Summer drought impacts micropredator abundance and microbial food web structure in a rewetted fen peatland
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
Abstract Summer drought significantly affects soil microbiome diversity and functioning, and metabolic interactions in wetland ecosystems, yet its effects on the microbial food web are less understood. We investigated the dynamics of bacterivorous microorganisms and prey bacteria (PBac) in a rewetted fen peatland before, during, and after a summer drought using small subunit ribosomal RNA (SSU rRNA) gene sequencing and quantitative metatranscriptomics. We identified bacterivores including bacteria (e.g. Myxobacteria), protists, and nematodes, as well as. Patescibacteria and,,,andarchaea (PD) having a host-dependent lifestyle. In addition, bacteriophage transcripts were enumerated. The summer drought increased the diversity of bacterivorous protists (BPro) and bacteria (BBac) in the fen, along with decreases in the water level and increases in redox potential. The SSU rRNA transcripts abundance for all bacterivores (with the exception of the PD) increased during the drought, reaching a peak in October. The transcript abundance of all bacterivores remained above predrought level for at least four months after the drought ended. This became more evident when assessing the bacterivore-to-prey-bacteria ratios, with the ratios of aerobic BBac, BPro, and nematode to PBac increasing by more than two-fold compared to predrought. In contrast, the PD and bacteriophage-to-prey ratios remained rather stable. This study provides a holistic view of the diversity and composition of bacterivo
Abstract
Abstract Summer drought significantly affects soil microbiome diversity and functioning, and metabolic interactions in wetland ecosystems, yet its effects on the microbial food web are less understood. We investigated the dynamics of bacterivorous microorganisms and prey bacteria (PBac) in a rewetted fen peatland before, during, and after a summer drought using small subunit ribosomal RNA (SSU rRNA) gene sequencing and quantitative metatranscriptomics. We identified bacterivores including bacteria (e.g. Myxobacteria), protists, and nematodes, as well as. Patescibacteria and,,,andarchaea (PD) having a host-dependent lifestyle. In addition, bacteriophage transcripts were enumerated. The summer drought increased the diversity of bacterivorous protists (BPro) and bacteria (BBac) in the fen, along with decreases in the water level and increases in redox potential. The SSU rRNA transcripts abundance for all bacterivores (with the exception of the PD) increased during the drought, reaching a peak in October. The transcript abundance of all bacterivores remained above predrought level for at least four months after the drought ended. This became more evident when assessing the bacterivore-to-prey-bacteria ratios, with the ratios of aerobic BBac, BPro, and nematode to PBac increasing by more than two-fold compared to predrought. In contrast, the PD and bacteriophage-to-prey ratios remained rather stable. This study provides a holistic view of the diversity and composition of bacterivores in a fen peat microbiome, including the PD and bacteriophages, and suggests a long-lasting impact of summer drought on bacterivore and food web dynamics. The strong responses of aerobic bacterivores may lead to changes in ecosystem functioning through modulated trophic interactions in a changing climate.