Kajian Mekanisme Penghambatan Resistensi oleh Beberapa Minyak Atsiri Citrus sp terhadap Bakteri Resisten Escherichia coli

Abstract

The prevalence of foodborne diseases continues to rise due to the bacterial resistance of Escherichia coli. On the other hand, antibiotic resistance and its adverse effects have led to a decline in antibiotic use. The main focus of this study is to investigate the mechanism by which Citrus species peel essential oil (EO) inhibits bacterial resistance in a strain of E. coli. The essential oils of Citrus species were isolated through the hydrodistillation method. The best MIC values were obtained at 250 μg/mL for Citrus microcarpa EO, Citrus hystrix EO, Citrus limon EO, and Citrus amblycarpa EO, with their MBC at 500 μg/mL. Only Citrus microcarpa EO, Citrus hystrix EO, and Citrus limon EO showed synergistic effects when combined with tetracycline (FIC Index 0,5). The test of biofilm formation showed the best result for the combination of Citrus microcarpa EO and tetracycline at 2% formation. In contrast, the test of efflux pump inhibitors demonstrated Citrus microcarpa EO as the best value (250 μg/mL). In the membran permeability test at OD 260 nm and 590 nm, the mixture of Citrus microcarpa EO and tetracycline also presented the best value of absorbance at 0,488 and the uptake of crystal violet with more than half (64,37%). To support this result, the morphology test was performed using SEM, and potassium ion leakage was also counted by ICP-OES. The results for both tests also revealed that the combination of Citrus microcarpa EO and tetracycline produced the best results compared to others. In contrast, the test of efflux pump inhibitors demonstrated Citrus microcarpa EO as the best value.