Serratia silvae sp. nov., Isolated from Forest Soil

The Gram-negative, oxidase-negative, catalase-positive, rod-shaped strain Arafor3(T) was isolated from forest soil (France). Comparative 16S rRNA gene analysis and phylogenetic analysis based on (1) multilocus sequence analysis (MLSA) with four housekeeping genes (atpD, gyrB, infB and rpoB) and (2) genomes indicated that strain Arafor3(T) shared 98.83% 16S rRNA gene sequence similarity with the type strain of Serratia fonticola DSM 4576(T) and was closely related to this same strain in the MLSA and in the phylogenomic tree reconstruction. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) comparisons of strain Arafor3(T) with its nearest neighbor S. fonticola DSM 4576(T) showed 93.5% identity and 55.7% sequence similarity, respectively, and were lower than the 96% and 70% species-level cut-off values relating to these analyses (Logan et al. in Int J Syst Evol Microbiol 59:2114-21, 2009, ). The strain differed from S. fonticola in that it was urease and arginine dihydrolase negative. The major fatty acids of strain Arafor3(T) are C-16:0, C-16:1 omega 7c/C-16:1 omega 6c, (C14:0), C-14:0 3-OH/(16:1) isoI, and C-18:1 omega 7c. The major respiratory quinone is Q8. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and 6 unknown lipids. The mol G + C% content of the genomic DNA of strain Arafor3(T) was 53.49%. Hence, Arafor3(T) represents a novel species within the genus Serratia, for which the name Serratia silvae sp. nov. is proposed. The type strain is Arafor3(T) (=LMG 32338(T) = CIP 111939(T)).

Automated summary

The strain Arafor3(T) was isolated from forest soil in France, and it is a Gram-negative, oxidase-negative, catalase-positive, rod-shaped bacterium. Through genetic analysis, it was found that Arafor3(T) has a high similarity with Serratia fonticola DSM 4576(T) in terms of 16S rRNA gene sequence and other genetic markers, although there are also some differences, such as negative urease and arginine dihydrolase activity. Based on these findings, a new species within the genus Serratia, named Serratia silvae sp. nov., is proposed for Arafor3(T). The strain's fatty acid composition, respiratory quinone, polar lipid profile, and genomic DNA mol G + C% content were also determined.