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Pseudomonas putida with Microbial Electrochemical Technologies
Published in Sonia M. Tiquia-Arashiro, Deepak Pant, Microbial Electrochemical Technologies, 2020
One solution could be to introduce fermentative pathways of other microbes into P. putida, even though this was attempted with limited success (Nikel and de Lorenzo 2013; Steen et al. 2013), this would also lead to loss of carbon in the form of by-products that need to be made for redox balancing. Instead, one could also provide the cells with an alternative to O2 as the final electron acceptor that does not involve carbon as an electron acceptor. The prime solution for such an endeavor is the use of bioelectrochemical methods employing electrodes as solid electron acceptors. This concept was only recently demonstrated. This chapter will provide the first review regarding the research progress in this field and also address their future perspectives. It will discuss the central carbon metabolism of P. putida and then introduce the use of an anode for oxygen free chemical production in this obligate aerobic organism, and, finally, we will provide an outlook on the remaining bottlenecks to establish an electrode-driven biochemical production process using P. putida.
Microalgal competence in urban wastewater management: phycoremediation and lipid production
Published in International Journal of Phytoremediation, 2021
Dig Vijay Singh, A. K. Upadhyay, R. Singh, D. P. Singh
The superoxide dismutase (SOD) activity in both the microalgae was stimulated with increasing concentration of WW. The SOD activity in the Oscillatoria sp. was found to be the highest at 75% concentration of WW. The maximum increase in the SOD activity of C. humicola and Oscillatoria sp. at 100% and 75% WW was respectively about 1.43 fold and 1.32 fold higher than the control. SOD is a ubiquitous enzyme present in oxygen generating cellular compartments and plays vital role in protecting the aerobic organism from the oxidative damage (Ighodaro and Akinloye 2018; Mishra et al. 2019). Thus, an enhanced production of SOD with increasing concentration of WW might be due to rapid ROS accumulation and cellular defense response of microalgae toward the stress conditions. The SOD enzyme removes the superoxide radicals and restrains the formation of hydroxyl radicals within the microalgal cell (Singh et al. 2018). An increase in the SOD activity with rising WW concentrations signifies the tolerance of microalgae toward the WW stress.
Lab-scale bioremediation technology: Ex-situ bio-removal and biodegradation of waste cooking oil by Aspergillus flavus USM-AR1
Published in Bioremediation Journal, 2022
Nurshafiqah Jasme, Nur Asshifa Md Noh, Ahmad Ramli Mohd Yahya
ITS sequence is commonly used to identify isolated fungus. The PCR amplification of ITS region of strain USM-AR1 resulted a single band with approximately 600 bp (Figure 2). The ITS region of the oil-degraded USM-AR1 strain was sequenced and submitted to GenBank. Based on BLAST search, the strain USM-AR1 showed 99.82% similarity with MH864266 (ITS) of Aspergillus flavus CBS126857 in GenBank. As depicted in Figure 3, this strain belongs to the species of Aspergillus flavus. Aspergillus flavus USM-AR1 is an aerobic organism as Aspergillus species are usually highly aerobic and mostly can be found in almost all oxygen-rich environments.
Applications of electron spin resonance spectroscopy in photoinduced nanomaterial charge separation and reactive oxygen species generation
Published in Journal of Environmental Science and Health, Part C, 2021
Xiumei Jiang, Mary D. Boudreau, Peter P. Fu, Jun-Jie Yin
Adding electrons to O2 generates superoxide anion radicals, which possess a short half-life time of around 5 seconds in biological systems. Accumulation of superoxide anion radicals can result in oxidation damage to biomolecules. Therefore, almost every aerobic organism expresses superoxide dismutase (SOD), which catalyzes the dismutation of superoxide anion radicals into molecular oxygen and hydrogen peroxide. In the lab, superoxide anion radicals can be generated in situ by the xanthine/xanthine oxidase system.41 Like hydroxyl radicals, ESR detection of superoxide anion radicals also requires the application of spin traps. DMPO and BMPO are commonly used for ESR detection of superoxide anion radicals and spin adducts DMPO/•OOH and BMPO/•OOH will be produced. ESR spectrum of DMPO/•OOH has hyperfine fit parameters aN = 14.2 G, aHβ = 11.4 G, and aHγ1 = 1.2 G. The ESR spectrum characteristic for BMPO/•OOH adduct has hyperfine splitting parameters of aN = 13.4 G, aHβ = 12.1 G. It is worth noting that DMPO/•OOH adducts can decay to DMPO/•OH adducts, leading to misinterpretation of the experimental results. SOD is often added into the reaction system before adding DMPO to verify the presence of superoxide anion radicals. If the detected DMPO/·OH adducts are indeed derived from the conversion of DMPO/•OOH adducts, it can be expected that the signal of DMPO/•OH adducts will completely disappear upon SOD addition. He et al. studied the superoxide scavenging activity of gold (Au) nanoparticles using a xanthine/xanthine oxidase system.42 As shown in Figure 3, addition of xanthine oxidase to the solution containing xanthine, DTPA, and BMPO in pH 7.4 PBS buffer resulted in a strong ESR signal attributable to BMPO/•OOH (Figure 4a). As expected, the ESR signal intensity decreased considerably when 1.25 U/mL SOD was added to the xanthine/xanthine oxidase system control system as a result of its ability to dismutase superoxide (Figure 4b). Au nanoparticles coated with PVP and tannic acid showed similar effects seen as a reduction in the intensity of the signal for BMPO/•OOH by almost half for Au nanoparticles coated with PVP and near complete disappearance for Au nanoparticles coated with tannic acid (Figure 4c and 4d). This study provided evidence that superoxide anion radical in nanomaterial-mediated reactions can be detected using ESR coupled spin trapping system.