Phototrophic microbes form endolithic biofilms in ikaite tufa columns (SW Greenland)

Trampe, E; Castenholz, RW; Larsen, JEN; Kühl, M

Phototrophic microbes form endolithic biofilms in ikaite tufa columns (SW Greenland)

Trampe, E Castenholz, RW Larsen, JEN Kühl, M

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Publication Type:: Journal Article
Citation:: Environmental Microbiology, 2017, 19 (11), pp. 4754 - 4770
Issue Date:: 2017-11-01

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Field	Value	Language
dc.contributor.author	Trampe, E	en_US
dc.contributor.author	Castenholz, RW	en_US
dc.contributor.author	Larsen, JEN	en_US
dc.contributor.author	Kühl, M https://orcid.org/0000-0002-1792-4790	en_US
dc.date.available	2017-09-20	en_US
dc.date.issued	2017-11-01	en_US
dc.identifier.citation	Environmental Microbiology, 2017, 19 (11), pp. 4754 - 4770	en_US
dc.identifier.issn	1462-2912	en_US
dc.identifier.uri	http://hdl.handle.net/10453/125014
dc.description.abstract	© 2017 Society for Applied Microbiology and John Wiley & Sons Ltd Marine tufa-columns, formed by the hydrated carbonate mineral ikaite, present a unique alkaline microbial habitat only found in Ikka Fjord (SW-Greenland). The outermost parts of the ikaite columns exhibit a multitude of physico-chemical gradients, and the porous ikaite is colonized by endolithic phototrophic biofilms serving as a substrate for grazing epifauna, where scraping by sea urchins affects overall column-topography. We present a detailed study of the optical microenvironment, spatial organization, and photosynthetic activity of endolithic phototrophs within the porous ikaite crystal matrix. Cyanobacteria and diatoms formed distinctly coloured zones and were closely associated with ikaite-crystals via excretion of exopolymers. Scalar-irradiance measurements showed strong attenuation of visible light (400–700 nm), where only ∼1% of incident irradiance remained at 20 mm depth. Transmission spectra showed in vivo absorption signatures of diatom and cyanobacterial photopigments, which were confirmed by HPLC-analysis. Variable-chlorophyll-fluorescence-imaging showed active photosynthesis with high-light acclimation in the outer diatom layer, and low-light acclimation in the underlying cyanobacterial part. Phototrophs in ikaite thus thrive in polymer-bound endolithic biofilms in a complex gradient microhabitat experiencing constant slow percolation of highly alkaline phosphate-enriched spring water mixing with cold seawater at the tufa-column-apex. We discuss the potential role of these biofilms in ikaite column formation.	en_US
dc.relation.ispartof	Environmental Microbiology	en_US
dc.relation.isbasedon	10.1111/1462-2920.13940	en_US
dc.subject.classification	Microbiology	en_US
dc.subject.mesh	Diatoms	en_US
dc.subject.mesh	Biofilms	en_US
dc.subject.mesh	Cyanobacteria	en_US
dc.subject.mesh	Calcium Carbonate	en_US
dc.subject.mesh	RNA, Ribosomal, 16S	en_US
dc.subject.mesh	Ecosystem	en_US
dc.subject.mesh	Seawater	en_US
dc.subject.mesh	Photosynthesis	en_US
dc.subject.mesh	Greenland	en_US
dc.subject.mesh	Estuaries	en_US
dc.title	Phototrophic microbes form endolithic biofilms in ikaite tufa columns (SW Greenland)	en_US
dc.type	Journal Article
utslib.citation.volume	11	en_US
utslib.citation.volume	19	en_US
utslib.for	0605 Microbiology	en_US
utslib.for	0603 Evolutionary Biology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	closed_access
pubs.issue	11	en_US
pubs.publication-status	Published	en_US
pubs.volume	19	en_US

Abstract:

© 2017 Society for Applied Microbiology and John Wiley & Sons Ltd Marine tufa-columns, formed by the hydrated carbonate mineral ikaite, present a unique alkaline microbial habitat only found in Ikka Fjord (SW-Greenland). The outermost parts of the ikaite columns exhibit a multitude of physico-chemical gradients, and the porous ikaite is colonized by endolithic phototrophic biofilms serving as a substrate for grazing epifauna, where scraping by sea urchins affects overall column-topography. We present a detailed study of the optical microenvironment, spatial organization, and photosynthetic activity of endolithic phototrophs within the porous ikaite crystal matrix. Cyanobacteria and diatoms formed distinctly coloured zones and were closely associated with ikaite-crystals via excretion of exopolymers. Scalar-irradiance measurements showed strong attenuation of visible light (400–700 nm), where only ∼1% of incident irradiance remained at 20 mm depth. Transmission spectra showed in vivo absorption signatures of diatom and cyanobacterial photopigments, which were confirmed by HPLC-analysis. Variable-chlorophyll-fluorescence-imaging showed active photosynthesis with high-light acclimation in the outer diatom layer, and low-light acclimation in the underlying cyanobacterial part. Phototrophs in ikaite thus thrive in polymer-bound endolithic biofilms in a complex gradient microhabitat experiencing constant slow percolation of highly alkaline phosphate-enriched spring water mixing with cold seawater at the tufa-column-apex. We discuss the potential role of these biofilms in ikaite column formation.

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http://hdl.handle.net/10453/125014