6 × 107 to 1.7 × 108 CFU over 24 hours, (n = 3, Figure 1). This indicates that Bdellovibrio effectively suppressed the population growth of P. tolaasii, most likely due to killing by predation. Figure 1 Reduction in P. tolaasii OD600 nm over 24 hours, in vitro , in the presence of Bdellovibrio bacteriovorus . Mean OD600nm of P. tolaasii

2192T samples in the absence AZD5363 manufacturer or presence of live B bacteriovorus HD100 added at 4 × 106 or 1.6 × 107 Plaque Forming Units (PFU) (n = 4). The MI-503 nmr increase in OD600nm in the absence of Bdellovibrio indicates P. tolaasii 2192T growth, while no increase in the presence of 4 × 106 or 1.6 × 107 B. bacteriovorus HD100 indicates inhibition of P. tolaasii 2192T growth. Error bars indicate 95% Confidence Intervals for each OD600nm value. Brown blotch lesion intensity was reduced by Bdellovibrioapplication onto mushrooms Given B. bacteriovorus HD100 was observed to suppress P. tolaasii 2192T growth in vitro, we reasoned that Nutlin-3 in vitro this effect might be replicated in a more natural environment. We first aimed to determine whether symptoms of P. tolaasii infection, a function of bacterial metabolism and growth, were reduced with Bdellovibrio treatment in a natural context. The intensity of lesions formed

by P. tolaasii 2192T on the post-harvest pileus surface of the cultivated button mushroom Agaricus bisporus was measured in the presence and absence of B. bacteriovorus HD100, as shown in Figure 2 . Mushroom pilei inoculated with P. tolaasii

2192T alone, in the absence of any treatment with B. bacteriovorus HD100, formed dark, wet surface lesions, the primary symptom of brown blotch disease, after 48 hours at 29°C (mean intensity MTMR9 = 0.019 1/PV ± 0.0005, n = 30). In contrast, pilei treated with a King’s Medium B control (the preferred growth medium of P. tolaasii) did not form these dark lesions (mean intensity = 0.012 1/PV ± 0.0005, n = 30); similarly, those treated with B. bacteriovorus HD100 alone, and not inoculated with P. tolaasii 2192T, also did not form dark lesions (mean intensity = 0.010 1/PV ± 0.0005, n = 30), so Bdellovibrio application itself did not have a significant adverse effect on the appearance of mushroom pilei. Figure 2 Lesion intensity on P. tolaasii -inoculated mushrooms in the presence and absence of Bdellovibrio . Lesion intensities on mushroom pilei under 5 different treatment conditions, detailed to the right of the graph. Each P tolaasii 2192T inoculation contained 1.7 × 106 CFU, and each B. bacteriovorus HD100 inoculation contained 2.9 × 106 PFU. Higher lesion intensity indicates a greater level of brown blotch disease symptoms and therefore a higher level of P. tolaasii infection. Horizontal black bars indicate the mean lesion intensity value for each treatment group. Student’s t-test of significance between B. bacteriovorus HD100 treated and non-treated mushrooms inoculated with P. tolaasii 2192T: **p < 0.01, ***p <0.001. Post-harvest mushrooms treated with B.