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From Waste to Value Added Products Bioelectrochemical Approaches for Sustainable
Published in Gunjan Mukherjee, Sunny Dhiman, Waste Management, 2023
Francisco Javier Bacame-Valenzuela, Jesùs Pérez-García, Mayra Figueroa-Magallon, Yolanda Reyes-Vidal
Pyocyanin production has been studied under different environmental conditions such as pH, temperature, agitation, and substrates such as glucose, arabinose, acetate, including compounds in wastewater. Those BES configurations that allow pyocyanin biosynthesis can take advantage of this biomolecule for energy generation, incorporating it in the TEE process to the electrode, due to its redox capacity (Shen et al. 2014). Furthermore, other studies demonstrated that P. aeruginosa reduces pyocyanin as part of its metabolic cycle and that pyocyanin is oxidized at the electrode as an electron acceptor rather than oxygen (Guan et al. 2019). This process occurs in the presence of substrates that donate electrons and that could be carbohydrates (Yong et al. 2014a, 2017) (Figure 5A). However, the reverse process can also occur, where pyocyanin is reduced at the electrode and then oxidized by P. aeruginosa. This phenomenon results in the detachment of oxides from the electrode, inducing corrosion (Figure 5B). This process occurs in the presence of electron-accepting substrates such as nitrate, where nitrate is reduced by microorganisms to molecular nitrogen (Jia et al. 2017, Zhou et al. 2018).
Alternative indicator systems for water quality analysis
Published in Cara Gleeson, Nick Gray, The Coliform Index and Waterborne Disease, 1996
Pseudomonas aeriginosa is a Gram-negative, non-sporulating opportunistic pathogen which causes infection in wounds, as well as ear and urinary tract infections, meningitis and respiratory infections (Feacham et al., 1983). It has interesting growth properties, forming both oxidase and catalase, growing at 42°C but not at 4°C It is also able to reduce nitrates and nitrites, produce ammonia from the breakdown of acetamide, and is able to hydrolyse casein but not starch. An important characteristic of the pseudomonad is that it can produce the blue-green pigment pyocyanin or the fluorescent pigment fluorescein, or both. Pseudomonas aeriginosa is particularly associated with disease among swimmers. Numerous cases of folliculitis, dermatitis, ear and urinary tract infections due to P. aeriginosa, contracted after swimming in contaminated waters, have been reported (Yoshpe-Purer and Golderman, 1987). Because of this association, and its consistent presence in high numbers in sewage, P. aeriginosa was thought to have potential as an indicator of water quality, particularly recreational waters (Cabelli, 1978). However, as this organism is known to be ubiquitous in nature and can multiply under natural conditions, it is in practice of little use in faecal contamination studies. While it should not be used as an indicator organism, bottled waters are required to be free of the organism and so must be monitored at bottling plants (EU, 1995). Brief details of the isolation of P. aeriginosa is given in section 1.5, with full details given by the Department of the Environment (1994a) and APHA (1992).
Extremophilic Microbes and their Extremozymes for Industry and Allied Sectors
Published in Ajar Nath Yadav, Ali Asghar Rastegari, Neelam Yadav, Microbiomes of Extreme Environments, 2021
Hiran Kanti Santra, Debdulal Banerjee
Pseudomonas aeruginosa (a gammaproteobacteria) produces pyocyanin, an electrochemically active metabolite involved in biological activities like gene expressions, fitness maintenance of bacterial cell and biofilm formation, which is responsible for the blue-green characteristic coloration of the Pseudomonas sp. and also have antimicrobial (antibacterial and antifungal) activity (Jayaseelan et al. 2014).
Synthesis, characterization and applications of endophytic fungal nanoparticles
Published in Inorganic and Nano-Metal Chemistry, 2020
Ranjani S, Shariq Ahmed M, Mohd Adnan, Senthil Kumar N, Ruckmani K, Hemalatha S
This study demonstrates that EFNps can be synthesized through a green approach that is an inexpensive, eco-friendly method using endophytic fungal extract. Present study was focused on synthesizing silver nanoparticles from endophytic fungal extract and the nanoparticles was characterized by various techniques each resembling its own characteristics like UV-Vis spectroscopy for knowing the surface Plasmon resonance of the nanoparticles, FT-IR for the functional groups present in the nanoparticles. Particle size analyzer for finding out the size of nanoparticles using Brownian movement. Zeta analyzer to study the stability of Nanoparticles. FESEM to characterize the morphology of Nanoparticles, EDAX to study the elemental composition of endophytic fungal nanoparticles. The antimicrobial study of the silver nanoparticles was carried out by agar well diffusion method, MIC, MBC and biofilm assay and it has showed good antibacterial effect against the ATCC (27853) and clinical strain of Pseudomonas aeruginosa. The pyocyanin which is a toxin produced by Pseudomonas aeruginosa was extracted from the treated and untreated cultures of Pseudomonas aeruginosa and the concentration of pyocyanin has decreased in the treated one than the control. The present study concludes that the endophytic fungal nanoparticles synthesized using endophytic fungal extract could be used as a best antimicrobial agent against multi drug resistant Pseudomonas aeruginosa to overcome the draw backs of antibiotic resistance. Further formulation and validation of endophytic fungal nanoparticles (EFNps) will have significant application in pharmaceutical and medical application.
A review of design, operational conditions and applications of microbial fuel cells
Published in Biofuels, 2018
Rachna Goswami, Vijay Kumar Mishra
Several microbes have the capability to transfer electrons to the anode, which are the result of the metabolism of organic matters (see Table 1). The development of methods that use bacteria to generate electricity represents a probable method for bioenergy production as the bacteria are self-replicating and, therefore, the catalysts for organic matter oxidation are self-sustaining. In the initial studies by Potter [10], the yeast Saccharomyces cerevisae and bacteria such as Bacillus coli (later classified as E. coli) were shown to produce a voltage, consequential in electricity generation. Oceanic sediment, soil, wastewater, fresh water sediment and activated sludge are excellent resources for these microorganisms [48,49]. Geobacter belongs to dissimilatory metal reducing microorganisms, which generate biologically significant energy in the form of ATP in the dissimilatory reduction of metal oxides in anaerobic circumstances in soils and sediments. The electrons are transported to the final electron acceptor like Fe2O3 mainly by a direct interaction of mineral oxides and the metal reducing microorganisms [50,51]. The anodic reaction in mediatorless MFCs developed with metal reducing bacteria, generally from the families of Shewanella, Rhodoferax and Geobacter, is close to this method as the anode works as the final electron acceptor identical to the solid mineral oxides [50-52]. S. putrefaciens, G. sulferreducens, G. metallireducens and R. ferrireducens pass electrons to the solid electrode (anode) using this arrangement. As maximum real mediatorless MFCs function with dissimilatory metal reducing microorganisms, an exemption was reported with C. butyricum [53,54]. Electron mediators equivalent to Mn4+ or neutral red (NR) included into the anode specifically improve the performance of MFCs with anodophile S. putrefaciens [55]. Mediators perform a significant function in electron transport for such type of microbes that are incapable to transfer the electrons to the anode. Mediators accumulate the electrons from microbes and discharge them at the surface of the anode. Actinobacillus succinogenes, Desulfovibrio desulfuricans, E. coli, Proteus mirabilis, P. vulgaris and Pseudomonas fluorescens need external mediators, while a number of microbes can offer their own. For instance, Pseudomonas aeruginosa generates pyocyanin molecules as electron shuttles. When MFC is inoculated with marine sediments or anaerobic sludge, there will be mixed cultured microorganism in the anode chamber. Mixed culture MFCs have better functions. Complex mixed cultures (anodic microcosm) allow much wider substrate utilization, suggesting that MFCs have broader substrate specificity. In mixed culture MFCs (with anaerobic sludge) there are both electrophiles/anodophiles and groups that use natural mediators within the same chamber [20]. Some of the bacterial species used in MFCs are described below.