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In vitro growth response of bread‐spoilage Bacillus strains to selected natural antimicrobials
Author(s) -
Pattison T.L.,
Lindsay D.,
von Holy A.
Publication year - 2003
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.200390037
Subject(s) - antimicrobial , food science , bacillus licheniformis , food spoilage , bacillus subtilis , preservative , laboratory flask , bacillus pumilus , chemistry , bacterial growth , bacillus (shape) , propionate , microbiology and biotechnology , biology , bacteria , biochemistry , genetics
This study assessed the in vitro responses of Bacillus (B.) strains isolated from ropey bread to natural antimicrobials under optimum growth conditions. The responses of six Bacillus strains [ B. subtilis (2), B. licheniformis (2) and B. pumilus (2)] to acetic acid (AA), lactic acid (LA), calcium lactate (CL) and a lactate‐containing cocktail (LCC), singly and in combinations were determined and compared to calcium propionate (CP). Isolates were each inoculated into flasks containing Nutrient Broth (NB) and the respective antimicrobial treatments and pHs were left unadjusted. A duplicate set of flasks, also containing NB and the respective antimicrobials, but adjusted to pH's corresponding to those of baked brown bread containing the same antimicrobials was also inoculated. Growth curves were obtained spectrophotometrically and used to estimate lag times. The organic acids used in this study [0.1% (v/v) AA and 0.25% (v/v) LA] singly and in combination with each other and with CL, CP or LCC, completely inhibited the growth of all six Bacillus strains, but only at non‐adjusted pHs. The efficacies of LA, AA and CL notably decreased when the pH of the test media containing the respective preservatives was adjusted to the corresponding in situ (bread) values. However, the natural antimicrobials were still as effective as CP in retarding growth of the six Bacillus strains at the in situ (bread) pH values.