Biology subjects

Krzynowek, A.

Publications and source records attributed to Krzynowek, A..

3 recordsLinked to original sources

bioRxiv2025

PlasticEnz: An integrated database and screening tool combining homology and machine learning to identify plastic-degrading enzymes in meta-omics datasets

PlasticEnz is a new open-source tool for detecting plastic-degrading enzymes (plastizymes) in metagenomic data by combining sequence homology-based search with machine learning. It integrates custom Hidden Markov Models, DIAMOND alignments, and polymer-specific classifiers trained on ProtBERT embeddings to identify candidate depolymerases from contigs, genomes, or protein sequences. PlasticEnz supports 11 plastic polymers with ML classifiers for PET and PHB, achieving F1 > 0.7 on independent test sets. Applied to plastic-exposed microcosms and field metagenomes, the tool recovered known PETases and PHBases, distinguished plastic-contaminated from pristine environments, and clustered predictions with validated reference enzymes. PlasticEnz is fast, scalable, and user-friendly, providing a robust framework for exploring microbial plastic degradation potential in complex communities. Author SummaryPlastic pollution is a global problem, and one promising solution is using microbes that can break them down. However, finding the enzymes responsible for this in complex environmental samples is not easy. We developed PlasticEnz, a free and easy-to-use tool that helps researchers identify plastic-degrading enzymes or "plastizymes" in metagenomic data. PlasticEnz combines traditional sequence similarity search methods with machine learning models trained on known plastizymes. It works with protein sequences, contigs, or genomes with ML components optimised for detection of two common plastic polymers: PET and PHB. We tested PlasticEnz on both controlled lab experiments and real-world samples from plastic-polluted soils and clean environments. The tool successfully identified known plastic-degrading enzymes and even helped distinguish between polluted and pristine sites. By making plastizyme detection more accessible, PlasticEnz enables researchers to better explore the microbial potential for plastic degradation, which could support future bioremediation efforts.

bioinformatics↗

bioRxiv2024

Effects of microplastics on Daphnia-associated microbiomes in situ and in vitro

Microplastics (MP) pollution in aquatic environments is a growing global concern. MP, defined as plastic fragments smaller than 5mm, accumulate in freshwater reservoirs, especially those located in urban areas, impacting the resident biota. This study investigated the effects of MP on the performance and microbiome of Daphnia, a keystone organism in freshwater ecosystems, through both in situ sampling of freshwater ponds and a controlled 23-day in vitro exposure experiment. Using 16S rRNA gene sequencing and whole-genome shotgun sequencing, the microbiome community composition and functional capacity was analysed and correlated with MP pollution levels. Urban ponds showed higher MP concentrations in both water and sediment than natural ponds with significant differences in MP composition. Bacterioplankton communities were more diverse and richer than the Daphnia-associated microbiomes. Overall, the in situ study showed that the composition of the Daphnia-associated community co-varied with high MP levels but also with temperature and redox potential. Moreover, the functional analysis showed increased relative abundances of PET degradation enzymes and antibiotic resistance genes (ARGs) in microbiomes from high-MP ponds. In the in vitro experiment, the bacterioplankton inoculum source significantly influenced Daphnia survival and microbiome composition. Daphnia exposed to high MP concentrations inoculated with bacterioplankton pre-exposed to MP exhibited significantly higher survival rates, suggesting potential adaptive benefits from MP-associated microbiomes. Network analysis identified specific taxa associated with MP within the Daphnia microbiome. Our study suggests adaptive responses of freshwater host-associated microbiomes to MP pollution including biodegradation with potential benefits for the host.

ecology↗

bioRxiv2023

Starvation response strategies of human gut bacteria Bacteroides thetaiotaomicron and Roseburia intestinalis and their impact on co-culture dynamics

Bacterial growth often alters the environment, which in turn can impact interspecies interactions among bacteria. Here, we used an in vitro batch system containing mucin beads to emulate the dynamic host environment and to study its impact on the interactions between two abundant and prevalent human gut bacteria, the primary fermenter Bacteroides thetaiotaomicron and the butyrate producer Roseburia intestinalis. By combining machine learning and flow cytometry, we found that the number of viable B. thetaiotaomicron cells decreases with glucose consumption due to acid production, while R. intestinalis survives post-glucose depletion by entering a slow growth mode. Both species attach to mucin beads, but only viable cell counts of B. thetaiotaomicron increase significantly. The number of viable co-culture cells varies significantly over time compared to those of monocultures. A combination of targeted metabolomics and RNA-seq showed that the slow growth mode of R. intestinalis represents a diauxic shift towards acetate and lactate consumption, whereas B. thetaiotaomicron survives glucose depletion and low pH by foraging on mucin sugars. In addition, most of the mucin monosaccharides we tested inhibited the growth of R. intestinalis but not B. thetaiotaomicron. We encoded these causal relationships in a kinetic model, which reproduced the observed dynamics. In summary, we explored how R. intestinalis and B. thetaiotaomicron respond to nutrient scarcity and how this affects their dynamics. We highlight the importance of understanding bacterial metabolic strategies to effectively modulate microbial dynamics in changing conditions.

microbiology↗