Pseudomonas aeruginosa cells adapted to Rosmarinus officinalis L. essential oil and 1,8-cineole acquire no direct and cross protection in a meat-based broth

Assessment of chemically characterised Rosmarinus officinalis L. essential oil and its major compounds as plant‐based preservative in food system based on their efficacy against food‐borne moulds and aflatoxin secretion and as antioxidant

“…Rosmarinus officinalis L., commonly known as rosemary, has long been used as medicinal plant for improving memory, tonic, stimulant, astringent, anti‐inflammatory amd carminative agent (Prajapati et al ., ). Although, the antimicrobial efficacy of R. officinalis essential oil (ROEO) has been reported (De Azeredo et al ., ; Gomes Neto et al ., ), its aflatoxin inhibitory potency, the practical efficacy in food system and its antifungal mode of actions are lacking. Therefore, this study was performed to explore chemically characterised ROEO as an antifungal, aflatoxin suppressor and antioxidant agent.…”

Predicting the growth situation of Pseudomonas aeruginosa on agar plates and meat stuffs using gas sensors

“…A vital food microorganism, Pseudomonas aeruginosa is a common opportunistic human pathogen that is widely distributed in the environment; it plays an important role in the spoilage of a variety of foods12. There is an urgent need to develop a rapid, accurate and sensitive method to predict the quality of P. aeruginosa in foods, especially in high value foods such as meat.…”

Tolerance evaluation in Salmonella enterica serovar Typhimurium challenged with sublethal amounts of Rosmarinus officinalis L. essential oil or 1,8‐cineole in meat model

“…Typhimurium exposed (24 h cycles) to increasing amounts of ROEO or CIN survived (as demonstrated by viable cell counts) in meat broth containing these compounds in concentrations up to MIC/4, revealing a onefold decrease in the value of the MIC previously determined. The inhibition of the cells already present in the broth upon the addition of sublethal amounts of the tested substances could be related to the manifestation of cell injury; because when bacterial cells are kept continuously exposed in a stressing but nonlethal environment, as was provided by the sublethal amounts of the ROEO or CIN, the cells may lose viability and the capacity to survive over time (Gomes Neto et al ., ). It has been hypothesised that bacterial cells injured by exposure to antimicrobials, such as essential oils and their constituents, at concentrations lower than the MIC may develop an imbalance between anabolism and catabolism sufficient to disrupt growth, making them unable to form colonies on agar (Dodd et al ., ).…”

“…The induction of bacterial cross‐protection was performed by an overnight exposure of the bacterium to sublethal amounts of ROEO or CIN in meat broth, followed by exposure to other stressing agents (high temperature, low pH and NaCl) according to previously described procedure (Gomes Neto et al ., ). Preliminary experiments were performed for evaluating the thermotolerance, acid tolerance and salt tolerance of the test bacterial strain.…”

“…The capacity of S . Typhimurium to develop tolerance to ROEO or CIN was also assessed through exposure of the bacterium to increasing amounts of the antimicrobials (1/16 MIC, 1/8 MIC, 1/4 MIC, 1/2 MIC, MIC and 2 × MIC) throughout successive 24‐h habituation cycles in meat broth, according to a previously described procedure (Gomes Neto et al ., ), including a prolonged exposure time. In this procedure, 2 mL of the bacterial suspension was inoculated into 18 mL of the meat broth supplemented with ROEO or CIN (final concentration 1/16 of the MIC) in screw‐capped tubes, shaken for 30 s using a vortexer (viable cells counts of approximately 6 log CFU mL −1 ) and incubated statically for 24 h at 35 °C.…”