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Production of Organic Acids from Agro-Industrial Waste and Their Industrial Utilization
Published in Anil Kumar Anal, Parmjit S. Panesar, Valorization of Agro-Industrial Byproducts, 2023
Navneet Kaur, Parmjit S. Panesar, Shilpi Ahluwalia
Most wild strains employed for succinic acid production utilize TCA and glyoxylate shunt and convert phosphoenolpyruvate (PEP) to a mixture of acids like acetic, formic, and oxaloacetate first and then into malic, fumaric, and succinic, thereby leading to low productivity. However, under anaerobic fermentation conditions, PEP is converted to oxaloacetate with the help of the enzyme PEP carboxylase or PEP carboxykinase. Pyruvate can also be directly converted into oxaloacetate or malate with the addition of carbon dioxide (CO2) by the enzyme pyruvate carboxylase. Then, under the action of the enzyme malate dehydrogenase and fumarase, oxaloacetate and malate are converted to fumarate, finally resulting in the production of two moles of succinate by fumarate reductase (Cao et al., 2013; Mancini et al., 2019). The design and operation of bioreactors play an important role in the production of succinic acid. The importance of each bioreactor is discussed below.
Metabolic Engineering of Yeast, Zymomonas mobilis, and Clostridium thermocellum to Increase Yield of Bioethanol
Published in Ayerim Y. Hernández Almanza, Nagamani Balagurusamy, Héctor Ruiz Leza, Cristóbal N. Aguilar, Bioethanol, 2023
S. Sánchez-Muñoz, M. J. Castro-Alonso, F. G. Barbosa, E. Mier-Alba, T. R. Balbino, D. Rubio-Ribeaux, I. O. Hernández-De Lira, J. C. Santos, C. N. Aguilar, S. S. Da Silva
There are some examples that can be listed to show the potential of metabolic engineering in different steps of bioprocesses. One of them is the conversion of lignocellulosic biomass (LCB) (upstream process) into mono-saccharides using heterologous cellulases, a main critical step in biorefineries, as its enhancement can help in cost saving achievements [25, 26]. Another important step is fermentation (core process), and at this process level, several strategies could be applied. For example, deletion of genes or sequences that interrupt strategic cell responses, such as, autophagy, that is a recycling process of cellular components; in some cases, its interruption enhance the biomass growth rate (ex. yeast) and consequently, a positive influence in the production of some products like ethanol could occur [27–29]. Fermentation has been well-studied for the application of several molecular tools. The most used one could be the overexpression of specific enzymes. For example, in citric acid production, pyruvate carboxylase is a key enzyme in the reduction of the tricarboxylic acid cycle, and it is closely related to the formation of this important biomolecule, thus the overexpression of this enzyme could lead to a higher production of this organic acid [30, 31]. Other examples of metabolic engineering tools applied to microorganisms for enhancing the production of biomolecules are shown in Table 5.1.
Vitamins and Nutrition
Published in Richard J. Sundberg, The Chemical Century, 2017
Biotin, sometimes called vitamin B7 or H, is present in most foods, but in very small amounts. The richest natural sources are “royal jelly,” which is produced by honeybees and induces the reproductive ability of queen bees, and brewer’s yeast. Milk, liver, and egg yolks are the most important sources in the human diet. Another likely source is absorption in the gut of biotin produced by microorganisms. Biotin is strongly bound by avidin, a protein found in egg white, and biotin deficiency can be produced by use of avidin to remove biotin. Biotin is sensitive to oxidation and its level is reduced by many types of food processing. Biotin is a coenzyme for a family of enzymes that catalyze carboxylation, decarboxylation, and transcarboxylation. One of these enzymes, pyruvate carboxylase, is critical in carbohydrate biosynthesis.
Acute metformin administration increases mean power and the early Power phase during a Wingate test in healthy male subjects
Published in European Journal of Sport Science, 2022
Victor José Bastos-Silva, Alisson Henrique Marinho, José Bruno Bezerra da Silva, Filipe Antônio de Barros Sousa, Sara Learsi, Pedro Balikian, Gustavo Gomes de Araujo
An increase in MP was accompanied by a tendency (p = 0.08) and moderate effect size (ES = 0.49) in the peak lactate values. This result may be associated with decreased mitochondrial energy production (Cameron et al., 2018). Furthermore, it seems that metformin reduces the activity of the pyruvate carboxylase enzyme, responsible for pyruvate metabolisation in oxaloacetate during gluconeogenesis process (Matyukhin, Patschan, Ritter, & Patschan, 2020). Thereby, the impairment of such enzyme function increases pyruvate conversion in lactate rather than oxaloacetate (Matyukhin et al., 2020). The impairment of oxaloacetate conversion could increase fast ATP turnover by the glycolytic pathway, explaining the effect of metformin on MP. Besides, Pilmark et al. (2021) found an increase in fasting lactate levels after three weeks of medication, which was also maintained after 12 weeks of training plus metformin. Metformin increases the glucose uptake by enterocytes and subsequently increases lactate concentration in enterocytes to increased glycolysis. That said, your study’s moderate effect size may be explained due to the greater use of anaerobic metabolism during exercise. Despite these results, under normal circumstances, therapeutic levels of metformin administration have no effect on the accumulation of lactate in the blood. Metformin-associated lactic acidosis seems to reflect the prolonged use of high doses of metformin, which is not related to our experiment (Rajasurya, Anjum, & Surani, 2019).
Water metal contaminants in a potentially mineral-deficient population of Haiti
Published in International Journal of Environmental Health Research, 2018
Zorimar Rivera-Núñez, Zezhen Pan, Bazelais Dulience, Haley Becker, Joe Steensma, Angela Hobson, Daniel E. Giammar, Lora L. Iannotti
The Mn findings, elevated especially in wells, may be of particular public health significance given the neurotoxic effects of Mn exposure and interplay with particular mineral deficiencies in human nutrition. Neurotoxicity of manganese after occupational exposures has been well-documented (USEPA 2007), and there is increasing evidence of neurotoxicity, including decreases in neurobehavioural functioning, if consumed orally, especially in early life (Pappas et al. 1997; Woolf et al. 2002; Levy and Nassetta 2003; Wasserman et al. 2006; Bouchard et al. 2007). Manganese is also an essential micronutrient required for the functioning of many enzymes (e.g., pyruvate carboxylase) and can serve to activate many others (e.g., kinases, decarboxylases)(Tsai et al. 2015). Of particular note might be the underlying public health issue of iron deficiency in undernourished populations of Haiti (Lönnerdal and Klimis-Tavantzis 1994), as manganese absorption may be higher with iron deficiency and can replace iron in the enzyme cytosolic aconitase with consequences for translational events (Iannotti et al. 2015a).
Heavy metal (loid)s phytotoxicity in crops and its mitigation through seed priming technology
Published in International Journal of Phytoremediation, 2023
Rajesh Kumar Singhal, Mahesh Kumar, Bandana Bose, Sananda Mondal, Sudhakar Srivastava, Om Parkash Dhankher, Rudra Deo Tripathi
The excess accumulation of HMs alters plant processes in a multi-directional way; it increases bioaccumulation and bio-magnifications of HMs in crops resultantly decreasing yields (Sahid et al. 2015). HMs toxicity interferes/reduces the process of germination, uptake, transport, and consumption of essential nutrients, protein metabolism, photosynthetic attributes, water potential, nitrate reductase, and carbonic anhydrase activities, leading to an inhibition of overall growth and finally crop yields (Zhang H et al. 2020). Zn is an essential micronutrient but its higher concentration inhibits seed germination, root growth, and alters the morphology of plants (Rout and Das 2009). Likewise, Cd exposures primarily target photosynthesis inhibition associated with alterations in chloroplast ultrastructure, chlorophyll biosynthesis pathways, damaging photosystem II (PSII), and uncoupling of the chloroplastic electron transport mechanism. Moreover, it drastically affects the H+-ATPase in the plasma membrane and tonoplast curtails the activities of enzyme phosphoenol pyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase, which reduces the biomass accumulation and assimilation to reproductive parts. Likewise, the HMs severely affect the root structure architecture, which ultimately inhibits the absorption and transportation of crucial nutrients (Janicka-Russak et al. 2012; Liu JH et al. 2015; Qin et al. 2020; Dey et al. 2021; Indu Lal et al. 2021). HMs also increase methylglyoxal (MG) content, a by-product of various metabolic pathways, which can initiate/provoke ROS generation, resulting in the overall reduction of plant growth (Mahmud et al. 2018; Ghori et al. 2019). Further, HMs have the potential to induce the production of ROS, causing the peroxidation of membrane lipids. The drastic effects of HMs on seed germination, photosynthesis, antioxidant defense, growth attributes, and mineral transportation are schematically highlighted in Figure 2.