Enrichment of anoxic groundwater with different size fractions and media yields contrasting microbial communities
2021 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE credits
Student thesis
Sustainable development
Not refering to any SDG
Abstract [en]
The deep biosphere has been researched extensively the recent years due to the adaptations of microbes living in the harsh environment. Approximately 40-60% of all bacterial cells are found in the terrestrial subsurface, which resides between the first few meters below the surface to several kilometres below the continental surface.
Anoxic groundwater was sampled from Äspö Hard Rock Laboratory and added to media with either acetate or lysed Pseudomonas aeruginosa cells as electron donors. The groundwater was either added unfiltered, 0.45 µm filtered or 0.1 µm filtered. Over time, one culture from each medium was sacrificed each week for DNA extraction and cell counts. Bacterial and archaeal abundances were determined via qPCR and the 16S rRNA gene was amplified and sequenced. Higher DNA concentrations were measured for the unfiltered cultures than the filtered. 16S rRNA gene copy numbers for both Bacteria and Archaea were the highest for the unfiltered lysate. Some corresponding trends between Bacteria and Archaea could be seen where bacterial populations and archaeal populations decreased and increased depending on each other. Different microbial populations occurred in the different media and size fractions. The unfiltered cultures had lower alpha diversity than filtered cultures. Beta diversity between the filtered samples were similar in the early cultures, but differed more in the later cultures, while the unfiltered cultures were clustered to their own. Filtered cultures had high relative abundance of Patescibacteria, Omnitrophicaeota and Nanoarchaeota while the unfiltered cultures had high abundances of Firmicutes and Proteobacteria. Filtering groundwater allowed smaller and potentially slower growing microbes proliferate while perhaps being outcompeted by other microbes in the unfiltered cultures. This study shows that it is possible to select for different microbes being cultured from the same anoxic groundwater by modifications in the media and size fractions, potentially cultivating never-before cultured microbes in the future.
Place, publisher, year, edition, pages
2021. , p. 32
Keywords [en]
Biology, microbiology, anaerobic microbes, enrichment cultures, deep biosphere
National Category
Natural Sciences Microbiology
Identifiers
URN: urn:nbn:se:lnu:diva-107220OAI: oai:DiVA.org:lnu-107220DiVA, id: diva2:1599478
Subject / course
Biology
Educational program
Biology Programme, 180 credits
Supervisors
Examiners
2021-10-012021-10-012021-10-01Bibliographically approved