Biology subjects

Balcazar, J. L.

Publications and source records attributed to Balcazar, J. L..

2 recordsLinked to original sources

bioRxiv2026

Anti-defense systems of viral communitie vary with genomic traits, host immunity and environmental stress

Abstract: Background Despite the ecological importance of viral anti-defense systems (ADS), yet how viral ADS repertoires vary across microbial ecosystems remains poorly understood. Here, we integrated global virus datasets with metagenomes from heavy metal-contaminated soils and chromium-stress microcosms to investigate ecological determinants of viral ADS. Results We found that ADS repertoires were constrained by viral genome capacity, with most ADS-carrying viruses encoded a single system, whereas multi-ADS occurred mainly in larger genomes. Viral lifestyle partitioned ADS, with temperate viruses enriched in ADS targeting early-stage defenses and virulent viruses preferentially encoding ADS against mid- and late-stage defense. ADS composition also varied by host lineage and across habitats, linking viral ADS repertoires to host immune landscapes and ecosystem-specific viral strategies. Moreover, along the heavy metal contamination gradient, changes in the prevalence of ADS-carrying viruses occurred alongside shifts in prokaryotic defense profiles. In addition, expanded ADS repertoires may further increase dissemination potential of MGE-borne adaptive genes, highlighting viral ADS as a potential contributor to the adaptive evolution of microbial community. Conclusions These findings reveal that viral ADS are shaped by genomic traits, host immunity and environmental stress, with implications for virus-host interaction and microbial adaptive evolution. More broadly, this study extends anti-defense research beyond individual virus-host systems, offering an integrative, community-level perspective to guide future studies testing whether and how virus-prokaryote immune interactions contribute to microbial community dynamics and evolution in changing environments.

microbiology↗

bioRxiv2025

On-site microbial community analysis in rivers: integrating autonomous sampling with a portable sequencing workflow

Studies focused on bacterial diversity in rivers often face significant limitations. Traditional sampling approaches frequently overlook spatial and temporal variability at the reach scale. Molecular techniques, such as metabarcoding and metagenomics, can partially address this issue by providing deeper insights. However, this approach usually involves highly specialized laboratories and high costs, making large-scale and long-term monitoring of river networks unfeasible in most cases. Thus, we developed a methodology based on remote-controlled boats, allowing the collection of integrated samples in freshwater ecosystems. Combined with a portable laboratory, this approach enabled the development of new surface water monitoring strategies. Here, we describe the operational application of this system for in situ monitoring of bacterioplankton communities across 8 sections of the Ter River (Catalonia, Spain). [To explore its potential, we applied both 16S rRNA gene sequencing using Nanopore technology (MinION) in the field, and shotgun metagenomics using Illumina technology in the laboratory, acknowledging the intrinsic differences between sequencing targets, platforms, and analysis pipelinesMinIONMinION sequencing enabled microbiome characterization and identification of the main bacterial taxa just 72 h after sampling, offering significantly lower costs and reduced manpower requirements. Furthermore, amplification facilitated the full characterization of bacterioplankton diversity along the river, preventing the exclusion of uncommon taxa. While shotgun metagenomics is still necessary for understanding the functional activity of these organisms, our approach provides a cost-effective framework for developing efficient follow-up sampling methodologies.

microbiology↗