[Efficiency of microbe filtration of air filter for rearing germfree animals (author's transl)]

Filtration efficiency of 3 types of air filter frame and cylinder (Fig. 1) was examined by culture of the air obtained from the operating isolators at intervals of 3 to 21 days. The air of isolator was bubled in 30 ml of nutrient broth for 30 or 120 minutes (4approximately15 l/min.) and each of 1 ml of the broth was inoculated into thioglycollate medium (TGC), cooked meat medium (CMM), heart infustion broth (HIB) and glucose peptone water (GPW). The media were incubated for 7 to 14 days at 30 or 25 degrees C. As seen in Table 1, microbes could be effectively removed through all types of filter for over 10 months, though there were a very few positive cases suggesting technically acidental contamination at sampling.