Salmonella , a bacterial, food-borne pathogen, can contaminate meat, milk, and vegetables. While appropriate measures are available to control Salmonella , the inhibitory phytochemicals from plants are gaining increased attention. Punicalagin, a natural antibiotic, is one of the main active tannins isolated from Punica granatum L . To obtain a broader understanding of the effect of punicalagin on the cell membranes of Salmonella typhimurium , the killing kinetics, extracellular potassium concentration, release of cell constituents, intracellular pH (pH in ), membrane potential, and morphological features were characterized to elucidate the mechanisms of action. Treatment with punicalagin induced an increase in the extracellular concentrations of potassium and a release of cell constituents. A higher pH gradient, an increase in the pH in and cell membrane depolarization were observed after punicalagin treatment. Electron microscopy observations showed that the cell membrane structures of S. typhimurium were damaged by punicalagin. It is concluded that punicalagin inhibits the proliferation of S. typhimurium and destroys the integrity of the cell membrane, leading to a loss of cell homeostasis. These findings indicate that punicalagin has the potential to be used as a food preservative in order to control S. typhimurium contamination in food and reduce the risk of salmonellosis.
Category Archives: microbial contamination
Research – Researchers identify biofilm hotspots, document danger zones
Scientists in Austria have investigated where biofilms hide and what bacteria can be found in them.
Biofilms are proven sources of contamination in the food industry. They can cause additional costs in production and can be a danger to consumer health.
Researchers at the unit of food microbiology at Vetmeduni Vienna looked at biofilms in an Austrian meat processing environment that included pork, poultry and beef. Knowledge gained on presence and composition, published in the International Journal of Food Microbiology, could help to prevent and reduce biofilm formation within food processing environments.
Research – Study suggests green tea extracts could reduce risk of infection with diarrhoea-causing Norovirus
Scientists also found that green tea extract in combination with chitosan films can reduce levels of bacteria such as E coli and L innocua to undetectable levels after 24 hours of exposure
It’s not uncommon for one to get an upset stomach occasionally, particularly after eating outside food. This is often the result of different kinds of bacteria and viruses present in the food items. In a research, published in the International Journal of Food Science on 4 July 2020, scientists found that green tea extracts can help in reducing the risk of getting infected with a diarrhoea-causing virus known as norovirus.
Borneo – Alert in Brunei as Sabah reports 43 cholera cases
According to the Ministry of Health (MoH), the Malaysian Ministry of Health has reported 43 cholera cases in several areas in Sabah since January 2020 until now.
Continuous monitoring by the MoH showed no cases of cholera detected in Brunei Darussalam. Cholera is an intestinal infection caused by the ‘vibrio cholera’ virus that spreads through contaminated food and water. The main symptom is diarrhoea. Other symptoms include vomiting and abdominal pain. Severe cholera infection can lead to dehydration and death, if left untreated.
RASFF Alert – Animal Feed- Aflatoxins – Groundnuts
RASFF – aflatoxins (B1 = 4.9; Tot. = 32.4 µg/kg – ppb) in feed groundnuts from Argentina in the UK
RASFF Alert – Animal Feed – Salmonella – Dog Chews
RASFF – Salmonella enterica ser. Rissen (presence /25g) and Salmonella enterica ser. Typhimurium (presence /25g) in dog chews from Germany in Austria
Research – Evasion of Plant Innate Defense Response by Salmonella on Lettuce
To establish host association, the innate immune system, which is one of the first lines of defense against infectious disease, must be circumvented. Plants encounter enteric foodborne bacterial pathogens under both pre- and post-harvest conditions. Human enteric foodborne pathogens can use plants as temporary hosts. This unique interaction may result in recalls and illness outbreaks associated with raw agricultural commodities. The purpose of this study was to determine if Salmonella enterica Typhimurium applied to lettuce leaves can suppress the innate stomatal defense in lettuce and utilization of UD1022 as a biocontrol against this ingression. Lettuce leaves were spot inoculated with S. Typhimurium wild type and its mutants. Bacterial culture and confocal microscopy analysis of stomatal apertures were used to support findings of differences in S. Typhimurium mutants compared to wild type. The persistence and internalization of these strains on lettuce was compared over a 7-day trial. S. Typhimurium may bypass the innate stomatal closure defense response in lettuce. Interestingly, a few key T3SS components in S. Typhimurium were involved in overriding stomatal defense response in lettuce for ingression. We also show that the T3SS in S. Typhimurium plays a critical role in persistence of S. Typhimurium in planta. Salmonella populations were significantly reduced in all UD1022 groups by day 7 with the exception of fliB and invA mutants. Salmonella internalization was not detected in plants after UD1022 treatment and had significantly higher stomatal closure rates (aperture width = 2.34 μm) by day 1 compared to controls (8.5 μm). S. Typhimurium SPI1 and SPI2 mutants showed inability to reopen stomates in lettuce suggesting the involvement of key T3SS components in suppression of innate response in plants. These findings impact issues of contamination related to plant performance and innate defense responses for plants.
Research -New study shows link between animal operation and orchard contamination
One in every five air samples in almond orchards adjacent to a poultry operation tested positive for E. coli during a two-year study published recently.
“Microorganisms Move a Short Distance into an Almond Orchard from an Adjacent Upwind Poultry Operation” comes as romaine growers continue to study the impact of a 100,000-head cattle feed lot adjacent to Arizona growing fields.
Lettuce growers from regions in California are also looking at implications of having animal operations in the areas near food crops. The Food and Drug Administration recently posted a conclusion that animal operations were the likely cause behind romaine E. coli outbreaks in 2018-19.
The almond research, published in the peer-reviewed journal Applied and Environmental Microbiology,
Research -Evaluation of Public Health Risk for Escherichia coli O157:H7 in Cilantro
This study sought to model the growth and die-off of Escherichia coli (E. coli) O157:H7 along the cilantro supply chain from farm-to-fork to investigate its risk to public health. Contributing factors included in the model were on farm contamination from irrigation water and soil, solar radiation, harvesting, and transportation and storage times and temperatures. The developed risk model estimated the microbiological risks associated with E. coli O157:H7 in cilantro and determined parameters with the most effect on the final concentration per serving for future mitigation strategies. Results showed a similar decrease in the E. coli O157:H7 (median values) concentrations along the supply chain for cilantro grown in both winter and summer weather conditions. With an estimated 0.1% prevalence of E. coli O157:H7 contamination for cilantro post-harvest used for illustration, the model predicted the probability of illness from consuming fresh cilantro as very low with fewer than two illnesses per every one billion servings of cilantro (1.6 x 10-9; 95th percentile). Although rare, 3.7% and 1.6% of scenarios run in this model for summer and winter grown cilantro, respectively, result in over 10 cases per year in the United States. This is reflected in real life where illnesses from cilantro are seen rarely but outbreaks have occurred. Sensitivity analysis and scenario testing demonstrated that ensuring clean and high quality irrigation water and preventing temperature abuse during transportation from farm to retail, are key to reducing overall risk of illness.
Posted in Contaminated water, E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, STEC, STEC E.coli, Uncategorized, Water, water microbiology, Water Safety
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