Miyuki A. Thirumurthy, Andrew Hitchcock, Angelo Cereda et al.

Frontiers in Microbiology • 2020

Biophotovoltaic devices utilize photosynthetic organisms such as the model cyanobacterium Synechocystis sp. PCC 6803 ( Synechocystis ) to generate current for power or hydrogen production from light. These devices have been improved by both architecture engineering and genetic engineering of the phototrophic organism. However, genetic approaches are limited by lack of understanding of cellular mechanisms of electron transfer from internal metabolism to the cell exterior. Type IV pili have been implicated in extracellular electron transfer (EET) in some species of heterotrophic bacteria. Furthermore, conductive cell surface filaments have been reported for cyanobacteria, including Synechocystis . However, it remains unclear whether these filaments are type IV pili and whether they are involved in EET. Herein, a mediatorless electrochemical setup is used to compare the electrogenic output of wild-type Synechocystis to that of a Δ pilD mutant that cannot produce type IV pili. No differences in photocurrent, i.e., current in response to illumination, are detectable. Furthermore, measurements of individual pili using conductive atomic force microscopy indicate these structures are not conductive. These results suggest that pili are not required for EET by Synechocystis , supporting a role for shuttling of electrons via soluble redox mediators or direct interactions between the cell surface and extracellular substrates.

Ahmad Zul Izzi Fauzi, Muhammad Iqbal Ahmad, Lim Kar Keng et al.

Malaysian Journal of Bioengineering and Technology (MJBeT) • 2024

Progressing to sustainable and renewable energy sources is essential for addressing climate change and reducing reliance on fossil fuels. Biohydrogen production, which is the production of hydrogen via biological processes, can be one solution since it provides high-value energy and environmental benefits. This review aims to provide summary information about the three basic strategies involved in biohydrogen production: dark fermentation, photo fermentation, and microbial electrolysis cells (MECs). Dark fermentation is the fermentative conversion of organic matter via anaerobic microbes into hydrogen and other products. While this approach is simple and could work with diverse waste substrates, scalability is limited due to low hydrogen yields and the need for substrate pretreatment. Photosynthetic bacteria employ light to transform organic substrates into hydrogen. Photosynthetic bacteria use light to convert organic substrates into hydrogen, indicating that this process could complement dark fermentation. However, its dependence on light and low efficiency present significant challenges. Microbial electrosynthesis (MEC) converts hydrogen into energy by reducing it from carbon dioxide and using electroactive bacterium combined with an external voltage to produce gas from organic matter that is well-aligned but complex with wastewater treatment while also facing costs that make them highly operational. These technologies are likely to see improvements in genetic engineering, new designs for reactors, and the use of them with other industrial processes to improve productivity and profitability. Ongoing research and development are essential to realize large-scale, practical methods for biohydrogen production. This review covers the potential of biosynthetic and anaerobic approaches in this field.

Delphine Moreau, Richard D. Bardgett, Roger D. Finlay et al.

Functional Ecology • 2019

Abstract Nitrogen is the major nutrient limiting plant growth in terrestrial ecosystems, and the transformation of inert nitrogen to forms that can be assimilated by plants is mediated by soil micro‐organisms. The last decade has witnessed many significant advances in our understanding of plant–microbe interactions with evidence that plants have evolved multiple strategies to cope with nitrogen limitation by shaping and recruiting nitrogen‐cycling microbial communities. However, most studies have typically focused on the impact of plants on only one, or relatively few, processes within the nitrogen cycle. This review synthesizes recent advances in our understanding of the various routes by which plants influence the availability of nitrogen via an array of interactions with different guilds of nitrogen‐cycling micro‐organisms. We also propose a plant trait‐based framework for linking plant nitrogen acquisition strategies to the activities of nitrogen‐cycling microbial guilds. In doing so, we provide a more comprehensive picture of the ecological relationships between plants and nitrogen‐cycling micro‐organisms in terrestrial ecosystems. Finally, we identify previously overlooked processes within the nitrogen cycle that could be targeted in future research and be of interest for plant health or for improving plant nitrogen acquisition, while minimizing nitrogen inputs and losses in sustainable agricultural systems. A plain language summary is available for this article.

Lola Gonzalez Olias, Alba Rodríguez-Otero, Petra J. Cameron et al.

The 1st International Electronic Conference on Biosensors • 2020

The increasing use of fertilisers rises the risk of eutrophication, a sudden algal bloom that seriously damage ecosystems due to critical oxygen depletion. Continuous monitoring of oxygen in environmental waters could improve the detection of eutrophication and prevent anoxic conditions. However, online and in situ dissolved oxygen sensors are yet to be implemented due to poor portability and power requirements. Here, we propose a ceramic soil microbial fuel cell as a self-powered sensor for algal growth detection via monitoring of dissolved oxygen in water. The sensor signal follows the characteristic photosynthetic cycle, with a maximum day current of 0.18 ± 0.2 mA and a minimum night current of 0.06 ± 0.34 mA, which correlates with dissolved oxygen (R2 = 0.85 (day); R2= 0.5 (night)) and algal concentration (R2 = 0.63). A saturated design of experiments on seven factors suggests that temperature, dissolved oxygen, nitrates, and pH are the most influential operational factors in the voltage output. Moreover, operating the system at maximum power point (Rext = 2 kΩ) improves the sensor sensitivity. To the best of our knowledge, this is the first proposed MFC-based biosensor for in-field, early detection of eutrophic events.

Ganesh Mahidhara, Deepshikha Gupta, Ch. Sasikala et al.

International Journal of Hydrogen Energy • 2020

Paulina Rusanowska, Łukasz Barczak, Adam Starowicz et al.

Energies • 2025

Electrical stimulation is increasingly explored as a strategy to accelerate the development of electroactive biofilms in microbial fuel cells (MFCs), yet its integration with photosynthetic MFCs (pMFCs) remains insufficiently understood. This study evaluated how short-term anodic stimulation (0.5–5 V, 4 days) affects biofilm formation and COD removal, and how subsequent operation with photosynthetic cathodes—Chlorella sp., Arthrospira platensis and Tetraselmis subcordiformis—modulates anodic microbial communities and functional potential. Stimulation at 1 V yielded the best activation effect, resulting in the highest voltage output, power density and fastest COD removal kinetics, whereas 5 V inhibited biofilm development. During pMFC operation, Chlorella produced the highest voltage (0.393 ± 0.064 V), current density (0.14 ± 0.02 mA·cm−2) and Coulombic efficiency (~19%). Arthrospira showed moderate performance, while Tetraselmis generated no current despite efficient COD removal. 16S rRNA sequencing revealed distinct cathode-driven community shifts: Chlorella enriched facultative electroactive taxa, Arthrospira promoted sulfur-cycling bacteria and Actinobacteria, and Tetraselmis induced strong methanogenic dominance. Functional prediction and qPCR confirmed these trends, with Chlorella showing increased pilA abundance and Tetraselmis displaying enriched methanogenic pathways. Overall, the combined use of optimal anodic stimulation and photosynthetic cathodes demonstrates that cathodic microalgae strongly influence anodic redox ecology and energy recovery, with Chlorella-based pMFCs offering the highest electrochemical performance.

Tao Lu, Mingjing Ke, Michel Lavoie et al.

Microbiome • 2018

We document a novel metabolic network in which soil microbiota influenced plant flowering time, thus shedding light on the key role of soil microbiota on plant functioning. This opens up multiple opportunities for application, from helping to mitigate some of the effects of climate change and environmental stress on plants (e.g. abnormal temperature variation, drought, salinity) to manipulating plant characteristics using microbial inocula to increase crop potential.

Cristina Romera‐Castillo, Maria Pinto, Teresa M. Langer et al.

Nature Communications • 2018

Approximately 5.25 trillion plastic pieces are floating at the sea surface. The impact of plastic pollution on the lowest trophic levels of the food web, however, remains unknown. Here we show that plastics release dissolved organic carbon (DOC) into the ambient seawater stimulating the activity of heterotrophic microbes. Our estimates indicate that globally up to 23,600 metric tons of DOC are leaching from marine plastics annually. About 60% of it is available to microbial utilization in less than 5 days. If exposed to solar radiation, however, this DOC becomes less labile. Thus, plastic pollution of marine surface waters likely alters the composition and activity of the base of the marine food webs. It is predicted that plastic waste entering the ocean will increase by a factor of ten within the next decade, resulting in an increase in plastic-derived DOC that might have unaccounted consequences for marine microbes and for the ocean system.

Sarvjeet Kukreja, Kajal Thakur, Neha Salaria et al.

Journal of Pure and Applied Microbiology • 2017

The depletion of fossil fuel for energy production is one of the major problems being faced worldwide. As an alternative to fossil fuels, first and second generation biofuel was developed from corn, grains and lignocellulosic agricultural residues. These generations are inefficient in achieving the desired rate of biofuel production, climate change mitigation and economic growth. Therefore, third generation biofuel specifically derived from microalgae have proved to be a promising unconventional energy source. Microalgae are microscopic organisms that grow in salt or fresh water and have been used for producing metabolites, cosmetics and for energy production. The conventional approaches used for biofuel production include pyrolysis, gasification, direct combustion and thermomechanical liquefaction. The search for biological and eco-friendly approaches led to the emergence of Microbial Fuel Cell (MFC), which provide a new solution to energy crisis. Integration of photosynthetic organisms such as microalgae into MFC resulted in a new approach i.e. Microbial Solar Cell, which can convert solar energy into electrical energy via photosynthesis. Microbial solar cells have broad range application in wastewater treatment, biodiesel processing and intermediate metabolite production.

Pedro H. M. Andrade, Christophe Volkringer, Thierry Loiseau et al.

Applied Materials Today • 2024

Metal-Organic Frameworks (MOFs) have gained considerable attention due to their potential applications in gas storage, separation, and catalysis. These porous materials exhibit properties of interest for semiconductor physics and homogeneous photocatalysis, in which concepts from coordination chemistry and semiconductor physics are often mixed. In the photocatalysis field, the optical band gap of the semiconductors is a crucial parameter that determine their functionality. Despite all the interest of MOFs, there is still a considerable lack of information about their band gap evaluation (especially if the gap is direct or indirect) using UV–Vis spectroscopy, and there is a considerable scattering in these values. The Tauc plot method is frequently used to access band gaps, even though it is not always accurate, especially for distinguishing direct and indirect band gaps. A more complete and precise analysis can be reached by using additional experimental techniques (XPS, UPS, and IPES spectroscopies), that are not always of easy access. This work examines several approaches for determining the band gap of MOF materials and proposes methodologies for a correct data interpretation, which leads to a better agreement between experimental and theoretical gaps. Several methods were analyzed to access the band gap of different MOF materials – UiO-66(Zr), UiO-66(Hf), UiO-66(Zr/Ti), UiO-66(Hf/Ti), UiO-67(Zr)_NH2, UiO-67(Zr/Hf)_NH2, UiO-67(Hf)_NH2, MIL-125(Ti), and MIL-125(Ti)_NH2 – purely from diffuse reflectance UV–vis (DR-UV–vis) data. The Kubelka-Munk and log(1/R) approaches were considered for transforming the DR-UV–vis spectra and the results demonstrate that the former method is more suitable, as it provides spectra with sharper absorption edges, which facilitates the interpretation and characterization of the optical band gaps. This study also highlights the importance of pre-data treatment and baseline correction in cases where a pre-absorption edge is present. Finally, by applying the Kramers-Kronig transformation to the reflectance spectra, and the Boltzmann regression to the Kubelka-Munk data, a solid base was created for determining if a material has a direct or an indirect gap. In addition, for some materials, the need for acquiring both the indirect and direct band gap values was discussed, as in some of these hybrid materials, both of these transitions can occur simultaneously. This paper guides the research community towards a most suitable methodology for assessing optical band gaps in hybrid materials, as it assists researchers in selecting the best methodology for their needs while avoiding typical mistakes in data interpretation.

Yixin Zhang, Le You, Pu Deng et al.

ACS Applied Materials & Interfaces • 2022

Exoelectrogens are known to be specialized in reducing various extracellular electron acceptors to form conductive nanomaterials that are integrated with their cell bodies both structurally and functionally. Utilizing this unique capacity, we created a strategy toward the design and fabrication of a biohybrid electronic material by exploiting bioreduced graphene oxide (B-rGO) as the structural and functional linker to facilitate the interaction between the exoelectrogen community and external electronics. The metabolic functions of exoelectrogens encoded in this living hybrid can therefore be effectively translated toward corresponding microbial fuel cell applications. Furthermore, this material can serve as a fundamental building block to be integrated with other microorganisms for constructing various electronic components. Toward a broad impact of this biohybridization strategy, photosynthetic organelles and cells were explored to replace exoelectrogens as the active bioreducing components and as formed materials exhibited 4- and 8-fold improvements in photocurrent intensities as compared with native bioelectrode interfaces. Overall, a biologically driven strategy for the fabrication and assembly of electronic materials is demonstrated, which provides a unique opportunity to precisely probe and modulate desired biofunctions through deterministic electronic inputs/outputs and revolutionize the design and manufacturing of next-generation (bio)electronics.

Paul Bolay, Rokhsareh Rozbeh, M. Isabel Muro‐Pastor et al.

mBio • 2021

Among prokaryotes, cyanobacteria have an exclusive position as they perform oxygenic photosynthesis. Cyanobacteria substantially differ from other bacteria in further aspects, e.g., they evolved a plethora of unique regulatory mechanisms to control primary metabolism. This is exemplified by the regulation of glutamine synthetase (GS) via small proteins termed inactivating factors (IFs). Here, we reveal another small protein, encoded by the ssr0692 gene in the model strain Synechocystis sp. PCC 6803, that regulates flux into the ornithine-ammonia cycle (OAC), the key hub of cyanobacterial nitrogen stockpiling and remobilization. This regulation is achieved by the interaction with the central carbon/nitrogen control protein P II , which commonly controls entry into the OAC by activating the key enzyme of arginine synthesis, N -acetyl-l-glutamate kinase (NAGK). In particular, the Ssr0692 protein competes with NAGK for P II binding and thereby prevents NAGK activation, which in turn lowers arginine synthesis. Accordingly, we termed it P II - i nteracting r egulator of a rginine synthesis (PirA). Similar to the GS IFs, PirA accumulates in response to ammonium upshift due to relief from repression by the global nitrogen control transcription factor NtcA. Consistent with this, the deletion of pirA affects the balance of metabolite pools of the OAC in response to ammonium shocks. Moreover, the PirA-P II interaction requires ADP and is prevented by P II mutations affecting the T-loop conformation, the major protein interaction surface of this signal processing protein. Thus, we propose that PirA is an integrator determining flux into N storage compounds not only depending on the N availability but also the energy state of the cell. IMPORTANCE Cyanobacteria contribute a significant portion to the annual oxygen yield and play important roles in biogeochemical cycles, e.g., as major primary producers. Due to their photosynthetic lifestyle, cyanobacteria also arouse interest as hosts for the sustainable production of fuel components and high-value chemicals. However, their broad application as microbial cell factories is hampered by limited knowledge about the regulation of metabolic fluxes in these organisms. Our research identified a novel regulatory protein that controls nitrogen flux, in particular arginine synthesis. Besides its role as a proteinogenic amino acid, arginine is a precursor for the cyanobacterial storage compound cyanophycin, which is of potential interest to biotechnology. Therefore, the obtained results will not only enhance our understanding of flux control in these organisms but also help to provide a scientific basis for targeted metabolic engineering and, hence, the design of photosynthesis-driven biotechnological applications.

Oscar Guadarrama‐Pérez, Víctor Hugo Guadarrama-Pérez, Victoria Bustos‐Terrones et al.

Electrochimica Acta • 2024

Rehab H. Mahmoud, Khaled Kirah, Ola M. Gomaa

Bioresource Technology Reports • 2023

Ning Ling, Tingting Wang, Yakov Kuzyakov

Nature Communications • 2022

Microbial composition and functions in the rhizosphere-an important microbial hotspot-are among the most fascinating yet elusive topics in microbial ecology. We used 557 pairs of published 16S rDNA amplicon sequences from the bulk soils and rhizosphere in different ecosystems around the world to generalize bacterial characteristics with respect to community diversity, composition, and functions. The rhizosphere selects microorganisms from bulk soil to function as a seed bank, reducing microbial diversity. The rhizosphere is enriched in Bacteroidetes, Proteobacteria, and other copiotrophs. Highly modular but unstable bacterial networks in the rhizosphere (common for r-strategists) reflect the interactions and adaptations of microorganisms to dynamic conditions. Dormancy strategies in the rhizosphere are dominated by toxin-antitoxin systems, while sporulation is common in bulk soils. Functional predictions showed that genes involved in organic compound conversion, nitrogen fixation, and denitrification were strongly enriched in the rhizosphere (11-182%), while genes involved in nitrification were strongly depleted.

Sharbani Kaushik, Pranab Goswami

ACS Applied Materials & Interfaces • 2018

The biosensing application of microbial fuel cell (MFC) is hampered by its long response time, poor selectivity, and technical difficulty in developing portable devices. Herein, a novel signal form for rapid detection of ethanol was generated in a photosynthetic MFC (PMFC). First, a dual chambered (100 mL each) PMFC was fabricated by using cyanobacteria-based anode and abiotic cathode, and its performance was examined for detection of alcohols. A graphene-based nanobiocomposite matrix was layered over graphite anode to support cyanobacterial biofilm growth and to facilitate electron transfer. Injection of alcohols into the anodic chamber caused a transient potential burst of the PMFC within 60 s (load 1000 Ω), and the magnitude of potential could be correlated to the ethanol concentrations in the range 0.001-20% with a limit of detection (LOD) of 0.13% ( R 2 = 0.96). The device exhibited higher selectivity toward ethanol than methanol as discerned from the corresponding cell-alcohol interaction constant ( K i ) of 780 and 1250 mM. The concept was then translated to a paper-based PMFC (p-PMFC) (size ∼20 cm 2 ) wherein, the cells were merely immobilized over the anode. The device with a shelf life of ∼3 months detected ethanol within 10 s with a dynamic range of 0.005-10% and LOD of 0.02% ( R 2 = 0.99). The fast response time was attributed to the higher wettability of ethanol on the immobilized cell surface as validated by the contact angle data. Alcohols degraded the cell membrane on the order of ethanol > methanol, enhanced the redox current of the membrane-bound electron carrier proteins, and pushed the anodic band gap toward more negative value. The consequence was the potential burst, the magnitude of which was correlated to the ethanol concentrations. This novel approach has a great application potential for selective, sensitive, rapid, and portable detection of ethanol.

Michael Shaffer, Mikayla Borton, Bridget B. McGivern et al.

Nucleic Acids Research • 2020

Microbial and viral communities transform the chemistry of Earth's ecosystems, yet the specific reactions catalyzed by these biological engines are hard to decode due to the absence of a scalable, metabolically resolved, annotation software. Here, we present DRAM (Distilled and Refined Annotation of Metabolism), a framework to translate the deluge of microbiome-based genomic information into a catalog of microbial traits. To demonstrate the applicability of DRAM across metabolically diverse genomes, we evaluated DRAM performance on a defined, in silico soil community and previously published human gut metagenomes. We show that DRAM accurately assigned microbial contributions to geochemical cycles and automated the partitioning of gut microbial carbohydrate metabolism at substrate levels. DRAM-v, the viral mode of DRAM, established rules to identify virally-encoded auxiliary metabolic genes (AMGs), resulting in the metabolic categorization of thousands of putative AMGs from soils and guts. Together DRAM and DRAM-v provide critical metabolic profiling capabilities that decipher mechanisms underpinning microbiome function.

Lingyan Huang, Xing Liu, Zhishuai Zhang et al.

The ISME Journal • 2021

The direct conversion of CO 2 to value-added chemical commodities, thereby storing solar energy, offers a promising option for alleviating both the current energy crisis and global warming. Semiconductor-biological hybrid systems are novel approaches. However, the inherent defects of photocorrosion, photodegradation, and the toxicity of the semiconductor limit the application of these biohybrid systems. We report here that Rhodopseudomonas palustris was able to directly act as a living photosensitizer to drive CO 2 to CH 4 conversion by Methanosarcina barkeri under illumination after coculturing. Specifically, R. palustris formed a direct electric syntrophic coculture with M. barkeri. Here, R. palustris harvested solar energy, performed anoxygenic photosynthesis using sodium thiosulfate as an electron donor, and transferred electrons extracellularly to M. barkeri to drive methane generation. The methanogenesis of M. barkeri in coculture was a light-dependent process with a production rate of 4.73 ± 0.23 μM/h under light, which is slightly higher than that of typical semiconductor-biohybrid systems (approximately 4.36 μM/h). Mechanistic and transcriptomic analyses showed that electrons were transferred either directly or indirectly (via electron shuttles), subsequently driving CH 4 production. Our study suggests that R. palustris acts as a natural photosensitizer that, in coculture with M. barkeri, results in a new way to harvest solar energy that could potentially replace semiconductors in biohybrid systems.

Yustika Desti Yolanda, Sangsik Kim, Weonjung Sohn et al.

Desalination and Water Treatment • 2024

Hydroponics has increasingly been recognized as an important agricultural method due to its stable crop yields under rapidly changing environmental conditions. However, the efficient treatment of nutrient-rich hydroponic wastewater remains a major challenge. This study investigates the effect of anodic pH on the performance of microalgae–microbial fuel cells (mMFCs), focusing on bioelectricity generation, photosynthetic oxygen supply, nutrient removal and recovery, and carbon capture. The mMFC system achieved a maximum power density of 122.5 mW/m², a chemical oxygen demand removal efficiency of 93.7%, and an anode-side total nitrogen removal efficiency of 27.5% at an acidic anodic pH. In addition, the cathode chamber had a total ammonium nitrogen removal efficiency of 22.6%, which was ascribed to a combination of ammonium migration and subsequent nitrogen assimilation, and a phosphate removal efficiency of 100%, likely due to microalgal uptake and adsorption. The mMFC also effectively captured CO 2 with an algal biomass yield of 0.01379 g·L -1 ·d -1 and a CO₂ fixation rate of 0.02528 g·L -1 ·d -1 . These findings provide insights into the optimization of mMFCs as a sustainable solution for managing nutrient-rich hydroponic wastewater, contributing to energy-efficient and resource-recovering wastewater treatment technologies. • mMFCs were explored for nutrient recovery from hydroponic wastewater and energy generation. • The mMFCs demonstrated CO₂ fixation and algal biomass production. • Microalgae enabled aeration-free operation, potentially reducing energy use. • Anodic pH 6 outperformed pH 7 and 8 in MPD, COD removal, and TN removal efficiency. • The mMFCs removed 22.6% TAN and 100% PO₄³⁻ in cathode chamber.

Ira Rai, Ankesh Ahirwar, Anshuman Rai et al.

Sustainable Energy Technologies and Assessments • 2022

Xueqin Chen, Yan Gao, Yongbing Qi et al.

Angewandte Chemie International Edition • 2024

The fabrication of high-performance microbial fuel cells requires the evaluation of the activity of electrochemically active bacteria. However, this is challenging because of the time-consuming nature of biofilm formation and the invasive nature of labeling. To address this issue, we developed a fast, label-free, single-cell Raman spectroscopic method. This method involves investigating the "pure" linear Stark effect of endogenous CO in the silent region of biological samples, which allows for probing the intrinsic electric field in the outer-membrane cytochromes of live bacterial cells. We found that reduced outer-membrane cytochromes can generate an additional intrinsic electric field equivalent to an applied potential of +0.29 V. We also found that the higher the electrical activity of the cell, the larger the generated electric field. This was also reflected in the output current of the constructed microbial fuel cells. Raman spectroscopy was employed to facilitate the assessment of electrochemical activity at the single-cell level in highly-diluted bacterial samples. After analysis, inactive bacteria were ablated by laser heating, and 20 active cells were cultured for further testing. The rapid and high-throughput probing of the intrinsic electric field offers a promising platform for high-efficiency screening of electrochemically active bacterial cells for bioenergetic and photosynthetic research.

Guangjie Liang, Yuan Liu, Ziyun Gu et al.

Chemical Engineering Journal • 2024

Lionel Guidi, Samuel Chaffron, Lucie Bittner et al.

Nature • 2016

Antonina Rita Limongi, Emanuele Viviano, Maria De Luca et al.

Applied Sciences • 2021

The need to safeguard our planet by reducing carbon dioxide emissions has led to a significant development of research in the field of alternative energy sources. Hydrogen has proved to be the most promising molecule, as a fuel, due to its low environmental impact. Even if various methods already exist for producing hydrogen, most of them are not sustainable. Thus, research focuses on the biological sector, studying microalgae, and other microorganisms’ ability to produce this precious molecule in a natural way. In this review, we provide a description of the biochemical and molecular processes for the production of biohydrogen and give a general overview of one of the most interesting technologies in which hydrogen finds application for electricity production: fuel cells.

Jae-Hoon Hwang, Jared Church, Seung‐Jin Lee et al.

Environmental Engineering Science • 2016

Given that sustainable energy production and advanced wastewater treatment for producing clean water are two major challenges faced by modern society, microalgae make a desirable treatment alternative by providing a renewable biomass feedstock for biofuel production, while treating wastewater as a growth medium. Microalgae have been known to be resilient to the toxic contaminants of highly concentrated organic wastewater (e.g., organic nitrogen, phosphorus, and salinity) and are excellent at sorbing heavy metals and emerging contaminants. Economic and environmental advantages associated with massive algae culturing in wastewater constitute a driving force to promote its utilization as a feedstock for biofuels. However, there are still many challenges to be resolved which have impeded the development of algal biofuel technology at a commercial scale. This review provides an overview of an integrated approach using microalgae for wastewater treatment, CO2 utilization, and biofuel production. The main goal of this article is to promote research in algae technologies by outlining critical needs along the integrated process train, including cultivation, harvesting, and biofuel production. Various aspects associated with design challenges of microalgae production are described and current developments in algae cultivation and pretreatment of algal biomass for biofuel production are also discussed. Furthermore, synergistic coupling of the use of microalgae for advanced wastewater treatment and biofuel production is highlighted in a sustainability context using life cycle analysis.

E Yu Konovalova, Lepakshi Barbora, Konstantin Chizhik et al.

IOP Conference Series Earth and Environmental Science • 2020

Abstract Microbial fuel cells make it possible to generate electricity by eliminating and using wastewater components. For these purposes, the most viable microbial associations in microbial fuel cells. The presence of strains of different microorganisms allows you to consume a much wider range of compounds. Multicomponent makes them more resistant to the negative effects of stressful environmental factors. An example of such associations are silt sediments of biological treatment plants. The purpose of this work was to create a new microbial association. Microbial association was formed from previously isolated strains from activated sludge from the petrochemical plant, Micrococcus luteus and Serratia marcescens . Model wastewater was taken as substrates. The generation of electricity was carried out in microbial fuel cell models that we developed. These designs allowed access to the contents of microbial fuel cells without violating sterility and anaerobic conditions in the anode chamber. In the experiments, the voltage, current in microbial fuel cells were measured and the power was calculated. Experiments have shown high electrogenic activity when working together with Micrococcus luteus and Serratia marcescens cohosts for a good variety of the proposed bioagent complex. The search and isolation of energy-efficient strains and the compilation of a new consortium from them will not only increase the current output in microbial fuel cells to more significant values, but also bring such microbial fuel cells into the category of promising developments for alternative energy. This work was supported by the Ministry of Education and Science of the Russian Federation (project RFMEFI58317X0060 “Bioremediation and bioconversion of waste using a complex of photosynthetic organisms and heterotrophs in aerobic and anaerobic conditions with bioenergy generation”).

Shentan Liu, Hongpu Xue, Yue Wang et al.

Bioresources and Bioprocessing • 2022

Wetlands are an important carbon sink for greenhouse gases (GHGs), and embedding microbial fuel cell (MFC) into constructed wetland (CW) has become a new technology to control methane (CH 4 ) emission. Rhizosphere anode CW-MFC was constructed by selecting rhizome-type wetland plants with strong hypoxia tolerance, which could provide photosynthetic organics as alternative fuel. Compared with non-planted system, CH 4 emission flux and power output from the planted CW-MFC increased by approximately 0.48 ± 0.02 mg/(m 2 ·h) and 1.07 W/m 3 , respectively. The CH 4 emission flux of the CW-MFC operated under open-circuit condition was approximately 0.46 ± 0.02 mg/(m 2 ·h) higher than that under closed-circuit condition. The results indicated that plants contributed to the CH 4 emission from the CW-MFC, especially under open-circuit mode conditions. The CH 4 emission from the CW-MFC was proportional to external resistance, and it increased by 0.67 ± 0.01 mg/(m 2 ·h) when the external resistance was adjusted from 100 to 1000 Ω. High throughput sequencing further showed that there was a competitive relationship between electrogenic bacteria and methanogens. The flora abundance of electrogenic bacteria was high, while methanogens mainly consisted of Methanothrix, Methanobacterium and Methanolinea. The form and content of element C were analysed from solid phase, liquid phase and gas phase. It was found that a large amount of carbon source (TC = 254.70 mg/L) was consumed mostly through microbial migration and conversion, and carbon storage and GHGs emission accounted for 60.38% and 35.80%, respectively. In conclusion, carbon transformation in the CW-MFC can be properly regulated via competition of microorganisms driven by environmental factors, which provides a new direction and idea for the control of CH 4 emission from wetlands.

Jialu Li, Junfeng Shen, Tian Hou et al.

Advanced Science • 2024

The development of semi-artificial photosynthetic systems, which integrate metal-organic frameworks (MOFs) with industrial microbial cell factories for light-driven synthesis of fuels and valuable chemicals, represents a highly promising avenue for both research advancements and practical applications. In this study, an MOF (PCN-222) utilizing racemic-(4-carboxyphenyl) porphyrin and zirconium chloride (ZrCl 4 ) as primary constituents is synthesized. Employing a self-assembly process, a hybrid system is constructed, integrating engineered Escherichia coli (E. coli) to investigate light-driven hydrogen and lysine production. These results demonstrate that the light-irradiated biohybrid system efficiently produce H 2 with a quantum efficiency of 0.75% under full spectrum illumination, the elevated intracellular reducing power NADPH is also observed. By optimizing the conditions, the biohybrid system achieves a maximum lysine production of 18.25 mg L -1 , surpassing that of pure bacteria by 332%. Further investigations into interfacial electron transfer mechanisms reveals that PCN-222 efficiently captures light and facilitates the transfer of photo-generated electrons into E. coli cells. It is proposed that the interfacial energy transfer process is mediated by riboflavin, with facilitation by secreted small organic acids acting as hole scavengers for PCN-222. This study establishes a crucial foundation for future research into the light-driven biomanufacturing using E. coli-based hybrid systems.

Emma Barahona, Emilio Jiménez‐Vicente, Luis M. Rubio

Scientific Reports • 2016

When produced biologically, especially by photosynthetic organisms, hydrogen gas (H 2 ) is arguably the cleanest fuel available. An important limitation to the discovery or synthesis of better H 2 -producing enzymes is the absence of methods for the high-throughput screening of H 2 production in biological systems. Here, we re-engineered the natural H 2 sensing system of Rhodobacter capsulatus to direct the emission of LacZ-dependent fluorescence in response to nitrogenase-produced H 2 . A lacZ gene was placed under the control of the hupA H 2 -inducible promoter in a strain lacking the uptake hydrogenase and the nifH nitrogenase gene. This system was then used in combination with fluorescence-activated cell sorting flow cytometry to screen large libraries of nitrogenase Fe protein variants generated by random mutagenesis. Exact correlation between fluorescence emission and H 2 production levels was found for all automatically selected strains. One of the selected H 2 -overproducing Fe protein variants lacked 40% of the wild-type amino acid sequence, a surprising finding for a protein that is highly conserved in nature. We propose that this method has great potential to improve microbial H 2 production by allowing powerful approaches such as the directed evolution of nitrogenases and hydrogenases.

Kundan Samal, Naushin Yasmin, Priya Kumari

Journal of environmental chemical engineering • 2020

Wenjing Wang, Yanqing Sheng

The Science of The Total Environment • 2024

Savas Anastassiadis

World Journal of Biology and Biotechnology • 2016

Carbon atom Carbon atom is most important and abundant constituent of existing and new generated biological mater and biomass and the basis of all forms of life on earth. It is involved in the composition and construction of organic micro- and macromolecules, cells and living organisms, storage molecules, fossils, fossil fuels, biofuels and energy resources of living and nonliving organic matter. Initially originated from atmospheric carbon dioxide, it is absorbed and incorporated into organic molecules by photosynthetic plants and microorganisms through photosynthetic processes to form glucose and other less or more complex organic molecules, enabling and sustaining life on Earth. A semantic part of CO2 has been captured, trapped and immobilized in various forms of fossils, not participating in biogeochemical carbon cycles for millions of years, or is dissolved in oceans. Carbon sources is also one of most important parameters, strongly influencing microbial growth and the accumulation of cellular metabolites, fermentation technologies, process economics and feasibility of industrial production. Advanced developments in recombinant technologies, such as metabolic and genetic engineering, systems and synthetic biology, as well as in bioengineering, biotechnology, industrial microbiology and fermentation technology will expand the opportunities of literally unseen microbial world.

T. Srinivasa Kumar, Satya Eswari Jujjavarapu

Journal of Cleaner Production • 2023

Banu Taşkan, Ergin Taşkan

Bioresource Technology • 2022

Jiansheng Li, Yao Tian, Yinuo Zhou et al.

Transactions of Tianjin University • 2020

Abstract Abiotic–biological hybrid systems that combine the advantages of abiotic catalysis and biotransformation for the conversion of carbon dioxide (CO 2 ) to value-added chemicals and fuels have emerged as an appealing way to address the global energy and environmental crisis caused by increased CO 2 emission. We illustrate the recent progress in this field. Here, we first review the natural CO 2 fixation pathways for an in-depth understanding of the biological CO 2 transformation strategy and why a sustainable feed of reducing power is important. Second, we review the recent progress in the construction of abiotic–biological hybrid systems for CO 2 transformation from two aspects: (i) microbial electrosynthesis systems that utilize electricity to support whole-cell biological CO 2 conversion to products of interest and (ii) photosynthetic semiconductor biohybrid systems that integrate semiconductor nanomaterials with CO 2 -fixing microorganisms to harness solar energy for biological CO 2 transformation. Lastly, we discuss potential approaches for further improvement of abiotic–biological hybrid systems.

Bo Chuan Huang, Ying-Chen Yi, Jo‐Shu Chang et al.

Scientific Reports • 2019

Shewanella oneidensis MR-1, a bioelectricity generating bacterium, is broadly used in bioremediation, microbial fuel cell and dissimilatory reduction and recovery of precious metals. Herein, we report for the first time that photo induction as a trigger to stimulate gold nanoparticles (Au@NPs) formation by MR-1, with wavelength and light intensity as two key variables. Results indicated that sigmoidal model is the best fit for Au@NPs formation at various wavelengths (with R 2 > 0.97). Light intensity in terms of photosynthetic photon flux density (PPFD) critically influences the rate constant in the low-light intensity region (PPFD < 20), while wavelength controls the maximum rate constant in the high-light region (PPFD > 20). By deletion of Mtr pathway genes in MR-1, we proposed the mechanism for light induced Au@NP formation is the excitation effect of light on certain active groups and extracellular polymeric substances (EPS) on the cell surface. Also, the release of electrons from proteins and co-enzyme complexes enhance electron generation. To the best of our knowledge, this is the first-attempt to explore the effect of photo-induction on Au@NPs production by MR-1, which provides an alternative cost-effective and eco-friendly process in green chemical industry.

Lingyan Huang, Xing Liu, Jiahuang Tang et al.

Bioelectrochemistry • 2019

Lailatus Sa’diya, Amatul Firdausy Khansa, Andarista Putri Darsono et al.

IOP Conference Series Earth and Environmental Science • 2024

Abstract Rapid economic growth and increasing electrical energy consumption have raised significant challenges to the provision of sustainable electrical energy. This research aims to examine the effect of variations in the population density of microalgae and the type of electrode (graphite and nickel) on the electrical voltage produced. This research was carried out experimentally using a randomized block design (RAK) consisting of 5 treatments and 3 repetitions. Electrical voltage data was taken every 60 minutes for 12 hours (6 hours of light and 6 hours of dark) for all treatments. The results showed that the use of different types of electrodes in the PMFC circuit did not affect the electrical voltage produced because both electrodes produced voltage electricity with a difference that is not much different, namely for graphite electrodes between 38.1 mV – 135.6 mV in the light phase and between 16.7 mV – 144.1 mV in the dark phase, while for nickel electrodes it is between 18.2 mV – 135.4 mV in the light phase and between 18.3 mV – 156 mV in the dark phase. Variations in population density of the microalgae Scenedesmus sp. used in the PMFC circuit have a significant effect (P&lt;0.05) on the electrical voltage produced, namely in the light phase of treatment (P4) 2×10 7 it is 131.53 ± 25.12 mV for graphite electrodes and 137.90 ± 17.26 mV for nickel electrodes, while in the dark phase treatment (P3) 2×10 6 it was 168.70 ± 18.55 mV for graphite electrodes and 139.70 ± 27.35 mV for nickel electrodes.

Farhan Fikri Safii, Syeda Takmeel Zahra, Mohammad Ali Sofyan

AIP conference proceedings • 2023

Mariajoseph Angelaalincy, Senthilkumar Nangan, Rathinasamy Karpagam et al.

ACS Omega • 2017

In this study, a freshwater microalga, Scenedesmus sp. SB1, was isolated, purified, and identified by its internal transcribed spacer region (ITS1-5.8S-ITS2). Media optimization through the Plackett-Burman Design and response surface methodology (RSM) showed a maximum exopolysaccharide (EPS) production of 48 mg/L (1.8-fold higher than that for unoptimized media). Characterization using gas chromatography-mass spectrometry, Fourier transform infrared, X-ray diffraction, and thermogravimetric analysis reveals that the EPS is a sulfated pectin polysaccharide with a crystallinity index of 15.2% and prompt thermal stability. Furthermore, the photoelectrogenic activity of Scenedesmus sp. SB1 inoculated in BG-11 and RSM-optimized BG-11 (ROBG-11) media was tested by cyclic voltammogram studies, revealing the potential of the inoculated strain in ROBG-11 toward photosynthetic algal microbial fuel cells over normal BG-11. To the best of our knowledge, functional group characterization, physical and thermal property and media optimization for EPS production by RSM and electrogenic activity studies are reported for the first time in Scenedesmus sp. SB1.