RESUMO
This study aimed to investigate the chemical composition, using GC-MS, and anti-biofilm potential of black cardamom essential oil (BCEO) against biofilms of Escherichia coli O157:H7 and Salmonella Typhimurium JSG 1748 through inhibition of bacterial quorum sensing. GC-MS quantification demonstrated that BCEO contains 1,8-cineole (44.24%), α-terpinyl acetate (12.25%), nerolidol (6.03%), and sabinene (5.96%) as the major bioactive compounds. Antioxidant assays for BCEO revealed the total phenolic and flavonoid mean values were 1325.03 ± 7.69 mg GAE 100/g and 168.25 ± 5.26 mg CE/g, respectively. In regards to antimicrobial potential, Candida albicans was the most sensitive species compared to Streptococcus mutans, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Salmonella Typhimurium with the following zones of inhibition; 14.4 ± 0.52, 13.2 ± 0.42, 11.2 ± 0.28, 11.0 ± 0.52, 8.2 ± 0.24 and 6.6 ± 0.18 mm in diameter, respectively. Biofilm inhibition by BCEO was concentration-dependent, when various concentrations of 0.03, 0.06, 0.12, 0.25 and 0.5% were applied, 33.67, 34.14, 38.66, 46.65 and 50.17% of Salmonella Typhimurium biofilm was inhibited, while 47.31, 54.15, 76.57, 83.36 and 84.63% of Escherichia coli biofilm formation was prevented. Chromobacterium violaceum ATCC 12,472 and its product violacein, was used as a microbial indicator for enhancement or inhibition of quorum sensing. Our data showed that 0.5% of BCEO inhibited violacein production without influencing the growth of Chromobacterium violaceum, while 1% of BCEO, caused 100% inhibtion of violacein production together with 30% inhibition of growth. This study shows that BCEO possesses promising antioxidant and antimicrobial potential, and found anti-biofilm activities linked to the quenching of the quorum sensing system of E. coli and S. Typhimurium.
RESUMO
Foodborne pathogens, microbial recurrent infections, and antibiotic resistance have driven researchers to explore natural compounds as safe alternative antimicrobials. In this study, the chemical profile, antimicrobial, and mutagenic activities of the Elletaria cardamomum essential oil were investigated. GC-MS analysis identified the major bioactive components as α-terpinyl acetate, 1,8-cineole, linalool acetate, and sabinene, at concentrations of 34.95, 25.30, 8.13, and 5.48% respectively, of the essential oil's content. Regarding antimicrobial activity, the minimum inhibitory concentration of green cardamom essential oil was 1% against Escherichia coli O157:H7 and Pseudomonas aeruginosa ATCC 14213. Green cardamom essential oil, when used at concentrations of 0.015, 0.031, 0.062, and 0.125% (v/v) prevented biofilm formation of Escherichia coli O157:H7 by 64.29, 65.98, 70.41, and 85.59%, respectively. Furthermore, these concentrations inhibited 6.13, 45.50, 49.45, and 100%, respectively, of the Salmonella Typhimurium JSG 1748 biofilm. A mutagenicity assay confirmed that green cardamom essential oil has no demonstrable mutagenic activity against the tested strains. The study's findings suggest that green cardamom derived bioactive compounds are safe organic antimicrobials, effective in controlling biofilm formation by Gram-negative pathogens. Moreover, such compounds could possibly be used in the food industry (e.g., bakery, dairy, meat, and other food products) as a safe alternative to chemical preservatives (antimicrobials) to enhance shelf life by improving the antimicrobial status while at the same time imparting a pleasant and appealing aroma for consumers.