Towards sustainable ethylene production with cyanobacterial artificial biofilms

Abstract

Photosynthetic cyanobacteria hold a great potential for the direct conversion of solar energy and CO2 into ‘green’ ethylene. The present study aims to develop a thin-layer artificial biofilm technology for...

Nanocellulose-based mechanically stable immobilization matrix for enhanced ethylene production: a framework for photosynthetic solid-state cell factories

“…1,2 One such compound is ethylene, a major chemical building block and an attractive fuel source that is currently produced from fossil sources using energy-intensive steam-cracking, which generates significant amounts of greenhouse gases and toxic co-products. 3,4 To improve the production efficiency of traditional PCFs based on suspension culturing, many of its physiological and technical drawbacks can be overcome by immobilizing the photosynthetic cells, i.e. distributed within a thin layer of the solid or gel-like carrier matrix.…”

“…[5][6][7][8] This transition can improve light-to-product conversion efficiency by enabling more uniform irradiation of photosynthetic cells and restricting cell division, while simultaneously reducing water and energy consumption. 9,10 Cell immobilization has been shown to increase the yield of ethylene production by 2-fold when compared to suspended cells, as well as the light-to-ethylene conversion efficiency by 3.5 times 4 under non-submerged conditions. Using alginate cross-linked with divalent cations (e.g.Ca 2+ and Ba 2+ ) has been the conventional state-of-the-art solution for immobilizing green algae and cyanobacteria, despite its limitations in mechanical properties, such as wet strength and porosity.…”

“…[11][12][13] Alginate-based matrices are especially poorly suited for many environments with high ionic concentrations, such as wastewaters, 6,14 as their ionic bonds are reversible depending on the concentration and species of the surrounding ions 6,15 . Similarly, biocatalytic ethylene production with cyanobacteria presents especially challenging conditions, as Vajravel et al (2020) reported that the optimal production requires the addition of 200 mM sodium bicarbonate (NaHCO3) as an inorganic carbon supplement, which leads to precipitation of Ca 2+ ions as insoluble CaCO 3 , disrupting the Ca-cross-linking of alginate. Thus, a liquid-conveying intermediate was used to support the alginate matrix.…”

“…Thus, a liquid-conveying intermediate was used to support the alginate matrix. 4 Here, we present a novel solid-state cell factory matrix design exemplified by efficient biocatalytic ethylene production with entrapped cyanobacteria. The self-standing matrix architecture, which utilises never-dried hydrogel thin films from TEMPOoxidized cellulose nanofibers (TCNF) 16 , is able to operate in challenging conditions of submerged cultivation.…”

Engineering Photosynthetic Bioprocesses for Sustainable Chemical Production: A Review

“…In PNSB, Rhodobacter capsulatus cells immobilized on agar produced hydrogen stably for over 70 days ( Elkahlout et al, 2019 ). In cyanobacteria engineered to produced ethylene, cells immobilized in an artificial biofilm matrix produced ethylene for up to 38 days ( Vajravel et al, 2020 ). The reuse of cells without a growth phase could reduce yield losses incurred during the growth of the organisms.…”