Enhanced photosynthesis and characterisation of carbohydrate production of Synechococcus PCC 7002

Romero, David Sanchez ; Steffen, Christine Sophie

4. term

Sustainable Biotechnology, Master

2019

2019-06-10

54 pages

Cyanobacteria are promising producers of carbohydrates from CO2 as feedstock in biorefineries due to the lack of requirement for arable land. To increase carbohydrate production, photosynthesis was enhanced in Synechococcus PCC 7002 by overexpressing bifunctional fructose 1,6- bisphosphatase/sedoheptulose 1,7-bisphosphatase (BiBPase). Growth and carbohydrate composition of Synechococcus PCC 7002 wild type and trcBiBP mutant was studied and compared. Physiological differences were analysed with OD730 measurements, microscopies and Nile Red staining. Glucose, sucrose, glycogen and cellulose were quantified by enzymatic digestion and subsequent glucose quantification by colorimetric GOPOD assay. TrcBiBP showed increased cell size, slower growth, higher glycogen and cellulose content than wild type. However, the increase of carbohydrates was not statistically significant, likely due to variability in the growth conditions of the experimental setup. The results were partially inconsistent to a previous study in which trcBiBP showed faster growth and lower glycogen content than wild type (De Porcellinis et al., 2014). This contradiction was potentially caused by different methodologies regarding selection and maintenance of trcBiBP cells. The slower growth was hypothesized to be caused by insufficient nitrogen in the medium. However, nitrogen deprivation was found to barely affect growth and glycogen production of trcBiBP. In contrast, consistently with literature studies (Möllers et al., 2014) nitrogen deprivation lead to a significant increase of glycogen content in Synechococcus PCC 7002 wild type, making it the more promising candidate to produce carbohydrates for biorefineries.

Synechococcus PCC 7002 ; carbohydrates ; biorefineries ; BiBPase

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