RESUMEN
Objective:To analyze the biological characteristics, phylogenic features and clinical significance of SQ219 and SQ220 isolated from clinical sputum and midstream urine specimens.Methods:The culture and biochemical characteristics of the two strains were observed. VITEK2 System, drug sensitivity testing and MALDI-TOF mass spectrometry were used for bacterial identification. Phylogenetic analysis based on 16S rRNA and core genome was performed. The average nucleotide identity (ANI) based on whole genome sequences was calculated.Results:SQ219 and SQ220 were Gram-stain-negative, aerobic, catalase- and oxidase-positive, and non-motile bacteria. Their optimum growth was observed in NaCl-free medium at 30℃ and pH7. Flexirubin-type pigments were produced by SQ220 on Colombia blood agar, but not by SQ219. Both SQ219 and SQ220 were resistant to aztreonam, amikacin, tobramycin and colistin, which was consistent with the drug resistance phenotype of genus Chryseobacterium. The genome sequences of SQ219 and SQ220 were 5.08 Mb and 4.80 Mb in length, and the G+ C contents were 36.72% and 36.36%, respectively. Both strains carried β-lactam resistance gene ( blaCGA). 16S rRNA phylogenetic analysis showed that SQ219 and SQ220 were closely related to Chryseobacterium gambrini DSM18014 T with the similarities of 98.93% and 98.36%, respectively. Core genome phylogenetic analysis revealed that SQ219 and SQ220 were highly homologous to Chryseobacterium gambrini DSM18014 T. However, the ANI values between the two strains and Chryseobacterium gambrini DSM18014 T were 92.49% and 93.27%, respectively, below the threshold for prokaryotic species identification. Conclusions:Based on the phenotypic and phylogenetic data, SQ219 and SQ220 represent a novel species of the genus Chryseobacterium. This study would help promote the understanding of the evolution of Chrysobacterium and provide reference for the identification of new species of Chrysobacterium.
RESUMEN
Objective:To identify and characterize one Spiroplasma strain (designated as DGKH1) isolated from the blood of a patient with sepsis. Methods:The traditional bacterial culture, staining, morphological observation, physiological and biochemical identification, 16S rRNA gene sequencing, phylogenetic analysis, genome sequencing, and the genome-related index analysis were performed to accurately determine the taxonomic status of the strain DGKH1. Antibiotic susceptibility testing was performed using a specific kit for culturing and testing Ureaplasma urealyticum/ Metamycoplasma hominis. Results:The strain DGKH1 could weakly grow on Columbia blood agar, chocolate agar, and Haemophilus chocolate 2 agar. However, it did not grow in liquid culture medium containing tetracycline (4 μg/ml), doxycycline (1 μg/ml), minocycline (1 μg/ml), josamycin (2 μg/ml), roxithromycin (1 μg/ml), clarithromycin (1 μg/ml), or telithromycin (1 μg/ml). DGKH1 resembling Metamycoplasma hominis formed "fried egg-like colonies" on Mycoplasma solid culture medium. DGKH1 could not be stained by Gram staining. When observed under transmission electron microscopy (TEM) using phosphate buffer as the matrix, the bacteria were spiral-shaped. Results of 16S rRNA gene sequence alignment showed that DGKH1 was highly similar (99.85%) to Spiroplasma eriocheiris CCTCC M 207170 T. However, the urea decomposition test was positive, which was different from all of the known Spiroplasma species. The phylogenetic analysis based on whole genome showed that DGKH1 was clustered in a small branch along with Spiroplasma eriocheiris CCTCC M 207170 T. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 94.14% and 56.00%, respectively, both below the threshold for prokaryotic species identification. Conclusions:DGKH1 represented a potential new species of genus Spiroplasma, closely related to Spiroplasma eriocheiris. Some microbiological characteristics of DGKH1 were similar to Mycoplasmas. However, the natural host and epidemiological data of DGKH1 need to be further studied.