Usage of Cyanobacteria for Carbon Capture and Polyhydroxyalkanoate Production

presentation, poster

English

Topic that resonates strongly with society is carbon dioxide pollution. More than 35 billion tons of CO2 were emitted to the atmosphere in 2021. 100 billion tons of carbon dioxide are naturally absorbed and emitted every year through natural cycles of Earth. Capture and usage of carbon dioxide together with reducing the CO2 emission per year could slow down warming of Earth surface. Cyanobacteria are phototrophic gram-negative bacteria belonging to the prokaryotes. They are ecologically extremely important as they are capable of oxygenic plant-like photosynthesis. This ability caused cyanobacteria played a key role not only in biological, but also in geological history of our planet. Polyhydroxyalakanoates (PHAs) are microbial biopolymers and occur as intracellular granules. PHAs are biopolymers with similar properties as petrochemical synthetic plastics5. PHAs do not solve in water, they are resistant against UV light, they are biocompatible and non-toxic. They are fully biodegradable, PHAs decompose biologically to water and carbon dioxide under aerobic conditions6,7. Nevertheless, PHA production is not only time-consuming, but also financially demanding, for reducing the production cost the waste materials are being used as an input material while serve as an energy source for heterotrophic bacteria. As the cyanobacteria are capable of photosynthesis, they do not demand carbon source and for PHA synthesis they need only CO2 and light source. Technology using the waste CO2 as a carbon source for cyanobacteria producing PHAs could be greatly beneficial for environment. In this study, two Synechocystis strains were tested for PHAs production, as cyanobacteria naturally produce 3-hydroxybutyrate (3HB). Both strains were also tester for copolymer production copolymer of 3HB and 4-hydroxybuytrate (4HB) which was for the first time reported in cyanobacteria in Synechococcus sp. PCC7002 in 2015 and in PCC6803 in 2020. The composition of co-polymer differs in Synechocystis sp. PCC6803 and Synechocystis salina CCALA192 and the composition of co-polymers also varies depending on the precursor concentration. PCC6803 and CCALA192 cultivated with acetate -butyrolactone accumulated co-polymer 3HB-co-4HB with different fractions of 4HB. Role of PHAs in cyanobacterial metabolism seems to be very complex. In the beginning of our work with cyanobacteria, the production of PHB was around 2 % of PHB in cell dry weight. So deeper understanding together with well-adjusted cultivation conditions can make cyanobacteria the PHAproducers in present and in future rich in CO2.

cyanobacteria, carbon capture, polyhydroxyalkanoates

ŠEDRLOVÁ, Z.; OBRUČA, S.

13. 9. 2023

ESBP

Brno

107

107

163

https://esbp2023.com/src/ESBP2023_Book_of_Abstracts.pdf