Category Archives: Microbiology

Research – Antimicrobial Activity and Action Approach of the Olive Oil Polyphenol Extract Against Listeria monocytogenes

Posted on August 11, 2019 by | Leave a comment

Frontiers in Microbiology

Olive oil polyphenol extract (OOPE) has been reported to have antibacterial activity; however, its effect on Listeria monocytogenes is less studied so far. This study, thus, aimed to reveal its antimicrobial activity and action approach against L. monocytogenes via evaluating the minimum inhibitory concentration (MIC) as well as the changes of intracellular adenosine 5′-triphosphate (ATP) concentration, cell membrane potential, bacterial protein, DNA, and cell morphology. The results showed that OOPE could inhibit the growth of L. monocytogeneswith a measured MIC of 1.25 mg/ml. L. monocytogenes cells treated by OOPE showed significant reduction in intracellular ATP concentrations, bacterial protein, or DNA (p < 0.05), in comparison with those without any treatment. In addition, OOPE was observed to depolarize strain cells and alter cell morphology, resulting in damaged cell membrane and, thereby, leakage of cell fluid. These findings demonstrated that OOPE had inhibition on L. monocytogenes via its action on cells, suggesting its potential as a natural preservative.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Pathogen, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, pathogenic, Technology, Uncategorized

Research – Bacteria-killing gel heals itself while healing you

Posted on August 10, 2019 by | Leave a comment

Science Daily

McMaster researchers have developed a novel new gel made entirely from bacteria-killing viruses.

The anti-bacterial gel, which can be targeted to attack specific forms of bacteria, holds promise for numerous beneficial applications in medicine and environmental protection.

Among many possibilities, it could be used as an antibacterial coating for implants and artificial joints, as a sterile growth scaffold for human tissue, or in environmental cleanup operations, says chemical engineer Zeinab Hosseini-Doust.

Her lab, which specializes in developing engineering solutions for infectious disease, grew, extracted and packed together so many of the viruses — called bacteriophages, or simply phages — that they assembled themselves spontaneously into liquid crystals and, with the help of a chemical binder, formed into a gelatin-like substance that can heal itself when cut.

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Posted in bacterial contamination, Bacterial Infections, Bacteriophage, Food Micro Blog, Food Microbiology Blog, Microbiology, Research, Uncategorized, Virus

Research – How hygienic is the cutting Board – and it can make you sick?

Posted on August 9, 2019 by | Leave a comment

Oracle Record

Cutting boards to withstand quite a lot: they are not intended to withstand sharp knives, in the ideal case of discolour, no undesirable smell and germ-free as possible remain. The least well know, that cutting boards are the ideal breeding do can be place for sick germs. The a swear, therefore, on plastic boards, the other on wood. How to get germs in or on the Board? This can have various reasons.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, microbial contamination, Microbiology, Uncategorized

Research -Slow growth determines nonheritable antibiotic resistance in Salmonella enterica

Posted on August 8, 2019 by | Leave a comment

Science Mag

kswfoodworld Salmonella

Image CDC

Slow growth for bacterial persistence

Even bacteria that do not carry mutations or genes that confer resistance to specific antibiotics can survive antibiotic treatment, a phenomenon known as persistence (see the Focus by Kaldalu and Tenson). Several models have been proposed to account for bacterial persistence, including the activation of toxins in toxin-antitoxin modules, the production of the alarmone guanosine (penta) tetraphosphate [(p)ppGpp], and a reduction in intracellular adenosine triphosphate (ATP) abundance. Pontes and Groisman demonstrated that Salmonella exhibited persistence even in the absence of toxin-antitoxin modules or (p)ppGpp production and under conditions that increased intracellular ATP. These and additional findings show that slow growth alone is sufficient for persistence and may contribute to the difficulty in treating some bacterial infections.

Abstract

Bacteria can withstand killing by bactericidal antibiotics through phenotypic changes mediated by their preexisting genetic repertoire. These changes can be exhibited transiently by a large fraction of the bacterial population, giving rise to tolerance, or displayed by a small subpopulation, giving rise to persistence. Apart from undermining the use of antibiotics, tolerant and persistent bacteria foster the emergence of antibiotic-resistant mutants. Persister formation has been attributed to alterations in the abundance of particular proteins, metabolites, and signaling molecules, including toxin-antitoxin modules, adenosine triphosphate, and guanosine (penta) tetraphosphate, respectively. Here, we report that persistent bacteria form as a result of slow growth alone, despite opposite changes in the abundance of such proteins, metabolites, and signaling molecules. Our findings argue that transitory disturbances to core activities, which are often linked to cell growth, promote a persister state regardless of the underlying physiological process responsible for the change in growth.

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Posted in Antibiotic Resistance, antimicrobial resistance, Antimicrobials, Food Micro Blog, Food Microbiology Blog, microbial contamination, Microbiology, Salmonella, Uncategorized

Research – Detection of Virulence Plasmid–Encoded Genes in Salmonella Typhimurium and Salmonella Kentucky Isolates Recovered from Commercially Processed Chicken Carcasses

Posted on August 7, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Salmonella enterica serovar Typhimurium is one of the leading causes of nontyphoidal gastroenteritis of humans in the United States. Commercially processed poultry carcasses are frequently contaminated with Salmonella serovar Kentucky in the United States. The aim of the study was to detect the Salmonella virulence plasmid containing the spv genes from Salmonellaisolates recovered from commercially processed chicken carcasses. A total of 144 Salmonella isolates (SalmonellaTyphimurium, n = 72 and Salmonella Kentucky, n = 72) were used for isolation of plasmids and detection of corresponding virulence genes (spvA, spvB, and spvC). Only four (5.5%) Salmonella Typhimurium isolates tested positive for all three virulence genes and hence were classified as possessing the virulence plasmid. All isolates of Salmonella Kentucky were negative for the virulence plasmid and genes. These results indicate that the virulence plasmid, which is very common among clinical isolates of Typhimurium and other Salmonella serovars (e.g., Enteritidis, Dublin, Choleraesuis, Gallinarum, Pullorum, and Abortusovis), may not be present in a significant portion of commercially processed chicken carcass isolates.

HIGHLIGHTS

  • Virulence plasmid was detected only in 5.5% of Salmonella Typhimurium isolates.

  • All virulence plasmid–positive Salmonella isolates were positive for spvA, spvB, and spvC genes.

  • No Salmonella Kentucky isolates were positive for the virulence plasmid and genes.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, microbial contamination, Microbiology, Salmonella, Uncategorized

Research – Preservation of ready-to-eat salad: A study with combination of sanitizers, ultrasound, and essential oil-containing β-cyclodextrin inclusion complex

Posted on August 6, 2019 by | Leave a comment

Science Direct

Highlights

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Peracetic acid is a good alternative to chlorine for fresh produce sanitization.

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Ultrasound enhanced peracetic acid efficiency.

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Sachet with essential oil did not contribute to salad preservation.

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Complexation with β-CD did not attenuate EO odor.

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EO in vitro antimicrobial activity does not imply preservative property in food.

Abstract

The microbiological quality of a ready-to-eat salad treated with different sanitizers (sodium dichloroisocyanurate (SD), peracetic acid (PA) or isolated or combined with ultrasound (US)), and packaged alongside sachets containing β-cyclodextrin/Pimenta dioica essential oil inclusion complex was evaluated. Consumer acceptability was also assessed. Furthermore, treatments were investigated against Listeria monocytogenes intentionally inoculated. SD, SD + US, and PA treatments showed similar efficiency against psychrotrophic (log reduction < 1) and lactic acid bacteria (log reductions of 1.18 ± 0.25, 1.28 ± 0.19 and 1.03 ± 0.22 for SD, SD + US, and PA, respectively). Concerning yeasts and molds, SD and SD + US reached the greatest log reduction (counts < 4 log CFU g−1), whereas PA + US was more efficient than PA. Against L. monocytogenes, SD, SD + US and PA + US led to the best results. The presence of sachet, however, did not contribute to salad preservation. Sensory evaluation showed that salads stored alongside sachets were the least accepted by consumers with scores between 5 and 6 for overall impression attribute, while samples without sachets received average scores >7. These findings are of great importance since they demonstrate the need for studies that evaluate the properties of EO when applied in a food system.

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Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Safety, Food Technology, Food Testing, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Technology, Uncategorized

Research – These gut bacteria prevent mice from becoming obese — what could that mean for us?

Posted on August 6, 2019 by | Leave a comment

Science Daily

Researchers at University of Utah Health have identified a specific class of bacteria from the gut that prevents mice from becoming obese, suggesting these same microbes may similarly control weight in people. The beneficial bacteria, called Clostridia, are part of the microbiome — collectively trillions of bacteria and other microorganisms that inhabit the intestine.

Published online in the journal Science on July 25, the study shows that healthy mice have plenty of Clostridia — a class of 20 to 30 bacteria — but those with an impaired immune system lose these microbes from their gut as they age. Even when fed a healthy diet, the mice inevitably become obese. Giving this class of microbes back to these animals allowed them to stay slim.

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Posted in Food Micro Blog, Food Microbiology Blog, Microbiology, Uncategorized

Research – Moving Away from Population-Based Case-Control Studies during Outbreak Investigations

Posted on August 5, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Population-based case-control studies are a time- and labor-intensive component of foodborne outbreak investigations. One alternative is a binomial trial that asks the question “if the likelihood of each case’s having eaten a given food is no different from that of the average person in the population, how often would we find, by chance alone, that x of n (or more) cases would have eaten this food?” Calculating a binomial trial requires background exposure data. We conducted case-control studies and binomial trials in two foodborne outbreaks and compared results. In both outbreaks, using binomial trials we found much less than a 5% probability that the number of cases eating the suspected food vehicle would have occurred by chance. These results were comparable with results of the case-control studies, but with considerably less effort. When background exposure data are available, binomial trials are an efficient way to explore hypotheses that can be further tested by traceback efforts to identify a common source.

HIGHLIGHTS

  • Population-based case-control studies are time- and labor-intensive.

  • Binomial trials of case exposures produce similar results with less effort.

  • Calculating a binomial trial requires background exposure data.

  • Binomial associations require product tracebacks to identify a common source.

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Posted in food bourne outbreak, Food Micro Blog, Food Microbiology, Food Microbiology Blog, foodborne outbreak, foodbourne outbreak, microbial contamination, Microbiology, outbreak, Uncategorized

Research – Keeping livestock in the yard just might help your baby’s immune system

Posted on August 4, 2019 by | Leave a comment

Science Daily

Getting up close — and a little dirty — with farm animals just might help us fend off illness, say researchers who’ve further demonstrated the benefits of early exposure to a wide variety of environmental bacteria.

Scientists from The Ohio State University found that bacteria and other microbes from rural Amish babies was far more diverse — in a beneficial way — than what was found in urban babies’ intestines. And, in a first-of-its-kind experiment, they found evidence of how a healthier gut microbiome might lead to more robust development of the respiratory immune system.

The study was published this month in the journal Frontiers in Immunology.

“Good hygiene is important, but from the perspective of our immune systems, a sanitized environment robs our immune systems of the opportunity to be educated by microbes. Too clean is not necessarily a good thing,” said the study’s co-lead author Zhongtang Yu, a professor of microbiology in Ohio State’s Department of Animal Sciences and a member of the university’s Food Innovation Center.

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Posted in Food Micro Blog, Food Microbiology Blog, microbial contamination, Microbiology, Uncategorized

Research – Prediction of Persistence of Listeria monocytogenes ST451 in a Rabbit Meat Processing Plant in the Czech Republic

Posted on August 3, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

This study was focused on characterization of the genetic diversity of Listeria monocytogenes isolated from packed fresh rabbit meat obtained from one producer via retail outlets. The partial aim was to compare the characteristics of a suspect persistent strain with strains from human cases. The occurrence of L. monocytogenes in vacuum-packed rabbit meat was monitored during 2013 to 2016. All strains were characterized by serotyping, pulsed-field gel electrophoresis, and multilocus sequence typing (MLST). Selected strains, which represented each year, were analyzed using the whole genome sequencing method. L. monocytogenes was detected in 21 (38%) of 56 originally packed rabbit meat samples from one food producer during the whole monitored period. All strains showed the identical serotype (1/2a), AscI/ApaI pulsotype (735/2), and sequence type (ST451). The clonal similarity of strains from rabbit meat was also confirmed on the basis of core genome MLST (on 1,701 loci). This fact suggests the occurrence of a suspect persistent strain in the meat processing plant. Results of core genome MLST enabled us to unambiguously exclude rabbit meat as a source of listeriosis in humans caused by the indistinguishable AscI/ApaI pulsotype and sequence type, although all strains carried all genes important for the virulence of L. monocytogenes. No specific genes that may be associated with its persistence in the food processing environment were detected among the tested strains of ST451.

HIGHLIGHTS

  • Rabbit meat is not often reported as a source of L. monocytogenes.

  • Rare ST451 was detected as a suspect persistent strain for the first time.

  • Genetic factors linked to persistence of L. monocytogenes ST451 were not found.

  • PMSC mutations in inlA, inlB, and LIPI-1 genes were not detected in tested strains.

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