Biology subjects

Garcia-Oliva, F.

Publications and source records attributed to Garcia-Oliva, F..

3 recordsLinked to original sources

bioRxiv2026

Depth-Resolved Microbial Community Structure and Phosphorus Deficiency Across a 34-cm Mat-Sediment Core in Poza Roja 2, Cuatrocienegas

Stratified benthic deposits offer crucial modern analogs for Precambrian biogeochemical dynamics, yet whether the vertical organization of deep sedimentary columns reflects depositional history, present-day geochemical conditions, or both remains poorly understood, particularly under extreme oligotrophy. Here, we present a depth-resolved exploratory survey of a continuous 34-cm sediment core partitioned into 11 discrete horizons (L1 to L11) from Poza Roja 2, an alkaline, sub-hypersaline pond in the Cuatro Cienegas Basin, Mexico. Integrating physical stratigraphy, organic carbon and nutrient stoichiometry, and 16S rRNA gene metabarcoding, we evaluated down-core microbial community structure alongside acute phosphorus scarcity. Molar C:Po and N:Po ratios exceeded canonical Redfield proportions (106:16:1) in every layer, by up to 48.5-fold and 87.8-fold, respectively, both peaking in layer L4. Unconstrained ordination (PCoA) and hierarchical clustering grouped the layers into three compositional zones: upper (L2-L4), intermediate (L5-L6), and basal (L8-L11), with L1 and L7 occupying transitional positions. Archaea accounted for 31.0% of prokaryotic reads, ranging from 8.3% (L5) to 43.7% (L9), and were dominated by SM1-50 (Thermoplasmatota) and Halobacteriota. The phototrophic heliobacterium Heliorestis peaked in the intermediate zone (47.6% of bacterial reads in L6). Constrained Redundancy Analysis models lacked statistical significance (P >= 0.12), highlighting the exploratory nature of a single core (n = 11). This pilot characterization provides a baseline for understanding deep biogenic archives under severe nutrient limitation.

microbiology↗

bioRxiv2025

The Hidden Guardians: From Active Cells to Spores in a 20-Year Journey into the Microbial Heart of a Drying Oasis

The Cuatro Cienegas Basin (CCB) in Coahuila, Mexico, a Ramsar Wetland, is historically characterized by a unique network of pozas renowned for microbial diversity. Among them, the Churince hydrological system epitomized a delicate balance of endemic species, stable water regimes, and complex microbial assemblages. Over the last five decades, however, Churince underwent a catastrophic [~]99% water loss, primarily driven by intensive agricultural extraction. We showed that this desiccation not only caused hydrological collapse but also reshaped microbial physiology. Longitudinal records from 2007 to 2019, combining satellite imagery, piezometer data, and field observations, documented progressive declines beginning in 2011 and culminating in the complete desiccation of the Intermediate Lagoon by 2019. To track microbial responses, we employed a cultivation-based approach distinguishing vegetative cells from dormant spores, enabling direct physiological assessment of metabolic activity versus dormancy. As water diminished, spore abundance increased relative to vegetative forms, revealing a shift toward dormancy as a survival strategy under extreme desiccation. Complementary mesocosm experiments showed that reduced diversity further enriched for spores, illustrating how loss of community complexity accelerated dormancy and erosion of active assemblages. Together, these results demonstrated that habitat loss triggered microbial community change, which we frame as a microbial extension of the ecological concept of community disassembly. By combining two decades of hydrological evidence with microbial physiology, this study fills a critical gap in understanding how wetland drying selects for microbial dormancy. These findings underscore the urgent need for sustainable agriculture and integrated water management to preserve biodiversity and ecosystem function in threatened wetlands worldwide.

microbiology↗

bioRxiv2020

Testing the two-step model of plant root microbiome acquisition under multiple plant species and soil sources

The two-step model for plant root microbiomes considers soil as the primary microbial source. Active selection of the plants bacterial inhabitants results in a biodiversity decrease towards roots. We collected in situ ruderal plant roots and their soils and used these soils as the main microbial input for single genotype tomatoes grown in a greenhouse. We massively sequenced the 16S rRNA and shotgun metagenomes of the soils, in situ plants, and tomato roots. Tomato roots did follow the two-step model, while ruderal plants did not. Ruderal plants and their soils are closer than tomato and its soil, based on protein comparisons. We calculated a metagenomic tomato root core of 51 bacterial genera and 2,762 proteins, which could be the basis for microbiome-oriented plant breeding programs. The tomato and ruderal metagenomic differences are probably due to plant domestication trade-offs, impacting plant-microbe interactions.

microbiology↗