Browsing by Author "Manzano, Marlene"
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- ItemEarly successional patterns of bacterial communities in soil microcosms reveal changes in bacterial community composition and network architecture, depending on the successional condition(2017) Rodriguez-Valdecantos, Gustavo; Manzano, Marlene; Sanchez, Raimundo; Urbina, Felipe; Hengst, Martha B.; Antonio Lardies, Marco; Ruz, Gonzalo A.; Gonzalez, BernardoSoil ecosystem dynamics are influenced by the composition of bacterial communities and environmental conditions. A common approach to study bacterial successional dynamics is to survey the trajectories and patterns that follow bacterial community assemblages; however early successional stages have received little attention. To elucidate how soil type and chemical amendments influence both the trajectories that follow early compositional changes and the architecture of the community bacterial networks in soil bacterial succession, a time series experiment of soil microcosm experiments was performed. Soil bacterial communities were initially perturbed by dilution and subsequently subjected to three amendments: application of the pesticide 2,4-dichlorophenoxyacetic acid, as a pesticide-amended succession; application of cycloheximide, an inhibitor affecting primarily eukaryotic microorganisms, as a eukaryotic-inhibition bacterial succession; or application of sterile water as a non-perturbed control. Terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA gene isolated from soil microcosms was used to generate bacterial relative abundance datasets. Bray-Curtis similarity and beta diversity partition-based methods were applied to identify the trajectories that follow changes in bacterial community composition. Results demonstrated that bacterial communities exposed to these three conditions rapidly differentiated from the starting point (less than 12 h), followed different compositional change trajectories depending on the treatment, and quickly converged to a state similar to the initial community (48-72 h). Network inference analysis was applied using a generalized Lotka-Volterra model to provide an overview of bacterial OTU interactions and to follow the changes in bacterial community networks. This analysis revealed that antagonistic interactions increased when eukaryotes were inhibited, whereas cooperative interactions increased under pesticide influence. Moreover, central OTUs from soil bacterial community networks were also persistent OTUs, thus confirming the existence of a core bacterial community and that these same OTUs could plastically interact according to the perturbation type to quickly stabilize bacterial communities undergoing succession.
- ItemExclusion of small mammals and lagomorphs invasion interact with human-trampling to drive changes in topsoil microbial community structure and function in semiarid Chile(2018) Alfaro, Fernando D.; Manzano, Marlene; Abades T., Sebastián R.; Trefault Carrillo, Nicole Natalie; De la Iglesia Cabezas, Rodrigo Alonso; Gaxiola Alcantar, Aurora; Marquet, P. A. (Pablo A.); Gutiérrez, Julio R.; Meserve, Peter L.; Kelt, Douglas A.; Belnap, Jayne; Armesto, Juan J.
- ItemAzorella Cushion Plants and Aridity are Important Drivers of Soil Microbial Communities in Andean Ecosystems(2021) Rodriguez-Echeverria, Susana; Delgado-Baquerizo, Manuel; Morillo, Jose A.; Gaxiola, Aurora; Manzano, Marlene; Marquet, Pablo A.; Gonzalez, Leticia; Cavieres, Lohengrin A.; Pugnaire, Francisco I.; Armas, CristinaCushion plants are specialized keystone species of alpine environments that can have a positive effect on ecosystem structure and function. However, we know relatively little about how cushion plants regulate the diversity and composition of soil microbial communities, major drivers of soil processes and ecosystem functioning. Identifying what factors drive the diversity and composition of soil microbial communities in high-elevation ecosystems is also fundamental to predict how global changes will affect their conservation and the services and functions they provide. Thus, we sampled four sites along the southern Andes following the vegetation belt of Azorella cushion species. The field sites spread along a latitudinal gradient and had contrasting levels of aridity, UV-B radiation, mean temperature and soil properties. Overall, Azorella, as well as aridity and UV-B radiation, were the major drivers of the distribution, composition and diversity of soil microbial communities in the studied ecosystems of the Chilean Andes. UV-B radiation affected particularly soil fungi, while soil properties such as pH, total C and N content, essential predictors of microbial diversity globally, had a much lower effect on the composition of soil microbial communities. Understanding the factors driving the structure and composition of microbial communities, particularly the role of cushion plants and the feedbacks between plant, climate and soil is of uttermost importance for the preservation of the functionality of high-elevation ecosystems threatened by climate change.
- ItemRelationship between soil nutrients and mycorrhizal associations of two Bipinnula species (Orchidaceae) from central Chile(2016) Mujica, María Isabel; Saez, Nicolás; Cisternas, Mauricio; Manzano, Marlene; Armesto, Juan J.; Pérez Trautmann, María Fernanda
- ItemRole of eukaryotic microbiota in soil survival and catabolic performance of the 2,4-D herbicide degrading bacteria Cupriavidus necator JMP134(2007) Manzano, Marlene; Moran, Ana C.; Tesser, Bruno; Gonzalez, BernardoCupriavidus necator ( formerly Ralstonia eutropha) JMP134, harbouring the catabolic plasmid pJP4, is the best-studied 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide degrading bacterium. A study of the survival and catabolic performance of strain JMP134 in agricultural soil microcosms exposed to high levels of 2,4-D was carried out. When C. necator JMP134 was introduced into soil microcosms, the rate of 2,4- D removal increased only slightly. This correlated with the poor survival of the strain, as judged by 16S rRNA gene terminal restriction fragment length polymorphism (T-RFLP) profiles, and the semi-quantitative detection of the pJP4-borne tfdA gene sequence, encoding the first step in 2,4- D degradation. After 3 days of incubation in irradiated soil microcosms, the survival of strain JMP134 dramatically improved and the herbicide was completely removed. The introduction of strain JMP134 into native soil microcosms did not produce detectable changes in the structure of the bacterial community, as judged by 16S rRNA gene T-RFLP profiles, but provoked a transient increase of signals putatively corresponding to protozoa, as indicated by 18S rRNA gene T-RFLP profiling. Accordingly, a ciliate able to feed on C. necator JMP134 could be isolated after soil enrichment. In native soil microcosms, C. necator JMP134 survived better than Escherichia coli DH5 alpha (pJP4) and similarly to Pseudomonas putida KT2442 ( pJP4), indicating that species specific factors control the survival of strains harbouring pJP4. The addition of cycloheximide to soil microcosms strongly improved survival of these three strains, indicating that the eukaryotic microbiota has a strong negative effect in bioaugmentation with catabolic bacteria.
- ItemSoil bacterial community structure of fog-dependent Tillandsia landbeckii dunes in the Atacama Desert(Springer, 2021) Alfaro, Fernando D.; Manzano, Marlene; Almiray, Cristian; García B., Juan Luis; Osses, Pablo; Río López, Camilo del; Vargas Vásquez, Constanza Giovanna; Latorre H., Claudio; Koch, Marcus A.; Siegmund, Alexander; Abades, SebastianThe interplay between plants and soil drives the structure and function of soil microbial communities. In water-limited environments where vascular plants are often absent and only specialized groups of rootless plants grow, this interaction could be mainly asymmetric, with plants supporting nutrients and resources via litter deposition. In this study, we use observational approaches to evaluate the impact of local distribution of Tillandsia landbeckii across elevation on soil bacterial community structure and composition in the Atacama Fog Desert. Tillandsia landbeckii is a plant without functional roots that develops on meter-scale sand dunes and depends mainly on marine fog that transports resources (water and nutrients) from the Pacific Ocean. Our data show that soil bacterial abundance, richness, and diversity were significantly higher beneath T. landbeckii plants relative to bare soils. However, these differences were not significant across T. landbeckii located at different elevations and with different input of marine fog. On the other hand, bacterial community composition was significantly different with T. landbeckii plants across elevations. Further, samples beneath T. landbeckii and bare soils showed significant differences in bacterial community composition. Around 99% of all operational taxonomic units (OTUs) were recorded exclusively beneath T. landbeckii, and only 1% of OTUs were observed in bare soils. These findings suggest that the presence of T. landbeckii promotes significant increases in bacterial abundance and diversity compared with bare soils, although we fail to demonstrate that local-scale changes in elevation can affect patterns of soil bacterial diversity and abundance beneath T. landbeckii.