Use of a Thermophile Desiccation-Tolerant Cyanobacterial Culture and Os Redox Polymer for the Preparation of Photocurrent Producing Anodes

Abstract

Oxygenic photosynthesis conducted by cyanobacteria has dramatically transformed the geochemistry of our planet. These organisms have colonized most habitats, including extreme environments such as the driest warm desert on Earth: the Atacama Desert. In particular, cyanobacteria highly tolerant to desiccation are of particular interest for clean energy production. These microorganisms are promising candidates for designing bioelectrodes for photocurrent generation owing to their ability to perform oxygenic photosynthesis and to withstand long periods of desiccation. Here, we present bioelectrochemical assays in which graphite electrodes were modified with the extremophile cyanobacterium Gloeocapsopsis sp. UTEXB3054 for photocurrent generation. Optimum working conditions for photocurrent generation were determined by modifying directly graphite electrode with the cyanobacterial culture (direct electron transfer), as well as using an Os polymer redox mediator (mediated electron transfer). Besides showing outstanding photocurrent production for Gloeocapsopsis sp. UTEXB3054, both in direct and mediated electron transfer, our results provide new insights into the metabolic basis of photocurrent generation and the potential applications of such an assisted bioelectrochemical system in a worldwide scenario in which clean energies are imperative for sustainable development.

Bio-Inspired Redox-Adhesive Polydopamine Matrix for Intact Bacteria Biohybrid Photoanodes

“…Among the possible strategies for tuning photoinduced extracellular electron transfer, the immobilization of the active components in redox matrices has been reported including Osmium − , and naphthoquinone-based redox polymers . However, these polymers require a separated synthetic procedure and lack of adhesive properties.…”

“…Electrodes morphology was observed by a MERLIN Zeiss field emission gun scanning electron microscope (FE-SEM) with an operating voltage of 5 kV, cutting samples of the desired size directly from the free-standing electrode and performing imaging analyses on such samples without any further manipulation. components in redox matrices has been reported including Osmium [27][28][29]53 and naphthoquinone-based redox polymers. 30 However, these polymers require a separated synthetic procedure and lack of adhesive properties.…”

Immobilized Nanomaterials for Environmental Applications

“…The interfacing of photosynthetic bacteria with modified electrode surfaces and metallic NPs promotes enhanced current densities [ 86 ]. For instance, Gacitua et al [ 87 ] developed an Os-based redox polymer, which was combined with the cyanobacterium, Gloeocapsopsis sp. UTEXB3054, achieving a photo-current density of 2.3 μA/cm 2 .…”

Development of biophoto anodes usingUlvophyceae macroalgae

“…5 In BPVE, photosynthetic membranes or whole photosynthetic organisms can use water as a source of electrons in the presence of light, 6 while atmospheric CO 2 is reduced to form carbohydrates. 7 The ability to produce energy from photosynthesis has been studied in subcellular clusters such as isolated photosystems I and II, [8][9][10][11] thylakoid membranes, [12][13][14][15][16][17][18][19] chloroplasts, [20][21][22] as well as various photosynthetic microorganisms such as cyanobacteria 4,[23][24][25] or microalgae. [26][27][28][29] Since the mentioned subcellular structures present few barriers, electrons can be transferred to the external component as electrodes more quickly and efficiently than from complete cell structures.…”

“…4 Nonetheless, their extraction and purication processes make them more expensive and fragile, suffering from long-term instability due to the unfavorable environment. 24 On the other hand, photosynthetic organisms such as cyanobacteria 4,[23][24][25] and microalgae [26][27][28][29] are economical to grow 25,30 and are self-sustaining 4,30 with the ability of selfrepairing 6 under adequate environmental conditions. The exogenous electrochemical communication (EEC) 31 of multicellular organisms, such as macroalgae, has been shown by Shlosberg et al 32 using a clip electrode and chronoamperometry with a high applied potential of 0.5 V vs. Ag/AgCl KClsat .…”