Biology subjects

Burkhardt-Holm, P.

Publications and source records attributed to Burkhardt-Holm, P..

3 recordsLinked to original sources

bioRxiv2026

Riverine plastic litter restructures microbial vitamin B12 metabolism and generates functional heterogeneity

Rivers transport most land-derived plastic waste to the ocean, yet how this reshapes microbial metabolic potential remains poorly resolved. We characterized plastisphere and water-column communities across 14 stations along the River Rhine, integrating ATR-FTIR polymer characterization, 16S/18S rRNA amplicon profiles, and 120 metagenome-assembled genomes. Plastisphere communities were taxonomically distinct from water communities (PERMANOVA R = 0.258, p = 0.0001) and, despite no overall shift in functional centroid (R = 0.245, p = 0.125), were markedly more heterogeneous in functional composition across sites (permutest p = 0.0047). Aerobic corrin ring synthesis, the core B12 biosynthetic pathway, was among the most differentially dispersed functions and enriched on plastic at all seven paired stations (Wilcoxon exact test, W = 3, p = 0.004079). This signal coincided with a diatom-dominated eukaryotic plastisphere community; diatoms cannot synthesize B12 and depend on bacterial provisioning, linking functional and taxonomic restructuring via a plausible cross-domain mechanism. Plastisphere communities were also less tightly coupled to the river's dissolved nutrient gradient than water communities (envfit R = 0.64 vs. 0.82). Together, these results indicate that riverine plastic litter does not merely accumulate biomass passively but actively restructures specific metabolic capacities of its colonizers, exemplified by vitamin B12 metabolism.

microbiology↗

bioRxiv2025

Microbial Colonisation of Polyethylene in Offshore Marine Environments: Insights from the Southern and South Atlantic Oceans.

Plastic debris is a pervasive environmental pollutant with polyethylene (PE) among the most abundant floating polymers in marine environments. While microbial colonisation of marine plastics has been extensively documented, studies predominantly focus on Northern Hemisphere coastal waters, leaving microbial dynamics in remote Southern Hemisphere oceanic regions poorly characterised. In this study, we employed ribosomal amplicon sequencing and shotgun metagenomics to characterise microbial colonisation patterns on PE films deployed during two oceanographic transects across the Southern Ocean and South Atlantic Ocean over 14 days of incubation. We evaluated environmental factors including geographic location, incubation regime (indoor/outdoor), and exposure conditions (UV radiation, temperature, and salinity) as potential drivers shaping microbial communities. Our results demonstrate clear differentiation in microbial community structure driven primarily by transect location and environmental conditions, rather than material type. Dominant taxa identified included Pseudomonadota known for hydrocarbon degrading capabilities and Cyanobacteria associated with phototrophic traits. Metagenomic analyses revealed enrichment of functional pathways linked to biofilm formation, hydrocarbon degradation, and iron metabolism. This study expands the current understanding of microbial colonisation processes on marine plastics, highlighting environmental factors influencing early plastisphere community structure and functional potential in understudied oceanic regions.

microbiology↗

bioRxiv2025

Success factors for inter- and transdisciplinary research. Lessons from a decade of studies on invasive aquatic species.

Ecological research for environmental management occupies a unique and demanding space at the interface of societal needs and academic research. Projects in this space must reconcile stakeholder involvement and real-world applicability with academic requirements such as disciplinary excellence and career advancement. Here, we present a post-hoc account of a 12-year inter- and transdisciplinary research initiative on the management of invasive gobies in central Europe. Based on a synthesis of inputs, outputs, and outcomes, we distill facilitating conditions that increased the likelihood of the project reaching its goals across political, administrative, societal, institutional, team, and individual levels. Rather than "success factors" in a deterministic sense, these are conditions and practices that created a favorable environment for both academic and applied outcomes. The interaction of these domains created windows of opportunity that could be seized for both scientific progress and societal impact. By reflecting from the perspective of natural scientists directly engaged in such a project, we aim to complement existing social science frameworks with an insider view of the lived realities of inter- and transdisciplinary collaboration. Our retrospective can inform policy makers, funders, and institutions seeking to create enabling environments for interface research, and may support fellow natural scientists in proactively preparing the ground for their own initiatives.

scientific communication and education↗