Controlled cell disruption: a comparison of the forces required to disrupt different micro-organisms

A cell disrupter has been developed which can measure the forces required to disrupt both eukaryotic and prokaryotic cells. It operates a continuous process and will disrupt both large and small volumes. Shear forces are set up when a suspension under laminar flow conditions is released under high pressure through a short orifice. If the applied pressure is altered, the shear forces are simultaneously changed so that the amount of cell disruption can be compared under different known and repeatable conditions. The disrupter is now manufactured and supplied by Stansted Fluid Power Limited, Stansted, England. Phase-contrast microscopy has shown that the disrupter will break a variety of organisms including Chlorella, Aspergillus fumigatis, Fusarium sp., Saccharomyces cerevisiae, Escherichia coli, Lactobacillus casei, Bacillus subtilis, Clostridium perfringens, Streptococcus faecalis, Streptococcus zooepidermicus and Staphylococcus aureus. The cells are not all broken at one pressure but a certain pressure must be applied before disruption starts which will then increase rapidly as the applied pressure is increased. The applied pressure required to disrupt half the population in a culture is different from one species to another, rods being disrupted more easily than spheres. The case of disruption seems to be related to the shape and chemical composition of the cell wall. Furthermore, the disrupting process, in an unsynchronized culture is not random and may be related to the statistical size distribution of the cells.