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Potential of Microalgae for Protein Production
Published in Sanjeet Mehariya, Shashi Kant Bhatia, Obulisamy Parthiba Karthikeyan, Algal Biorefineries and the Circular Bioeconomy, 2022
Elena M. Rojo, Alejandro Filipigh, David Moldes, Marisol Vega, Silvia Bolado
Osmotic shock is a disruption technique based on the rapid increase or decrease of salt concentrations in the solution (Dixon and Wilken, 2018). The cell wall ruptures as a result of permeation in order to attain equilibrium with the medium that enables protein extraction (Krishna Koyande et al., 2020). The type and concentration of salts, incubation time, and biomass concentration are all important factors that affect the efficiency of the method (Nitsos et al., 2020). For the extraction of bioproducts, hypotonic conditions (low osmotic pressure) are ideal but have disadvantages, including inefficiency and the high salinity of the resulting wastewater (Dixon and Wilken, 2018). This method also takes longer than other processes (such as autoclaving and microwave irradiation) and is economically unfeasible on a large scale (Corrêa et al., 2021). Krishna Koyande et al. (2020) studied the recovery of whole proteins from Chlorella vulgaris using osmotic shock through a liquid biphasic flotation (LBF) system. The study concluded that a protein recovery yield of 93% could be achieved using osmotic shock (as opposed to only 84.8% without osmotic shock). In this work, 0.1g of microalgae biomass was dissolved in 40mL of salt solution with a 500g/L concentration. The salt solution was then diluted to 200g/L, causing the osmotic shock.
Nanobiotechnology Advances in Bioreactors for Biodiesel Production
Published in Madan L. Verma, Nanobiotechnology for Sustainable Bioenergy and Biofuel Production, 2020
Bhaskar Birru, P. Shalini, Madan L. Verma
Osmotic shock facilitates cell disruption through the change in salt concentration which causes the imbalance of osmotic pressure between the exterior and interior of the cell. Cell disruption can be done in two ways, i.e., hyper-osmotic stress and hypo-osmotic stress (Halim et al. 2012). In the case of hyper-osmotic stress, a higher concentration in the exterior of the cell allows the cellular fluids to diffuse outside of the cell which leads to cell wall disruption. On contrary to this, hypo-osmotic stress attributes lower salt concentration in the exterior of the cell leading to the flow of water into the cell which aids for cell disruption (Kim et al. 2013). Hypo-osmotic stress requires a large amount of water for industrial-scale applications. Thus, hyper-osmotic stress is a reliable technique for microalgae cell disruption. Osmotic shock is cost-effective and is an easy process (Prabakaran and Ravindran 2011).
Sustainable Pre-treatment Methods for Downstream Processing of Harvested Microalgae
Published in Kalyan Gayen, Tridib Kumar Bhowmick, Sunil K. Maity, Sustainable Downstream Processing of Microalgae for Industrial Application, 2019
Hrishikesh A. Tavanandi, A. Chandralekha Devi, K. S. M. S. Raghavarao
Salt changes the osmotic pressure and acts on the cell wall membrane, leading to excessive shock, which results in disruption and cell death. In the area of biotechnical applications, the osmotic shock is used as a technology for lysis of cells, where they are exposed first to either low or high concentrations of salt, leading to osmotic pressure and cell wall degradation. This is due to the fact that water quickly flows from lower to higher salt concentrations. Thus, if cells are exposed first to a high salt concentration, water flows into the cell after exposure to a low salt concentration, resulting in a pressure increase in the cell, which then explodes (Stanbury et al. 2013). On the contrary, when the cells are exposed to a high salt concentration after exposure to a low concentration, water flows out of the cell, leading to cell wall disruption. Different salts such as CaCl2 and NaNO3 have been used for the extraction of biomolecules. Calcium chloride breaks down into ions in aqueous solution, such as a solution the cells are kept in, and the ions create a transient state of permeability in the cell membrane, allowing the small particles to pass through. Silveira et al. in their work achieved a maximum concentration and purity of 3.68 mg mL−1 and 0.46, respectively, at a solvent ratio of 1:12 and extraction time of 4 h at 25 °C (Silveira et al. 2007). A few more case studies on the extraction of biomolecules from microalgae using salts are presented in Table 5.2.
An efficient method for recombinant production of human alpha synuclein in Escherichia coli using thioredoxin as a fusion partner
Published in Preparative Biochemistry & Biotechnology, 2020
Babak Saffari, Mehriar Amininasab, Sara Sheikhi, Jamshid Davoodi
The overexpression of amyloidogenic proteins in E. coli can be problematic due to their inherent tendency to form insoluble inclusion bodies and the toxicity of the formed aggregates.[10] Recovery of the recombinant protein in biologically active form from these aggregates requires additional purification steps that may reduce the final yield. Fusion of the target protein with a more soluble partner might be a way to tackle these difficulties.[11]Escherichia coli thioredoxin A (trx) is a small (108 amino acid) cytoplasmic protein with inherent properties that suit it to a role as a fusion tag. It is indeed distinguished from many other carrier partners by its propensity to confer stability and high solubility to a wide range of target polypeptides that otherwise aggregate in bacterial host cells.[12] It has been revealed that trx can express at levels as high as 40% of the total bacterial protein content while remaining fully soluble.[13] Moreover, trx is among the rare cytoplasmic proteins that are released into extracellular solution by osmotic shock treatment, which was originally introduced to extract periplasmic proteins of E. coli.[14] Osmotic shock treatment excludes a considerable fraction of cellular proteins including cytoplasmic proteases, and hence facilitates the purification process.
Current research and perspectives on microalgae-derived biodiesel
Published in Biofuels, 2020
Kartik Singh, Deeksha Kaloni, Sakshi Gaur, Shipra Kushwaha, Garima Mathur
Other methods of oil extraction include the use of certain enzymes and osmotic shock. In osmotic shock, pressure is developed across the cell wall that leads to cell disruption. Pressure is developed as a result of high salt concentrations, called hyper-osmotic stress. One other promising approach for cell disruption is the use of enzymes. Some of the most commonly used enzymes are cellulase, neutrase and pectinase. The enzyme breaks the cell wall without harming the whole cell structure and, unlike chemical methods, does not interfere with the fatty acids. They are expensive but yield high extraction efficiency [60].