Volume: 1, 2022
1st International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: E001
DOI: https://doi.org/10.24326/ICDSUPL1.E001
Published online: 26 April 2022
ICDSUPL, 1, E001 (2022)
Polyhydroxyalkanoates and exopolysaccharides production by cyanobacteria microbiomes: Collection, selection and upscaling of natural microbiomes
Beatriz Altamira-Algarra1, Eva González-Flo1, Joan García1
1 GEMMA-Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Escola d’Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya-BarcelonaTech, Av. Eduard Maristany 16, Building C5.1, E-08019 Barcelona, Spain
* Corresponding author: joan.garcia@upc.edu
Abstract
Polyhydroxyalkanoates (PHA) and exopolysaccharides (EPS) are biopolymers generally produced on an industrial scale using pure culture systems fed with synthetic substrates. These processes have intrinsically high production costs, preventing them from being economically competitive with the majority of synthetic polymer production processes. In order to reduce these costs, the use of cyanobacteria grown in wastewater emerges as an opportunity to the production of biopolymers. Cyanobacteria are microorganisms capable of producing both bioproducts through their photoautotrophic metabolism (use of CO2 and solar energy), so their production is a sustainable and efficient alternative. In natural habitats, microbiomes are functionally robust while maintaining flexibility towards environmental changes. These features promise to be beneficial for industrial applications, where culture stability is a very significant parameter. However, the use of microbiomes for bioproducts obtaining is limited by several factors, including the lack of strategies to control the process and monitor its composition. In an effort to obtain a stable cyanobacterial microbiome producing PHA and EPS, environmental samples were collected from different locations (constructed wetland, river, canal and urban lake). These samples were grown in laboratory conditions to obtain microbiomes rich in cyanobacteria. To that end, cultures were grown in BG-11 medium without phosphorus (P). P limitation was used to favour the growth of cyanobacteria against other phototrophic organisms (i.e., green algae) by the addition of K2HPO4 to have a P concentration in the flasks of 0.2 mg·L-1. The results of the applied selection pressure are confirmed by microscopic observation in a bright light and a fluorescence microscope, and molecular analysis of 16s rRNA. Microscopic observations demonstrate the presence of filamentous cyanobacteria and punctate colony-forming cyanobacteria. Results of the 16s rRNA analysis show that i) P limitation decreases the number of bacterial populations in the environmental samples collected, and ii) the high presence of cyanobacteria in the microbiomes. The most abundant ASVs microorganisms detected belonging to cyanobacteria, proteobacteria and bacteroidetes phyla were i) Prochlorococcus_MIT9313 and Pseudanabaena_PCC 7403, ii) Aquimonas voraii and iii) Alphaproteobacteria, respectively. Cyanobacteria-rich microbiomes produced up to 2%dcw PHA and 24 mg·L-1 EPS in BG-11 medium under P limitation. Production could be increased by the cultivation of the microbiomes under optimal conditions for biopolymers synthesis, such as nutrient limitation and the use of acetate as an organic carbon source.
How to cite
B. Altamira-Algarra, E. González-Flo, J. García, 2022. Polyhydroxyalkanoates and exopolysaccharides production by cyanobacteria microbiomes: Collection, selection and upscaling of natural microbiomes. In: 1st International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL1/E001