Speaker
Prof. Morten Kam Dahl Dueholm, Department of Chemistry and Bioscience, Aalborg University, Denmark

Please contact seminars@cluttereawag.ch for access details to join online via zoom.

Abstract

Anaerobic digestion represents a key technology for the transformation of organic waste into renewable energy (biogas), and relies on complex microbial communities that work in concert to degrade the complex substrates into methane and CO2. Unfortunately, our knowledge of the diversity and function of the bacteria and archaea in these communities is still poor. Here, we sequenced more than half a million high-quality, full-length 16S rRNA gene sequences from 285 anaerobic digesters (ADs) across the world. The sequences were processed into full-length 16S rRNA amplicon sequence variants (FL-ASVs) which were added to the MiDAS 4 database for bacteria and archaea in wastewater treatment systems to create ‘MiDAS 5’. The expansion of the MiDAS database significantly increased the coverage for bacteria and archaea in anaerobic digesters worldwide, leading to an improved rate of genus and species-level classification. Taking advantage of MiDAS 5, we carry out an amplicon-based, global-scale microbial community profiling of the sampled ADs using three common sets of primers targeting different regions of the 16S rRNA gene in bacteria and/or archaea. We revealed how environmental conditions and biogeography shape the anaerobic digester microbiota. We also identify core and conditionally rare or abundant taxa, encompassing less than 1000 genera and species. These represent approximately 83-99% and 10-64% of the accumulated read abundance across samples depending on the amplicon primers used, respectively. Finally, we examined the global diversity of functional groups with known importance for the AD process.