The technique, which has potential biosecurity and food safety applications, also can estimate the amount of microbes present and whether they pose an active health risk. This could help neutralize potential threats and improve food processing techniques, said Arun Bhunia, a professor of food science at Purdue University.
"For food safety and biosecurity purposes, you need a quick test - a first line of defense - to be able to tell if there is something pathogenic in the food or water," Bhunia said.
The technology utilizes live mammalian cells that release a measurable amount of a signaling chemical when harmed. Optical equipment and computer software can then analyze this quantity to estimate the amount of harmful microbes present, Bhunia said.
"This is very important," he said. "With many toxins or pathogens, there is an effective dose or threshold you must pass before you have to worry. By providing information on quantity, this technology gives you a higher degree of confidence in the test and what steps must be taken to alleviate the problem."
The technology can recognize very small amounts of Listeria monocytogenes, a bacterium that kills one in five infected and is the leading cause of food-borne illness. It also recognizes several species of Bacillus, a non-fatal but common cause of food-poisoning, said Pratik Banerjee, a Purdue researcher and first author of a study detailing the technology that is published in the February issue of the journal Laboratory Investigation.
The cells are suspended in collagen gel, a useful substance for capturing particles of a desired size, and put into small wells within multi-well plates. Each well can test one sample, so tests can be expanded to quickly analyze as many samples as desired.
By using live cells, called biosensors, this technology can identify actively harmful pathogens but ignore those that are inactive, or harmless. Some analogous tests lack this capability, making them prone to false alarms and entailing a relatively lengthy incubation period to grow out any living microbes, Banerjee said. The new technology's discerning power also could help optimize processes to kill harmful microbes or deactivate toxins, he said.
Another advantage to the technique is its mobility and versatility, Bhunia said. The multi-well plates and their contents of gel-suspended mammalian cells could be efficiently prepared in a central location. When desired, the plates could then be shipped to the test location, like a food processing plant, so that analysis could take place on-site, he said.
This technology tests for bacteria and toxins that attack cell membranes. For this reason, researchers employed cells with high amounts of alkaline phosphatase, the signaling chemical released upon damage to the cell membrane. Researchers could conceivably employ other types of cells within this framework to detect additional types of pathogens, Bhunia said.
Samples of food and water are added to biosensor wells before being incubated for one to two hours. To each well a chemical is added that reacts with the biosensor's alkaline phosphatase, yielding a yellow product quantified by a special camera and a computer. A precise calculation may be unnecessary sometimes, however.
"When a large amount of pathogen is present, you can literally see the color change taking place before your eyes," Banerjee said.
The suspension of live mammalian cells within a collagen gel is unique, according to the researchers.
"This is the first time that anybody has trapped these kinds of cells alive in a collagen framework," Bhunia said.
Researchers are trying to get these cells to live within the gel beyond four to six days, a current limitation. But Bhunia said this time-span could be expanded to two weeks, the shelf-life he deems necessary for the technique to have commercial value.
The study was funded by the U.S. Department of Agriculture and Purdue's Center for Food Safety Engineering.
"This paper outlines two key accomplishments: one, we found a way to immobilize cells, which is a necessary and difficult prerequisite for further study. Two, we are able to simultaneously perform multiple tests on a large number of samples," Bhunia said.Writer: Douglas M. Main, (765) 496-2050, firstname.lastname@example.org
Douglas M. Main | EurekAlert!
Highly sensitive sensors to measure the heart and brain activity
20.09.2019 | Christian-Albrechts-Universität zu Kiel
Motion pictures from living cells: Research team from Jena and Bielefeld improves superresolution microscopy
20.09.2019 | Leibniz-Institut für Photonische Technologien e. V.
For applications such as light-emitting diodes or solar cells, organic materials are nowadays in the focus of research. These organic molecules could be a promising alternative to currently used semiconductors such as silicon or germanium and are used in OLED displays. A major problem is that in many organic semiconductors the flow of electricity is hampered by microscopic defects. Scientists around Dr. Gert-Jan Wetzelaer and Dr. Denis Andrienko of the Max-Planck-Institute for Polymer Research have now investigated how organic semiconductors can be designed such that the electric conduction is not influenced by these defects.
The basic principle of the first light bulb, invented by Thomas Edison in the 19th century, was quite simple: Electrons – negatively charged particles – flow...
How long the battery of your phone or computer lasts depends on how many lithium ions can be stored in the battery's negative electrode material. If the battery runs out of these ions, it can't generate an electrical current to run a device and ultimately fails.
Materials with a higher lithium ion storage capacity are either too heavy or the wrong shape to replace graphite, the electrode material currently used in...
To process information, photons must interact. However, these tiny packets of light want nothing to do with each other, each passing by without altering the...
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.
The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.
At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.
Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...
19.09.2019 | Event News
10.09.2019 | Event News
04.09.2019 | Event News
24.09.2019 | Life Sciences
24.09.2019 | Life Sciences
24.09.2019 | Materials Sciences