**3.1. Isolation and screening on MSM**

The viable count of mesophilic and spore-forming bacteria and *Pseudomonas* was fairly high (7–8 log cfu/ml) (Table 2); thus, we selected 119 isolates (46 labeled as mesophilic bacteria, 44 and 29 belonging to *Bacillus* and *Pseudomonas* genera, respectively).


**Table 2.** Viable count (log cfu/g) of mesophilic bacteria (M), *Bacillus* (B), and *Pseudomonas* (P) in OMW samples. Data are the average (n=2).

The isolates were streaked on MSM with cinnamic or vanillic acids; Figure 1 shows the results for vanillic acid. Namely, 12 isolates were able to grow in presence of 0.5 g/l of this compound (Figure 1a) and 9 with 1g/l (Figure 1b). None of the isolates grew with cinnamic acid. Figure 1: Screening of the isolates on MSM with vanillic acid (0.5 g/l and 1.0 g/l). The numbers on the pictures indicate if the targets are able or not able to grow.

Figure 2: Screening of the isolates on MSM with vanillic acid (0.5 g/l and 1.0 g/l) after the induction. **Figure 1.** The numbers on the pictures indicate if the targets are able or not able to grow. Screening of the isolates on MSM with vanillic acid (0.5 g/l and 1.0 g/l). The numbers on the pictures indicate if the targets are able or not able to grow.

The screening was also performed after isolate growing in MSM broth with low amounts of phenols; this step could be referred as an induction phase, aimed at inducing the resistance to phenols. Figure 2 shows the results with 1 g/l of vanillic acid. There were 32 out of 119 isolates that acquired the ability to grow in MSM with vanillic acid; at the lowest concentration (0.5 g/ l) 49 strains were able to grow. The same protocol was also used for cinnamic acid, but only a single isolate was able to grow after induction both at 0.5 g/l and 1 g/l (the isolate 26M).

Figure 3: Viability of the isolate 6P in MSM+caffeic acid (mean values ± standard deviation). \*, viable **Figure 2.** Screening of the isolates on MSM with vanillic acid (0.5 g/l and 1.0 g/l) after the induction. The numbers on the pictures indicate if the targets are able or not able to grow.

count in MSM+caffeic acid are significantly different from control.
