From two samples of microbial biofilms, damaging the mural paintings at the Saint-Catherine chapel of Castle Herberstein (Austria), four and nine coryneform bacteria were isolated, respectively. A polyphasic taxonomic study of these isolates, including morphological, biochemical and chemotaxonomic characterization, REP-PCR fingerprinting, 16S rDNA sequence analysis, DNA base ratio and DNA-DNA hybridizations, allocated them to the genus Brachybacterium. The isolates of the two samples both represent new species, for which the names Brachybacterium fresconis sp. nov. and Brachybacterium sacelli sp. nov. are proposed. The respective type strains are LMG 20336T (= DSM 14564T) and LMG 20345T (= DSM 14566T).