Photophysiology of nitrogen fixing aquatic cyanobacteria, including the novel “nitroplast”
prof. RNDr. Ondřej Prášil, Ph.D. (Laboratoř fotosyntézy, centrum Algatech - Mikrobiologický ústav AV ČR)
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Prof. RNDr. Ondřej Prášil, Ph.D. is the leader of the Microbial Photosynthesis Group at the Algatech centre in Třeboň, part of the Institute of Microbiology of the Czech Academy of Sciences. Ondřej Prášil focuses on the study of photosynthesis regulation in microorganisms using biophysical methods. His teaching activities focus on the field of photosynthesis, bioenergetics and biophysics.
Publications of the speaker: https://orcid.org/0000-0002-0012-4359
CV of the speaker HERE.
Abstract
Diazotrophy, the ability to assimilate nitrogen gas (N2) into bioavailable organic forms (NH4) is limited to a selected group of prokaryotes. Diazotrophs are known as an important source of new nitrogen to plants. In aquatic environments, the major diazotrophs are photosynthetic oxygen evolving cyanobacteria. Diazotrophic cyanobacteria use photosynthesis to generate reductants and energy that fuel the energy demanding process of breaking the triple bond of N2. The catch is that the nitrogenase, the core enzyme of diazotrophy is highly sensitive to oxygen and is in its presence deactivated. This puts diazotrophic cyanobacteria that generate oxygen as a byproduct of photosynthesis into a dilemma. In the talk I will discuss recent data from our laboratory on the different strategies how diazotrophic cyanobacteria regulate the seemingly incompatible processes of nitrogen fixation and photosynthesis. I will focus on the example of the globally important multicellular cyanobacterium Trichodesmium and on the recently described endosymbiosis between the eukaryotic photosynthetic alga and the nitrogen fixing non-photosynthetic cyanobacterium UCYN-A, called “nitroplast”.