title: Bacterial maximum non-inhibitory and minimum inhibitory concentrations of different water activity depressing solutes.
abstract: The NaCl MNICs (maximum non-inhibitory concentrations) and MICs (minimum inhibitory concentrations) for growth of various strains of six bacterial species were determined and then compared with those obtained for seven other solutes. The influence of prior growth conditions on the MNICs and MICs was also evaluated. No significant changes on the MNICs and MICs were found among the strains studied within each species. Among all factors investigated, only growth phase -for Gram-negatives- and growth at high NaCl concentrations led to a change in the NaCl MNICs. Species could be classified depending on its NaCl MNICs and MICs (in decreasing order) as follows: Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii, Enterococcus faecium, Escherichia coli and Salmonella Typhimurium. Similar results were obtained for KCl, LiCl, and sodium acetate, but not for the remaining solutes investigated (sucrose, glycerol, MgCl2 and CaCl2). Results obtained indicate that, in general, Gram-negatives showed lower MNICs and MICs than Gram-positives for all the solutes, S. aureus being the most solute tolerant microorganism. When compared on a molar basis, glycerol showed the highest MNICs and MICs for all the microorganisms -except for S. aureus- and LiCl the lowest ones. NaCl MNICs and MICs were not significantly different from those of KCl when compared on a molar basis. Therefore, the inhibitory action of NaCl could not be linked to the specific action of Na(+). Results also showed that the Na(+) tolerance of some species was Cl(-) dependent whereas for others it was not, and that factors others than aw-decrease contribute to the inhibitory action of LiCl, CaCl2 and MgCl2.
authors.affiliation: Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain. Electronic address: guiceb@unizar.es.
authors.forename: G
authors.initials: G
authors.lastname: Cebrián
authors.affiliation: Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Arroyo
authors.affiliation: Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Mañas
authors.affiliation: Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Condón
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D002122:Calcium Chloride / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D018021:Lithium Chloride / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D012492:Salts / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D012996:Solutions / Q000494:pharmacology*; D013045:Species Specificity; D013395:Sucrose / Q000494:pharmacology; D014867:Water / Q000737:chemistry*
chemical_list: D012492:Salts; D012996:Solutions; D015636:Magnesium Chloride; D014867:Water; D012965:Sodium Chloride; D013395:Sucrose; D018021:Lithium Chloride; D002122:Calcium Chloride; D005990:Glycerol
keywords: Food-borne pathogens; NaCl; Osmotolerance; Selective plating; Water activity