Open AccessTwo‐dimensional mapping of photopigment distribution and activity of Chloroflexus ‐like bacteria in a hypersaline microbial mat
Author(s) -
Bachar Ami,
Polerecky Lubos,
Fischer Jan P.,
Vamvakopoulos Kyriakos,
De Beer Dirk,
Jonkers Henk M.
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00534.x
Subject(s) - biology , photopigment , bacteria , ecology , microbiology and biotechnology , botany , genetics , retinal
Pigment analysis in an intact hypersaline microbial mat by hyperspectral imaging revealed very patchy and spatially uncorrelated distributions of photopigments Chl a and BChl a / c , which are characteristic photopigments for oxygenic (diatoms and cyanobacteria) and anoxygenic phototrophs ( Chloroflexaceae ). This finding is in contrast to the expectation that these biomarker pigments should be spatially correlated, as oxygenic phototrophs are thought to supply the Chloroflexaceae members with organic substrates for growth. We suggest that the heterogeneous occurrence is possibly due to sulfide, whose production by sulfate‐reducing bacteria may be spatially heterogeneous in the partially oxic photic zone of the mat. We furthermore mapped the near‐infra‐red‐light controlled respiration of Chloroflexaceae under light and dark conditions and found that Chloroflexaceae are responsible for a major part of oxygen consumption at the lower part of the oxic zone in the mat. The presence of Chloroflexaceae was further confirmed by FISH probe and 16S rRNA gene clone library analysis. We assume that species related to the genera Oscillochloris and ‘ Candidatus Chlorothrix’, in contrast to those related to Chloroflexus and Roseiflexus , depend less on excreted photosynthates but more on the presence of free sulfide, which may explain their presence in deeper parts of the mat.