Chemical fingerprints of four different Satureja montana L. essential oils (SEOs) were assayed by an untargeted metabolomics approach based on Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) coupled with either electrospray ionization or atmospheric pressure chemical ionization ion sources. Analysis and relative quantification of the non-polar volatile fraction were conducted by gas chromatography (GC) coupled to MS. FT-ICR MS confirmed significant differences in the polar metabolite composition, while GC-MS analyses confirmed slight fluctuations in the relative amount of major terpenes and terpenoids, known to play a key role in antimicrobial mechanisms. Oil in eater (O/W) nanoemulsions (NEs) composed by SEOs and Tween 20 or Tween 80 were prepared and analyzed in terms of hydrodynamic diameter, ζ-potential and polydispersity index. The results confirm the formation of stable NEs homogeneous in size. Minimum inhibitory and minimum bactericidal concentrations of SEOs were determined towards Gram-positive (Listeria monocytogenes, Staphylococcus aureus, Staphylococcus haemolyticus) and Gram-negative clinical isolates (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Serratia marcescens). Commercial SEO showed strongest antibacterial activity, while SEO 3 was found to be the most active among the lab made extractions. MIC and MBC values ranged from 0.39 to 6.25 mg·mL⁻¹. Furthermore, a SEO structured in NEs formulation was able to preserve and improve antimicrobial activity.

Careless use conditions of filter jugs were applied to simulate and evaluate the behavior of two ubiquitous aquatic bacterial species, Pseudomonas aeruginosa and Enterobacter aerogenes. According to a reference protocol, nine different jugs of popular brands sold in the Italian market were used for the test. Separately, a suspension of the two bacteria was spiked in water used for filling the jugs. The concentration of the test organisms and total aerobic microbial count (TAMC) was measured daily in the filtered water along a period corresponding to the cartridge lifetime. Results showed a different trend of bacterial behavior. E. aerogenes was detectable exclusively on the first day after jug filling, while P. aeruginosa confirmed its persistence over time in all the jugs and its ability to potentially colonize surfaces and cartridges. The TAMC was detected at a concentration range from 10² to 10⁷ CFU/100 mL in all the tests, high values that were not far from those raised in bottled flat natural mineral water weeks after bottling.