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ENUMERATION OF TEMPERATURE‐STRESSED Pseudomonas aeruginosa UTILIZING SELECTIVE PROCEDURES
Author(s) -
KUKULINSKYFULLER JANET C.,
NELSON F. EUGENE
Publication year - 1977
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1977.tb01512.x
Subject(s) - cetrimide , agar , enumeration , chemistry , pseudomonas aeruginosa , chromatography , food science , plate count , distilled water , tryptic soy broth , microbiology and biotechnology , total viable count , agar plate , biology , bacteria , mathematics , medicine , dentistry , chlorhexidine , combinatorics , genetics
Sublethally stressed cells of Pseudomonas aeruginosa were enumerated using the plate count procedure with Plate Count Agar (PCA) and several selective media. Exponential phase (5 hr) cultures were stressed at 1 or 5°C in phosphate buffered distilled water for 0, 5 and 30 min and 24 hr. Counts on all media decreased as time of stress increased. Cold‐stressed organisms plated on Acetamide Agar (ACE), King's Medium B with cetrimide (KMB), Trypicase Soy Agar with nitrofurantoin (TSN) and Naladixic Acid Cetrimide Agar (NAC) gave lower counts than those obtained on PCA, but KMB and NAC were the only media that gave statistically different counts at the 95% confidence level. Stationary phase (24 hr) cultures were stressed at 55°C in reconstituted milk‐solids‐not‐fat to obtain approx 99% kill. Counts of heat‐stressed organisms on ACE, KMB, TSN, NAC and Pseudosel BBL (PSE) were significantly lower than counts on PCA. Incubation of plates at 41°C reduced the count of heat‐stressed cells significantly from counts obtained at 35 or 37°C on all media, including nonselective PCA. Only PSE affected counts of unstressed organisms, the counts being significantly lower than those on PCA. Counts of temperature‐stressed p. aeruginosa may be substantially decreased when selective procedures are used.