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

A Gram-stain-negative, aerobic, mobile, and rod-shaped bacterium, designated JJ3, was isolated from peanut rhizospheric soil in Qingdao, Shandong Province, China, and was characterized using a polyphasic approach. Strain JJ3 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 B. According to the 16S rRNA gene sequence comparisons, the strain JJ3 was identified as a member of the genus Pseudomonas and was most closely related to Pseudomonas japonica JCM 21532 and Pseudomonas alkylphenolica JCM 16553 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 belonged to the Pseudomonas putida subcluster. Genomic comparison of strain JJ3 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 were C17:0 cyclo (24.0%), C (21.4%), summed features 3 (Cω7c and/or Cω6c) (11.5%) and summed features 8 (Cω7c and/or Cω6c) (10.5%). The major polar lipids of strain JJ3 were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The physiological, biochemical, and genetic characteristics support the assignment of JJ3 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 (= JCM 32579 = KCTC 62384 = CGMCC 1.16493) as the type strain.