Occurrence of Aspergillus allahabadii on sandstone at Bayon temple, Angkor Thom, Cambodia

Microbial biofilms on surface of sandstone is detrimental to the integrity of the substratum material and they are biodeteriogens responsible for the damage of sandstone over time. We observed that fungi formed extensive biofilms on areas previously colonized by autotrophic and heterotrophic microbial biofilms causing darkening of the stone surface. Appearance of fungi on these biofilms has resulted in removal of the preformed biofilm through extensive examination of sandstone surfaces in Angkor Thom, Cambodia. One fungus, isolated from the surface with capability of removing biofilms, was purified and identified as Aspergillus allahabadii during our survey and sampling of microbial biofilms at Bayon temple, Angkor Thom, Cambodia in 2008. Ribosomal RNA (ITS and 5.8S) and beta-tubulin gene sequences were phylogenetically analyzed to confirm the taxonomy of this strain. In addition, its protein profile and enzyme assays were also carried out and beta-galactosidase was the highest among 7 enzymes tested. Our results suggest that fungi may have an important role in removing microbial biofilms on surfaces of stone and potential mechanisms and applications are discussed. (C) 2012 Elsevier Ltd. All rights reserved.