BackgroundPlant-bacteria associations have been extensively studied for their potential in increasing crop productivity in a sustainable manner. Serratia marcescens is a species of Enterobacteriaceae found in a wide range of environments, including soil.ResultsHere we describe the genome sequencing and assessment of plant growth-promoting abilities of S. marcescens UENF-22GI, a strain isolated from mature cattle manure vermicompost. In vitro, S. marcescens UENF-22GI is able to solubilize P and Zn, to produce indole compounds (likely IAA), to colonize hyphae and counter the growth of two phytopathogenic fungi. Inoculation of maize with this strain remarkably increased seedling growth and biomass under greenhouse conditions. The S. marcescens UENF-22GI genome has 5 Mb, assembled in 17 scaffolds comprising 4662 genes (4528 are protein-coding). No plasmids were identified. S. marcescens UENF-22GI is phylogenetically placed within a clade comprised almost exclusively of non-clinical strains. We identified genes and operons that are likely responsible for the interesting plant-growth promoting features that were experimentally described. The S. marcescens UENF-22GI genome harbors a horizontally-transferred genomic island involved in antibiotic production, antibiotic resistance, and anti-phage defense via a novel ADP-ribosyltransferase-like protein and possible modification of DNA by a deazapurine base, which likely contributes to its competitiveness against other bacteria.ConclusionsCollectively, our results suggest that S. marcescens UENF-22GI is a strong candidate to be used in the enrichment of substrates for plant growth promotion or as part of bioinoculants for agriculture.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5130-y) contains supplementary material, which is available to authorized users.

20 Plant-bacteria associations have been extensively studied for their potential in increasing crop 21 productivity in a sustainable manner. Serratia marcescens is a Gram-negative species found in a wide 22 range of environments, including soil. Here we describe the genome sequencing and assessment of 23 plant-growth promoting abilities of S. marcescens UENF-22GI (SMU), a strain isolated from mature cattle 24 manure vermicompost. In vitro, SMU is able to solubilize P and Zn, to produce indole compounds (likely 25 IAA), to colonize hyphae and counter the growth of two phytopathogenic fungi. Inoculation of maize 26with SMU remarkably increased seedling growth and biomass under greenhouse conditions. The SMU 27 genome has 5 Mb, assembled in 17 scaffolds comprising 4,662 genes (4,528 are protein-coding). No 28 plasmids were identified. SMU is phylogenetically placed within a clade comprised almost exclusively of 29 environmental strains. We were able to find the genes and operons that are likely responsible for all the 30 interesting plant-growth promoting features that were experimentally described. Genes involved other 31interesting properties that were not experimentally tested (e.g. tolerance against metal contamination) 32were also identified. The SMU genome harbors a horizontally-transferred genomic island involved in 33 antibiotic production, antibiotic resistance, and anti-phage defense via a novel ADP-ribosyltransferase-34 like protein and possible modification of DNA by a deazapurine base, which likely contributes to the 35 SMU competitiveness against other bacteria. Collectively, our results suggest that S. marcescens UENF-36