Niabella hirudinis and Niabella drilacis sp. nov., isolated from the medicinal leech Hirudo verbana

Abstract

Two Gram-negative, rod-shaped bacteria, strains E96(T) and E90(T), were isolated from medicinal leeches (Hirudo verbana) and characterized by a polyphasic taxonomic approach. Phylogenetic analysis based on the nearly full-length 16S rRNA gene sequence showed that the two strains shared 98.1% sequence similarity and were affiliated with the genus Niabella within the phylum Bacteroidetes, with 94.4-97.6% sequence similarity to type strains of species of the genus Niabella and highest sequence similarity to the type strain of Niabella aurantiaca (97.3 and 97.6%, respectively). Niabella-related 16S rRNA gene sequences were recently detected in the bladders of Hirudo verbana; however, no cultured representatives were so far available. Genomic fingerprint analysis using repetitive element primed (rep)- and randomly amplified polymorphic DNA (RAPD)-PCRs and DNA-DNA hybridization experiments clearly showed that the strains were different from each other (DNA-DNA relatedness values of 39.1%, reciprocal 28.0%) and from the type strains of N. aurantiaca (<19.7%) and Niabella tibetensis (<41.1%). Chemotaxonomic analyses confirmed the affiliation to the genus Niabella. Both strains contained MK-7 as the predominant menaquinone. The major fatty acids of both strains were iso-C15:0, iso-C15:1 G, iso-C17:0 3-OH and summed feature 3 (C16:1ω7c and/or iso-C15:0 2-OH), which is characteristic for the genus Niabella. Based on genotypic, chemotaxonomic and physiological characterization, we propose two novel species of the genus Niabella, Niabella hirudinis sp. nov., with strain E96(T) ( =DSM 25812(T) =CCM 8411(T) =LMG 26956(T)) as the type strain, and Niabella drilacis sp. nov., with strain E90(T) ( =DSM 25811(T) =CCM 8410(T) =LMG 26954(T)) as the type strain.