Isolation and characterization of Fibrella aquatica sp. nov. from freshwater, Fibrella musci sp. nov. from moss on soil and Fibrella arboris sp. nov. from moss on a tree

Three Gram-negative, facultatively anaerobic, rod-shaped, non-motile and reddish-pigmented bacterial strains, designated GW2-5^T, WM1^T and Tmos10^T, were isolated from distinct environments in the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the three strains belonged to the genus <i>Fibrella</i>. The type strain GW2-5ᵀ grew at temperatures of 10-35 °C (optimum: 25 °C), pH levels of 6.0-12.0 (optimum: pH 7.0) and NaCl concentrations of 0-0.5% (optimum: 0%). Strain WM1ᵀ grew at temperatures of 10-37 °C (optimum: 30 °C), pH levels of 5.0-12.0 (optimum: pH 7.0) and NaCl concentrations of 0-1% (optimum: 0%). Strain Tmos10ᵀ grew at temperatures of 10-35 °C (optimum: 25 °C), pH levels of 5.0-12.0 (optimum: pH 7.0) and NaCl concentrations of 0-0.5% (optimum: 0%). The three strains exhibited the highest 16S rRNA gene sequence similarity to <i>Fibrella forsythiae</i> HMF5405ᵀ (98.7%) for strain GW2-5ᵀ, <i>Fibrella aestuarina</i> BUZ 2ᵀ (98.7%) for strain WM1ᵀ and <i>Fibrella forsythiae</i> HMF5405ᵀ (96.6%) for strain Tmos10ᵀ. The average nucleotide identity values ranged from 73.5% to 86.6%, while the digital DNA-DNA hybridization values ranged from 19.5% to 31.4% between the three novel isolates and species belonging to the genus <i>Fibrella</i>. Based on phenotypic, physiological, biochemical, genomic and phylogenetic characteristics, strains GW2-5^T, WM1^T and Tmos10^T are proposed as novel species within the genus <i>Fibrella</i>. They are designated as <i>Fibrella aquatica</i> sp. nov. (type strain GW2-5^T=KACC 23817^T=TBRC 19128^T), <i>Fibrella musci</i> sp. nov. (type strain WM1^T=KACC 23815^T=TBRC 19127^T) and <i>Fibrella arboris</i> sp. nov. (type strain Tmos10^T=KACC 23816^T=TBRC 19129^T), respectively.