title: Poly-γ-Glutamic Acids Contribute to Biofilm Formation and Plant Root Colonization in Selected Environmental Isolates ofBacillus subtilis.
abstract: Bacillus subtilisis long known to produce poly-γ-glutamic acids (γ-PGA) as one of the major secreted polymeric substances. InB. subtilis, the regulation of γ-PGA production and its physiological role are still unclear.B. subtilisis also capable of forming structurally complex multicellular communities, or biofilms, in which an extracellular matrix consisting of secreted proteins and polysaccharides holds individual cells together. Biofilms were shown to facilitateB. subtilis-plant interactions. In this study, we show that different environmental isolates ofB. subtilis, all capable of forming biofilms, vary significantly in γ-PGA production. This is possibly due to differential regulation of γ-PGA biosynthesis genes. In many of those environmental isolates, γ-PGA seems to contribute to robustness and complex morphology of the colony biofilms, suggesting a role of γ-PGA in biofilm formation. Our evidence further shows that in selectedB. subtilisstrains, γ-PGA also plays a role in root colonization by the bacteria, pinpointing a possible function of γ-PGA inB. subtilis-plant interactions. Finally, we found that several pathways co-regulate both γ-PGA biosynthesis genes and genes for the biofilm matrix inB. subtilis, but in an opposing fashion. We discussed potential biological significance of that.
authors.affiliation: Department of Plant Pathology, Nanjing Agricultural UniversityNanjing, China; Department of Biology, Northeastern UniversityBoston, MA, USA.
authors.forename: Yiyang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Plant Pathology, Nanjing Agricultural UniversityNanjing, China; Department of Biology, Northeastern UniversityBoston, MA, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Yan
authors.affiliation: Department of Biology, Northeastern UniversityBoston, MA, USA; Institute of Biotechnology, Zhejiang UniversityHangzhou, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Biology, Northeastern University Boston, MA, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Plant Pathology, Nanjing Agricultural UniversityNanjing, China; Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Integrated Management of Crop Diseases and PestsNanjing, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Guo
authors.affiliation: Department of Biology, Northeastern University Boston, MA, USA.
authors.forename: Yunrong
authors.initials: Y
authors.lastname: Chai
keywords: Bacillus subtilis; biofilm formation; poly-γ-glutamic acid; root colonization