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Effect of culture age, pre‐incubation at low temperature and pH on the thermal resistance of Aeromonas hydrophila
Author(s) -
Condón S.,
García María L.,
Otero A.,
Sala F.J.
Publication year - 1992
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1992.tb01842.x
Subject(s) - aeromonas hydrophila , incubation , d value , thermal resistance , incubation period , aeromonas , population , strain (injury) , chemistry , microbiology and biotechnology , bacteria , biology , biochemistry , thermal , anatomy , medicine , genetics , physics , environmental health , meteorology
S. CONDON, M.L. GARCIA, A. OTERO AND F.J. SALA. 1992. The thermal resistance of Aeromonas hydrophila strain NCTC 8049 was determined within the range 48°‐65°C with a thermoresistometer TR‐SC and McIlvaine buffer. The effects of culture age, pre‐incubation at 7°C and the pH of the heating menstruum were evaluated. The pattern of thermal death was dependent on culture age. Cells heated in the late logarithmic growth phase (15 h at 30°C) were twice as resistant as those in the early stage (5 h at 30°C), and the maximum D ‐value was obtained after 72 h incubation (5.5 total increase). The age of the cells did not affect z ‐values significantly. The heat resistance of cells incubated for 48 h at 30°C increased (twice) after holding at 7°C for 72 h. Pre‐incubation at low temperature of older cultures (72 h, 30°C) did not influence their D ‐values. Maximum heat resistance was found at pH 6.0 and minimal at pH 4.0. Decreasing the pH from 6.0 4.0 reduced D ‐values by a factor of 5. Although the strain studied was heat‐sensitive ( D 55°C = 0.17 min; z = 5.11°C), survivor curves of cultures older than 50 h showed a significant tailing. Organisms surviving in the tails were only slightly more resistant than were the original population.