planktonic and biofilm-forming bacteria. However, the surface topography of these cells was significantly different, and unusual invaginations (about 30–40 per cell taking into consideration 50% cell surface visibility) of the external membrane in biofilm-forming bacteria were observed (fig. 2 a). Based on AFM profiles, the invaginations had a 171±43 nm diameter (Fig. 3 c).and a 31.1±7.5 nm depth, whereas the distance from their centres were nearly 288±80 nm (Fig. 3 e).

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