Algae and cyanobacteria on painted buildings in Latin America

The algal and cyanobacterial types present on discoloured surfaces of painted buildings in ve Latin American countries, Argentina, Bolivia, Brazil, Mexico and Peru, were examined. The bio lms were found to contain algae, cyanobacteria, protozoa, fungi, slime moulds, actinomycetes and other bacterial groups. A total of 1363 di erent morphotypes were detected at 88 sites. Of these, 63.4% were non- lamentous genera and 61.9% of the total phototrophs were cyanobacteria. Synechocystis-like forms were the most biodiverse, often comprised the major biomass and were present in 64.8% of sites. Oscillatoriales were the next most diverse group. The algal genus, Chlorella, showed the most widespread occurrence (68.2% of sites). A signi cantly lower percentage of the population (55.8%) was composed of cyanobacteria in residential as compared with urban and rural locations, probably because of better building maintenance in the former. The implications of the results for standard algicide testing are discussed