title: Culturable endophytic bacteria from the salt marsh plant Halimione portulacoides: phylogenetic diversity, functional characterization, and influence of metal(loid) contamination.
abstract: Halimione portulacoides is abundant in salt marshes, accumulates mercury (Hg), and was proposed as useful for phytoremediation and pollution biomonitoring. Endophytic bacteria promote plant growth and provide compounds with industrial applications. Nevertheless, information about endophytic bacteria from H. portulacoides is scarce. Endophytic isolates (n = 665) were obtained from aboveground and belowground plant tissues, from two Hg-contaminated sites (sites E and B) and a noncontaminated site (site C), in the estuary Ria de Aveiro. Representative isolates (n = 467) were identified by 16S rRNA gene sequencing and subjected to functional assays. Isolates affiliated with Proteobacteria (64 %), Actinobacteria (23 %), Firmicutes (10 %), and Bacteroidetes (3 %). Altererythrobacter (7.4 %), Marinilactibacillus (6.4 %), Microbacterium (10.2 %), Salinicola (8.8 %), and Vibrio (7.8 %) were the most abundant genera. Notably, Salinicola (n = 58) were only isolated from site C; Hoeflea (17), Labrenzia (22), and Microbacterium (67) only from belowground tissues. This is the first report of Marinilactibacillus in the endosphere. Principal coordinate analysis showed that community composition changes with the contamination gradient and tissue. Our results suggest that the endosphere of H. portulacoides represents a diverse bacterial hotspot including putative novel species. Many isolates, particularly those affiliated to Altererythrobacter, Marinilactibacillus, Microbacterium, and Vibrio, tested positive for enzymatic activities and plant growth promoters, exposing H. portulacoides as a source of bacteria and compounds with biotechnological applications.
authors.affiliation: CESAM, Departamento de Biologia, Universidade de Aveiro, Aveiro, Portugal.|iBiMED and CESAM, Departamento de Biologia, Campus de Santiago, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
authors.forename: Cátia
authors.initials: C
authors.lastname: Fidalgo
authors.affiliation: iBiMED and CESAM, Departamento de Biologia, Campus de Santiago, Universidade de Aveiro, 3810-193, Aveiro, Portugal. ihenriques@ua.pt.
authors.forename: Isabel
authors.initials: I
authors.lastname: Henriques
authors.affiliation: CESAM, Departamento de Biologia, Universidade de Aveiro, Aveiro, Portugal.
authors.forename: Jaqueline
authors.initials: J
authors.lastname: Rocha
authors.affiliation: CESAM, Departamento de Biologia, Universidade de Aveiro, Aveiro, Portugal.
authors.forename: Marta
authors.initials: M
authors.lastname: Tacão
authors.affiliation: CESAM, Departamento de Biologia, Universidade de Aveiro, Aveiro, Portugal.
authors.forename: Artur
authors.initials: A
authors.lastname: Alves
mesh_terms: D039903:Actinobacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D000192:Actinomycetales / Q000254:growth & development / Q000302:isolation & purification; D027703:Amaranthaceae / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring; D008628:Mercury / Q000378:metabolism; D010802:Phylogeny; D018749:RNA, Plant; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012965:Sodium Chloride; D053833:Wetlands
chemical_list: D018749:RNA, Plant; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D008628:Mercury
keywords: Bacteria; Endophyte; Extracellular enzymes; Halimione portulacoides; Plant growth promotion; Salt marsh plants