Lichen-like colonies of pure Trentepohlia on limestone monuments |
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Authors: | Peter Gaylarde Gelsa Englert Otto Ortega-Morales Christine Gaylarde |
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Affiliation: | aPraca Julio Bozzano, Porto Alegre—RS, 90040-240 Brazil;bLaboratory of Mineral Processing, UFRGS, Porto Alegre—RS, Brazil;cDep. de Microbiología Ambiental y Biotecnología, Universidad Autónoma de Campeche, Av. Agustín Melgar, Col. Lindavista, C.P.24030, Campeche, Camp., México;dDepartment of Biophysics, Federal University of Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre—RS, 91500-970, Brazil |
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Abstract: | Biofilms were collected on discoloured limestone samples and on adhesive tape from historic buildings at the Mayan site of Edzna, in Campeche, Mexico. Grey, brown, and black areas were colonised predominantly by coccoid and colonial cyanobacteria, also detected as endoliths. The major biomass on the pink stone surface was Trentepohlia. At low power, surface micropits containing crustose-lichen-like black colonies were seen within these pink areas. These were apparently pure colonies of T. umbrina; no filamentous fungi were detected here. The black colour was produced by dense, amorphous pigment deposits in the colony centres. Insolation levels were high (400 μmphotons m−2 s−1) and the moisture content of the stone was 0.7%. The high carotenoid:chlorophyll-α ratio of Trentepohlia biofilms (3.9:1) is an adaptation protecting against environmental stress. Trentepohlia caused severe local erosion (pitting) and, when present as a more uniform biofilm, the well-known pink surface discoloration. |
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Keywords: | Cyanobacteria Algae Trentepohlia Limestone Historic monuments |
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