3.7. Metal-induced antibacterial activity
E. coli DH5α and B. subtilis 168 were used as model species to evaluate mass transfer from the clay to bacteria. The 24 hours of incubation at 37 oC of untreated host matrices (NaMt, BoltornTMH20 and H20@NaMt) with a population of 74.106 CFU.mL-1 revealed no antibacterial activity in three independent experiments with bothE. coli and B. subtilis strains. For conciseness, only data obtained with B. subtilis were mentioned herein (Fig. 3.a) . In contrast, copper-loaded (Cu/NaMt) and silver-loaded (Ag/NaMt) clays exhibited noticeable antibacterial activity (Fig. 4) , demonstrating that clay minerals can behave as MNP-hosting matrices. This improvement would be due to metal incorporation (Gordon et al., 2010; Potera, 2012; Vincent, Duval, Hartemann, & Engels‐Deutsch, 2018; Yun’an Qing et al., 2018) but the mechanisms remain to be elucidated..