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Interaction of Antibiotics and Water Activity on Streptococcus thermophilus and Lactobacillus bulgaricus
Author(s) -
LARSEN RAÚL F.,
AÑÓN MARÍA CRISTINA
Publication year - 1989
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.1365-2621.1989.tb07913.x
Subject(s) - streptococcus thermophilus , lactobacillus , penicillin , lactobacillus delbrueckii subsp. bulgaricus , sucrose , glycerol , chemistry , lactic acid , antibiotics , microbiology and biotechnology , food science , bacteria , fermentation , biochemistry , biology , genetics
Acid production was determined in cultures of Streptococcus thermophilus and Lactobacillus bulgaricus in the presence of penicillin and gentamycin in milks with water activity adjusted between 0. 992 and 0.943 by adding glycerol, glucose or sucrose. Resistance of S. thermophilus A TCC 19258 and CRL 410 to penicillin increased when a w was lowered with glycerol from 0.992 to 0.995, and from 0.992 to 0.985 in L. bulgaricus ATCC 11842. Susceptibility to gentamycin increased in both species with reduction of a w . Susceptibility of S. thermophilus CRL 410 to penicillin increased in most cases when a w was adjusted with glucose, while acid production at a a w of 0.985 was always higher than that of the controls (a w 0.992) when sucrose was used. With L. bulgaricus CRL 420, lower acid production was observed at all penicillin concentrations, whether glucose or sucrose was used as the humectant.