Unfortunately, using common antibiotics to treat animal infection is increasing in which leads to undesirable side effects such as antibiotic residuals in animal products and occurrence bacterial resistance to antibiotics. Therefore, researchers are searching for an alternative to traditional antibiotics with fewer side effects like herbal essential oils and antimicrobial peptides (AMPs) such as Oregano and Cinnamon essential oils as well as recombinant thanatin peptide. Minimum Inhibitory Concentrations (MIC) was used based on a microbroth dilution method by 96-well microtiter with four replicates with Oregano and Cinnamon essential oils as well as thanatin peptide. After MIC, bacteria species were cultured and minimum bactericidal concentration (MBC) was determined as that showing no growth. The results of MIC assay showed a strong activity against salmonella enteritidis bacteria with the value of MIC equal to 6 μg/ml by thanatin. Moreover, the lowest amount of MBC was observed on E. coli0157 and salmonella enteritidis approximately 25 μg/ml. Thanatin is one of the member of cationic AMPs that have received a great attention regarding growth inhibitory against wide range of microorganisms including Gram-negative and Gram-positive bacteria, as well as several fungi species. Thanatin showed a strong growth inhibitory against bacteria in compare with Oregano and Cinnamon essential oils. Thus, developing new antibiotics such as thanatin would be a great replacement for common antibiotics and may lead to a great progress in eliminating livestock pathogens.

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