Taweesak Malimas

Heterogeneity of Strains Assigned to Gluconobacter frateurii Mason and Claus 1989 Based on Restriction Analysis of 16S-23S rDNA Internal Transcribed Spacer Regions

Twenty-three strains, which were assigned to Gluconobacter frateurii and maintained at Culture Collection NBRC, were re-identified at the species level on the basis of restriction analysis of 16S-23S rDNA ITS regions by digestion with six restriction endonucleases: Bsp1286I, MboII, AvaII, TaqI, BsoBI, and BstNI. The strains examined were divided into six groups, Group III-1, Group III-2, Group III-3, Group III-4, Group III-5, and Group IV. Group III-1 and Group III-4 respectively were divided into two subgroups, Subgroup III-1a, Subgroup III-1b and Subgroup III-4a, Subgroup III-4b. Gluconobacter frateurii NBRC 3264T was included in Group III-2, along with strains NBRC 3265 and NBRC 3270, and G. thailandicus BCC 14116T was included in Group III-3, along with strains NBRC 3254, NBRC 3256, NBRC 3258, NBRC 3255, and NBRC 3257. These groupings were supported by a phylogenetic tree based on 16S-23S rDNA ITS sequences. Strains of group III-2 and Group IV were unequivocally re-identified as G. frateurii, but strains of Group III-3, Group III-4, and Group III-5 were not necessarily re-identified as G. frateurii. The results obtained indicate that the 23 strains have a taxonomically heterogeneous nature, and they are referred to as the G. frateurii complex.

Identification ofGluconobacter strains isolated in Thailand based on 16S–23S rRNA gene ITS restriction and 16S rRNA gene sequence analyses

Ninety-seven acetic acid bacteria, which were isolated from fruits, flowers and other material collected in Thailand by an enrichment culture approach, were assigned to the genusAcetobacter by phenotypic and chemotaxonomic characterisations. On the basis of 16S–23S rRNA gene ITS restriction and 16S rRNA gene sequence analyses, the ninety-seven isolates were grouped into three groups and identified at the specific level: 1) group A including fifty-three isolates, which were identified asAcetobacter pasteurianus, 2) group B including forty-two isolates, which were identified asAcetobacter orientalis and 3) group C including two isolates, which were identified asAcetobacter lovaniensis. There was no isolate to be assigned to other 15 species of the genusAcetobacter.