Chryseobacterium tongliaoense sp. nov., an aniline blue-degrading strain isolated from agricultural soil

Abstract

Aniline blue (AB) is a toxic dye with a wide range of applications. Although bacteria can degrade AB, their biodiversity remains limited. In this study, strain MD-1 ^T, capable of degrading AB, was screened from corn field soil obtained in Tongliao city in Inner Mongolia Autonomous Region, China. Strain MD-1 ^T degraded 81.7% of AB (100 mg·L⁻¹) within 72 h. Cells were aerobic, short rod, non-spore-forming and non-motile. The strain grew optimally at 30 °C, 1% (w/v) NaCl and pH 7.0. Phylogenetic trees of 16S rRNA gene sequences indicated that strain MD-1 ^T was classified in the genus Chryseobacterium, and shared 95.9%-96.8% similarities with type strains of the genus Chryseobacterium. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain MD-1 ^T and the related Chryseobacterium type strains were in the range of 20.9–41.2% and 76.9–90.3%, respectively. The fatty acid profile was mainly composed of C_15:0 iso, summed feature 9 (C_17:1 iso ω9c and/or C_16:0 10-methyl), C_17:0 iso 3OH and summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), the major polar lipids were phosphatidylethanolamine (PE), three unidentified aminolipids (AL1-3), an unidentified aminophospholipid (APL) and seven unidentified lipids (L1-7). The only isoprenoid quinone was MK-6. The size of the genome of strain MD-1 ^T was 4.5 Mb with a G + C content of 36.5 mol%. Based on the low 16S rRNA gene sequence similarities, low dDDH and ANI values and differential phenotypic characteristics, we hypothesized that strain MD-1 ^T represents a novel species in the genus Chryseobacterium, for which the name Chryseobacterium tongliaoense sp. nov is proposed. The type strain is MD-1 ^T (= MCCC 1K09437^T = KCTC 102309 ^T). This study provided new microbial resource potential for remediation of AB pollution sustainably and efficiently.