Microorganisms cell disruption

Ultrasound (sonication) This is a chemical-free process to cause cell disruption by inducing cavitation (bubbles) into a solution. The bubbles generate turbulence and pressure differences during both formation and bursting that can lead to rupture of microorganisms. The technique is still under research. 

Ozone and its related radicals weaken the biofilm matrix and allows for removal of biomass by sheer forces. The free radicals can also form H O that penetrates the cell walls of a microorganism and disrupts cell physiology. 

Tubular bowl centrifuges are routinely used in smaller-scale separations of suspended material from fermentation beer. The objective may be to recover the cells which are to be disrupted to recover intracellular bioproducts. Alternatively, for extracellular bioproducts, the beer hcis to be clarified (be free of cells, cellular debris, etc.). Table 7.3.1 provides the dimensions and/or densities of a few types of microorganisms/cells/particles. Two special features of the separation of the suspensions in fermentation beer as feed are their very low density difference (pp-Pi) and smaller particle sizes. In the separation of suspended materials from the fluid in nonbiological systems, (pp -pf) is considerably larger. Further, the particle dimensions have wide variations. 

Transposon integration mutagenesis can be used to allow the selection of metalloid-resistant mutants with enhanced MICs.147 Ledgham et al.148 found a transposon-disrupted gene in a mutant - with a three-fold increase in Se-resistance - that encoded a protein from a member of the DedA family of membrane proteins that was implicated in the uptake of selenite through cell membranes. This is a reasonable hypothesis for how metalloid resistance occurs in some microorganisms. 

Recovery. The principal purpose of recovery is to remove nonproteinaceous material from the enzyme preparation. Enzyme yields vary, sometimes exceeding 75%. Most industrial enzymes are secreted by a microorganism, and the first recovery step is often the removal of whole cells and other particulate matter (19) by centrifugation (20) or filtration (21). In the case of cell-bound enzymes, the harvested cells can be used as is or disrupted by physical (eg, bead mills, high pressure homogenizer) and/or chemical (eg, solvent, deteigent, lysozyme [9001-63-2], or other lytic enzyme) techniques (22). Enzymes can be extracted from disrupted microbial cells, and ground animal (trypsin) or plant (papain) material by dilute salt solutions or aqueous two-phase systems (23). 

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