Microbial population balancing as a quantitative aid for evaluating release from a high pressure homogeniser

A mass balancing technique has been devised to quantify the number of microorganisms released as an aerosol. Mass balances have been successfully carried out in a 0.36 m3 containment cabinet and a 8.37 m3 soft-film isolation cabinet. Initially an atomizer was used to produce a defined microbial aerosol and an Aerojet-General glass cyclone was used to collect dispersed micro-organisms. In this way, cell recoveries of over 50% were achieved for Saccharomyces cerevisiae released into the 0.36 m3 cabinet. This mass balancing technique was used, together with polymerase chain reaction, to estimate microbial release from a high pressure homogenizer, operated under the conditions of containment category B1 inside the soft-film cabinet. The incidental release of the micro-organisms as an aerosol is very small in comparison to the number present in the process fluid.