Several growth curves for selected pathogens
and hygiene indicators alone and vs selected
dairy starter cultures (LAB) and commercial probiotics
have been performed. All strains for LAB
and commercial probiotics were inoculated as
pure cultures into skim milk to get an initial
cocci:bacilli:enterocci ratio of 2:1:1 and a concentration
of approx 107 cfu mL–1 until challenge
vs selected pathogens and hygiene indicators.
Selected pathogens came from the collection of
the Laboratorio di Ispezione degli Alimenti di
O.A. or were reference strains (Escherichia coli,
CSH26 K12, Staphylococcus aureus, 27R,
Salmonella Derby 27, Pseudomonas fluorescens
ATCC 13525, Listeria innocua ATCC 33090).
Each strain was inoculated into skim milk to get
an initial concentration of approx 106 cfu mL–1.
Growth curves in skim milk for the following
challenges were studied: i) sterility control; ii)
association LAB; iii) association of LAB vs each
selected pathogen or hygiene indicator; iv)
selected pathogen or hygiene indicator alone.
The challenges were carried out in BHI broth and in skim milk at 37°C. The highest reduction
was observed in milk but in general the association
of LAB and the probiotic was able to limit
the growth of pathogens and hygiene indicators.