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Biotechnological Intercession in Biofuel Production
Published in Rouf Ahmad Bhat, Moonisa Aslam Dervash, Khalid Rehman Hakeem, Khalid Zaffar Masoodi, Environmental Biotechnology, 2022
Wasia Showkat, Moonisa Aslam Dervash, Khalid Z. Masoodi, Javeed A. Mugloo, S. A. Gangoo, Saba Mir
Under fermentation conditions, “CAD1 and COMT” down-regulated “Brachypodium distachyon” plants produced 9% and 17% more ethyl alcohol than control (Papp et al., 2016). About 46% and 44% enhancement in saccharification efficiencies can be demonstrated by two “B. distachyon” mutants that exhibit point mutations at diverse locations in the “CAD gene.” Lignin reduction in these species proves to be quite fruitful for saccharification competence. Five brown midrib (bm) maize mutants and four bm sorghum mutants possessing decreased lignin, have been characterized as “CAD or COMT mutants” which resulted in 22% and 21% amplification in the alteration of cellulose to ethyl alcohol, respectively, thereby increasing digestibility (Bansal et al., 2018). Saccharification efficiency shows three-fold increase due to overexpression of polygalacturonase or pectin methylesterase in transgenic “Arabidopsis.” tobacco and wheat leaves, with the alteration of pectin composition or architecture (Papanikolaou and Aggelis, 2019). Additionally, transgenic stems also show increased efficiency of enzymatic saccharification. Pectin degradation in poplar by overexpression of pectate lyase (that degrades HG) leads to upgradation in wood saccharification, as a consequence of the higher liberation of pentoses and hexoses (Ghildiyal et al., 2017).
UV Light Processing Effects on Quality, Nutritional Content, and Sensory Attributes of Juices, Milk, and Beverages
Published in Tatiana Koutchma, Ultraviolet Light in Food Technology, 2019
PPO is responsible for enzymatic browning in many juices. This copper-containing enzyme catalyzes the oxidation of various phenolic substrates; of particular importance is the oxidation of o-dihydroxy phenols to o-quinones, whose polymerization leads to the formation of undesirable brown pigments (Terefe et al., 2014). POD catalyzes the oxidation of a wide variety of compounds in the presence of hydrogen peroxide. When acting on phenolic compounds, POD contributes to enzymatic browning much like PPO. PME causes undesired cloud instability in citrus juices. It catalyzes the hydrolysis of methyl ester groups from pectin and leads to the formation of a calcium pectate gel that causes cloud loss. LOX is responsible for the generation of volatile flavor compounds and free radicals in many juices. It catalyzes the oxidation of polyunsaturated fatty acids into hydroperoxides. This process also leads to loss of nutritional quality and color. Here, a number of studies investigated the effect of UV treatment on the activity of PPO, POD, LOX, and PME enzymes in buffers and various fruit and vegetable juices such as apple, carrot, orange, grape, and mango nectar. Proteolytic activity (PRO), which is a measure of total protease enzyme activity, was only reported in pineapple juice. Residual activity of enzymes following UV treatment was reported or calculated as the percent remaining activity following the highest reported dose when compared to untreated enzymes.
Natural enzymes used to convert feedstock to substrate
Published in Ruben Michael Ceballos, Bioethanol and Natural Resources, 2017
Lyase performs a transeliminative reaction on α-1,4 glycosidic bonds of polygalacturonic acid polymers to form Δ-4,5 unsaturated C–C bonds at the nonreducing ends of the cleaved pectin polysaccharides (Albersheim et al., 1960; Moran et al., 1968). There are two types of lyases: pectate lyase or pectate transeliminase (PGL) and pectin lyase or pectin transeliminase (PL). PGL acts on pectin to cleave glycosidic bonds generating unsaturated oligogalacturonates or digalacturonates. PGLs are Ca2+ dependent and act specifically on nonesterified pectin (pectate) (Starr and Moran, 1962; Pickersgill et al., 1994; Mayans et al., 1997; Seyedarabi et al., 2010). The enzyme is grouped into five of the polysaccharide lyase families: 1, 2, 3, 9, and 10 (Lombard et al., 2014; CAZy, 2015). PGLs are divided into two types: endo-PGL and exo-PGL. The endo-PGLs (e.g., EC4.2.2.2) act on substrates at random internal sites within the chain. The exo-PGLs (e.g., EC 4.2.2.9) act on the reducing end to catalyze substrate cleavage. Unlike PGLs, PLs (e.g., EC 4.2.2.10) are not Ca2+ dependent. PLs catalyze the random cleavage of highly esterified pectin and produce unsaturated methyloligogalacturonates (Figure 3.6c) (Albersheim et al., 1960; Edstrom and Phaff, 1963; Delgado et al., 1992; Vitali et al., 1998). PLs belong to polysaccharide lyase family 1 (Lombard et al., 2014; CAZy, 2015).
Effect of PCM-based cold storage system under periodic and continuous operations on physico-chemical characteristics of mango (Mangifera indica L.) fruit and performance evaluation of mango cold storage systems
Published in International Journal of Ambient Energy, 2022
K. Karthikeyan, Vairavan Mariappan, P. Sarafoji, K. Uma Bharathi, M. Loganathan, M. Jaya Bharata Reddy, R. Anish
The loss of textural quality in fruits is closely associated with the degradation of cell wall pectins, hemicellulose and cellulose components due to the expression and activity of cell-wall-degrading enzymes (Sun et al. 2013). The pectin substances are the main structural elements in the primary cell wall and regulate cell adhesion. During ripening, the main cell-wall-degrading enzymes, such as polygalacturonase (PG), pectin methylesterase (PME), pectate lyases, 1,4-β-d-glucanase/glucosidase and β-galactosidase (β-gal), dissolved the concentration of cell wall pectin and led solubilisation and depolymerisation of cell wall pectin polysaccharide (Goulao and Oliveira 2008). Cold storage inhibits the activities of cell-wall-degrading enzymes closely related to fruit softening by reducing the rate of metabolic processes during senescence (Deng et al. 2014), resulting in maintaining firmness in the fruit. In this study, mango fruits stored in G24, P12 and P24 storage fruits showed higher firmness retention than fruits stored in G12 and control storage conditions. Fruits stored in P12 and P24 storage conditions indicate results by reducing cell-wall-degrading enzyme activities, polysaccharides solubilisation, and delaying ripening. A significant finding of peel firmness retention by P12 storage condition is concordance with the previous study reported using an evaporative cooler whose temperature was maintained between 14.3°C–19.2°C (Tefera, Seyoum, and Woldetsadik 2007).
Microstructural changes in blanched, dehydrated, and rehydrated onion
Published in Drying Technology, 2022
S. Savitha, Snehasis Chakraborty, Bhaskar N. Thorat
The cell wall of onion cells is made of a rigid structure that is formed by cellulose and xyloglucan microfibrils and a pectin gel matrix. Fresh or hydrated onion cell walls are rigid and the structure or shape is maintained due to the turgor pressure of water (75% by mass). The pectin matrix, which is heterogeneous with hard and soft regions, holds the walls. The soft regions in the pectin matrix comprise single-chain methyl-esterified galacturonans and galactans, while, the hard regions comprise Ca-pectate gels and methyl-esterified aggregates. The pectic gel maintains the mechanical properties across the cell wall. The interaction between cellular microfibrils and the pectin matrix is governed by the degree of hydration. On dehydration, the rigidity and porosity of the cell wall change, causing it to collapse by reducing the distance between the microfibrils and cell walls. A different porous structure is formed, and the soft region hydrogels are turned into a glassy network.[2,13,35,36]
Optimisation of physical parameters pH and temperature for maximised activity and stability of Vibrio cholerae L-asparaginase by statistical experimental design
Published in Indian Chemical Engineer, 2021
Remya Radha, Sathyanarayana N. Gummadi
Response surface methodology (RSM) is one of the most relevant multivariate techniques used in analytical optimisation as it includes the interactive effects among the variables under study and depicts the complete effects of the parameters on the responses [16]. It was reported that central composite design results in smaller and less time consuming experimental designs [17]. Research on E. coli using response surface methodology achieved a 10-fold enhancement in asparaginase production [18]. Moreover, the optimisation of physical and chemical parameters of enzymes pectin lyase and pectate lyase resulted an improved activity fold of 1.3 and 1.4 fold respectively by response surface methodology [12]. On behalf of this, a central composite design method has been used in this study to optimise the physical parameters pH and temperature for attaining the maximised specific activity and stability of V. cholerae L-asparaginase.