Finished individual study activities
Low light photosynthesis in the benthic zone of Dalby Bay
- Project type: Research project, 10 ECTS
- Student: Simon Weber
- Supervisor(s): Karl Attard, Leah Brinch-Iversen
- Start: 1. February 2023
- End: 31 July 2023
Recent studies show that phytoplankton can be active at very low light intensity (< 1 µmol PAR m-2 s-1). However, the low light activity of microalgae inhabiting sediments (microphytobenthos) remains largely unknown. The aim of my project is to investigate photosynthetic activity of microphytobenthos under low light. Here, I will acclimate benthic diatoms to different light intensities and investigate the photosynthetic response using Pulse Amplitude Modulated (PAM) fluorometry. An in-depth analysis of sediment properties and microscopic imaging will be done to augment the photosynthetic measurements.
Pressure effects on virus-bacteria interactions
- Project type: Research project, 10 ECTS
- Student: Elise Marie Dinesen
- Supervisor(s): Ronnie N. Glud & Mathias Middelboe
- Start: 1 September 2022
- End: 31 January 2023
Viruses play major roles in marine environments where they contribute to bacterial mortality and biogeochemical cycling. Little is known about the effects of pressure on virus-bacteria interactions, such as the induction of prophages and viral production from lytic infections. The aim of the current project is to quantify viral production in a marine sediment, in response to hydrostatic pressure along gradients from 1 to 1000 bars, during short term incubations in pressure chambers. Based on sediment samples from a muddy sediment in Øresund, slurries will be prepared with 1 ml surface sediment (0-1 cm horizon) diluted 1:10 with virus-free bottom water in 10 ml exetaines. The exetainers are incubated in 5 replicates at pressure range covering 1, 200, 400, 600, 800, and 1000 bars for ca 12 h. Samples will be collected for quantification of viruses and bacteria at T=0 and t=12 h.
The expected increase in free viral particles in the sediment slurries is the combined result of prophage induction and lytic viral production. To provide a measure of the potential for prophage induction in the sediment, and the effects of pressure on that process, a parallel experiment will be established, where the number of free phages will be quantified after exposure to Mitomycin C, an artificial agent stimulating prophage induction in bacterial cells. By quantifying prophage induction in parallel sediment slurries with Mitomycin C across the same pressure gradient as above, we will examine the 1) the number of inducible prophages in the microbial population and 2) the effects of pressure on prophage induction.
Effects of temperature on the microbial driven enzymatic processes in sediment.
- Project type: Research project , 10 ECTS
- Student: Silje Waaler Pedersen
- Supervisor(s): Ronnie N. Glud & John Paul Balmonte
- Start: 1 September 2021
- End: 31 januar 2022
My current research aim is to investigate the effects of temperature on microbial driven enzymatic processes in sediments. Temperature is one of many factors affecting the activity of enzymes. Dynamics in temperature, is expected to play an important role in degradation of organic matter in sediments. Not only will I look at enzyme activity in whole microbial communities but also on extracted enzyme assays from the same communities. Thereby the relative importance of cellular processes versus pure enzyme kinetics for the community response towards temperature dynamics can be assessed.
Effects of hydrostatic pressure on microbial activity with particular focus on anaerobic heterotrophic carbon degradation
- Project type: Internship
Student: Louis Quichaud
Supervisor: Ronnie N. Glud
Start: 8. February 2021
End: 11. June 2021
Bacteria in Hadal trenches are known to degrade organic matter in aerobic conditions (using oxygen). However, it has recently been shown that some bacteria in the trenches can also produce their energy in anaerobic conditions (without oxygen) using organic matter. The aim of this internship is to study the impact of hydrostatic pressure on bacteria doing fermentation (or anaerobic degradation) and on fermentation pathways themselves. Bacteria’s relationship with viruses will also be studied. This will be done using several techniques including, but not limited to, radio- and stable isotope tracer analysis, cell and virus counting, data analysis and calculations of microbial growth.