A novel bacterial strain, S40T, with strong antifungal activity was isolated from the rhizosphere of green potato collected from Zealand, Denmark. Polyphasic analysis with a combined phenotypic, phylogenetic and genomic approach was used to characterize S40T. Phylogenetic analysis based on the 16S rRNA gene and MLSA (concatenated gyrB, rpoD, infB and atpD sequences) showed that strain S40T was affiliated with the genus
Serratia
and with
Serratia plymuthica
PRI-2C as the closest related strain [average nucleotide identity (ANI), 99.26 %; DNA–DNA hybridization (dDDH), 99.20%]. However, whole genome sequence analyses revealed that S40T and
S. plymuthica
PRI-2C genomes displayed lower similarities when compared to all other
S. plymuthica
strains (ANI ≤94.34 %; dDDH ≤57.6 % relatedness). The DNA G+C content of strain S40T was determined to be 55.9 mol%. Cells of the strain were Gram-negative, rod-shaped, facultative anaerobic and displayed growth at 10–37 °C (optimum, 25–30 °C) and at pH 6–9 (optimum, pH 6–7). Major fatty acids were C16 : 0 (27.9 %), summed feature (C16 : 1
ω6c/C16 : 1 ω7c; 18.0 %) and C17 : 0 cyclo (15.1 %). The respiratory quinone was determined to be Q8 (94 %) and MK8 (95 %) and the major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The results of phenotypic, phylogenetic and genomic analyses support the hypothesis that strain S40T represents a novel species of the genus
Serratia
, for which the name Serratia inhibens sp. nov. is proposed. The type strain is S40T (=LMG 31467T=NCIMB 15235T). In addition, we propose that
S. plymuthica
PRI-2C is reclassified and transferred to the species S. inhibens as S. inhibens PRI-2C.