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Culturable endophytic bacteria from the salt marsh plant Halimione portulacoides: phylogenetic diversity, functional characterization, and influence of metal(loid) contamination


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.

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This work was financed by the European Funds through COMPETE and by National Funds through the Portuguese Foundation for Science and Technology (FCT) within project PhytoMarsh (PTDC/AAC-AMB/118873/2010–FCOMP-01-0124-FEDER-019328). The authors acknowledge FCT financing to CESAM (UID/AMB/50017/2013) and Institute for Research in Biomedicine (iBiMED–UID/BIM/04501/2013), Artur Alves (FCT Investigator Programme–IF/00835/2013), Isabel Henriques (FCT Investigator Programme–IF/00492/2013), and Cátia Fidalgo (PhD grant–SFRH/BD/85423/2012).

Authors acknowledge Paula Castro and Diogo Proença for kindly providing positive and negative control strains used in this study.

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Correspondence to Isabel Henriques.

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Fidalgo, C., Henriques, I., Rocha, J. et al. Culturable endophytic bacteria from the salt marsh plant Halimione portulacoides: phylogenetic diversity, functional characterization, and influence of metal(loid) contamination. Environ Sci Pollut Res 23, 10200–10214 (2016).

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  • Endophyte
  • Bacteria
  • Halimione portulacoides
  • Salt marsh plants
  • Plant growth promotion
  • Extracellular enzymes