Resumo

GALINDO-ALCAZAR, O.; MEDINA-JARITZ, N.B.; GARDUNO-SOLORZANO, G.  e  OLVERA-RAMIREZ, R.. Cyanobacteria and microalgae from surface biofilm from Malinalco, Mexico, an archaeological site. Polibotánica [online]. 2018, n.45, pp.131-146. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.45.10.

Most constructions of the architectural heritage built on rock are at risk, not only for damage caused by the passage of time and exposure to different environmental conditions, but also by the alterations produced due to the colonization of microorganisms (heterotrophic bacteria, cyanobacteria, algae and fungi) on its surface, which induce in it a set of processes that lead to mechanical and chemical alteration, called biodeterioration. The objective of this work was to identify to which taxonomic entity belong the cultivable phototrophic microorganisms that were found in superficial biofilms on the monuments of the archaeological zone of Malinalco, State of Mexico, Mexico and cyanobacteria partial characterization. Biofilm sampling was done in four of the six monuments of that zone, where microbial growth was observed, a portion was taken with a spatula and placed in sterile containers, cultured in BG-11 solid medium and isolated by micromanipulation. Twenty-three isolates including cyanobacteria an microlagae through literature were identified and grouped into 18 genera, of which thirteen taxa are Cyanobacteria, seven are Chlorophytes and three belong to Charophytes. The best represented taxa for this archaeological zone are the filamentous cyanobacteria of the Order Oscillatoriales that were found in three of the four monuments.

In addition, phycobiliproteins were extracted and quantified from six strains of cyanobacteria that showed an intense brown color due to the presence of phycoerythrin. The strain with a high content of this pigment was Pseudanabaena sp. with 0.7 mg / mL, isolated from the monolithic temple. In seven strains of cyanobacteria the presence of exopolysaccharides (EPS) was demonstrated in some of its forms: capsule, sheath (o pod), dispersed mucilage or polysaccharides released into the medium, using the technique of toluidine blue and quantified the amount of EPS produced by these strains.

Palavras-chave : biodeterioration; archaeological monuments; cyanobacteria; biofilms; phycobiliproteins; exopolysaccharides.