Fundidesulfovibrio agrisoli sp. nov., A Nitrogen-Fixing Bacterium Isolated from Rice Field

A strictly anaerobic nitrogen-fixing strain, designated SG106(T), was isolated from rice field. The 16S rRNA gene sequence analysis showed that strain SG106(T) was closely related to the type strain of Fundidesulfovibrio magnetotacticus (97.3%). In phylogenetic (based on 16S rRNA gene sequences) and phylogenomic (constructed using a concatenated alignment of 117 conserved bacterial single-copy genes with GTDB-Tk) trees, strain SG106(T) clustered with members of the genus Fundidesulfovibrio. Strain SG106(T) grew at 20-40 ? and 0-0.4% (w/v) NaCl. Desulfoviridin was found in the strain SG106(T). The genomic DNA G + C content of strain SG106(T) was 66.0%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG106(T) and the closely related F. magnetotacticus were 78.4% and 21.7%, respectively. Genome analysis showed that strain SG106(T) encodes genes for nitrogen fixation (nifHDK). Acetylene reduction experiments showed that the nitrogenase activity of strain SG106(T) could reach 224.7 mu mol C2H4 g(-1) protein h(-1). Based on the above results, strain SG106(T) represents a novel species of the genus Fundidesulfovibrio, for which the name Fundidesulfovibrio agrisoli sp. nov. is proposed. The type strain is SG106(T) (= GDMCC 1.3136(T) = JCM 35588(T)).