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AAT Bioquest

How do I lyse cells?

Posted September 30, 2020


Answer

Cell lysis is the method, wherein the outer cellular membrane is disturbed to release the intracellular components such as DNA, RNA, proteins and other cellular organelles. Cell lysis is a method in which the outer cell membrane is broken down or destroyed in order to release inter-cellular components such as DNA, RNA, protein or organelles from a cell. Cell lysis could be performed by various techniques that can be categorized into mechanical and non-mechanical methods.  

Mechanical methods include high-pressure homogenization and bead milling. High-pressure homogenization technique is used for large scale microbial culture. In this method, cells in media are forced through an orifice valve using high pressure. Bead milling technique is utilized for lab-scale samples. Here, the bead is added to the samples and allowed for agitation. During this process, beads collide with the cells at high speeds breaking open the cell membrane and releasing the intracellular components by shear force.  

Non-mechanical cell lysis methods include physical disruption, chemical disruption and enzymatic lysis. 

Physical disruption utilizes external force to rupture the cell membrane. The different forces include heat, pressure and sound energy. They can be classified as thermal lysis, cavitation and osmotic shock. Thermal lysis is conducted by the repeated freeze-thaw cycle. This method is attractive for small sample size as it is time-consuming. Cavitation is a technique used for the formation and subsequent rupture of cavities or bubbles. These cavities can be formed by reducing the local pressure by increasing the velocity, ultrasonic vibration, etc. Osmotic shock method is based on the difference in salt concentration between outside and inside of the cells. When outside salt concentration is lower, water enters the cells, resulting in cell swelling and finally bursting. It is suitable for mammalian cell types as their membrane is fragile.  

The chemical methods use lysis buffers to disrupt the cell membrane. Chemical lysis can be classified as alkaline lysis and detergent lysis. 

In the enzymatic method, enzymes such as lysozyme, zymolyase, protease, etc are used to disturb the cell membrane. The enzymatic method could be used for large scale as they are commercially available. Another advantage is that enzymes are highly specific to cell type. 

Additional resources

A review on macroscale and microscale cell lysis methods

ReadiUse™ bacterial cell lysis buffer *5X*