Effect of Skimmilks Cultured with Different Strains of Leuconostoc Citrovorum on Growth of Some Bacteria and Yeasts

MARYSkimmilks cultured with four different strains of Leuconostoe citrovorum were tested for their ability to inhibit growth of other microorganisms.Milks were inoculated with L. citrovorum, incubated, acidified with citric acid, reincubated, and subsequently filtered.The filtrate from each cultured skimmilk was subdivided and portions adjusted to pH values of 4.5, 4.7, 4.9, and 5.1.Each filtrate was then evaluated by means of a disc assay procedure, for its inhibitory effect on other microorganisms.Filtrates from skimmilks fermented by two cultures of L. citrovorum regularly inhibited one strain of Staphylococcus aureus, two strains each of Aerobacter aerogenes, Alcaligenes viseolactis, Escherichia coli~ Pseudomonas fragi, and six strains of Pseudomonas fluorescens.Often an increase in pit was accompanied by a decrease in frequency of inhibition and zone size.Filtrates from skimmilks fermented by the two other cultures of L. citrovorum displayed less inhibitory activity throughout and, sometimes, none at higher pH values.No filtrates tested inhibited Torula gl~tinis, Saccharomyces cere~isiae, Saccharomyces fragilis~ or Mycotorula lipolytica.