The use of fatty acid methyl ester analysis (FAME) for the identification of heterotrophic bacteria present on three mural paintings showing severe damage by microorganisms.

Mural paintings in Carmona (Spain), Herberstein (Austria) and Greene (Germany), showing visible deterioration by microorganisms, were sampled to investigate the biodiversity of the heterotrophic bacteria present. Four hundred twenty-eight bacterial strains were isolated from which 385 were characterized by fatty acid methyl ester analysis (FAME). The isolates were grouped into 41 clusters on the basis of their FAME profiles, 20 isolates remained ungrouped. The majority (94%) of the isolates comprised the gram-positive bacteria and the main clusters were identified as Bacillus sp., Paenibacillus sp., Micrococcus sp., Arthrobacter sp. and Staphylococcus sp. Other clusters contain nocardioform actinomycetes and gram-negative bacteria, respectively. A cluster of the latter contained extreme halotolerant bacteria isolated in Herberstein. The FAME profiles of this cluster showed a high similarity with Halomonas.