D. Enzyme Digestion: Enzymatic methods are specific, gentle and most effective but costly. Lysozyme is commercially available to treat bacteria to release intracellular products. In addition to lysozyme, there are three other types of bacteriolytic enzymes, glycosidases, acetylmuramyl-L-alanineamidase and endopeptidase. Few protease are also found to be bacteriolytic. Yeast cell lysis requires a mixture of different enzymes such as glucanase, protease, mannanase or chitinase. Plant cells can be lysed by cellulose and pectinase. In most of the enzyme mediated cell lysis method, the rupture of cell wall depends on the osmotic pressure of the external medium. In few cases, enzymatic digestion is performed to remove external cell wall and then in second step protoplast is disrupted by gentle agitation.

3. Mechanical Methods: In the simpliest mechanical cell disruption method used in laboratory is waring blender and pestle-morter. Both are effective towards animal and plant tissue as well as filamentous organisms. In industrial scale, cell disruption is carried out by (i) bead mill or (ii) high pressure homogenizer.

1. Bead Mill Disruption- The bead mill (horizontal or vertical) consists of a grinding cylinder with a central shaft fitted with a number of impellers which can move in clockwise or anti-clockwise direction with the help of a motor (Figure 28.5). The grinding cylinder is filled with the beads made up of glass, alumina, titanium carbide, zirconium oxide or zirconium silicate. There is an inlet to supply the cell suspension and a outlet to collect the sample after the process. When bead mill runs cells experience a shear forces between produced between moving beads and cells. The rate and degree of cell disruption depends on cell type, thickness of cell wall, localization of product, type and agitation speed of impeller, bead size, its density and loading, residence time and temperature. Cell disruption in a bead mill and release of a produce is a first order kinetics and it may be given by first order equation

Here, Cmax is the concentration of product that can be released from a given amount of cell suspension, C is the concentration of product released at a given time “t” and k is the first order constant. This relationship holds true only for batch mode of operation. The value of k depends on type of impeller, bead size and loading, speed of agitation and temperature.