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Mora-Ruiz, M. D., Alejandre-Colomo, C., Ledger, T., Gonzalez, B., Orfila, A., & Rossello-Mora, R. (2018). Non-halophilic endophytes associated with the euhalophyte Arthrocnemum macrostachyum and their plant growth promoting activity potential. FEMS Microbiol. Lett., 365(19), 11 pp.
Abstract: Numerous microbial taxa establish natural relations with plants, and especially endophytes can be relevant in the development and growth promotion of their host. In this work, we explore the diversity of non-halophilic microorganisms inhabiting the endosphere of the halophyte Arthrocnemum macrostachyum. A total of 1045 isolates were recovered using standard non-saline media, which clustered into 22 operational phylogenetic units (OPUs) including 7 putative new species and 13 OPUs not previously detected as endophytes. The more abundant isolates corresponded to close relatives of Kushneria indalinina/K. marisflavi, Providencia rettgeri, Pseudomonas zhaodongensis and Bacillus safensis, which made up to similar to 62% of the total isolates. We also isolated OPUs not detected by the culture-independent approach reinforcing the need of culturing to reveal the microbial diversity associated with plants. Additionally, the plant growth promoting activity was evaluated by representative strains of the more abundant OPUs (total = 94 strains) including also some previously isolated halophiles from the same plants. Under both saline and non-saline conditions, some strains principally those affiliated to Paenibacillus borealis, Staphylococcus equorum, Salinicola halophilus and Marinococcus tarijensis, presented growth promoting activity in Arabidopsis thaliana, which was evaluated as an increment of weight and root length.
Keywords: Arthrocnemum macrostachyum; (non)-halophiles; operational phylogenetic unit; plant growth promoting activity
Mora-Ruiz, M. D., Cifuentes, A., Font-Verdera, F., Perez-Fernandez, C., Farias, M. E., Gonzalez, B., et al. (2018). Biogeographical patterns of bacterial and archaeal communities from distant hypersaline environments. Syst. Appl. Microbiol., 41(2), 139–150.
Abstract: Microorganisms are globally distributed but new evidence shows that the microbial structure of their communities can vary due to geographical location and environmental parameters. In this study, 50 samples including brines and sediments from Europe, Spanish-Atlantic and South America were analysed by applying the operational phylogenetic unit (OPU) approach in order to understand whether microbial community structures in hypersaline environments exhibited biogeographical patterns. The fine-tuned identification of approximately 1000 OPUs (almost equivalent to “species”) using multivariate analysis revealed regionally distinct taxa compositions. This segregation was more diffuse at the genus level and pointed to a phylogenetic and metabolic redundancy at the higher taxa level, where their different species acquired distinct advantages related to the regional physicochemical idiosyncrasies. The presence of previously undescribed groups was also shown in these environments, such as Parcubacteria, or members of Nanohaloarchaeota in anaerobic hypersaline sediments. Finally, an important OPU overlap was observed between anoxic sediments and their overlaying brines, indicating versatile metabolism for the pelagic organisms. (C) 2017 Elsevier GmbH. All rights reserved.
Keywords: Archaea; Bacteria; Brines; Hypersaline sediments; Operational phylogenetic units; Salterns