A Study on the Antimicrobial Activity of Thymol Intended as a Natural Preservative

Abstract

A quantitative investigation on the inhibitory activity of thymol against some microorganisms that could represent a potential spoilage risk both in acid and mild thermally treated foods is presented in this work. In order to assess potential biostatic or biocidal activity of thymol, both the growth kinetics and dose-response profiles were obtained and analyzed. A suitable macrodilution methodology based on a turbidimetric technique was adopted to produce inhibitory data used for characterizing microbial susceptibility against thymol at sub-MIC levels. Microbial growth was monitored through absorbance measurements at 420 nm as a function of contact time with the active compound. Moreover, for each tested microorganism, the noninhibitory concentration (NIC) and the MIC were quantified. Results prove that thymol can exert a significant antimicrobial effect on each phase of the growth cycle. The microbial susceptibility and resistance were found to be nonlinearly dose related. It is worth noting that significant biostatic effects were observed at sub-MIC levels.

Evaluation of antimicrobial and antioxidant activities of natural phenolic compounds against foodborne pathogens and spoilage bacteria

“…Our mean MIC values for thymol against ten strains each of S. aureus (400 mg/ml), B. cereus (580 mg/ml) and E. coli (including STEC) (255 mg/ml) were about two times higher than those reported in previous studies by using one single strain (Burt, Vlielander, Haagsman, & Veldhuizen, 2005;Falcone, Speranza, del Nobile, Corbo, & Sinigaglia, 2005;Karapinar & Aktug, 1987). With regard to carvacrol, our mean MIC values against each of ten strains of S. aureus (367 mg/ml) and B. cereus (330 mg/ml) were 1.5e2.0 times higher than those reported by other authors using one to four strains (Arfa et al, 2006;Ultee et al, 2002).…”

Óleo essencial de orégano: interferência da composição química na atividade frente a Salmonella Enteritidis

“…No entanto, a eficácia da atividade bactericida de OEO pode variar em função dos teores de timol e carvacrol presentes, que dependem de fatores abióticos como tipo de solo, clima, práticas agrícolas, variedade do orégano e processo de extração do óleo essencial (CONSENTINO et al, 1999;JULIANO;MATTANA;USAI, 2000;FALEIRO et al, 2002;FALCONE et al, 2005;OUSSALAH et al, 2006).…”

Antimicrobial herb and spice compounds in food

“…Application of edible and bio-base films with different EOs in the packaging process of sausage casing and processed cheese slices will need further investigation (Seydim & Sarikus, 2006). However, some materials, such as thymol, have not been recognized as food-grade additives by European legislation (Falcone, Speranza, Del Nonile, Corbo, & Sinigaglia, 2005).…”

“…Broad spectrum antibacterial effect against Gram-positive and Gram-negative pathogenic micro-organisms Ceylan and Fung (2004) and Skocibusic et al (2006) Blackberry ( (2004) Garlic (Allium vineale) Broad spectrum antibacterial effect against Gram-positive and Gram-negative pathogenic micro-organisms Ceylan and Fung (2004) Mint (Mentha piperita) Broad spectrum antibacterial effect against Gram-positive and Gram-negative pathogenic micro-organisms Ceylan and Fung (2004) Onion (Allium cepa) Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Staphylococcus aureus Ceylan and Fung (2004) (2008), Davidson and Naidu (2000), Falcone et al (2005), Ghosh, Kaur, and Ganguli (2007), Graumann and Holley (2008), Gutierrez et al (2008aGutierrez et al ( , 2008b, Hammer et al (1999), Ibrahim, Salameh, Phetsomphou, Yang, and Seo (2006), Ibrahim, Yang, and Seo (2008) (2007), Kuete et al (2008), Li, Zhu et al (2008), and Yilmaz (2006) (continued on next page) Wang, Chen, & Fu, 2007), specific derivative from the fruits of Eucalyptus globulus (Tan et al, 2008), EOs from thymol and carvacrol at1:2000 dilutions and cinnamic aldehyde and eugenol extracted from cinnamon and clove at 0.1-1.0% w/v, 0.06% v/v concentration (Davidson & Naidu, 2000), aerial parts of Ammoides atlantica (Coss. et Dur.)…”