WO2023240374A1

WO2023240374A1 - Multicellular algae-based bio-photoanode and bioreactor

Info

Publication number: WO2023240374A1
Application number: PCT/CL2023/050051
Authority: WO
Inventors: Federico TASCA; Sergio Andrés CHOQUE MUÑOZ
Original assignee: Universidad De Santiago De Chile
Priority date: 2022-06-15
Filing date: 2023-06-15
Publication date: 2023-12-21
Also published as: CL2022001603A1

Abstract

The present invention relates to a multicellular algae-based bio-photoanode and bioreactor for producing power and oxygen, with the aim of generating electricity and purifying and ionising air.

Description

BIOPHOTOMANODE AND BIOREACTOR BASED ON MULTI-CELLULAR ALGAE

DESCRIPTIVE MEMORY

FIELD OF APPLICATION OF THE INVENTION

The invention refers to a biophotoanode and bioreactor based on multicellular algae for the production of current and oxygen, with the aim of generating electricity, and purifying and ionizing the air.

DESCRIPTION OF PREVIOUS ART

The combustion of fossil fuels to generate mechanical energy is the largest source of greenhouse gases, which accumulate in the atmosphere and cause global warming and climate change. This unbalanced accumulation of CO2 drives the search for carbon-neutral energy sources. In this context, biological photovoltaic energy (BPVE) represents a great challenge, given the low cost and high sustainability of the constituent elements, as well as the use of solar energy, which is considered an infinite reservoir of energy.

In BPVE, photosynthetic membranes or whole organisms can use water as a source of electrons in the presence of light while atmospheric CO2 is reduced to form carbohydrates. The ability to produce energy from photosynthesis has been studied in subcellular groups such as isolated photosystems I and II, thylakoid membranes, chloroplasts and photosynthetic microorganisms such as cyanobacteria and microalgae. Given the The aforementioned subcellular structures present few barriers, electrons can be transferred to external components such as electrodes more easily and efficiently than from complete cellular structures. But their extraction and purification processes make them more expensive and fragile, and they suffer long-term instability due to the harsh environment. On the other hand, photosynthetic organisms such as cyanobacteria and microalgae are economical to cultivate, self-sustaining with the capacity for self-repair under suitable environmental conditions. All studies reported so far were performed using living unicellular organisms, while exogenous electrochemical communication (EEC) of multicellular organisms such as macroalgae has not yet been demonstrated.

For example, the invention patent application CL 2065-2020 describes a photobioreactor that comprises a base mechanical structure to cultivate cyanobacteria and microalgae, and support a control unit, and sensors and actuators for automatic management of the culture; and for harvesting, cleaning and restoring the culture medium.

On the other hand, patent application CN 107058114 describes marine microalgae that have electricity-generating activity and their application in electrochemistry. The purpose of this invention is to provide a microalgae Nanochloropsis sp. generator of electricity from the ocean given the current situation of research into electricity-generating microalgae and their application in microbial fuel cells.

In this same sense, US Patent 10,665,866 describes a method for preparing an electrode for use in a biophotovoltaic device, which includes the steps of: coating a self-assembled film on a substrate using the technique of Langmuir-Blodgett; and immersing the coated substrate in a culture of microalgae, followed by incubation thereof so that microalgae grow on it, thus obtaining a biofilm, characterized in that the self-assembled film is derived from graphene.

Additionally, the non-patent document titled “Exoelectrogenic bacteria that power microbial fuel cells” (Bruce E. Logan), describes microorganisms that can generate electrical current in microbial fuel cells. Enriched anode biofilms have generated power densities of up to 6.9 W per m2 (anode projected area) and are therefore approaching theoretical limits. Thus, this article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell-cell communication.

In this same sense, the non-patent document titled "Technological potentials of photosynthetic biofilm in environmental remediation and energy generation" (Alfonso, A.; Areco, M.; Curutchet, G), discloses that the Microbial Fuel Cell (MCC) ) is a device that uses the metabolism of different microorganisms to obtain electrical energy. In general, it has two chambers interconnected by electrodes and a salt bridge. In one of the chambers, anaerobic bacteria are placed that, from the degradation of organic matter , produce energy (electrons) that they release into the medium. These electrons are captured by the electrode called the anode, and for a physical reason they flow to the electrode located in the second chamber, which is called the cathode. For this phenomenon to occur it is It is necessary that there be an electron acceptor at the cathode, such as oxygen, which is obtained by aeration or agitation. This is where it is An advantage is to use microalgae in CCMs. If these organisms are grown on the cathode, the need to add oxygen is eliminated, as this results from the photosynthesis process.

Finally, the non-patent document titled “Effect of different irradiance levels on bioelectricity generation from algal biophotovoltaic (BPV) devices" (Cheng-Han Thong, Siew-Moi Phang, Fong-Lee Ng, Vengadesh Periasamy, Tau-Chuan Ling, Kamran Yunus , Adrian C. Fisher), developed algal biophotovoltaic (BPV) platforms to harvest electrons and generate bioelectricity through algal photosynthesis. It is mentioned that light energy splits water molecules into oxygen, protons and electrons, by what such algal biophotovoltaic (BPV) platforms were used to harvest these electrons and generate bioelectricity through algal photosynthesis. In this study, the effective range of irradiance levels for power generation from BPV devices was determined of algae comprising cultures of Chlorella in suspension and immobilized with alginate on ITO anodes.

In this way, it is evident that the studies reported so far were carried out using living unicellular organisms, such as cyanobacteria and microalgae, while exogenous electrochemical communication (EEC) of multicellular organisms, such as macroalgae, has not yet been demonstrated.

Therefore, the present invention patent application describes the use of macroalgae for the production of photocorrhet and molecular oxygen, with the objective of generating electricity, and purifying and ionizing the air.

The advantage of using macroalgae lies in its photosynthesis machinery, located within the thylakoid membranes, within the chloroplast. The seaweed They are easy to grow and resistant to different environments, microalgae are commonly used in bioenergy production and pharmacology, while macroalgae are more frequently used in food production. Macroalgae are formed by a sheet, which adds a useful arrangement for capturing solar energy, since it allows avoiding cellular saturation of microorganisms on the electrode as when microalgae or cyanobacteria are used. This is an advantage that provides greater efficiency in capturing sunlight through the cells, avoiding saturation on the electrode surfaces.

BRIEF DESCRIPTION OF THE INVENTION

The invention refers to a biophotoanode and bioreactor based on multicellular algae for the production of current and oxygen, with the aim of generating electricity, and purifying and ionizing the air. Furthermore, the present invention refers to the use of macroalgae for the production of photocurrent and molecular oxygen, with the aim of generating electricity, and purifying and ionizing the air. The choice for macroalgae would be due to the fact that they present some advantages over microalgae in this area, such as their growth control is much easier, as well as their handling and waste treatment.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a macroscopic view of the green macroalgae (A) Ulva compressa, (B) U. lactuca and (C) U. unza. Section of the monostromatic thallus of (D) U. compressa and a surface view of the middle region of the thallus of (E) U. lactuca and (F) U. Unza. Images D – F were taken of algal autofluorescence by confocal microscopy with a 40x zoom.

Figure 2 shows chronoamperometry measurements of graphite electrodes modified with disks of (A) U. compressa, (B) U. lactuca and (C) U. unza. Light cycles of 50 s. 1st cycle after 100 s. Insert: CV of the same electrode in the absence (black curve) and in the presence of light (red line) and at a scan speed of 50 mVs ¹ . Electrolyte solution: 10 mM phosphate buffer at pH 7.5 including 10 mM NaCl and 5 mM MgCh.

Figure 3 shows amperometric measurements at 0.25 V versus Ag|AgCI sat. KCI of graphite electrodes modified with U. Unza disks in the presence of 0.5 mM FeCN. The inset shows the photocurrent achieved at different concentrations of FeCN. Electrolyte solution: 10 mM phosphate buffer including 10 mM NaCl and 5 mM MgCl2 _at pH 7.5. Light cycles from 300s on/light off from 300s.

Figure 4 shows amperometry measurements at 0.25 V vs. Ag|AgCI sat. KCI of graphite electrodes modified with U. Unza disks immobilized on the electrode surface in the presence of 1 mM (green line) and 0.5 mM (black line) benzoquinone (BQ). The inset shows the photocurrent achieved at different BQ concentrations. Electrolyte solution: A 10 mM phosphate buffer including 10 mM NaCl and 5 mM MgCl2 _at pH 7.5. Light cycles from 300 s on/off to 400 s.

Figure 5 shows amperometry measurements at 0.25 V versus Ag|AgCI Sat. U. Unza modified KCI graphite electrodes in the presence of 0.2 mM (green line) and 0.1 mM (black line) NQ. The inset shows the photocurrent achieved at different concentrations of NQ. Electrolyte solution, a 10 mM phosphate buffer including 10 mM NaCl and 5 mM MgCl2 _at pH 7.5. Light cycles from 200 s on/light off from 100 s.

DETAILED DESCRIPTION OF THE INVENTION

The invention refers to a biophotoanode and bioreactor based on multicellular algae for the production of current and oxygen, with the aim of generating electricity, and purifying and ionizing the air. Furthermore, the present invention relates to the use of macroalgae, such as green, red and brown photosynthetic algae, for the production of photocortent and molecular oxygen, with the aim of generating electricity, and purifying and ionizing the air.

Within one of the embodiments of the present invention and without limiting the scope, the macroalgae are selected from green, red and brown photosynthetic macroalgae, which are selected from the classes Chlorarachniophyta, Chlorophyta, Chromeridae, Cryptophyta, Cyanophyta, Dinophyta, Euglenophyta, Glaucophyta Haptophyta, Heterokontae, Rhodophyta, Ulvophyceae, More specifically, macroalgae of the genera Ulva and Chaetomorpha are described, more specifically the species Ulva Lactuca, Ulva Compressa and Chaetomorpha Antennina.

These macroalgae have been cultivated and the direct (without the use of exogenous mediators to the system) and mediated photocortent production (with the addition of exogenous mediators to the system) have been measured, which is intended to see how much direct production can be enhanced. This type of system can be used in microbial combustion cells (MFC), where the production of Anodic photocurrent is also accompanied by the production of O2, in the same cell.

This technology shows how the same factors that enhance the collection and production of photocurrent manage to do so with the production of oxygen. The mediated transfer achieves an increase with respect to the direct transfer and is achieved thanks to exogenous mediators that penetrate the algae to oxidize in the photosynthesis process and subsequently go out to reduce in contact with the electrode corresponding to the anode that manages to conduct this photocurrent. The mediators must be structurally small molecules, to be able to cross the different active transport channels or interact with transmembrane proteins, as well as to be able to more efficiently form conjugated polymers that improve their characteristics as bioelectrochemical mediators. An effective mediator but with low affinity will be able to enter the plant cell, but only up to the cytosolic space, on the other hand, a mediator with high affinity will be able to enter deeper, reaching the interior of the energy centers such as chloroplasts and even thylakoids. An example of this first instance are mediators that obtain electrons through redox reactions with transmembrane proteins in the external wall of the chloroplasts or endogenous mediators that have already emerged from the energy complexes, such as Fercyanide (FeCN), and If it is more similar, as in the case of Benzoquinone (BQ), it manages to enter the chloroplasts (and subsequent organelles where photosynthesis reactions occur), obtaining photocurrent directly from photosynthesis and not from more advanced endogenous redox intermediates in the transport chain. These mediators facilitate a very big problem in direct transfer, the maximum distance in that the electron can jump and that requires that the electron donor and acceptor of this mechanism be in direct contact, this is a molecular complication, since there is no contact between the electrode and the interior of the plant cell, so This mechanism is only achieved when there is contact between the electrode and specialized structures (such as transmembrane proteins) of a redox nature in the external walls of the plant cell, which achieves a minimum current given the loss intrinsic to the chain of reactions. priors and use of energy by the plant cell.

Macroalgae have several advantages over single-celled organisms, such as: easier monitoring and handling at an industrial level, greater resistance to process stress, therefore, they generate greater current and for longer, easier waste disposal, and do not require sugar sources. external as various bacteria. The increase in current that can be extracted from this system makes it possible to use it in low-consumption devices, such as industrial sensors, together with the natural action of decontaminating the air in photosynthesis at a higher rate and with more advantages. than higher plants, since it takes up fewer resources than these.

Thus, macroalgae can be used with all their advantages in systems that, due to their characteristics, require the ability to increase oxygen levels in their environment accompanied by the production of photocurrent that can be used from sensors of different ranges to secondary lighting.

EXAMPLES

Algae sampling: U. compresa, U. lactuca and U. unza were collected in Cachagua, Chile (32°35'S 71°27'W), a site free of metal contamination that has been selected as a sampling site since 2003 by the Biotechnology Group Marina, at the University of Santiago de Chile. These macroalgae were cultured in reconstituted seawater supplemented with Provasoli medium using a 16/8 h photoperiod under light/dark conditions at 14°C and with air bubbling using a peristaltic pump.

Electrode preparation and instrumentation:

The electrochemical cell was assembled with a traditional three-electrode configuration, i.e., an Ag|AgCI Kcisat reference electrode (Ohgalys, Rillieux-la-Pape, France), a platinum wire as a counter electrode, and a flat pyrolytic graphite electrode of modified edge with an algae disk (area, A = 0.28 cm ² ) as working electrode. The algal disk was secured with a dialysis membrane (SnakeSkin Dialysis Tubing 10,000 MW, Thermo Fisher Scientific, LOCATION, COUNTRY) previously soaked in electrolyte buffer solution and sealed with a rubber gasket. All chemicals for provasoli culture medium and mediators used in MET systems, [i.e., ferricyanide (FeCN), p -benzoquinone (BQ), or 1,4-naphthoquinone (NQ)] were purchased in the form of powder to Sigma Aldrich (Saint Louis, MI, United States) and used as received. Measurements were performed using an Autolab potentiostat (Autolab 304 micro, Utrecht, The Netherlands) equipped with NOVA 1.1 software. A 10 mM phosphate buffer including 10 mM NaCl and 5 mM MgCh at pH 7.5 was used as the electrolyte solution. Mediators were added during the MET experiments. mentioned in various concentrations. Cyclic voltammetry (CV) and amperometry were performed at a constant applied potential (Amp) in a dark room or in the presence of a fiber optic illuminator at a light intensity of 200 mMol/cm ² . A scan rate of 50 mVs ¹ was used on all CVs presented. All Amp measurements were performed by biasing the electrode at 0.25 V versus Ag|AgCI. At this potential, which is more positive than the E°' value, the mediators, which in turn means that all mediator molecules should be in their oxidized form. All measurements represent the analysis of five independent experiments. The error bars are the result of significant differences through an analysis of variance (ANOVA) with the Origin 8 software, considering a value of p <0.05.

Results without mediators, i.e. direct electron transfer (DET), from the macroalgae U. lactuca, U. unza and U. compressa to bare graphite electrodes are shown in Figure 1. Also shown are macroalgae in the presence of redox mediators for mediated electron transfer (MET). Redox mediators have been widely studied for their ability to penetrate the phospholipid structures of various microorganisms and the possibility of transporting electrons from photosystem II (and to photosystem I), where the reaction of oxygen evolution to the external environment and to electrodes begins. . For such MET investigations two different quinones were used, "benzoquinone" (BQ) and "naphthoquinone" (NQ) that have a high affinity for the photosynthetic centers, given the similarity with the endogenous quinones of photosynthesis and also "ferricyanide" (FeCN ), a non-specific mediator but impermeable that can interact with transmembrane proteins in the cytoplasmic membrane of algae. These results allow us to conclude that possibly all photosynthetic algae, such as green, red, and brown, could function in the direct transfer of electrons.

Macroalgae have tissues corresponding to the thallus, rhizoid, cauloid and phylloid. The thallus of Ulvophyceae algae can be tubular like U. compressa (Fig. 1 A) or lamellar like U. lactuca and U. unza (Fig. 1 B and 1 C) and a cross section of these corresponding algae is seen in the Figure 1, D-F. Photosynthetic organisms can be used in BPVE to catalyze water hydrolysis and simultaneously to obtain an electron flow, intercepting electrons from PS II and I. Defined photosynthetic strains are required for specific environmental conditions due to adaptation. Correct selection of strains is necessary to optimize photocurrent output in DET systems or to improve MET. DET is most desirable for its simplicity and the ability to avoid additional costs due to the need to add mediators to the solution. Apart from the economic factor, in many cases the mediators also imply an energy cost, since an extra overpotential is necessary to oxidize the mediators on the electrode surface.

U. unza, U. lactuca and U. compressa were molded to produce 0.28 cm ² disks, an area similar to that of the electrodes, and then used to modify the surface of the bare graphite electrodes. To investigate the DET rate, Amp measurements were performed with 50 s light cycles. Light cycles began after 100 s to stabilize the system and reach a baseline (Fig. 2). Representative measurements of macroalgae electrodes modified are shown in Fig. 2 with U. unza (Fig. 2A), U. lactuca (Fig. 2B) and U. compressa (Fig. 2C).

The CVs of the same electrodes in the presence and absence of light at a scan rate of 50 mVs ¹ are shown in Figs. 2A-C. All CVs show the typical shape of electrodes modified with apparently non-redox active species. The shapes of these CVs reveal a high resistance to charge transfer. With the three macroalgae, a small increase in the oxidative and reducing extremes of CVs in the presence of light could be noted. The CVs of the bare graphite electrodes show no changes between the presence or absence of light. The increase in the oxidative region could be associated with the photosynthetic reactions carried out by macroalgae exposed to light. The oxidative process starts at a potential of approximately 0.05 V for U. compressa and U. lactuca, while it starts at approximately 0 V for U. unza (Figs. 1A-C). Amperage measurements with the three macroalgae by polarizing the working electrode at various potentials showed the best results in terms of photocatalytic water oxidation current with a working electrode polarization of 0.25 V for the three algae (Fig. 2 ).

Amp measurements were performed in phosphate buffer at pH 7.5, keeping the electrode polarized at a potential of 0.25 V and using cycles of 50 s light and 50 s dark. The current measured under dark conditions is used as a reference to calculate the current density generated during light conditions. Therefore, during DET the following current densities were measured for each of the algae: 0.086 pAcm ² for U. compressa, 0.046 pAcm ² for U. lactuca and 0.038 pAcm ² for U.linza. The results with the error bars corresponding to the average of 5 measurements for 5 different electrodes are reported in Table 1. U. compressa is the macroalga that provides the highest photocorrhence among the species studied in the DET system. It has been reported that this macroalgae is capable of accumulating heavy metals, and being able to withstand different environmental pollutants.

The concentration of the mediator and its availability to the redox center, where redox processes occur, are primary factors to take into account when developing MET processes. In MET experiments with macroalgae, the concentration of FeCN was optimized by performing chronoamperometric experiments with various concentrations of FeCN. Amperometric experiments with U. Unza in the presence of various concentrations of FeCN showed an optimized current at 0.5 mM (inset of Fig. 3). The system required at least 300 s to reach the baseline after illumination for 300 s and maintaining a rest time of 200 s. With this system, typical photocoherences were on the order of 5.2 pA/cm ² , which represents an approximately 135-fold increase compared to DET measurements performed with the same macroalgae (Fig. 2 (C)). When in the presence of lower concentrations of FeCN, much lower photocatalytic currents of almost half of the photocatalytic current for 0.2 mM FeCN could be obtained, while the concentration was increased to 1 mM lower currents were also obtained ( inset of Fig. 3), probably due to a saturation effect on the part of the mediator, where the charge would be exchanged to other Fe redox centers instead of reaching the electrode surface. The results obtained with the three macroalgae in the presence of FeCN are summarized in Table 1.

Table 1 . Photocurrent obtained for Ulva Unza, Ulva compressa and Ulva Lactuca:

The photocurrent obtained for Ulva Unza, Ulva compressa and Ulva lactuca was carried out under direct electron transfer (DET) and mediated electron transfer (MET) conditions in the presence of 0.5 mM FeCN, 1 mM BQ or 0.2 NQ mm. Electrode polarized at 0.25 V vs. Ag|AgCI sat. KCI. 10 mM phosphate buffer including 10 mM NaC1 and 5 mM MgCl2 at pH 7.5 was used as the electrolyte solution.

While inorganic and charged FeCN can transport electrons from transmembrane proteins to the electrodes, organic and neutral mediators, similar to quinones, can penetrate the cytoplasmic membrane and exchange electrons directly with photosystem II. It has been shown that BQ can exchange electrons directly with the plastoquinone (PQ) pool in the photosynthetic electron transfer chain between photosystem II and the cytochrome b or f complex. Therefore, this mediator was also used with U. compressa, U. lactuca and U. unza to study the efficiency of their MET reactions.

Amperometry measurements of graphite electrodes modified with U. Unza discs in the presence of 1 mM (green line) or 0.5 mM (black line) BQ are shown in Fig. 4. After 400 s required to obtain baseline, the system was cycled with 300 s of light followed by 300 s of darkness. Under these conditions, the highest photocorrhence, 72.1 pA/cm ² , was obtained at a 1 mM BQ concentration. It should be noted that BQ is not soluble at higher concentrations. Furthermore, the system appears to be already unstable at a concentration of 1 mM. In fact, after a first cycle of 300 s of light, subsequent cycles showed lower currents and a decrease in the maximum current, most likely due to problems of hydrodynamics and permeability of the mediator within the cytoplasmic membrane of the macroalgae. Subsequently, MET experiments were performed with naphthoquinone (NQ), a different type of quinone. NQ is less soluble in aqueous solutions compared to BQ, so concentrations were in the range between 0.025 mM and 0.2 mM. Amperometric data for U. Unza with 0.1 and 0.2 mM NQ, with the electrode polarized at a potential of 0.25 V vs. Ag|AgCl (Fig. 5). After initially 100 s of darkness to reach a constant baseline, three light cycles of 200 s light/dark each were applied. In this case, a maximum of 3.4 pA/cm ² was obtained with the highest concentration of NQ (0.2 mM). The lower increase in photocortent obtained for the MET system with NQ compared to the system with BQ is attributed to the smaller amount of mediator that can be dissolved in the solution and therefore that can reach photosystem II, also with the lowest thermodynamic conduction. , strength since NQ has a lower E°' compared to BQ.

The current values obtained with U. Unza, U. compressa and U. lactuca under DET and MET conditions with the different mediators and those obtained with Paulschulzia pseudovolvox, Synechocystis sp. are shown. PCC 6803 and Anabaena variabilis for comparison (Table 1). According to the research groups of Gorton's ²¹ and Clifford's ⁴⁶ , we obtained a substantial improvement of the photocatalytic current measured on graphite electrodes when BQ was used as a mediator under MET conditions. In fact, an increase of around 40 folds with microalgae Paulschulzia pseudovolvox and the cyanobacterium Synechocystis sp. PCC 6803 were obtained, respectively, in MET systems with BQ as mediator. In our case, all MET systems showed a notable increase in photocorrhence. produced, similar to what was previously reported. Outstanding results were obtained for MET experiments with U. Unza modified electrodes with 1 mM BQ as a mediator, reaching a 1897-fold increase compared to the current obtained under DET conditions. The results obtained during the optimization of the BQ concentration are consistent with the results of ^{Lee's group 55} with the cyanobacterium Anabaena variabilis, for which the best BQ concentration for photocurrent extraction was 1 mM. In general, the DET photocurrent of live cells in BPVE systems is on the order of 10 nA/cm2. With the macroalga U. compressa as shown in this study we were able to obtain almost 100 nA/ ^cm2 .

Thus, it can be concluded that three macroalgae of the genus Ulvophyceae, i.e., U. compressa, U. lactuca and U. unza, were immobilized on graphite electrodes for biophotovoltaic experiments during the biophotoelectrooxidation of water to oxygen. Cyclic voltammetry and amperometry experiments were performed during cycles of light and dark conditions with or without added redox mediators. Outstanding results were obtained when U. compressa was used under DET conditions and current densities of almost 100 nA/cm ² were observed. Under MET conditions, the best results were obtained with U. Unza and 1 mM BQ and a current density of almost 75 pA/cm ² was detected. The present invention would be the first time that macroalgae are immobilized on electrodes for biophotovoltaic experiments.

While this invention has been described under the modalities indicated above, it may seem evident that other alternatives, modifications or variations would deliver the same results. Consequently, the embodiments of the invention are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims. All patents, patent applications, scientific articles and other public documents that, to the knowledge of the applicant, constitute the state of the art, have been properly cited in this application.

Claims

1 . A bioreactor for the production of photocurrent and oxygen, with the objective of producing electrical energy and purifying and ionizing the air, CHARACTERIZED because it comprises: green, red and brown photosynthetic macroalgae; and bioelectrochemical mediators; where the bioreactor is useful for the production of photocurrent and molecular oxygen.

2. The bioreactor according to claim 1, CHARACTERIZED because the green, red and brown photosynthetic macroalgae are selected from the classes Chlorarachniophyta, Chlorophyta, Chromeridae, Cryptophyta, Cyanophyta, Dinophyta, Euglenophyta, Glaucophyta Haptophyta, Heterokontae, Rhodophyta, Ulvophyceae.

3. The bioreactor according to claim 1, CHARACTERIZED because the bioelectrochemical mediators are selected from Ferricyanide, Benzoquinone.

4. Use of the bioreactor according to claims 1 to 3, CHARACTERIZED because it is useful for the production of photocurrent and oxygen, and that it serves to generate electricity, and purify and ionize the air.

5. A biophotoanode, CHARACTERIZED because it comprises the bioreactor according to claims 1 to 3.