1 activity was bactericidal at the concentration tested (Figure 6). Figure 6 Inhibitory action of purified mutacin F-59.1 against Micrococcus luteus ATCC 272. Growth of cells was followed by measuring the viable count (CFU/mL) following the addition of purified mutacin F-59.1 (1600 AU/mL) (square line) or not for control (diamond line). The activity spectra observed for mutacins F-59.1 and D-123.1 show inhibition of a wide range of pathogenic bacteria including Bacillus spp., Enterococcus spp., Listeria spp., Staphylococcus spp. and Streptococcus spp. (Table 2). Table 2 Inhibitory spectra of purified mutacins F-59
Indicator bacteria Activity of mutacin (AU/mL) D-123.1 F-59.1 Bacillus cereus ATCC 2 n.t.a 400 Bacillus subtilis ATCC #XAV-939 molecular weight randurls[1|1|,|CHEM1|]# 6051 n.t. 400 Enterococcus
faecium ATCC 19434 0 1600 Enterococcus faecalis ATCC 27235 400 200 Enterococcus hirae ATCC 8043 200 200 Lactobacillus salivarius SMQ 876 n.t. 0 Lactococcus lactis ATCC 11454 400 400 Listeria monocytogenes ATCC 15313 400 200b L. monocytogenes ATCC 700301 ScottA 200 200b L. monocytogenes ATCC 700302 ScottA 200 200b L. monocytogenes FRDC 1039 400 200b L. monocytogenes FRDC 88571 400 200b Listeria murrayi ATCC 25420 200 200b L. murrayi HPB 30 400 200b Listeria ivanovii HPB 28 400 200 Listeria grayi ATCC 19120 800 200 Micrococcus luteus ATCC 272 11600 3200 Pediococcus acidilactici UL5 400 800 Staphylococcus aureus ATCC 6538 n.t. 0 S. aureus ATCC 25923 0 0 S. aureus ATCC 43300 Thalidomide CBL0137 ic50 200 0 S. aureus R621 200 0 Staphylococcus carnosus 1600 800 Streptococcus mutans 59.1 n.t. 200b S. mutans 123.1 200d n.t. Streptococcus sobrinus ATCC 27352 200 800 Streptococcus salivarius ATCC 25923 800 800 Streptococcus pyogenes ATCC 10389 200 0 Streptococcus suis serotype 2 400 0 ATCC (Manassas, VA, USA); HPB (Health Canada, Ottawa, ON, Canada); FRDC (Agriculture and Agrifood Canada, Sainte-Hyacinthe, QC, Canada). aNot tested. bHazy inhibition zone was observed. Discussion The inhibitory activity produced by the fermentation of S. mutans 59.1 in SWP did not come from release of pediocin already present in the whey proteins
or permeate used to make the medium because no inhibitory activity in SWP was detected from non-fermented nor purified medium against M. luteus ATCC 272 and also because many other S. mutans strains were unable to produce an inhibitory activity by fermentation of the same medium [14, 15]. Of all the current microbiological broth media commonly used for the growth of Streptococcus sp., none permitted the production of a detectable level of mutacin activity by S. mutans 123.1. Activity of mutacin D-123.1 was only detected after growth on solid medium. The production of some bacteriocins and mutacins is controlled by quorum sensing mechanisms which are better expressed when cells are grown at high density compared to lower cell density obtained in liquid culture [6]. For the isolation of mutacin D-123.