Stenotrophomonas bentonitica sp. nov., isolated from bentonite formations

A Gram-stain negative, rod-shaped, aerobic bacterial strain, BII-R7(T), was isolated during a study targeting the culture-dependent microbial diversity occurring in bentonite formations from southern Spain. Comparative 16S rRNA gene sequence analysis showed that BII-R7(T) represented a member of the genus Stenotrophomonas (class Gammaproteobacteria), and was related most closely to Stenotrophomonas rhizophila e-p10(T) (99.2 % sequence similarity), followed by Stenotrophomonas pavanii ICB 89(T) (98.5 %), Stenotrophomonas maltophilia IAM 12423(T), Stenotrophomonas chelatiphaga LPM-5(T) and Stenotrophomonas tumulicola T5916-2-1b(T) (all 98.3 %). Pairwise sequence similarities to all other type strains of species of the genus Stenotrophomonas were below 98 %. Genome-based calculations (orthologous average nucleotide identity, original average nucleotide identity, genome-to-genome distance and DNA G+C percentage) indicated clearly that the isolate represents a novel species within this genus. Different phenotypic analyses, such as the detection of a quinone system composed of the major compound ubiquinone Q-8 and a fatty acid profile with iso-C(15 : 0) and anteiso-C(15 : 0) as major components, supported this finding at the same time as contributing to a comprehensive characterization of BII-R7(T). Based on this polyphasic approach comprising phenotypic and genotypic/molecular characterization, BII-R7(T) can be differentiated clearly from its phylogenetic neighbours, establishing a novel species for which the name Stenotrophomonas bentonitica sp. nov. is proposed with BII-R7(T) as the type strain (=LMG 29893(T)=CECT 9180(T)=DSM 103927(T)).