Stenotrophomonas tumulicola sp. nov., a major contaminant of the stone chamber interior in the Takamatsuzuka Tumulus

During investigation of the biological contamination of the 1300-year-old mural paintings and plaster walls inside the stone chambers of the Takamatsuzuka and Kitora Tumuli (TT and KT) in Asuka-mura, Nara Prefecture, Japan, the identity of 17 bacterial isolates from blackish mouldy spots and viscous gels (biofilms) collected from both tumuli (16 isolates from TT and one from KT) during our 2005-2007 microbiological survey was systematically elucidated. One cluster of the major bacterial isolates was assigned to the genus Stenotrophomonas (class Gammaproteobacteria ) by phylogenetic analysis of the 16S rRNA gene sequences. These isolates were divided into two groups A and B. Group A comprised 15 TT isolates that took a phylogenetic position near Stenotrophomonas chelatiphaga LPM-5 T . Based on our analysis of the phenotypic (cultural, morphological, physiological and chemotaxonomic) characteristics and genotypic/molecular characteristics (DNA base composition, DNA-DNA relatedness, and 16S rRNA and gyrB gene sequences), the novel species name Stenotrophomonas tumulicola sp. nov. is proposed for the group A isolates with the type strain T5916-2-1b T ( = JCM 30961 T  = NCIMB 15009 T ). Group B, which contained only one TT and one KT isolate, was closely related to [ Pseudomonas ] geniculata , [ P .] hibiscicola , [ P .] beteli , Stenotrophomonas maltophilia and Stenotrophomonas pavanii . The two isolates were genotypically and phenotypically assignable to S. maltophilia .