Patent ID: 8361741

Claim:
A method for retention testing sterilizing grade filters, comprising: a) providing a stock of Acholeplasma laidlawii; b) growing up the stock of Acholeplasma laidlawii for about 24 hours or less in a single serum-free growth medium that supports cell growth to a high titer and yields a cellular morphology where the cells are small, deaggregated and spherical, thereby producing a bacterial culture, wherein the serum-free growth medium comprises (i) a nutrient selected from the group consisting of about 4% tryptose, about 4% polypeptone, about 2% Mycoplasma Broth Base, and combinations thereof; (ii) bovine serum albumin (“BSA”); (iii) one or more pH stabilizers; (iv) glucose; and (v) one or more fatty acids; c) challenging a test filter by filtering the bacterial culture through the test filter at a known challenge level, thereby producing a filtrate downstream of the test filter; and d) detecting concentration of Acholeplasma laidlawii in the filtrate.