Microbes That Make Energy
Could Microbial Fuel Cells Be The Clean Energy Of The Future?
Is it possible that microbes could replace gas stations?
Microorganisms can generate energy by emitting electrons. This phenomenon, recognized since the era of Ben Franklin, has garnered recent interest in studies as a potential substitute for fossil fuels. Scientists have conducted research on energy-generating microorganisms to capture their energy and develop "batteries" capable of powering various equipment.
An article published in 2018 by the Berkeley News states that bacteria can generate energy. It has been previously shown that the discovered microorganisms were primarily extremophiles and pathogenic. A relatively new discovery is that the microorganisms in our digestive tract also generate energy. Lactobacillus, the most widely recognized microorganisms employed as probiotics, generate energy within our digestive system and may also produce energy through diverse fermentation processes. (Sanders, 2018) Lactobacillus utilizes the flavin molecule to produce energy. (Sanders, 2018) Flavin is a constituent of riboflavin, which is a form of vitamin B2. It is typically present in brewer's yeast, eggs, dairy products, mushrooms, soybeans, whole grains, and wheat germ. The human diet is rich in riboflavin. Is it possible to harness the energy bacteria produce and store it in a battery or a fuel cell?
Photosynthetic Bacteria
Rhodopseudomonas palustris is a versatile bacterium renowned for producing biohydrogen, making it a valuable resource for renewable energy applications. Several strains of R. palustris exhibit unique characteristics and capabilities, contributing to developing sustainable energy solutions.
Nitrogenase activity in R. palustris DX-1 makes hydrogen efficient in anaerobic and light conditions. It turns organic substrates into hydrogen, which can be used to make electricity in proton exchange membrane (PEM) fuel cells. (Li et al., 2022; Min et al., 2023)) Similarly, R. palustris PS3 engages in biohydrogen production through photofermentation, utilizing organic materials and sunlight, contributing to energy sustainability in both industrial and household contexts. R. palustris CGA009 is known for its robust hydrogen output, excelling in photofermentation by converting organic acids and light into hydrogen gas, which can be used directly in fuel cells. (Li et al., 2022) R. palustris TIE-1 is notable for its metabolic versatility, capable of both phototrophic and chemotrophic energy production and efficiently generating hydrogen under appropriate conditions, making it a flexible candidate for various applications. Additionally, R. palustris BisB18 focuses on optimizing substrate utilization, contributing to effective waste management and environmental sustainability. (Baj et al., 2021)
Microbially-produced hydrogen molecules are collected from bioreactors and integrated into fuel cells. Then, the hydrogen molecules are split into protons and electrons, generating electricity and producing water as a byproduct. This process offers a clean, renewable energy source, reducing reliance on fossil fuels and contributing to a sustainable energy future. Each strain's efficiency and suitability depend on specific environmental conditions and substrate availability, but collectively, R. palustris strains hold significant potential for advancing renewable energy technologies. Continued research and optimization are essential to enhance their scalability and practical application in various sectors.
Other Bioelectric Microbes
Apparently, several species of bacteria are capable of producing bioelectricity. They also tend to be anaerobic bacteria that reduce metals. Geobacter and Shewanella possess distinct properties that allow them to transmit electrons to external surfaces, generating electricity. Lactobacillus, as mentioned above, and a genetically engineered E. coli have also been studied for their extracellular electron transfer (EET). (Sanders, 2018: The Economic Times, 2023) EET is how these bacteria utilize conductive pili, or nanowires, to transport electrons beyond their cells.
Microbial fuel cells (MFCs) utilize these microorganisms to oxidize organic substrates, releasing electrons as a component of their metabolic process. Electrons are transmitted to an anode, generating an electric current that passes through an external circuit to a cathode. At the cathode, the electrons mix with protons and oxygen to produce water. This technique produces energy and aids in bioremediation by decomposing organic contaminants in wastewater. (Logan and Regan, 2006; Lal, 2013)
Geobacter species exhibit exceptional efficiency in this process and are commonly present in metal-rich environments, where they facilitate the reduction of insoluble iron and manganese oxides. Shewanella species, in contrast, exhibit versatility by using a diverse array of electron acceptors, enabling them to adapt to a multitude of environmental situations.
The electricity these bacteria produce in microbial fuel cells (MFCs) is a form of sustainable energy. As such, it can be utilized for small-scale power applications. Ongoing research aims to enhance the efficiency and scalability of these systems, investigate their possibilities in powering low-energy devices, and contribute to renewable energy solutions.
Conclusion
While these bacteria can generate biofuels, it is still a considerable time before they can replace traditional gas stations or power electric vehicles. Researchers are currently endeavoring to figure this out. Several investigations indicate that the energy output was not maintained for extended durations, with some instances lasting only a few hours. Multiple factors are contingent upon the specific species being utilized and the medium in which they are cultivated. Developing durable fuel cells powered by microorganisms will likely take at least a decade or more. Nevertheless, the abilities of these small organisms are truly astonishing.
References
The Economic Times. (2023, Sept 16). Microbes Can Create Electricity From Wastewater: Study. (Warning: This site has so many ads that it may be difficult for some computers to open and will suck RAM!!!) https://economictimes.indiatimes.com/news/science/microorganisms-can-create-electricity-from-wastewater-study/articleshow/103716537.cms?from=mdr
Bai, W., Ranaivoarisoa, T. O., Singh, R., Rengasamy, K., & Bose, A. (2021). N-Butanol production by Rhodopseudomonas palustris TIE-1. Communications Biology, 4(1), 1-16. https://doi.org/10.1038/s42003-021-02781-z
Lal, D. (2013). Microbes to Generate Electricity. Indian Journal of Microbiology, 53(1), 120-122. https://doi.org/10.1007/s12088-012-0343-2
Li, M., Ning, P., Sun, Y., Luo, J., & Yang, J. (2022). Characteristics and Application of Rhodopseudomonas palustris as a Microbial Cell Factory. Frontiers in Bioengineering and Biotechnology, 10. https://doi.org/10.3389/fbioe.2022.897003
Liu, C. H., Lee, S. K., Ou, I. C., Tsai, K. J., Lee, Y., Chu, Y. H.,... & Liu, C. T. (2021). Essential factors that affect bioelectricity generation by Rhodopseudomonas palustris strain PS3 in paddy soil microbial fuel cells. International journal of energy research, 45(2), 2231-2244. DOI:10.1002/er.5916 https://www.researchgate.net/publication/345735499_Essential_factors_that_affect_bioelectricity_generation_by_Rhodopseudomonas_palustris_strain_PS3_in_paddy_soil_microbial_fuel_cells
Logan, B. E., & Regan, J. M. (2006). Microbial fuel cells—challenges and applications. Environmental science & technology, 40(17), 5172-5180. https://pubs.acs.org/doi/pdf/10.1021/es0627592
Min, T., Zhang, R., Chen, L., & Zhou, Q. (2023). Reactive Transport Processes in Proton Exchange Membrane Fuel Cells. Encyclopedia, 3(2), 746-758. https://doi.org/10.3390/encyclopedia3020054
Sanders, R. (2018). Gut bacteria's shocking secret: They produce electricity. https://news.berkeley.edu/2018/09/12/gut-bacterias-shocking-secret-they-produce-electricity
Venkidusamy, K., & Megharaj, M. (2016). A Novel Electrophototrophic Bacterium Rhodopseudomonas palustris Strain RP2, Exhibits Hydrocarbonoclastic Potential in Anaerobic Environments. Frontiers in Microbiology, 7, 205318. https://doi.org/10.3389/fmicb.2016.01071
Hu, Y., Wang, Y., Han, X., Shan, Y., Li, F., & Shi, L. (2021). Biofilm biology and engineering of Geobacter and Shewanella spp. for energy applications. Frontiers in Bioengineering and Biotechnology, 9, 786416. https://doi.org/10.3389/fbioe.2021.786416