Danny Ducat | Interrogation of cyanobacterial metabolism through engineering bioproduction sinks
Channel: CyanoWorld
Date: 2022-04-27

Danny Ducat - Michigan State University, USA

Homepage: https://prl.natsci.msu.edu/people/faculty/danny-ducat/
Twitter: https://twitter.com/cyano_dan

'Bottom up' interrogation of cyanobacterial metabolism through engineering non-native bioproduction sinks

Projects in the Ducat lab include the engineering of strains of a model cyanobacterium (Synechococcus elongatus PCC 7942) that can secrete most of its fixed carbon as the simple sugar, sucrose. Such strains have potential as alternative carbohydrate crop species, particularly for the construction of synthetic communities containing both cyanobacteria and heterotrophs that derive their carbohydrate needs from their cyanobacterial partners: I will briefly review the construction and future challenges to the application of such synthetic co-cultures. Recently, we have also explored the impact of redirecting a substantial carbon flux to a secreted bioproduct. We find that sucrose-secreting strains exhibit a counter-intuitive enhancement of photosynthetic parameters when the pathway is activated. We see that induction of the sucrose export pathway leads to improved photosystem performance, increased Rubisco activity, improved carbon fixation rates, and reorganization of Rubisco within cyanobacterial cells. I will discuss our experimental results that suggest that the additional metabolic burden imposed by bioengineered metabolism can lead to the utilization of energy that is normally wasted due to "overpotential" in electron transport chain of the photosynthetic machinery. Finally, long-term adaptation of cyanobacteria to conditions where there is a high metabolic burden imposed by heterologous metabolism appears to involve regulation of rubisco activity, and of the carboxysome that houses cyanobacterial rubisco. I will review our findings in this area in the context of the potential dynamic regulation of carboxysomes to optimize carbon fixation in cyanobacteria.

This talk is part of the CyanoWorld online seminar series, hosted by Nicolas Schmelling and Ilka Axmann, and was held on Zoom on February 10th, 2022.

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