Sterile techniques

Abstract

A new type of air filter was developed and tested in the pure culturing of aerobic microorganisms. 2, This filter was compounded from layers of porous poly(viny1 alcohol) (PVA). When compared with the traditional glass wool filters, the PVA filters achieved high collection efficiency with considerably less resistance to air flow. The PVA filters will withstand temperatures of 130°C. One difficulty in evaluating high efficiency filters has been to get accurate measurements of the efficiency. Several workersz0 have suggested the use of Escherichia coli bacteriophage T, as a possible test organism. By using phage, it is possible to reduce collection efficiencies to ranges that are measurable to obtain a value which is characteristic for the filter. This efficiency can be converted into a calculated efficiency for bacteria by multiplying by some factor depending on the sizes of the two types of particles.