Chemical and Enzymatic Cell-Disruption Methods

Cells can also be disrupted chemically by detergents, osmotic shocks, organic solvents, and alkali treatments (Prasad, 2010). Detergents are molecules with hydrophilic and hydrophobic properties that allow them to interact both with water and lipids. The hydrophobic fnnction is nsnally ionic, whereas the hydrophobic aspect is normally a hydrocarbon (Joesten et al., 2006 Marriott and Gravani, 2006 Tadros, 2005). They disrupt cell membranes by penetrating between the layers and forming micelles that separate lipids and proteins. Many detergents are available for cell membrane solubilization such as sodium dodecyl sulfate and triton X. However, many of them, such as sodium dodecyl sulfate, break protein-protein interaction and denature the enzyme. 

A sudden change in salt concentration is referred to as osmotic shock. Cells are placed in a buffer solution at a high salt concentration and this results in water movement from inside the cell toward the bnffer medium. The cells are then transferred into a weak bnffer solntion or distilled water. The sudden change in concentration resnlts in cell disrnption. 

Organic solvents snch acetone, chloroform, or methanol can also be used to extract enzymes. These chemicals liberate the enzyme by creating pores and channels in the cell membrane. However, organic solvents use is limited in large-scale production due to their toxicity, flammability, high costs, and possible protein dena-turation effects (Ghosal and Srivastava, 2009). 

As an alternative to chemical disruption, enzymes can be used. Enzymes have the advantage of operating at mild conditions and have comparatively low energy requirements. Lysozyme is an example of an enzyme that can be used for a large number of applications. 

However, none of these methods is perfect. Therefore, a combination of two or more methods has been suggested in order to enhance disruption, save energy, and facilitate subsequent processing (D souza and KiUedar, 2008). There are two common combined approaches (1) combining non-mechanical methods and (2) pre-treating with chemical or enzymatic methods followed by mechanical methods. 

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