Chin-Tsan Wang(王金燦) *
Department of Mechanical and Electro-Mechanical Engineering,
National I-Lan University, I-Lan, 26047, Taiwan
*E-mail: ctwang@niu.edu.twWebsite: http://www.tw-cii.org/
摘要 (abstract)
Microbial fuel cells (MFCs) are known to be in a category of biofuel cells that employ microorganisms to produce electricity. In space conditions, specific problems related to microgravity require effective systems to maintain the viability of microorganisms and, more importantly, their ability to work. Escherichia coli (E. coli), a microorganism adopted primarily on MFCs, suffers from oxidative stress and accumulation of toxic secondary metabolites. Hence, it reduces the long-term stability. MFCs’ functionality and profitability in microgravity are challenging due to microorganisms being stressed through oxidation. As a result, they have low metabolic rates and produce toxic by-products that deteriorate the system. This stress can drastically reduce the mission time of MFCs, especially in long-term missions. This work aims to improve the efficiency and durability of MFCs in a microgravity environment using cysteine hydrochloride as a stressor (stress-reducing agent). More concretely, we want to avoid the production of secondary metabolites that could harm the cell and prevent oxidative stress to guarantee E. coli survival and constant energy production. An MFC setup was established using E. coli as the bio-catalyst and glucose as the primary substrate (electron donor). Microgravity, similar to what the system is likely to encounter when launched into space, was simulated using a Random Positioning Machine (RPM). Qualitative and quantitative comparisons were made between MFCs exposed to standard gravity and those exposed to microgravity conditions, developing various indices such as the metabolic activity of bacteria and electric utility. It emerged from the pilot data that adding cysteine hydrochloride considerably reduced the indication of oxidative stress in E. coli and the generation of secondary compounds. This enhancement was achieved with an increased bacterial survival rate and the duration of the MFCs exposed to microgravity conditions. Applying the MFCs with cysteine hydrochloride can show the way to the solutions needed to address the issues of microbial liveability and MFC sustaining ability in space atmosphere. The application of this method might thus prolong mechanistic MFC functionalities, which refer to consistent and reliable energy production in microgravity and provide beneficial improvements to space bioenergy systems. Key
Words: Microbial Fuel Cells, Microgravity, E. coli, Oxidative Stress, Cysteine Hydrochloride, Secondary Metabolites, Random Positioning Machine, Space bioenergy systems
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