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BACTERIOLOGICAL TESTING OF COMPRESSED AIR SUPPLIES
Author(s) -
Webber H. F. P.,
Taylor L.,
Compton J.
Publication year - 1952
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1952.tb02661.x
Subject(s) - agar , filtration (mathematics) , glass wool , chromatography , chemistry , compressed air , environmental science , pulp and paper industry , materials science , biology , composite material , mathematics , bacteria , engineering , statistics , genetics , layer (electronics) , organic chemistry
Nutrient agar (pH 7·4) was, in general, used for the tests, as wort agar (pH 4·85) allowed excessive growth of yeasts and moulds which suppressed bacterial development. Open exposure of plates to compressed air causes entrainment of organisms from the atmosphere, giving falsely high results. With appropriate shielding of the plates, however, this difficulty can be avoided, though care must be exercised in the choice of shielding device, or low results may be obtained as a result of imperfect deposition; a modification of the Hollaender & Dalla Valle apparatus (Publ. Hlth. Rep., Wash ., 1939, 54, 564) is preferred for comparative routine tests. If it is desired to use a filtration method, calcium alginate wool may be used as collecting medium, being thereafter dissolved in sodium hexametaphosphate solution as a preliminary to plating.