Cyanobacteria are a large group of prokaryotic organisms. Cyanobacteria are found in marine microbial mats that include many species of eukaryotic and prokaryotic organisms that can participate in mutualistic symbiotic relationships. One recently discovered species of cyanobacteria, UCYN-A, lacks the genes that encode ribulose bisphosphate carboxylase/oxygenase (RuBisCo), components of photosystem II, and the Krebs cycle. UCYN-A contains genes enabling nitrogen fixation, which allows the enzymatic conversion of atmospheric nitrogen to biologically available nitrogen compounds such as nitrate. Within the microbial community, there is relatively little available nitrogen. The majority of organisms in the microbial mat cannot fix nitrogen.
(a) Identify the metabolic process whereby UCYN-A is most likely to produce ATP.
(b) In low-nitrogen conditions, UCYN-A participates in a mutualistic symbiotic relationship with others in the microbial mat. Predict the most likely type of symbiotic relationship between UCYN-A organism and the other organisms in the microbial mat if nitrogen becomes readily available from another source. Provide reasoning to support your prediction.