Proyecto de Investigación: PGC2018-096956-B-C41
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PGC2018-096956-B-C41
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Distinct ecotypes within a natural haloarchaeal population enable adaptation to changing environmental conditions without causing population sweeps
(Nature Research Journals, 2020-12-20) Viver, T.; Conrad, R. E.; Orellana, L. H.; Urdiain, M.; González Pastor, J. E.; Hatt, J. K.; Amann, R.; Antón, J.; Konstantinidis, K. T.; Rosselló Móra, R.; Agencia Estatal de Investigación (AEI); National Science Foundation ( USNSF); Ministerio de Economía y Competitividad (MINECO); Amann, R. [0000-0002-0846-7372]; Rosselló Mora, R. [0000-0001-8253-3107]; Konstantinidis, K. [0000-0002-0954-4755]; Urdiain, M. [0000-0001-6834-0237]
Microbial communities thriving in hypersaline brines of solar salterns are highly resistant and resilient to environmental changes, and salinity is a major factor that deterministically influences community structure. Here, we demonstrate that this resilience occurs even after rapid osmotic shocks caused by a threefold change in salinity (a reduction from 34 to 12% salts) leading to massive amounts of archaeal cell lysis. Specifically, our temporal metagenomic datasets identified two co-occurring ecotypes within the most dominant archaeal population of the brines Haloquadratum walsbyi that exhibited different salt concentration preferences. The dominant ecotype was generally more abundant and occurred in high-salt conditions (34%); the low abundance ecotype always co-occurred but was enriched at salinities around 20% or lower and carried unique gene content related to solute transport and gene regulation. Despite their apparent distinct ecological preferences, the ecotypes did not outcompete each other presumably due to weak functional differentiation between them. Further, the osmotic shock selected for a temporal increase in taxonomic and functional diversity at both the Hqr. walsbyi population and whole-community levels supporting the specialization-disturbance hypothesis, that is, the expectation that disturbance favors generalists. Altogether, our results provide new insights into how intraspecies diversity is maintained in light of substantial gene-content differences and major environmental perturbations.
Novel Genes Involved in Resistance to Both Ultraviolet Radiation and Perchlorate From the Metagenomes of Hypersaline Environments
(Frontiers Media Extreme Microbiology, 2020-03-26) Lamprecht Grandío, María; Cortesao, Marta; Mirete, Salvador; Benguigui de la Cámara, Macarena; De Figueras, Carolina G.; Pérez Pantoja, Danilo; John White, Joseph; Eugenia Farías, María; Rosselló Móra, Ramon; González Castor, José Eduardo; Ministerio de Economía y Competitividad (MINECO); European Research Council (ERC); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Agencia Estatal de Investigación (AEI); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); White, Joseph [0000-0001-5017-5050]; González Pastor, José [0000-0002-7615-7042]
Microorganisms that thrive in hypersaline environments on the surface of our planet are exposed to the harmful effects of ultraviolet radiation. Therefore, for their protection, they have sunscreen pigments and highly efficient DNA repair and protection systems. The present study aimed to identify new genes involved in UV radiation resistance from these microorganisms, many of which cannot be cultured in the laboratory. Thus, a functional metagenomic approach was used and for this, small-insert libraries were constructed with DNA isolated from microorganisms of high-altitude Andean hypersaline lakes in Argentina (Diamante and Ojo Seco lakes, 4,589 and 3,200 m, respectively) and from the Es Trenc solar saltern in Spain. The libraries were hosted in a UV radiation-sensitive strain of Escherichia coli (recA mutant) and they were exposed to UVB. The resistant colonies were analyzed and as a result, four clones were identified with environmental DNA fragments containing five genes that conferred resistance to UV radiation in E. coli. One gene encoded a RecA-like protein, complementing the mutation in recA that makes the E. coli host strain more sensitive to UV radiation. Two other genes from the same DNA fragment encoded a TATA-box binding protein and an unknown protein, both responsible for UV resistance. Interestingly, two other genes from different and remote environments, the Ojo Seco Andean lake and the Es Trenc saltern, encoded two hypothetical proteins that can be considered homologous based on their significant amino acid similarity (49%). All of these genes also conferred resistance to 4-nitroquinoline 1-oxide (4-NQO), a compound that mimics the effect of UV radiation on DNA, and also to perchlorate, a powerful oxidant that can induce DNA damage. Furthermore, the hypothetical protein from the Es Trenc salterns was localized as discrete foci possibly associated with damaged sites in the DNA in cells treated with 4-NQO, so it could be involved in the repair of damaged DNA. In summary, novel genes involved in resistance to UV radiation, 4-NQO and perchlorate have been identified in this work and two of them encoding hypothetical proteins that could be involved in DNA damage repair activities not previously described.
