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Capsules of the diatom Achnanthidium minutissimum arise from fibrillar precursors and foster attachment of bacteria.

Leinweber K, Kroth PG - PeerJ (2015)

Bottom Line: We coupled scanning electron microscopy (SEM) to bright-field microscopy (BFM) and found that A. minutissimum capsules mostly possess an unstructured surface.Fibrils were also found on the frustules of non-encapsulated cells, implicating that A. minutissimum capsules may develop from fibrillar precursors.Energy-dispersive X-ray (EDX) spectroscopy revealed that the capsule material do not contain silicon, distinguishing it from the frustule material.

View Article: PubMed Central - HTML - PubMed

Affiliation: Konstanz Research School Chemical Biology , Germany ; Zukunftskolleg at the University of Konstanz , Germany ; Biology Department, University of Konstanz , Germany.

ABSTRACT
Achnanthidium minutissimum is a benthic freshwater diatom that forms biofilms on submerged surfaces in aquatic environments. Within these biofilms, A. minutissimum cells produce extracellular structures which facilitate substrate adhesion, such as stalks and capsules. Both consist of extracellular polymeric substance (EPS), but the microstructure and development stages of the capsules are so far unknown, despite a number of hypotheses about their function, including attachment and protection. We coupled scanning electron microscopy (SEM) to bright-field microscopy (BFM) and found that A. minutissimum capsules mostly possess an unstructured surface. However, capsule material that was mechanically stressed by being stretched between or around cells displayed fibrillar substructures. Fibrils were also found on the frustules of non-encapsulated cells, implicating that A. minutissimum capsules may develop from fibrillar precursors. Energy-dispersive X-ray (EDX) spectroscopy revealed that the capsule material do not contain silicon, distinguishing it from the frustule material. We furthermore show that bacteria preferentially attach to capsules, instead of non-encapsulated A. minutissimum cells, which supports the idea that capsules mediate diatom-bacteria interactions.

No MeSH data available.


Related in: MedlinePlus

Distribution of the number of bacteria cells adherent to diatom valve faces of different surface types (frustule or capsule) in xenic A. minutissimum biofilms.Bacteria were counted in SEM images, if they were in direct, visible contact with the valve face of either a frustule (N = 54) or a completely encapsulated diatom cell (N = 71; see Figs. 2B and 3A for illustration). Samples were taken from 11 to 31 days old cultures. Boxes represent 1st and 3rd quartile. Black center lines represent medians. Diamond symbols represent means. Whiskers extend to 1.5-fold of the inter-quartile range (IQR). Black dots represent extreme values that lie outside the IQR.
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fig-7: Distribution of the number of bacteria cells adherent to diatom valve faces of different surface types (frustule or capsule) in xenic A. minutissimum biofilms.Bacteria were counted in SEM images, if they were in direct, visible contact with the valve face of either a frustule (N = 54) or a completely encapsulated diatom cell (N = 71; see Figs. 2B and 3A for illustration). Samples were taken from 11 to 31 days old cultures. Boxes represent 1st and 3rd quartile. Black center lines represent medians. Diamond symbols represent means. Whiskers extend to 1.5-fold of the inter-quartile range (IQR). Black dots represent extreme values that lie outside the IQR.

Mentions: It became apparent during the SEM observations, that diatom-attached bacteria cells occurred more often on capsules than on frustules. To substantiate this observation, bacteria cells were counted on both diatom cell surface types (Fig. 7).


Capsules of the diatom Achnanthidium minutissimum arise from fibrillar precursors and foster attachment of bacteria.

Leinweber K, Kroth PG - PeerJ (2015)

Distribution of the number of bacteria cells adherent to diatom valve faces of different surface types (frustule or capsule) in xenic A. minutissimum biofilms.Bacteria were counted in SEM images, if they were in direct, visible contact with the valve face of either a frustule (N = 54) or a completely encapsulated diatom cell (N = 71; see Figs. 2B and 3A for illustration). Samples were taken from 11 to 31 days old cultures. Boxes represent 1st and 3rd quartile. Black center lines represent medians. Diamond symbols represent means. Whiskers extend to 1.5-fold of the inter-quartile range (IQR). Black dots represent extreme values that lie outside the IQR.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380156&req=5

fig-7: Distribution of the number of bacteria cells adherent to diatom valve faces of different surface types (frustule or capsule) in xenic A. minutissimum biofilms.Bacteria were counted in SEM images, if they were in direct, visible contact with the valve face of either a frustule (N = 54) or a completely encapsulated diatom cell (N = 71; see Figs. 2B and 3A for illustration). Samples were taken from 11 to 31 days old cultures. Boxes represent 1st and 3rd quartile. Black center lines represent medians. Diamond symbols represent means. Whiskers extend to 1.5-fold of the inter-quartile range (IQR). Black dots represent extreme values that lie outside the IQR.
Mentions: It became apparent during the SEM observations, that diatom-attached bacteria cells occurred more often on capsules than on frustules. To substantiate this observation, bacteria cells were counted on both diatom cell surface types (Fig. 7).

Bottom Line: We coupled scanning electron microscopy (SEM) to bright-field microscopy (BFM) and found that A. minutissimum capsules mostly possess an unstructured surface.Fibrils were also found on the frustules of non-encapsulated cells, implicating that A. minutissimum capsules may develop from fibrillar precursors.Energy-dispersive X-ray (EDX) spectroscopy revealed that the capsule material do not contain silicon, distinguishing it from the frustule material.

View Article: PubMed Central - HTML - PubMed

Affiliation: Konstanz Research School Chemical Biology , Germany ; Zukunftskolleg at the University of Konstanz , Germany ; Biology Department, University of Konstanz , Germany.

ABSTRACT
Achnanthidium minutissimum is a benthic freshwater diatom that forms biofilms on submerged surfaces in aquatic environments. Within these biofilms, A. minutissimum cells produce extracellular structures which facilitate substrate adhesion, such as stalks and capsules. Both consist of extracellular polymeric substance (EPS), but the microstructure and development stages of the capsules are so far unknown, despite a number of hypotheses about their function, including attachment and protection. We coupled scanning electron microscopy (SEM) to bright-field microscopy (BFM) and found that A. minutissimum capsules mostly possess an unstructured surface. However, capsule material that was mechanically stressed by being stretched between or around cells displayed fibrillar substructures. Fibrils were also found on the frustules of non-encapsulated cells, implicating that A. minutissimum capsules may develop from fibrillar precursors. Energy-dispersive X-ray (EDX) spectroscopy revealed that the capsule material do not contain silicon, distinguishing it from the frustule material. We furthermore show that bacteria preferentially attach to capsules, instead of non-encapsulated A. minutissimum cells, which supports the idea that capsules mediate diatom-bacteria interactions.

No MeSH data available.


Related in: MedlinePlus