Browsing by Author "De la Iglesia, R."

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    Decoupling of biotic and abiotic patterns in a coastal area affected by chronic metal micronutrients disturbances
    (2021) Glasner, B.; Henriquez-Castillo, C.; Alfaro, F. D.; Trefault, N.; Andrade, S.; De la Iglesia, R.
    Coastal systems are highly productive areas for primary productivity and ecosystem services and host a large number of human activities. Since industrialization, metal micronutrients in these regions have increased. Phytoplankton use metals as micronutrients in metabolic processes, but in excess, had deleterious effects. In coastal systems, picoeukaryotes represent a diverse and abundant group with widespread distribution and fundamental roles in biogeochemical cycling. We combined different approaches to explore picoeukaryotes seasonal variability in a chronically metal polluted coastal area at the south-eastern Pacific Ocean. Through remote and field measurements to monitor environmental conditions and 18S rRNA gene sequencing for taxonomic profiling, we determined metal chronic effect on picoeukaryote community?s structure. Our results revealed a stable richness and a variable distribution of the relative abundance, despite the physicochemical seasonal variations. These results suggest that chronic metal contamination influences temporal heterogeneity of picoeukaryote communities, with a decoupling between abiotic and biotic patterns.
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    Enhanced nitrogen and carbon removal in natural seawater by electrochemical enrichment in a bioelectrochemical reactor
    (2022) De La Fuente, M.J.; De la Iglesia, R.; Farias, L.; Glasner, B.; Torres-Rojas, F.; Muñoz, D.; Daims, H.; Lukumbuzya, M.; Vargas Cucurella, Ignacio Tomas; CEDEUS (Chile)
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    Molecular and population analyses of a recombination event in the catabolic plasmid pJP4
    (2006) Larraín-Linton, Juanita; De la Iglesia, R.; Melo Ledermann, Francisco Javier; González, B.
    Cupriavidus necator JMP134(pJP4) harbors a catabolic plasmid, pJP4, which confers the ability to grow on chloroaromatic compounds. Repeated growth on 3-chlorobenzoate (3-CB) results in selection of a recombinant strain, which degrades 3-CB better but no longer grows on 2,4-dichlorophenoxyacetate (2,4-D). We have previously proposed that this phenotype is due to a double homologous recombination event between inverted repeats of the multicopies of this plasmid within the cell. One recombinant form of this plasmid (pJP4-F3) explains this phenotype, since it harbors two copies of the chlorocatechol degradation tfd gene clusters, which are essential to grow on 3-CB, but has lost the tfdA gene, encoding the first step in degradation of 2,4-D. The other recombinant plasmid (pJP4-FM) should harbor two copies of the tfdA gene but no copies of the tfd gene clusters. A molecular analysis using a multiplex PCR approach to distinguish the wild-type plasmid pJP4 from its two recombinant forms, was carried out. Expected PCR products confirming this recombination model were found and sequenced. Few recombinant plasmid forms in cultures grown in several carbon sources were detected. Kinetic studies indicated that cells containing the recombinant plasmid pJP4-FM were not selectable by sole carbon source growth pressure, whereas those cells harboring recombinant plasmid pJP4-F3 were selected upon growth on 3-CB. After 12 days of repeated growth on 3-CB, the complete plasmid population in C. necator JMP134 apparently corresponds to this form. However, wild-type plasmid forms could be recovered after growing this culture on 2,4-D, indicating that different plasmid forms can be found in C. necator JMP134 at the population level.
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    Novel polymerase chain reaction primers for the specific detection of bacterial copper P-type ATPases gene sequences in environmental isolates and metagenomic DNA
    (WILEY, 2010) De la Iglesia, R.; Valenzuela Heredia, D.; Pavissich, J. P.; Freyhoffer, S.; Andrade, S.; Correa, J. A.; Gonzalez, B.
    Aims:
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    Soil bacteria are differentially affected by the resin of the medicinal plant Pseudognaphalium vira vira and its main component kaurenoic acid
    (2006) Gil, F.; De la Iglesia, R.; Mendoza, L.; Gonzalez, B.; Wilkens, M.
    The diterpenoid kaurenoic acid is the main component of the resin from the medicinal plant Pseudognaphalium vira vira. As some diterpenoids have antimicrobial properties, the effect of this resin and the kaurenoic acid on soil bacteria was studied. The resin of P. vira vira and purified kaurenoic acid were two to four times more effective as antibacterial agents with Gram-positive than with Gram-negative soil isolates. The chemical stability of kaurenoic acid and the antibacterial activity of both the resin and the diterpenoid were studied in microcosms containing plant-associated soil. After 15 days of incubation, the diterpenoid was stable, as determined by H-1 nuclear magnetic resonance and thin-layer chromatography, and soil extracts still exhibited antibacterial activity. However, after 30 days of incubation, loss of antibacterial activity of soil extracts correlated with removal or chemical modification of kaurenoic acid. The effect of the resin or this diterpenoid on the soil bacteria community was analyzed by the terminal restriction fragment length polymorphisms technique. After 15 days of incubation, the resin and the pure compound caused significant changes in the soil bacterial community. The relative abundance of specific bacterial groups was differentially affected by the resin components, being the effects with the resin stronger than with the kaurenoic acid. After 30 days of incubation, these changes mostly reverted. These results indicate that a plant resin containing diterpenoid compounds plays a significant role controlling specific groups of microorganisms in the soil associated with the plant.