The antimicrobial effect of red wine on Bacillus cereus in simulated gastrointestinal conditions

Abstract

Several studies describe the burgeoning health benefits of red wine consumption, including antioxidative,anti-carcinogenic, anti-inflammatory, anti-cardiovascular and antimicrobial properties. Thisstudy aimed to evaluate the antimicrobial activity of wine against Bacillus cereus vegetative cells andspores. The results of this work clearly show, via in vitro tests, that wine exerts a strong inactivationeffect against vegetative cells of two B. cereus strains. The red wine tested inactivated B. cereusstationary phase vegetative cells to undetectable numbers (< 500 CFU mL-1) in less than 10 s. Thus,further inactivation assays were carried out with wine diluted with water (1:4 and 1:8). Wine diluted 1:4caused a reduction of 4.5 log cycles on viable cell counts, in 20 s. Nevertheless, B. cereus sporeswere found to be highly resistant to the wine exposure, with decreases in the counts lower than 1.0 logcycles, after 3 h. The influence of wine components (ethanol, organic acids, low pH and phenoliccompounds) was investigated on vegetative cells. Organic acids, when combined with ethanol, actedsynergistically and conduced to a similar inhibition pattern as that of wine. The wine phenoliccompounds assayed displayed no activity against the vegetative cells at the concentrations studied.Regarding data obtained in simulated gastric conditions, in a simulated meal context, we can concludethat the ingestion of wine during a meal diminishes considerably the number of B. cereus cellspersisting in the alimentary tract. Pasteurized fresh cheese was found to be more protective to thecells than the chicken-rice matrix. We also evaluated the behavior of B. cereus spores undergastrointestinal conditions. In a consumption-like scenario, the treatment SGF (synthetic gastric fluid)-SIF (synthetic intestinal fluid) +Food+Wine, when compared to the system SGF-SIF+Food+Water, led to lower total counts of B. cereus in the intestine, showing that wine inhibits the multiplication of the cells obtained from the germination of spores.This work provides evidence that drinking wine with meals leads to a reduction of the number of viable cells of B. cereus and reduces the impact of the germination of spores that may occur in the smallintestine, thus lowering the risk of infection the aforementioned pathogen may cause.

Date of Award	Jun 2010
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	José António Couto (Supervisor) & Timothy Hogg (Co-Supervisor)