"The marine Synechococcus - heterotrophic bacteria association at individual cell level studied by Atomic Force Microscopy, High speed laser scanning confocal microscopy and NanoSIMS: implications for oceanic carbon biogeochemical cycle"

National Institute of Biology kindly invites you to attend the lecture:

"The marine Synechococcus - heterotrophic bacteria association at individual cell level studied by Atomic Force Microscopy, High speed laser scanning confocal microscopy and NanoSIMS: implications for oceanic carbon biogeochemical cycle"

by Francesca Malfatti, PhD, Marie Curie Fellow Researcher, National Institute of Oceanography and Experimental Geophysics), Trieste (Italy)

The lecture will take place on Thursday, the 10th April 2014, at 10 am in the Lecture Hall of the Marine Biology Station, Fornače 41, Piran

Abstract:

Marine bacteria are important players in the oceanic biogeochemical cycles. Since they exert their biological influence at the individual cell level it is essential to study their ecology at the microscale with high resolution tools. We found, by Atomic Force Microscopy, that a large fraction of marine Synechococcus cells, important unicellular primary producers, were associated with "free-living" heterotrophic bacteria (Malfatti and Azam 2009).

We have picked single cells and amplified single genome from the natural marine sample thus we have identified some heterotrophic bacteria associated with the Synechococcus cells. We have measured at the individual cell level the primary production of natural assemblages of Synechococcus by 14C microautoradiography. The rate of carbon fixation is significantly higher in the associated Synechococcus. We have measured the C and N exchange by nanoSIMS in the natural microbial assemblage between the Synechococcus and the heterotrophic bacterial population. We did not find any significant difference among the heterotrophic bacteria associated with Synechococcus in comparison with the free ones. We addressed the interaction specificity in model systems-using cultures of isolated marine heterotrophic bacteria (Vibrionales: SWAT3; Pseudoalteromonadales: Pseudoalteromonas flavipulchra) and Synechococcus isolates (WH8102, CC9311). We quantified by high-speed confocal microscopy the interaction time and the encounter rate between CC9311 and SWAT3. We found that Synechococcus cell growth was inhibited by the presence of heterotrophic bacteria, thus suggesting an antagonistic interaction. Our findings at individual cell level can have biogeochemical consequences on the regulation of primary productivity and carbon flow in the ocean.

Kindly invited!

About the lecturer:

Francesca Malfatti has obtained the Ph.D. under menthorship of prof. dr. F. Azam at Scripps Institution of Oceanography, Univeristy of California San Diego in 2009 (USA). From 2009 to 2014, she has been a Post-Doctoral Fellow in the same laboratory. At the beginning of 2014, she started her new position as a Marie Curie Fellow Researcher at National Institute of Oceanography and Experimental Geophysics), Trieste (Italy). During her research career she has published several SCI papers, she had many invited talks and trained several undergraduate students in the laboratory of prof. dr. F. Azam. She has joined 3 cruises, among them also a cruise to Antarctica investigating Plankton Community Structure and Iron Distribution in the Southern Drake Passage and she has led multidisciplinary international research and monitoring projects. She was awarded with IRPE Prize (International Recognition of Professional Excellence) in marine ecology field in 2010 for innovative and important contribution for the emerging field of microscale biogeochemistry of the surface ocean. She is a peer reviewer of many prestigious SCI journals and scientific foundations.