Escherichia coli, as a model microorganism in molecular biology and bioengineering, contains recombinant proteins, nucleic acids, and other bioactive substances with significant application value. escherichia coli lysis, as a crucial step in releasing intracellular substances, directly impacts the yield, activity, and subsequent purification efficiency of the target product through its technological selection and optimization. A deep understanding of the lysis mechanism and mastery of the characteristics of various technologies are of great significance for biological research and industrial production.
The core principle of escherichia. coli lysis lies in disrupting the structural integrity of its cell wall and cell membrane. The cell wall of escherichia coli is mainly composed of a peptidoglycan network structure, which is the main barrier against the external environment. Its lysis resistance is closely related to the degree of peptidoglycan cross-linking. Based on different mechanisms of action, lysis methods can be divided into three main categories: physical, chemical, and biological methods. Each method has its advantages and disadvantages and is suitable for different application scenarios.
Physical lysis methods rely on mechanical force or environmental changes to disrupt the cell structure, featuring high lysis efficiency and no chemical residue. Common ultrasonic lysis methods use the shear force generated by high-frequency vibration to break down cell walls. When the bacterial concentration is suitable, the lysis rate can reach up to 99.9%. However, the heat generated during this process can easily denature heat-sensitive proteins, requiring ice bath cooling. Repeated freeze-thaw cycles utilize the mechanical stress generated by ice crystal formation and thawing to disrupt the cell membrane. This method is simple and inexpensive, but its efficiency is relatively low, typically requiring several hours to achieve a lysis rate of over 50%, making it suitable for small-scale experiments. High-pressure lysis uses a high-pressure environment to cause rapid cell expansion and rupture, resulting in a high lysis rate while preserving product activity well, making it suitable for large-scale industrial production.
Chemical lysis uses chemical reagents to disrupt cell structure or interfere with metabolic processes. Isolation agents such as ethanol and sodium thiocyanate can induce cell lysis by weakening hydrophobic interactions and inhibiting peptidoglycan cross-linking. Their effect can be antagonized by anti-isolation agents such as sodium chloride. Surfactants achieve lysis by dissolving the lipid bilayer of the cell membrane. Mild surfactants can complete lysis without destroying protein activity, making them suitable for the extraction of heat-sensitive proteins. Chemical methods are simple to operate and require no special equipment, but chemical reagents may affect the activity of the target product, requiring rigorous subsequent purification.
Biolysis relies on the specific action of biomolecules, offering advantages such as mildness, high efficiency, and high specificity. Lysozyme is the most commonly used biological reagent, specifically degrading the glycosidic bonds of peptidoglycans, causing cell wall damage and subsequent cell rupture due to osmotic pressure imbalance. In recent years, pyroptosis has emerged as a novel biolysis technique. By expressing specific proteins in escherichia coli to induce programmed cell death, cell disruption can be achieved within 2 hours, and the prepared crude enzyme solution exhibits 60% higher relative activity than that obtained by ultrasonication, providing a new direction for green and environmentally friendly lysis methods. Furthermore, phage-mediated lysis utilizes holin proteins to form pores in the cell membrane, allowing lysozyme to enter the cell wall and exert its effects; the timing of lysis is precisely regulated.
In the future, with the development of synthetic biology, highly controllable, green, and efficient lysis techniques such as pyroptosis will be continuously optimized, providing stronger technical support for the development of biopharmaceuticals, metabolic engineering, and other fields, and promoting the in-depth development and utilization of escherichia coli resources.
