Functional interactions of Cyanobacteria under siege: impact of phage- and chytrid mediated top-down control on gene expression pattern

Last changed: 16 June 2021
Cyanobactaria. Photo.

The aim of this project is to investigate how cyanobacteria in lakes interact with viruses and aquatic fungi.

Cyanobacteria are the key prokaryotic primary producers in lakes. Carbon dioxide (CO2) that get fixed into their biomass enters the food web via top-down control forces. Among these forces, phages (virus that infects and replicates within bacteria and archaea) and Chytrids (a group of fungi that sometimes act as parasites and infect aquatic microbes) exhibit strain specificity for their cyanobacterial host. While phage infection provides accessible organic matter for prokaryotes through viral shunt and viral shuttle (see fact box), Chytrids direct the organic matter toward higher trophic levels via the mycoloop and mycoflux (see fact box).

Despite the crucial role of host specific top-down controls on the fate of fixed carbon, evolutionary history and microdiversification of Cyanobacteria, functional aspects of these interactions are largely unknown. In this project we explore the functional interactions of cyanobacterial community with their corresponding phages and Chytrids through high resolution metagenomic and metatranscriptomic analyses.



Funding from the Olsson-Borgh foundation (2020-2021).


Viral shunt is a mechanism in which particulate organic matter is recycling into dissolved organic matter, which can be readily taken up by microorganisms, and thus keeping it from migrating up trophic levels. Viral shuttle is a process where cells infected with viruses form larger particles that sinks faster and sometimes are grazed more.

Source: Wikipedia: Viral shunt.

Sullivan, Matthew B.; Weitz, Joshua S.; Wilhelm, Steven. 2017. "Viral ecology comes of age: Crystal ball". Environmental Microbiology Reports. 9 (1): 33–35.

Mycoloop is a process where parasitic fungi render otherwise inedible phytoplankton edible to zooplankton grazers, by fragmentation or by producing zoospores.

Mycoflux is any fungal interaction leading to aggregation or disintegration of organic matter.

Source: Grossart, HP., Van den Wyngaert, S., Kagami, M. et al. 2019. Fungi in aquatic ecosystems. Nat Rev Microbiol 17, 339–354.