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Fungal Enzymes in Organic Pollutants Bioremediation
Published in Pankaj Bhatt, Industrial Applications of Microbial Enzymes, 2023
Adam Grzywaczyk, Wojciech Smułek, Jakub Zdarta, Ewa Kaczorek
Laccases (EC. 1.10.3.2) belong to the oxidoreductase group of enzymes. They catalyze the oxidation and reduction reactions of a wide variety of compounds. Oxidases are enzymes that, in the presence of molecular oxygen, catalyze oxidation and reduction reactions by electron transfer. Laccases have four copper atoms in their active center and are built from 220–800 amino acids. This widespread in nature enzymes is found in fungi, microorganisms, and also plants. Arregui et al. indicate that laccase can be found in more than 1,000 bacteria and 6,200 eukaryotes, according to UniProtKB base (Arregui et al., 2019). Laccases’ broad spectrum of activity, and thus the variety of compounds they can oxidize, makes this group of enzymes the most widely used in recent years in bioremediation processes. One of their particular advantages is conducting oxidation processes with the participation of atmospheric oxygen, which ensures the high efficiency of catalyzed processes, often without the need to use cofactors or, for example, additional oxidants. At the same time, the frequency of their occurrence, also in fungal cells, significantly affects their low acquisition cost (Arregui et al., 2019). Hence, most of the literature includes studies on the use of this particular group of enzymes in bioremediation.
Copper
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Global Resources and Universal Processes, 2020
R. Parker David, F. Pedler Judith
Copper is an essential element for plant growth and is a component of many enzymes, including plastocyanin, and thus is an indispensable prosthetic group in Photosystem 2. Cu-containing proteins are also important in respiration (cytochrome c oxidase is the terminal oxidase of the mitochondrial electron chain), in detoxification of superoxide radicals (superoxide dismutase), and in lignification (polyphenol oxidase). Ascorbate oxidase, which contains eight Cu2+ ions, has been proposed as an indicator of plant Cu status, although its relevant biological function has yet to be determined.[10]
Bioremediation of Petroleum Products in Soil
Published in Edward J. Calabrese, Paul T. Kostecki, Principles and Practices for Petroleum Contaminated Soils, 2019
Christopher J. Englert, Earl J. Kenzie, James Dragun
Once inside the membrane, chemicals such as petroleum products are catabo-lized (i.e., degraded) by microorganisms using three general metabolic pathways: aerobic respiration, anaerobic respiration, and fermentation. In aerobic respiration, organic chemicals are oxidized to carbon dioxide and water or other end products using molecular oxygen as the terminal electron acceptor. Oxygen may also be incorporated into products of microbial metabolism through the action of oxidase enzymes. Microorganisms metabolize hydrocarbons by anaerobic respiration in the absence of molecular oxygen using inorganic substrates as terminal electron acceptors. In anaerobic respiration, CO2 is reduced to methane, sulfate to sulfide, and nitrate to molecular nitrogen or ammonium ion. Hydrocarbon sources are degraded by fermentation using substrate level phosphorylation as the terminal electron acceptor. In other words, the fermentation process occurs independent of oxygen and depends on organic compounds as electron acceptors. Fermentation results in a wide variety of end products including CO2, acetate, ethanol, propionate, and butrate.11
Extremozymes used in textile industry
Published in The Journal of The Textile Institute, 2022
Priyanka Kakkar, Neeraj Wadhwa
Bleaching is important wet processing to remove any natural pigment and provide pure white cotton fibers. Glucose oxidase enzyme is used for the bleaching of cotton fibers and the process is called biobleaching. In the presence of oxygen, glucose oxidase enzyme oxidise the glucose molecule into gluconic acid and hydrogen peroxide. Catalase, laccase is used to remove the left behind hydrogen peroxide called bleach cleanup. Small amount of catalase is sufficient to convert it into hydrogen and oxygen as shown in Figure 2. Catalase only acts on the hydrogen peroxide present on the fabric and the other material remain unharmed. Enzymatic cleaning of peroxide is eco-friendly and use less water by avoiding extensive washing and less energy consumption (Shahid et al., 2016), (Roy Choudhury, 2020). Geobacillus thermo pakistaniensis is used to isolate catalase and laccase (Basheer et al., 2017; Shaeer et al., 2019). Recombinant enzyme of catalase has been produced by encoding the gene CAT responsible for cold adaptive catalytic activity in psychrophile and its hetrogenous expression in E.coli. It is active in wide range of temperature form 20 to 70 °C (Sarmiento et al., 2015). Biopolishing is the process to remove fuzz and pilling from the fabric surface. Cellulase enzyme is used to treat the fabric surface. It makes the fabric texture smoother, better appearance, color brightness, and improves water absorbing property. Controlled enzymatic treatments optimise the surface properties of the fabric but may result in decrease in tensile strength which is commercially acceptable (Roy Choudhury, 2020).
Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process
Published in Preparative Biochemistry & Biotechnology, 2021
Moni Philip Jacob Kizhakedathil, Suraksha Suvarna, Prasanna D. Belur, Rungtiwa Wongsagonsup, Esperanza Maribel G. Agoo, Jose Isagani B. Janairo
Oxalate oxidase (EC 1.2.3.4) catalyzes the oxidative cleavage of oxalate to carbon dioxide with the reduction of molecular oxygen to hydrogen peroxide.[15] Hydrogen peroxide being relatively unstable decomposes into water and molecular oxygen leaving behind with no undesirable residues. Total oxalates (soluble and insoluble) were removed by incubating taro flour with known amount of OxO enzyme. Earlier study on eddoe-type taro starch proved that oxalate present in the flour could be removed by treating the flour using OxO enzyme.[10] For the eddoe-type taro, Kumar and Belur[10] had performed a one factor at a time approach in order to maximize the oxalate removal. That study had mainly focused on enzyme load and incubation time. They had reported 97% oxalate reduction (790 mg/100 g to 24.2 mg/100 g) with 6 U OxO incubated for 120 min.[10] As the variety of taro taken in this study was different (dasheen type), the oxalate content was estimated in the beginning. The oxalate content in the taro flour was about 2344 mg/100 g DW, indicating the high acrid nature of the taro corms. Due to this, requirement of higher enzyme load and longer incubation period could be expected to bring down oxalate content in the resultant starch to an acceptable level. Hence, the range of chosen independent variables was fixed based on the studies of Kumar and Belur[10] and some degree of speculation. The OxO treatment was performed at 55 °C to prevent gelatinization of starch. After OxO treatment, taro flour slurry was homogenized and taro starch was extracted according to the protocol described earlier.