Research On Isolation And Polyphasic Taxonomy Of A Phenol Tolerant Novel Species-Comamonas Zonglianii BF-3~T

Phenol is an aromatic compound which has been widely used in industry, such as medicine, pesticide, dye, oil refining. In recent years, it is found that phenol can cause significant environmental pollution and health problems, due to their toxicity and overall recalcitrance to degradation. Now, Phenol has been put into the list of preferentially controled pollutant as well as 65 kinds of poisonous pollutant in US Environmental Protection Agency. Meanwhile, it is also one of preferentially controled pollutant in our country.A bacterial strain, designated BF-3T was isolated from phenol-contaminated soil. It can endure 1000 mg·L-1 phenol. Based on morphological, biochemical tests and analysis of 16S rRNA gene sequence, BF-3T was identified as Comamonas species. But phylogenetic analysis based on 16S rRNA gene sequences showed that strain BF-3T formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genus Comamonas; it showed the highest sequence similarity to Comamonas aquatica LMG 2370T(96.8%). This low sequence similarity (less than 97%) indicated that strain BF-3Tcould be clearly differed from other Comamonas species. So BF-3T with other three closely related species (C. aquatica LMG 2370T,C. nitrativorans DSM 13191T and C. odontotermitis LMG 23579T) were investigated by polyphasic taxonomic approach in our study.Cells of strain BF-3T are aerobic, Gram-negative, non-sporulating, non-motile and short rod (0.6-0.8×0.9-1.5μm). Colonies on LB agar are circular, semi-transparent, pale yellow and convex after 2d incubation at 30℃. The optimum growth is observed at 25-37℃,0-1% NaC1 and pH 7-8. Strain BF-3T shows positive results for oxidase, catalase, arginine dihydrolase, urease, hydrolysis of gelatin, assimilation of Tween 40, Tween 80, gluconate, caprate, adipate and citrate reactions. Cells are resistant to ampicillin, gentamicin, rifampicin, penicillin G and streptomycin. The major fatty acids of BF-3T are 16:0, 18:1/18:1ω7c,17:0 cyclo and summed feature 3 (16:1ω7c and/or 15:0 iso 2-OH). The value of 17:0 cyclo is greater than other species of Comamonas. The DNA G+C content of strain BF-3T is 65.2±1 mol%. And strain BF-3T showed relatively low DNA-DNA relatedness to other three closely related species(25.4%-28.7%), these values well below the threshold of 70% recommended for the delineation of bacterial species.According to the phylogenetic analysis, DNA-DNA hybridization, whole-cell fatty acid composition as well as biochemical characteristics, strain BF-3T (=CCTCC AB 209170T=DSM 22523T) was clearly distinguished from all recognized Comamonas species and should be classified as a novel species of the genus Comamonas, for which the name Comamonas zonglianii sp. nov. is proposed.