Biology subjects

Jessen, G. L.

Publications and source records attributed to Jessen, G. L..

3 recordsLinked to original sources

bioRxiv2024

Multi-compartment impact of micropollutants and particularly antibiotics on bacterial communities using environmental DNA at river basin-level

Microbial communities, in particular bacterial assemblies, play pivotal roles in sustaining biogeochemical processes within ecosystems. They are also responsible for the degradation of toxic chemicals, while the development of resistance against antimicrobial drugs jeopardises human health. Bacterial communities respond to environmental conditions with diverse structural and functional changes depending on their compartment (water, biofilm or sediment), type of environmental stress, and type of pollution to which they are exposed. In this study, we combined amplicon sequencing of bacterial 16S rRNA genes from water, biofilm, and sediment samples collected in the anthropogenically impacted River Aconcagua basin (Central Chile, South America), in order to evaluate whether micropollutants alter bacterial community structure and functioning based on the type and degree of chemical pollution. Furthermore, we evaluated the potential of bacterial communities from differently polluted sites to degrade contaminants. Our results show a lower diversity at sites impacted by agriculture and urban areas, featuring high loads of micropollution with pesticides, pharmaceuticals and personal care products as well as industrial chemicals. Nutrients, antibiotic stress, and micropollutant loads explain most of the variability in the sediment and biofilm bacterial community, showing a significant increase of bacterial groups known for their capabilities to degrade various organic pollutants, such as Nistrospira and also selecting for taxa known for antibiotic resistance such as Exiguobacterium and Planomicrobium. Moreover, potential ecological functions linked to the biodegradation of toxic chemicals at the basing level revealed significant reductions in ecosystem-related services in sites affected by agriculture and wastewater treatment plant (WWTP) discharges across all investigated environmental compartments. Finally, we suggest transitioning from simple concentration-based assessments of environmental pollution to more meaningful toxic pressure values in order to comprehensively evaluate the role of micropollutants at the ecological (biodiversity) level. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/587215v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@4dfdc9org.highwire.dtl.DTLVardef@50c884org.highwire.dtl.DTLVardef@19c62aforg.highwire.dtl.DTLVardef@12db45_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIMicropollutant mixtures altered bacterial community structure and functioning C_LIO_LIAntibiotic stress correlated significantly with changes in community structure C_LIO_LIReduction of ecological functions related to the degradation of contaminants C_LIO_LIWater, biofilm, and sediments relevant for microbial ecotoxicology C_LI

microbiology↗

bioRxiv2023

Complex organic matter degradation by secondary consumers in chemolithoautotrophy-based subsurface geothermal ecosystems

Microbial communities in terrestrial geothermal systems often contain chemolithoautotrophs with well-characterized distributions and metabolic capabilities. However, the extent to which organic matter produced by these chemolithoautotrophs supports heterotrophs remains largely unknown. Here we compared the abundance and activity of peptidases and carbohydrate active enzymes (CAZymes) that are predicted to be extracellular identified in metagenomic assemblies from 63 springs in the Central American and the Andean convergent margin (Argentinian backarc of the Central Volcanic Zone), as well as the plume-influenced spreading center in Iceland. All assemblies contain two orders of magnitude more peptidases than CAZymes, suggesting that the microorganisms more often use proteins for their carbon and/or nitrogen acquisition instead of complex sugars. The CAZy families in highest abundance are GH23 and CBM50, and the most abundant peptidase families are M23 and C26, all four of which degrade peptidoglycan found in bacterial cells. This implies that the heterotrophic community relies on autochthonous dead cell biomass, rather than allochthonous plant matter, for organic material. Enzymes involved in the degradation of cyanobacterial- and algal-derived compounds are in lower abundance at every site, with volcanic sites having more enzymes degrading cyanobacterial compounds and non-volcanic sites having more enzymes degrading algal compounds. Activity assays showed that many of these enzyme classes are active in these samples. High temperature sites (> 80{degrees}C) had similar extracellular carbon-degrading enzymes regardless of their province, suggesting a less well-developed population of secondary consumers at these sites, possibly connected with the limited extent of the subsurface biosphere in these high temperature sites. We conclude that in < 80{degrees}C springs, chemolithoautotrophic production supports heterotrophs capable of degrading a wide range of organic compounds that do not vary by geological province, even though the taxonomic and respiratory repertoire of chemolithoautotrophs and heterotrophs differ greatly across these regions.

biochemistry↗

bioRxiv2019

Wide distribution of phage that infect freshwater SAR11 bacteria

Fonsibacter (LD12 subclade) are among the most abundant bacterioplankton in freshwater ecosystems. These bacteria belong to the order Pelagibacterales (SAR11) and are related to Pelagibacter (marine SAR11) that dominate many marine habitats. Although a handful of Pelagibacter phage (Pelagiphage) have been described, no phage that infect Fonsibacter have been reported. In this study, a complete Fonsibacter genome containing a prophage was reconstructed from metagenomic data. A circularized and complete genome related to the prophage, referred to as uv-Fonsiphage-EPL, shows high similarity to marine Pelagiphage HTVC025P. Additionally, we reconstructed three complete and one draft genome of phage related to marine Pelagiphage HTVC010P, and predicted a lytic strategy. The similarity in codon usage and co-occurrence patterns of HTVC010P-related phage and Fonsibacter suggested that these phage infect Fonsibacter. Similar phage were detected in Lake Mendota, Wisconsin, where Fonsibacter is also present. A search of related phage revealed the worldwide distribution of some genotypes in freshwater ecosystems, suggesting their substantial role in shaping indigenous microbial assemblages and influence on biogeochemical cycling. However, the uv-Fonsiphage-EPL and one lineage of HTVC010P-related phage have a more limited distribution in freshwater ecosystems. Based on this, and their close phylogenetic relatedness with Pelagiphage, we predict that they transitioned from saline into freshwater ecosystems comparatively recently. Overall, the findings provide insights into the genomic features of phage that infect Fonsibacter, and expand understanding of the ecology and evolution of these important bacteria.

microbiology↗