The genus Gibbsiella, which was isolated from oak trees displaying extensive stem bleeding, was recently reported by Brady et al. (1). The genus Gibbsiella consists of only one species named Gibbsiella quercinecans (NCPPB 4470T).
The genus Gibbsiella, which is a Gram negative, rod-shaped, non-spore forming and non-motile bacterium, has been closely related to genera Serratia, buy BIBW2992 Kluyvera, Klebsiella, and Raoultella (> 97%) by 16S rRNA sequence analysis. However, the genus Gibbsiella forms a distinct lineage within the family Enterobacteriaceae, this having been confirmed by both gyrB and rpoB gene sequencing. Streptococcus mutans is known as a primary pathogen of dental caries in humans (2). One of its virulence properties is the
ability to produce exopolysaccharides from sucrose (3, 4). The oral cavities of many animals are colonized by a large number of bacteria, including DAPT exopolysaccharide-synthesizing strains such as S. mutans. In this study, the microflora of the bear (Ursus thibetanus) oral cavity was investigated, focusing on exopolysaccharide-synthesizing strains. The exopolysaccharide-synthesizing strains selected for this study were Gram negative isolates from the oral cavities of bears. The strains formed large, raised, sticky colonies with irregular margins on mitis salivarius agar (Difco Laboratories, Detroit, MI, USA). During this research, a non-pigmented, non-motile, non-spore-forming Gibbsiella like strain, designated NUM 1720T, was isolated from the oral cavity of bears. The strain
was grown at 37°C under aerobic Plasmin conditions on brain-heart infusion agar (Difco Laboratories). The isolates were subjected to further taxonomic study. DNA was extracted from the bacterial cultures by using the Promega Genome kit (Promega, Madison WI, USA) according to the manufacturer’s instructions. To determine the phylogenetic affinity of the isolate, the almost-complete 16S rRNA gene was sequenced and subjected to a comparative analysis. The 16S rRNA gene was amplified using a PCR with primers 27f (5′-AGAGTTTGATCCTGGCTCAG-3′; E. coli positions 8–27) and 1525r (5′-AAAGGAGGTGATCCAGCC-3′; E. coli positions 1543–1525) according to the method described by Shinoda et al. (5). The PCR products were directly sequenced using a BigDye Terminator v1.1 cycle sequencing kit (Applied Biosystems, Stockholm, Sweden) and automatic DNA sequencer (3130 genetic analyzer; Applied Biosystems). The closest known relatives of the novel isolates were identified by performing database searches. Identification of the closest phylogenetic neighbors and calculation of pairwise 16S rRNA gene sequence similarities were achieved using the EzTaxon server (http://www.eztaxon.org/) (6). The topologies of the trees were evaluated by performing a bootstrap analysis of the sequence data, using CLUSTAL W software (7). Sequence similarity values were calculated manually.