Biology subjects

Capkova, K.

Publications and source records attributed to Capkova, K..

3 recordsLinked to original sources

bioRxiv2026

Utilization of cyanobacterial siderophore cyanochelin B by phylogenetically distant heterotrophs suggest its role in mediating microbial interactions

Cyanobacteria are key prokaryotic primary producers in diverse ecosystems, yet the role of cyanobacterial siderophores in shaping their associated microbiomes remains unexplored. Our study demonstrates the benefits provided to the heterotrophic co-habitants of filamentous cyanobacteria in terrestrial microbial biofilms, focusing on the recently discovered widespread siderophores cyanochelins. To address the acceptance of cyanochelin B (CychB) across multiple bacterial classes, we first investigated its role in providing iron to a model siderophore producer P. aeruginosa PAO1 and selected Pseudomonas natural isolates, which were found to utilize CychB under iron limiting conditions while downregulating endogenous siderophore production. In response to CychB, PAO1 expresses a siderophore internalization cluster, which is localized in multiple Pseudomonas natural isolates. Using metagenome analysis, we characterized the bacterial community recruited along with CychB producing Phormidesmis cyanobacteria under long-term iron starvation. Potential CychB acceptor bacteria associated with the CychB producer were predominantly lacking endogenous siderophore machineries. Using siderophore selective pressure, we isolated a genuine CychB acceptor, gram-negative bacterium Methyloversatilis sp. S146 and demonstrated that its genome hosts an iron processing cluster overexpressed after CychB feeding, recognizing Methyloversatilis as a candidate for further mechanistic investigation of iron acquisition-driven microbial interactions. Our results indicate that CychB supports a specific subset of co-habiting heterotrophic bacteria during iron starvation, further emphasizing the role of cyanobacteria as key drivers of nutrient flows within globally important microbial soil crust ecosystems, supporting microbial life in nutrient-limited environments. These findings provide a mechanistic foundation to elucidate the role of cyanochelins as a public good in these communities.

microbiology↗

bioRxiv2026

Holobiomes in succession: post-glacial microbial communities are structured by hosts, time and habitat heterogeneity

O_LIGlacier forefields in the high-desert region of Ladakh (northwestern Himalaya) are colonized by a variety of interdependent organisms, including lichens, prokaryotes, fungi, mosses, and vascular plants, along a successional gradient. Together with bulk soil, these hosts and their associated microorganisms form a broader microbial metacommunity (holobiome) whose structure, interactions and functions remain poorly underexplored in one of the Earths most extreme and climate-sensitive environments. C_LIO_LIUsing a multidisciplinary approach combining glacial chronosequence transects, GIS-derived topographic variables, soil properties, and plot cover measurements, we assessed the abiotic and biotic factors influencing bacterial and fungal communities sequenced from different hosts and bulk soil (hereafter sources). Microbial composition was primarily shaped by source identity, though certain sources, such as biological soil crusts (BSCs), mosses, and plant rhizospheres, also showed relationships with moraine age in either bacterial or fungal communities. C_LIO_LIBacterial and fungal community congruence was tested using Procrustes analyses, revealing that mosses maintained tightly coupled inter-kingdom relationships throughout the glacier forefields. However, the degree of congruence in plant rhizospheres and bulk soils was influenced by topographic variation and moraine age, respectively. C_LIO_LICo-occurrence network analyses revealed that early successional microbial communities were assembled more stochastically, with bacteria being more interconnected than fungi. In contrast, late successional stages were more compartmentalized, being more structurally stabile, likely driven by increased plant cover and functional redundancy among microbial taxa. C_LIO_LIKeystone bacterial and fungal taxa were identified in plant rhizospheres and bulk soil using a dual-criteria approach related to inter-kingdom congruence and network node eigenvalues. Furthermore, some of these taxa were associated with environmental factors, suggesting topographic heterogeneity and successional age can promote or deter the influence of keystone taxa. C_LIO_LISynthesis: This study reveals the impact of both macroorganism colonization (i.e. plants, mosses, and lichens) and microcommunity establishment (BSCs and bulk soil), as abiotic and biotic sources, on microbial metacommunity assembly in glacier forefields. By adopting a broader approach across different spatial scales, we demonstrate that while plant colonization plays a central role in shaping microbial metacommunities, its effects are modulated by topographic variation along the chronosequence. C_LI

microbiology↗

bioRxiv2025

Year-round rhythms: alpine plant species modulate soil and microbial dynamics during the growing season and under the snow.

O_LISoil-plant-microbe interactions are integral throughout most terrestrial ecosystems, yet the importance of plant phenology and seasonal dynamism upon these relationships remains unknown. Given the pronounced seasonality of alpine environments, we sampled 8 plant species occurring in two habitats (alpine meadow and subnival zone) across four seasons (including snow-covered winter) in the Central Eastern Alps to determine the plant growth strategies and plant nutrient parameters which closely couple with rhizosphere microbial parameters. C_LIO_LIIn subnival locations, plants exhibited stronger seasonal changes among leaf and root tissue nutrient concentrations and non-structural carbohydrates (NSCs) compared to those in lower elevation alpine meadows. However, rhizosphere microbial parameters (microbial biomass (MBC), extracellular enzymes, and community composition) demonstrated more seasonal changes in the alpine meadow locations. C_LIO_LIA phenological delay was observed in bacterial and fungal communities of the subnival zone, with peak plant rhizosphere differentiation occurring later in the season than in alpine meadows. Therefore, the prolonged cold conditions and shorter growing season in higher elevations likely add a temporal aspect to the commonly used elevational gradient approach, which is not often considered. C_LIO_LIMBC and enzymatic potential within the rhizosphere were high across all plant species in the alpine meadow during the winter sampling, despite notable differences in microbial community composition. In contrast, winter rhizosphere communities did not differ between plant species in subnival locations, although one species, Oxyria digyna, demonstrated much higher microbial activity along with higher NSCs and root N, suggesting some alpine plant species may acquire nutrients through microbial interactions during snow-covered winter periods. C_LIO_LISynthesis: This study provides the first look at the annual phenology of multiple alpine plant species and their associated rhizosphere microbiome. Our results demonstrate that seasonal microbial dynamics are highly influenced by abiotic factors (soil and microclimatic conditions), but plants are able to modulate these conditions through growth and nutrient acquisition strategies. Taken together, seasonality and independent plant species effects cannot be overlooked when assessing habitat nutrient cycling and ecosystem stability. C_LI

microbiology↗