Summary auto-generated
Researchers isolated two novel bacterial strains from industrial vinegar fermentations in Germany and characterized them using molecular and physiological methods. Strain LTH 2460T, isolated from red wine vinegar fermentation, and strain LTH 2458T, from cider vinegar fermentation, were studied through 16S rRNA gene sequencing, DNA-DNA hybridization, and physiological testing. Although 16S rRNA sequences showed approximately 99% similarity to existing Acetobacter species (LTH 2460T to A. europaeus and A. xylinus; LTH 2458T to A. pasteurianus), DNA-DNA hybridization revealed very low relatedness (below 34%), indicating they represent distinct species. Both strains possessed unique physiological characteristics, including the ability to grow in 30% glucose and tolerate high acetic acid concentrations. LTH 2460T accumulated substantial gluconic acid, while LTH 2458T could utilize methanol. Based on these findings, the authors propose two new species names: Acetobacter oboediens (LTH 2460T) and Acetobacter pomorum (LTH 2458T). The two species were differentiated from each other and related taxa by distinct ubiquinone compositions, DNA G+C contents, and carbon source utilization patterns. A species-specific oligonucleotide probe was also developed for A. oboediens identification.
Key findings
- Two novel Acetobacter species isolated from vinegar fermentations designated Acetobacter oboediens and Acetobacter pomorum, despite showing high 16S rRNA sequence similarity (≥99%) to related species
- DNA-DNA hybridization demonstrated these isolates have <34% relatedness to closely related species, confirming they are genetically distinct at the species level
- Both new species exhibit exceptional physiological traits including growth in 30% glucose and high acetic acid tolerance; A. oboediens accumulates 13% gluconic acid while A. pomorum can utilize methanol
- Distinct ubiquinone profiles and different DNA G+C contents (59.9 mol% vs. 50.5 mol%) further differentiate the two species from each other and existing Acetobacter taxa
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Abstract
Two strains of Acetobacter sp., LTH 2460Tand LTH 2458T, have been isolated from running red wine and cider vinegar fermentations, respectively. Taxonomic characteristics of the isolates were investigated. Comparative analysis of the 16S rRNA sequences revealed > 99% similarity between strain LTH 2460Tand the type strains of the related species Acetobacter europaeus and Acetobacter xylinus and between strain LTH 2458Tand Acetobacter pasteurianus. On the other hand, low levels of DNA relatedness (< 34%) were determined in DNA-DNA similarity studies. This relatedness below the species level was consistent with specific physiological characteristics permitting clear identification of these strains within established species of acetic acid bacteria. Based on these results, the names Acetobacter oboediens sp. nov. and Acetobacter pomorum sp. nov. are proposed for strains LTH 2460Tand LTH 2458T, respectively. The phylogenetic positions of the new species are reflected by a 16S rRNA-based tree. Furthermore, a 16S rRNA-targeted oligonucleotide probe specific for A. oboediens was constructed.