Changes in cell viability in response to fungal culture filtrates. Exponentially growing cells were incubated with >3 kDa (a, black boxes) and <3 kDa (b, grey boxes) fractions of the secreted fungal metabolite mixtures. Control cells (Co, white boxes) were incubated with culture medium only. All the abbreviations used for the treatments (wt Tr, Bo, Δ ech42) are as in Fig. 3. The 100% value correspond to cells treated for 10 min at 100°C. Data are means ± SD of three independent experiments. Bars labeled with a different letter differ significantly (P < 0.05) by Student's t test.