Reduction of biofilm formation on 3D printing materials treated with essential oils major compounds

3D printing food materials Daylight Magna Hard Black resin (DMHB resin) and polyethylene terephthalate (PET) are widely used in food industry. During contact with microorganisms, a microbial adhesion and biofilm formation is formed and which would be responsible for serious health risks. Therefore, the present study aimed to investigate the effect of thymol and carvacrol on the physicochemical characteristics of DMHB and PET using the contact angle method. Furthermore, the biofilm formation of Bacillus subtilis and Escherichia coli on 3D printing materials studied was done. In addition, the antibiofilm effect of tow naturally compounds tested against the bacteria studied was investigated. The results of the contact angle measurements showed a significant change in the physicochemical properties of both surfaces after treatment (p < 0.05). The environmental scanning electron microscopy (ESEM) analysis showed that both studied bacteria were able to induce biofilm formation on the DMHB with a percentage of 86.57% and 91.47% for E. coli and B. subtilis respectively. Regarding the PET, it is noted that the biofilm formation is favorable with B. subtilis (78.05%) and unfavorable with E. coli (0%). For the antibiofilm effect, the results showed that a minimum concentration SubCMI = 0.14 mg/mL for carvacrol and SubCMI = 0.039 mg/mL for thymol was sufficient to obtain better inhibition of biofilm formation. Indeed, these naturally compounds significantly reduced the amount of biofilm of B. subtilis and E. coli by up to 90% on both supports studied (p < 0.05). In the light of these findings, we can deduce that it is recommended to incorporate the studied major compounds into the composition of PET and resin materials in order to use them in the food industry.