Dyella aluminiiresistens sp. nov., a Al3+-tolerant bacterium with the ability to inhibit Fusarium oxysporum f. sp. melonis isolated from rhizosphere soil of muskmelon

A bacterial strain, designated as A6 T , was isolated from the rhizosphere soil of a healthy muskmelon in Wenchang, Hainan Province, China. The cells of strain A6 T were Gram-negative, aerobic, short rod and motile with a single polar flagellum. Strain A6 T could tolerate up to 55.0 mM Al 3+ and inhibited the growth of Fusarium oxysporum f. sp. melonis, which is the pathogen of muskmelon Fusarium wilt . Growth occurred at 15–37 ℃ (optimum at 30 ℃), pH 4.5–8.0 (optimum pH 6.5) and with 0–3.0 % NaCl (w/v; optimum, 0.5%). Strain A6 T shared the highest 16S rRNA gene sequence similarities with Dyella lutea Sa T (98.0%), followed by Dyella thiooxydans ATSB10 T (98.0%), Frateuria edaphi 5GH9-34 T (97.9%), Dyella nitratireducens DHG59 T (97.7%), Frateuria defendens DHo T (97.7%) and Frateuria soli 5GH9-11 T (97.7%). Phylogenetic trees based on 16S rRNA gene and genomic sequences indicated that strain A6 T belonged to the genus Dyella and formed a subclade with Dyella lutea Sa T and Dyella thiooxydans ATSB10 T . The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA–DNA hybridization (dDDH) values between A6 T and its closely related type strains were 78.8–80.8 %, 70.0–71.7 % and 20.5–22.1 %, respectively. The sole respiratory quinone was ubiquinone-8 (Q-8). The polar lipid profile consisted of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), two unidentified aminophospholipids (APL1-2) and three unidentified phospholipids (PL1-3). The major cellular fatty acids (≥5 %) were iso-C 17 : 0 , C 16 : 0 , summed feature 9 (iso-C 17 : 1 ω 9 c and/or C 16 : 0 10-methyl), iso-C 15 : 0 , iso-C 16 : 0 and anteiso-C 17 : 0 . The genome size of strain A6 T was 3.7 Mb with a DNA G+C content of 65.1%. Based on the phenotypic, phylogenetic, genotypic and chemotaxonomic features, strain A6 T represents a novel species in the genus Dyella , for which Dyella aluminiiresistens A6 T sp. nov. is proposed. The type strain is A6 T (= GDMCC 1.4640 T = KCTC 92542 T ).