title: Genome sequence of the plant growth promoting endophytic bacterium Enterobacter sp. 638.
abstract: Enterobacter sp. 638 is an endophytic plant growth promoting gamma-proteobacterium that was isolated from the stem of poplar (Populus trichocarpaxdeltoides cv. H11-11), a potentially important biofuel feed stock plant. The Enterobacter sp. 638 genome sequence reveals the presence of a 4,518,712 bp chromosome and a 157,749 bp plasmid (pENT638-1). Genome annotation and comparative genomics allowed the identification of an extended set of genes specific to the plant niche adaptation of this bacterium. This includes genes that code for putative proteins involved in survival in the rhizosphere (to cope with oxidative stress or uptake of nutrients released by plant roots), root adhesion (pili, adhesion, hemagglutinin, cellulose biosynthesis), colonization/establishment inside the plant (chemiotaxis, flagella, cellobiose phosphorylase), plant protection against fungal and bacterial infections (siderophore production and synthesis of the antimicrobial compounds 4-hydroxybenzoate and 2-phenylethanol), and improved poplar growth and development through the production of the phytohormones indole acetic acid, acetoin, and 2,3-butanediol. Metabolite analysis confirmed by quantitative RT-PCR showed that, the production of acetoin and 2,3-butanediol is induced by the presence of sucrose in the growth medium. Interestingly, both the genetic determinants required for sucrose metabolism and the synthesis of acetoin and 2,3-butanediol are clustered on a genomic island. These findings point to a close interaction between Enterobacter sp. 638 and its poplar host, where the availability of sucrose, a major plant sugar, affects the synthesis of plant growth promoting phytohormones by the endophytic bacterium. The availability of the genome sequence, combined with metabolome and transcriptome analysis, will provide a better understanding of the synergistic interactions between poplar and its growth promoting endophyte Enterobacter sp. 638. This information can be further exploited to improve establishment and sustainable production of poplar as an energy feedstock on marginal, non-agricultural soils using endophytic bacteria as growth promoting agents.
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, New York, United States of America.
authors.forename: Safiyh
authors.initials: S
authors.lastname: Taghavi
authors.forename: Daniel
authors.initials: D
authors.lastname: van der Lelie
authors.forename: Adam
authors.initials: A
authors.lastname: Hoffman
authors.forename: Yian-Biao
authors.initials: YB
authors.lastname: Zhang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Walla
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.forename: Lee
authors.initials: L
authors.lastname: Newman
authors.forename: Sébastien
authors.initials: S
authors.lastname: Monchy
mesh_terms: D004754:Enterobacter / Q000201:enzymology / Q000235:genetics*; D016680:Genome, Bacterial; D063245:Plant Development; D018517:Plant Roots / Q000382:microbiology; D010944:Plants / Q000382:microbiology; D032107:Populus / Q000254:growth & development* / Q000382:microbiology; D020133:Reverse Transcriptase Polymerase Chain Reaction