Biology subjects

Karst, S. M.

Publications and source records attributed to Karst, S. M..

3 recordsLinked to original sources

bioRxiv2018

ampvis2: an R package to analyse and visualise 16S rRNA amplicon data

SummaryMicrobial community analysis using 16S rRNA gene amplicon sequencing is the backbone of many microbial ecology studies. Several approaches and pipelines exist for processing the raw data generated through DNA sequencing and convert the data into OTU-tables. Here we present ampvis2, an R package designed for analysis of microbial community data in OTU-table format with focus on simplicity, reproducibility, and sample metadata integration, with a minimal set of intuitive commands. Unique features include flexible heatmaps and simplified ordination. By generating plots using the ggplot2 package, ampvis2 produces publication-ready figures that can be easily customised. Furthermore, ampvis2 includes features for interactive visualisation, which can be convenient for larger, more complex data.\n\nAvailabilityampvis2 is implemented in the R statistical language and is released under the GNU A-GPL license. Documentation website and source code is maintained at: https://github.com/MadsAlbertsen/ampvis2\n\nContactMads Albertsen (ma@bio.aau.dk)

bioinformatics↗

bioRxiv2017

Novel prosthecate bacteria from the candidate phylum Acetothermia revealed by culture-independent genomics and advanced microscopy

Members of the candidate phylum Acetothermia are globally distributed and detected in various habitats. However, little is known about their physiology and ecological importance. In this study, an OTU belonging to Acetothermia was detected at high abundance in two full-scale anaerobic digesters. The first closed genome from this phylum was obtained by differential coverage binning of metagenomes and scaffolding with nanopore data. Genome annotation and metabolic reconstruction suggested an anaerobic chemoheterotrophic lifestyle in which the bacterium obtain energy and carbon via fermentation of peptides, amino acids, and simple sugars to acetate, formate, and hydrogen. The morphology was unusual and composed of a central rod-shaped cell with bipolar prosthecae as revealed by fluorescence in situ hybridization combined with confocal laser scanning microscopy, Raman microspectroscopy and atomic force microscopy. We hypothesize that these prosthecae allow for increased nutrient uptake by greatly expanding the cell surface area, providing a competitive advantage under nutrient-limited conditions.

microbiology↗

bioRxiv2017

Identifying the abundant and active microorganisms common to full scale anaerobic digesters

Anaerobic digestion is widely applied to treat organic waste at wastewater treatment plants. Characterisation of the underlying microbiology represents a source of information to develop strategies for improved operation. To this end, we investigated the microbial community composition of thirty-two full-scale digesters over a six-year period using 16S rRNA gene amplicon sequencing. Sampling of the sludge fed into these systems revealed that several of the most abundant populations were likely inactive and immigrating with the influent. This observation indicates that a failure to consider immigration will interfere with correlation analysis and give an inaccurate picture of the active microbial community. Furthermore, several abundant OTUs could not be classified to genus level with commonly applied taxonomies, making inference of their function unreliable. As such, the existing MiDAS taxonomy was updated to include these abundant phylotypes. The communities of individual plants surveyed were remarkably similar - with only 300 OTUs representing 80% of the total reads across all plants, and 15% of these identified as likely inactive immigrating microbes. By identifying the abundant and active taxa in anaerobic digestion, this study paves the way for targeted characterisation of the process important organisms towards an in-depth understanding of the microbial ecology of these biotechnologically important systems.

microbiology↗