Examinando por Materia "Morfotipos"

Mostrando 1 - 1 de 1
  • No hay miniatura disponible
    Publicación
    Cultivable Microbial Community Structure Along a Light Gradient in a Tropical Volcaniclastic Cave
    (Universidad EAFIT, 2026-05-26) Correa-Gallego, Sebastián; Pinel Peláez, Nicolás
    Cave environments compress sharp changes in light, energy input, surface connectivity, and substrate heterogeneity into short spatial gradients. This makes them powerful natural systems for examining microbial responses to environmental heterogeneity. Yet the cultivable microbial fraction of tropical volcaniclastic caves remains poorly resolved. Organal-type pseudokarstic caves of the Colombian Andes are especially underrepresented in cave microbiology, despite their distinctive geomorphology and hydrological connection to montane landscapes. Here, I tested whether sector identity along the light-defined zonation of the Organal San Antonio, a tropical volcaniclastic cave at ~2350 m a.s.l. in Támesis, Antioquia, is associated with differences in the R2A-recoverable microbial fraction of cave sediments. Two cultivation experiments were conducted: an initial binary Light–Dark comparison and a primary three-sector experiment resolving Entrance, Transition, and Dark zones with aliquot-level gravimetric normalization, 15 °C incubation, and a twenty-three-cluster operational phenotypic crosswalk. In the primary experiment, cultivable density followed a step-like pattern across the gradient: Entrance and Transition sediments supported approximately 5.1–5.6 × 10⁵ CFU g⁻¹ field-moist sediment, whereas the fully aphotic Dark sector supported approximately 8.9 × 10⁴ CFU g⁻¹, a roughly sixfold reduction (η² = 0.652). Local morphotype-cluster richness and evenness showed no detectable sector-level differences, but community composition partitioned strongly with zonation (PERMANOVA R² = 0.573, p = 0.001) under balanced multivariate dispersion. The Transition sector supported a distinctive set of zone-restricted phenotypic clusters, contributing approximately 27% of its cultivable community, while the Dark sector combined reduced density with moderate abundance of aphotic-restricted clusters. Preliminary Gram, KOH, catalase, and microscopic characterization of representative isolates revealed Gram-level uncertainty and cellular heterogeneity within several cross-sector colony phenotypes, confirming that the morphotype crosswalk is useful for community-level comparison but not equivalent to taxonomic resolution. These results establish a first spatially resolved cultivable baseline for an organal-type tropical volcaniclastic cave and indicate that sector identity along a light-defined cave gradient is associated with lower cultivable density in the aphotic sector and strong morphotype-level compositional turnover, without a parallel decline in local morphotype-cluster diversity. The study defines the scale at which these patterns are valid: the aerobic, low-temperature, dilute-R2A cultivable fraction of sediment-associated microorganisms.