Tag Archives: applied and environmental microbiology

Research – Interstrain Interactions between Bacteria Isolated from Vacuum-Packaged Refrigerated Beef

Posted on March 29, 2015 by | Leave a comment

Applied and Environmental Microbiology

The formation of bacterial spoilage communities in food is influenced by both extrinsic and intrinsic environmental factors. Although many reports describe how these factors affect bacterial growth, much less is known about interactions among bacteria, which may influence community structure. This study investigated interactions among representative species of bacteria isolated from vacuum-packaged (VP) beef. Thirty-nine effectors and 20 target isolates were selected, representing 10 bacterial genera: Carnobacterium, Pseudomonas, Hafnia, Serratia, Yersinia, Rahnella, Brochothrix, Bacillus, Leuconostoc, and Staphylococcus. The influence of live effectors on growth of target isolates was measured by spot-lawn agar assay and also in liquid culture medium broth using live targets and effector cell-free supernatants. Inhibition on agar was quantified by diameter of inhibition zone and in broth by measuring detection time, growth rate, and maximum population density. A number of interactions were observed, with 28.6% of isolates inhibiting and 4.2% promoting growth. The majority of Pseudomonas isolates antagonized growth of approximately one-half of target isolates. Two Bacillus spp. each inhibited 16 targets. Among lactic acid bacteria (LAB), Carnobacterium maltaromaticum inhibited a wider range of isolates compared to other LAB. The majority of effector isolates enhancing target isolate growth were Gram-negative, including Pseudomonas spp. and Enterobacteriaceae. These findings markedly improve the understanding of potential interactions among spoilage bacteria, possibly leading to more mechanistic descriptions of bacterial community formation in VP beef and other foods.

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Research – Evidence of the Internalization of Animal Caliciviruses via the Roots of Growing Strawberry Plants and Dissemination to the Fruit

Posted on March 29, 2015 by | Leave a comment

Applied and Environmental Microbiology

Human norovirus (NoV) is the leading cause of foodborne disease in the United States, and epidemiological studies have shown that fresh produce is one of the major vehicles for the transmission of human NoV. However, the mechanisms of norovirus contamination and persistence in fresh produce are poorly understood. The objective of this study is to determine whether human NoV surrogates, murine norovirus (MNV-1) and Tulane virus (TV), can attach and become internalized and disseminated in strawberries grown in soil. The soil of growing strawberry plants was inoculated with MNV-1 and TV at a level of 108 PFU/plant. Leaves and berries were harvested over a 14-day period, and the viral titer was determined by plaque assay. Over the course of the study, 31.6% of the strawberries contained internalized MNV-1, with an average titer of 0.81 ± 0.33 log10 PFU/g. In comparison, 37.5% of strawberries were positive for infectious TV, with an average titer of 1.83 ± 0.22 log10 PFU/g. A higher percentage (78.7%) of strawberries were positive for TV RNA, with an average titer of 3.15 ± 0.51 log10 RNA copies/g as determined by real-time reverse transcriptase quantitative PCR (RT-qPCR). In contrast, no or little virus internalization and dissemination were detected when TV was inoculated into bell peppers grown in soil. Collectively, these data demonstrate (i) virally contaminated soils can lead to the internalization of virus via plant roots and subsequent dissemination to the leaf and fruit portions of growing strawberry plants and (ii) the magnitude of internalization is dependent on the type of virus and plant.

 

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Research – Investigators Link Poultry Contamination on Farm and at Processing Plant

Posted on June 3, 2013 by | Leave a comment

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Researchers at the University of Georgia, Athens, have identified a strong link between the prevalence and load of certain food-borne pathogens on poultry farms, and later downstream at the processing plant. They report their findings in a manuscript published ahead of print in the journal Applied and Environmental Microbiology.

“This study suggests that reducing foodborne pathogen loads on broiler chicken farms would help to reduce pathogen loads at processing, and may ultimately help to reduce the risk of foodborne illness,” says Roy Berghaus, an author on the study. “This is important because most of our efforts towards reducing foodborne pathogens are currently focused on what happens during processing. Processing interventions are effective but they can only do so much.”

 

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Posted in Campylobacter, Food Micro Blog, Food Microbiology, Food Safety, Food Technology, Food Testing, Pathogen, Research, Salmonella

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Research – Norovirus Killed by Electron Beam

Posted on May 13, 2013 by | Leave a comment

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Researchers at Texas A&M University have developed a way to pasteurize oysters without chemicals or heat using an electron beam. A study measuring the method’s efficacy on norovirus and hepatitis A appears in the June issue of the scientific journal Applied and Environmental Microbiology.

Although the CDC recommends that all shellfish be cooked to an internal temperature of 140˚, many people enjoy raw eating oysters raw. Pasteurization is one way to address the health risk of raw foods. And it’s one of the electron beam or E beam applications being explored at the National Center for Electron Beam Research at Texas A&M University.

The U.S. Food and Drug Administration (FDA) has already approved E beam technology as a way to control Vibrio vulnificus, a naturally occurring bacteria in shellfish that can cause life- threatening illness or death. In this study, researchers measured E beam’s efficacy on different levels of viral concentration. They found that at high levels of contamination the E beam was able to reduce norovirus levels by 12 percent and hepatitis A levels by 16 percent and at more moderate levels of contamination the method was able to reduce norovirus by 26 percent and hepatitis A by 90 percent

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Posted in Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Technology, Food Testing, Food Virus, Hepatitis A, Hepatitis E, Illness, Methods, Microbiology, Norovirus, Pathogen, Research

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