Comparative analyses of the bacterial diversity on two different biodeteriorated wall paintings by DGGE and 16S rDNA sequence analysis

The bacterial diversity associated with two different biodeteriorated wall paintings in Herberstein (Austria) and Greene (Germany) was investigated an d compared using a molecular approach combining fingerprinting by DGGE (den aturing gradient gel electrophoresis) with the screening of 16S rDNA clone libraries by DGGE and sequencing. In total, 70 16S rDNA sequences were obta ined. Twenty-three sequences were phylogenetically affiliated with genera o f the Actinobacteria, namely Arthrobacter, Actinobispora, Amycolata, Asiosp orangium, Frankia, Geodermatophilus, Nocardioides, Promicromonsopora, Pseud onocardia, Rubrobacter, Streptomonospora, Saccharopolyspora, Sphaerobacter and Thermocrismum. Twenty-seven sequences were affiliated with genera of th e Proteobacteria, namely Aquaspirillum, Chromohalobacter, Deleya, Erythroba cter, Halomonas, Porphyrobacter, Pseudomonas, Rhizobium, Salmonella and uni dentified gamma -Proteobacteria. Nineteen sequences were affiliated with un identified Cytophagales. One sequence was affiliated with the Chloroflexace ae group. Most genera were present in more than one sample. The bacterial c ommunities present on the two different wall paintings showed only similari ties in members of unidentified Cytophagales and of the genera Frankia, Geo dermatophilus and Arthrobacter. Cultivation experiments for one sample were carried out in parallel to the molecular approach. Isolates were clustered by FAME (fatty acid methyl ester analysis) and representative members of e ach cluster were additionally analyzed by DGGE. No similar organisms could be detected by the cultivation approach and the molecular approach. Isolate s were phylogenetically affiliated to the genera Bacillus, Paenibacillus, M icrococcus, Staphylococcus, Methylobacterium and Halomonas. The sequence of the isolated Halomonas differed from the Halomonas sequences, which were o btained by the molecular approach. The combined approach of molecular and c ulturing techniques gives a truer picture of all bacterial organisms on/in a surface than either alone. (C) 2000 Elsevier Science Ltd. All rights rese rved.