Pseudomonas qingdaonensis sp. nov., an aflatoxin-degrading bacterium, isolated from peanut rhizospheric soil

Abstract

A Gram-stain-negative, aerobic, mobile, and rod-shaped bacterium, designated JJ3^T, was isolated from peanut rhizospheric soil in Qingdao, Shandong Province, China, and was characterized using a polyphasic approach. Strain JJ3^T grew at 4–40 °C, at pH 5.0–9.0 and 0–4% NaCl. The strain was positive for both catalase and oxidase tests, and was able to degrade aflatoxin B₁. According to the 16S rRNA gene sequence comparisons, the strain JJ3^T was identified as a member of the genus Pseudomonas and was most closely related to Pseudomonas japonica JCM 21532^T and Pseudomonas alkylphenolica JCM 16553^T with sequence similarity of 99.0% and 98.9%, respectively. A multilocus sequence analysis (MLSA) of concatenating 16S rRNA, gyrB and rpoD gene sequences showed that strain JJ3^T belonged to the Pseudomonas putida subcluster. Genomic comparison of strain JJ3^T with its closest phylogenetic type strain using average nucleotide index (ANI) and digital DNA–DNA relatedness revealed 76.7–82.9% and 20.2–37.1%, respectively. All values were distinctly lower than the thresholds established for species differentiation. The predominant cellular fatty acids of strain JJ3^T were C17:0 cyclo (24.0%), C_16:0 (21.4%), summed features 3 (C_16:1ω7c and/or C_16:1ω6c) (11.5%) and summed features 8 (C_18:1ω7c and/or C_18:1ω6c) (10.5%). The major polar lipids of strain JJ3^T were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The physiological, biochemical, and genetic characteristics support the assignment of JJ3^T to the genus Pseudomonas, but are different to those of phylogenetically neighboring species to represent a novel species. The name Pseudomonas qingdaonensis sp. nov. is proposed, with JJ3^T (= JCM 32579^T = KCTC 62384^T = CGMCC 1.16493^T) as the type strain.

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