title: Profile of the culturable microbiome capable of producing acyl-homoserine lactone in the tobacco phyllosphere.
abstract: Bacterial populations coexisting in the phyllosphere niche have important effects on plant health. Quorum sensing (QS) allows bacteria to communicate via diffusible signal molecules, but QS-dependent behaviors in phyllosphere bacterial populations are poorly understood. We investigate the dense and diverse N-acyl-homoserine lactone (AHL)-producing phyllosphere bacteria living on tobacco leaf surfaces via a culture-dependent method and 16S rRNA gene sequencing. Our results indicated that approximately 7.9%-11.7% of the culturable leaf-associated bacteria have the ability to produce AHL based on the assays using whole-cell biosensors. Sequencing of the 16S rRNA gene assigned the AHL-producing strains to two phylogenetic groups, with Gammaproteobacteria (93%) as the predominant group, followed by Alphaproteobacteria. All of the AHL-producing Alphaproteobacteria were affiliated with the genus Rhizobium, whereas the AHL-producing bacteria belonging to the Gammaproteobacteria mainly fell within the genera Pseudomonas, Acinetobacter, Citrobacter, Enterobacter, Pantoea and Serratia. The bioassays of supernatant extracts revealed that a portion of the strains have a remarkable AHL profilefor AHL induction activity using the two different biosensors, and one compound i nthe active extract of a representative isolate, NTL223, corresponded to 3-oxo-hexanoyl-homoserine lactone. A large population size and diversity of bacteria capable of AHL-driven QS were found to cohabit on leaves, implying that cross-communication based AHL-type QS may be common in the phyllosphere. Furthermore, this study provides a general snapshot of a potential valuable application of AHL-producing bacteria inhabiting leaves for their presumable ecological roles in the phyllosphere.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. lariena@126.com
authors.forename: Di
authors.initials: D
authors.lastname: Lv
authors.forename: Anzhou
authors.initials: A
authors.lastname: Ma
authors.forename: Xuanming
authors.initials: X
authors.lastname: Tang
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Bai
authors.forename: Hongyan
authors.initials: H
authors.lastname: Qi
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhuang
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D054892:Metagenome / Q000502:physiology*; D010802:Phylogeny; D053038:Quorum Sensing / Q000502:physiology; D014026:Nicotiana / Q000382:microbiology*
chemical_list: D054742:Acyl-Butyrolactones