Optimization of thymol nanoencapsulation in gelatin and carrageenan polymer network and investigation of anti-biofilm effect against marine bacteria Bacillus sp.

Thymol is the main monoterpene phenol occurring in essential oils. The aim of this study was to encapsulate thymol, in natural polymers gelatin and carrageenan. In order to achieve the optimization of encapsulated thymol, the CCD method of the experiment design software was used. As a result, based on the analysis, it was found that the optimal conditions suggested by Design Expert 13 software were as follows: pH 6, thymol concentration 0.4% (W/V) and the ratio of carrageenan to gelatin =1, which in this case, the encapsulation efficiency, nanocapsule size and polydispersity index were obtained 91%, 112 nm, and 1.1, respectively. The encapsulated thymol gave lower minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) values than the unencapsulated thymol against Bacillus sp. strain. In addition, encapsulated thymol had 70% inhibition and eradication of biofilm in lower concentrations. In general, the results showed an improvement in antibacterial and antibiofilm activity for nanoencapsulated thymol against marine bacteria Bacillus sp. This formulation could be proposed as an alternative or adjuvant for controlling biofilm in marine bacteria in the first stage of the biofouling phenomenon.