Category Archives: Research

Research – Mode of action of nisin on Escherichia coli

Posted on February 1, 2020 by | Leave a comment

nrc research 

Nisin is a class I polycyclic bacteriocin produced by the bacterium Lactococcus lactis, which is used extensively as a food additive to inhibit the growth of foodborne Gram-positive bacteria. Nisin also inhibits growth of Gram-negative bacteria when combined with membrane-disrupting chelators such as citric acid. To gain insight into nisin’s mode of action, we analyzed chemical–genetic interactions and identified nisin-sensitive Escherichia coli strains in the Keio library of knockout mutants. The most sensitive mutants fell into two main groups. The first group accords with the previously proposed mode of action based on studies with Gram-positive bacteria, whereby nisin interacts with factors involved in cell wall, membrane, envelope biogenesis. We identified an additional, novel mode of action for nisin based on the second group of sensitive mutants that involves cell cycle and DNA replication, recombination, and repair. Further analyses supported these two distinct modes of action.

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Posted in E.coli, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, lactic acid bacteria, microbial contamination, Microbiology, Research, Uncategorized

Research – Indoor Particulate Matter From Smoker Homes Induces Bacterial Growth, Biofilm Formation, and Impairs Airway Antimicrobial Activity. A Pilot Study

Posted on February 1, 2020 by | Leave a comment

Frontiers

Background: Particulate matter (PM) air pollution causes deleterious health effects; however, less is known about health effects of indoor air particulate matter (IAP).

Objective: To understand whether IAP influences distinct mechanisms in the development of respiratory tract infections, including bacterial growth, biofilm formation, and innate immunity. Additionally, we tested whether IAP from Iowa houses of subjects with and without recent respiratory exacerbations recapitulated the National Institute of Standards and Technology (NIST) IAP findings.

Methods: To test the effect of NIST and Iowa IAP on bacterial growth and biofilm formation, we assessed Staphylococcus aureus growth and Pseudomonas aeruginosa biofilm formation with and without the presence of IAP. To assess the effect of IAP on innate immunity, we exposed primary human airway surface liquid (ASL) to NIST, and Iowa IAP. Lastly, we tested whether specific metals may be responsible for effects on airway innate immunity.

Results: NIST and Iowa IAP significantly enhanced bacterial growth and biofilm formation. NIST IAP (whole particle and the soluble portion) impaired ASL antimicrobial activity. IAP from one Iowa home significantly impaired ASL antimicrobial activity (p < 0.05), and five other homes demonstrated a trend (p ≤ 0.18) of impaired ASL antimicrobial activity. IAP from homes of subjects with a recent history of respiratory exacerbation tended (p = 0.09) to impair ASL antimicrobial activity more than IAP from homes of those without a history respiratory exacerbation. Aluminum and Magnesium impaired ASL antimicrobial activity, while copper was bactericidal. Combining metals varied their effect on ASL antimicrobial activity.

Conclusions: NIST IAP and Iowa IAP enhanced bacterial growth and biofilm formation. ASL antimicrobial activity was impaired by NIST IAP, and Iowa house IAP from subjects with recent respiratory exacerbation tended to impair ASL antimicrobial activity. Individual metals may explain impaired ASL antimicrobial activity; however, antimicrobial activity in the presence of multiple metals warrants further study.

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Posted in Biofilm, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Pseudomonas, Pseudomonas aeruginosa, Research, Staphylococcus aureus, Uncategorized

Europe -Listeriosis – Annual Epidemiological Report for 2017

Posted on January 31, 2020 by | Leave a comment

ECDC

Listeriosis – Annual Epidemiological Report for 2017

Surveillance report

Publication series: Annual Epidemiological Report on Communicable Diseases in Europe
Time period covered: This report is based on data for 2017 retrieved from The European Surveillance System (TESSy) on 11 September 2018.

For 2017, 30 countries reported 2 502 confirmed listeriosis cases in the EU/EEA. The EU/EEA age-standardised notification rate was 0.42 cases per 100 000 population. The highest rate was detected among people over 64 years of age (1.7 cases per 100 000 population). The annual number of listeriosis cases in the EU/EEA shows an increasing trend.

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Listeriosis – Annual Epidemiological Report for 2017 – EN – [PDF-1 MB]

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Posted in ECDC, food contamination, food death, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning Death, food recall, Food Safety, Food Safety Alert, Listeria, Listeria monocytogenes, listeriosis, Research, Uncategorized

Europe – Yersiniosis – Annual Epidemiological Report for 2017

Posted on January 31, 2020 by | Leave a comment

ECDC

kswfoodworld.com

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For 2017, 28 countries reported 6 890 confirmed yersiniosis cases in the EU/EEA. The overall notification rate was 1.8 per 100 000 population and remained stable from 2013–2017. The highest rate was detected in 0–4 year-old children (7.7 per 100 000 population). The highest rates were reported by Finland, Lithuania and the Czech Republic.

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Yersiniosis – Annual Epidemiological Report for 2017 – EN – [PDF-800.59 KB]

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Posted in ECDC, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, food recall, Food Safety, Food Safety Alert, Food Testing, Research, Uncategorized, Yersinia, yersinia enterocolitica

Europe -Salmonellosis – Annual Epidemiological Report for 2017

Posted on January 31, 2020 by | Leave a comment

ECDC

Salmonellosis is the second most commonly reported gastrointestinal infection and an important cause of foodborne outbreaks in the EU/EEA. In 2017, 92 649 laboratory-confirmed cases were reported of which 156 were fatal. The EU/EEA notification rate was 19.6 cases per 100 000 population. Salmonellosis notification rates have stabilised in the last five years after a long period marked by a declining trend. The notification rate was highest in young children 0−4 years with 94.1 cases per 100 000 population, eight times higher than in adults 25–64 years.

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Salmonellosis – Annual Epidemiological Report for 2017 – EN – [PDF-642.8 KB]

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Posted in food contamination, food death, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, microbial contamination, Microbiology, Research, Salmonella, Uncategorized

Research -Impacts of broadband and selected infrared wavelength treatments on inactivation of microbes on rough rice.

Posted on January 30, 2020 by | Leave a comment

Wiley Online

This study investigated the effects of broadband and selected infrared (IR) wavelength treatments of rough rice on microbial inactivation. Rough rice was treated at different IR wavelengths and product‐to‐emitter distances (110, 275, and 440 mm) followed by tempering at 60°C for 4 hr. The total mold and aerobic plate counts (APC) on non‐treated and treated samples were determined. Significant total mold reductions of 1.14 and 3.11 log CFU/g were obtained after IR heating using broadband and selected wavelengths, respectively (p < .05). The most significant reduction of APC using selected IR wavelength was 1.09 log CFU/g; the broadband IR wavelength had no effect on the mean APC. The IR treatments followed by tempering step resulted in greater reductions of total mold counts and APC (4.03 and 3.50 log CFU/g) in comparison to IR treatments without tempering (3.11 and 1.09 log CFU/g). Overall, bacteria showed more resistance to IR treatments than molds.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, mold, Mould Toxin, Research, Technology, Uncategorized

Research – A Study on Prevalence and Characterization of Bacillus cereus in Ready-to-Eat Foods in China

Posted on January 28, 2020 by | Leave a comment

Frontiers in Microbiology

Bacillus cereus is widely distributed in different food products and can cause a variety of symptoms associated with food poisoning. Since ready-to-eat (RTE) foods are not commonly sterilized by heat treatment before consumption, B. cereus contamination may cause severe food safety problems. In this study, we investigated the prevalence of B. cereus in RTE food samples from different regions of China and evaluated the levels of bacterial contamination, antibiotic resistance, virulence gene distribution, and genetic polymorphisms of these isolates. Of the tested retail RTE foods, 35% were positive for B. cereus, with 39 and 83% of the isolated strains harboring the enterotoxin-encoding hblACD and nheABC gene clusters, respectively. The entFM gene was detected in all B. cereus strains. The cytK gene was present in 68% of isolates, but only 7% harbored the emetic toxin-encoding gene cesB. Antimicrobial susceptibility testing revealed that the majority of the isolates were resistant not only to most β-lactam antibiotics, but also to rifamycin. Multilocus sequence typing (MLST) revealed that the 368 isolates belonged to 192 different sequence types (STs) including 93 new STs, the most prevalent of which was ST26. Collectively, our study indicates the prevalence, bacterial contamination levels, and biological characteristics of B. cereus isolated from RTE foods in China and demonstrates the potential hazards of B. cereus in RTE foods.

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Posted in Bacillus, Bacillus cereus, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiology, Research, Uncategorized

Research -Evaluation of JC9450 and Neutral Electrolyzed Water in Controlling Listeria monocytogenes on Fresh Apples and Preventing Cross-Contamination

Posted on January 26, 2020 by | Leave a comment

Frontiers in Microbiology

Recent multistate outbreaks and recalls of fresh apples due to Listeria monocytogenes contamination have increased consumer concerns regarding fresh and processed apple safety. This study aimed to evaluate the antimicrobial efficacy of two sanitizers, mineral oxychloride (JC9450) and neutral electrolyzed water (NEW), for inactivation of L. monocytogenes on fresh apples. A 2-min treatment of 0.125% (v/v) JC9450 with 100 ppm free available chlorine (FAC) or NEW with 110 ppm FAC caused 0.9–1.2 log10 CFU/apple reduction of L. monocytogenes on both Granny Smith and Fuji apples 24 h post-inoculation. Increasing JC9450 concentration to 0.25 and 0.50% significantly improved its bactericidal effect and reduced L. monocytogenes on Granny Smith apples by ~2.0 and 3.8 log10 CFU/apple, respectively, after a contact time of 2 min. At a shorter contact time of 30 sec, the inactivation efficacy of chlorine and 0.25–0.50% JC9450 against L. monocytogenes on apples was significantly reduced compared with the respective 2-min wash. Furthermore, no L. monocytogenes was recovered in deionized water prepared antimicrobial wash solution or on non-inoculated apples post-NEW with 110 ppm FAC or 0.125–0.5% JC9450 washes, indicating their ability to prevent cross-contamination. In addition, a 2-min exposure to NEW with 110 ppm FAC and 0.50% JC9450 reduced apple native microbiota including total plate count by 0.14 and 0.65 log10 CFU/apple, respectively, and yeast and mold counts by 0.55 and 1.63 log10 CFU/apple, respectively. In summary, L. monocytogenes attached on apples was difficult to eliminate. JC9450 and NEW demonstrated a dose-dependent reduction in L. monocytogenes on apples and successfully prevented cross-contamination, indicating their application potential in post-harvest washes of apples.

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Posted in Food Micro Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Research, Technology, Uncategorized

Research -Extension of shelf life of pasteurized trim milk using ultraviolet treatment

Posted on January 25, 2020 by | Leave a comment

Wiley Online

The demand for minimally processed foods has increased in the last few years and gains high acceptability among consumers as it has better nutritional value than highly processed foods. Pasteurized milk is minimally processed and consumed largely for its fresh taste and higher nutritional value compared to ultrahigh temperature (UHT) and powdered milk. However, one of the constraints is its limited shelf life under refrigeration, as it cannot retain quality and safety for more than 14 days. Nonthermal technologies can extend the shelf life of milk while using low energy. Ultraviolet (UV‐C) is well known to inactivate spores as well as vegetative cells. In this study, it was shown that 2.64 J/ml of UV‐C treatment applied on pasteurized trim milk can extend shelf life up to 53 days under refrigeration. This finding was also supported by the inactivation of 3.40 ± 0.14 log of thermoresistant Geobacillus stearothermophilus spores (ATCC 7953) in UHT (or sterilized) trim milk with similar UV‐C operating conditions. Therefore, microbial study together with physicochemical properties demonstrated that pasteurization followed by UV‐C can enhance the shelf life of trim milk considerably.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Geobacillus stearothermophilus, microbial contamination, Microbiology, Research, Technology, Uncategorized, UV Microbiology

Research -Climate change could unlock new microbes and increase heat-related deaths

Posted on January 23, 2020 by | Leave a comment

Science Daily

The Journal of Clinical Investigation (JCI) recently published “Viewpoint” articles by Johns Hopkins University School of Medicine professors who warn that global climate change is likely to unlock dangerous new microbes, as well as threaten humans’ ability to regulate body temperature.

Johns Hopkins Bloomberg Distinguished Professors Rexford Ahima, M.D., Ph.D., and Arturo Casadevall, M.D., Ph.D., M.S., along with William Dietz, M.D., Ph.D., director of the George Washington University’s Sumner M. Redstone Global Center for Prevention and Wellness, and Susan Pacheco, M.D., associate professor in the Department of Pediatrics at the University of Texas Health Science Center at Houston, authored journal articles relevant to their fields that detail how rising temperatures around the world pose dangerous threats to humanity.

Ahima, director of Johns Hopkins’ Division of Endocrinology, Diabetes and Metabolism, wrote in the journal that “global warming threatens human thermoregulation and survival.”

 

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Posted in Food Hygiene, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Safety, Food Temperature Abuse, Food Testing, Research, Uncategorized