Aquincola agrisoli sp. nov., isolated from rhizospheric soil of eggplant and in silico genome mining for the prediction of biosynthetic gene clusters.

A Gram-stain negative, aerobic, rod-shaped, motile and flagellated novel bacterial strain, designated MAHUQ-54(T), was isolated from the rhizospheric soil of eggplant. The colonies were observed to be light pink coloured, smooth, spherical and 0.2-0.6 mm in diameter when grown on R2A agar medium for 2 days. MAHUQ-54(T) was able to grow at 15-40 °C, at pH 5.5-9.0 and in the presence of 0-0.5 % NaCl (w/v). The strain gave positive results for both catalase and oxidase tests. The strain was positive for hydrolysis of l-tyrosine, urea, Tween 20 and Tween 80. On the basis of the results of 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Aquincola and is closely related to Aquincola tertiaricarbonis L10(T) (98.8 % sequence similarity) and Leptothrix mobilis Feox-1(T) (98.2 %). MAHUQ-54(T) has a draft genome size of 5 994 516 bp (60 contigs), annotated with 5348 protein-coding genes, 45 tRNA and 5 rRNA genes. The average nucleotide identity (ANI) and digital DNA-DNA hybridisation (dDDH) values between MAHUQ-54(T) and its closest phylogenetic neighbours were 75.8-83.3 and 20.8-25.3 %, respectively. In silico genome mining revealed that MAHUQ-54(T) has a significant potential for the production of novel natural products in the future. The genomic DNA G+C content was determined to be 70.4 %. The predominant isoprenoid quinone was ubiquinone-8. The major fatty acids were identified as C(16  :  0), summed feature 3 (comprising C(16  :  1)ω7c and/or C(16  :  1)ω6c) and summed feature 8 (comprising C(18  :  1)ω7c and/or C(18  :  1)ω6c). On the basis of dDDH, ANI value, genotypic analysis, chemotaxonomic and physiological data, strain MAHUQ-54(T) represents a novel species within the genus Aquincola, for which the name Aquincola agrisoli sp. nov. is proposed, with MAHUQ-54(T) (=KACC 22001(T) = CGMCC 1.18515(T)) as the type strain.