Biology subjects

Kalathera, J.

Publications and source records attributed to Kalathera, J..

2 recordsLinked to original sources

bioRxiv2023

Mass lysis of bacterial predators drives the enrichment of antibiotic resistance in soil microbial communities

While studies on anthropogenic activities and antibiotic resistance are numerous, the impact of microbial interactions on resistance in complex communities remains uncertain. Here we demonstrate a correlation between the presence of Myxococcus xanthus in natural soil communities and the abundance of antibiotic-resistant bacteria. Further, introducing M. xanthus isolates also enriches antibiotic resistance. This is due to the mass lysis of M. xanthus cells, which results in a toxic environment that fosters the proliferation of pre-existing resistant bacteria rather than de novo resistance evolution. Metagenomic analysis revealed that this enrichment is not limited to the tested antibiotics in culture-based methods, indicating its broader relevance. Crucially, these findings go beyond laboratory settings, showing M. xanthus introduction enriches resistant isolates in natural soil communities. Finally, we demonstrate that the mass lysis of M. xanthus cells during starvation-induced development--key aspect of the lifecycle of M. xanthus--also results in the enrichment of antibiotic resistance in soil communities. Together, we demonstrate how life-history traits in bacterial predators, like M. xanthus, significantly impact antibiotic resistomes in nature. This study also highlights the complex dynamics at play in the evolution and maintenance of antibiotic resistance, emphasizing the role of interspecies interactions in shaping antibiotic resistance profiles.

evolutionary biology↗

bioRxiv2023

Differential evolution of cooperative traits in aggregative multicellular bacterium Myxococcus xanthus driven by varied population bottleneck sizes

Repeated population bottlenecks influence the evolution and maintenance of cooperation1,2. However, it remains unclear whether bottlenecks select all cooperative traits expressed by an organism or only a subset of them. Myxococcus xanthus, a social bacterium, displays multiple cooperative traits, including growth, predation, sporulation in multicellular fruiting bodies, and germination 3-6. Using laboratory evolution experiment, we investigated the effect of repeated stringent versus relaxed population bottlenecks on the evolution of these four cooperative traits when they were all under selection. We found that only fruiting body formation and growth were positively selected under the stringent regimen, while the other two traits were negatively selected. The pattern was reversed in the relaxed regimen. Additionally, the relaxed regimen led to a significant increase in fitness when competed against ancestors across the entire lifecycle, whereas the stringent treatment did not change competitive fitness. Genomic analysis revealed that mutations in {sigma}54 interacting protein and DNA-binding response regulator protein are linked with the changes observed in stringent and relaxed regimens respectively. Further, similar trade-offs are also seen among natural populations of M. xanthus. Overall, we demonstrate that different bottleneck sizes drive the evolution of lifecycles in distinct manners, driven by trade-offs between cooperative life history traits.

evolutionary biology↗