Fig. 8

Bacillus spp. relative abundance in surfaces and air samples as detected by NGS analysis. The abundance of Bacillus spp. was evaluated in floor samples (left panel) as representative of train surfaces and in air samples (right panel) using 16S rRNA NGS. The results are expressed as mean values of percentage of relative abundance ± S.D. of all the samples collected at the indicated times (T0–T5)