Summary auto-generated
Researchers isolated a novel thermoacidophilic bacterium, designated strain CP-1T, from dried hibiscus flowers used in herbal tea. This Gram-positive, spore-forming bacterium grows optimally at 55-60°C and pH 4.5-5.0, functioning as a strict aerobe. Phylogenetic analysis of 16S rRNA gene sequences revealed it was distinct from previously characterized Alicyclobacillus and Sulfobacillus species. A distinguishing feature was the presence of ω-cycloheptane fatty acids as major membrane lipids, a characteristic previously found only in Alicyclobacillus cycloheptanicus. However, strain CP-1T displayed phenotypic and chemotaxonomic characteristics differing from A. cycloheptanicus. DNA-DNA hybridization showed only 10-16% relatedness to established Alicyclobacillus species and Sulfobacillus disulfidooxidans, well below the 70% threshold for species recognition. The bacterium metabolizes various carbohydrates heterotrophically without requiring growth factors. Based on comprehensive molecular and biochemical evidence, the authors propose this organism as a new species, Alicyclobacillus herbarius, with type strain CP-1T.
Key findings
- Alicyclobacillus herbarius is a novel thermoacidophilic bacterium isolated from herbal tea, growing optimally at 55-60°C and pH 4.5-5.0
- The species contains ω-cycloheptane fatty acids as major membrane lipids, a feature previously observed only in A. cycloheptanicus but with distinct phenotypic differences
- 16S rRNA phylogenetic analysis and DNA-DNA hybridization (10-16% relatedness) confirm this represents a distinct species separate from other Alicyclobacillus species
- The bacterium is a heterotrophic, strictly aerobic, motile rod that produces acid from multiple carbohydrates and has a GC content of 56.2 mol%
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Abstract
A thermo-acidophilic Gram-positive bacterium, strain CP-1(T), which grows aerobically at 35--65 degrees C (optimum 55--60 degrees C) and at pH 3.5--6.0 (optimum pH 4.5--5.0), was isolated from a herbal tea made from the dried flowers of hibiscus. Phylogenetic analysis of the 16S rRNA gene sequences showed that this bacterium was clearly distinguishable from previously described species of the genera Alicyclobacillus and Sulfobacillus. Strain CP-1(T) had unique omega-cycloheptane fatty acids as the major membrane lipid component, a characteristic which is peculiar to Alicyclobacillus cycloheptanicus. However, phenotypic and chemotaxonomic characteristics of strain CP-1(T) were different from those of the type strain of A. cycloheptanicus. DNA--DNA hybridization between the type strains of Alicyclobacillus species and Sulfobacillus disulfidooxidans was < 20%, indicating that strain CP-1(T) represents a distinct species. On the basis of these results, the name Alicyclobacillus herbarius is proposed for this organism. The type strain is strain CP-1(T) (=DSM 13609(T)=IAM 14883(T)=NRIC 0477(T)).