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10 June 2020 | Story Leonie Bolleurs | Photo Supplied
Dr Ehlers was appointed to serve on the National Forensic Oversight and Ethics Board of 10 members for a second term, based on her knowledge in the field of forensic sciences.

Dr Karen Ehlers from the Department of Genetics at the University of the Free State (UFS) was elected as a member of the National Forensic Oversight and Ethics Board (NFOEB) for a second term.

Dr Ehlers has been appointed to the board of 10 members based on her knowledge in the field of forensic sciences. She is currently conducting research focusing on the forensic application of Y-STR markers, the statistical analysis of DNA profiles, and touch DNA.

Making valuable contributions
Her expertise in the field of forensic genetics assists the board – which also handles complaints about alleged violations relating to the abuse of DNA samples and forensic DNA profiles – to oversee the operations of the Forensic Science Laboratory and the National Forensic DNA Database (NFDD). 

“The knowledge I gained from my current research at the UFS has enabled me to make valuable contributions to the board and its recommendations to the Minister of Police,” says Dr Ehlers. 

In her first term as member of the Board – following regular tracking and analysis of reports, the Board noted an increase in the number of outstanding forensic investigative leads – (hits on the National Forensic DNA Database) that were not followed up.

“After we made enquiries, it was determined that the provincial task teams that were to follow up on the leads, were ad hoc structures that lacked the necessary resources. The Board addressed this shortfall by engaging with various stakeholders and helping to establish permanent structures, called Forensic Investigative Units, with dedicated resources – both human and material – to effectively follow up on all forensic DNA investigative leads. The finalised Regulations were published for comment in the Government Gazette on 27 March 2020,” says Dr Ehlers.

Lowering SA crime rate
While serving on this board, she is ensuring that South Africa has a functioning DNA database that contributes to lowering the crime rate in the country. “As a member of the board, I hope to add value to its functioning. I feel that in the future, science will play an even bigger role in crime prevention, detection, and the solving of crimes,” she states.

Dr Ehlers is Programme Director of the Forensic Sciences Programme in the Department of Genetics. She teaches the Crime Scene Management module to second-year students and supervises seven honours, five MSc, and three PhD students. 

Besides her appointment as member of the NFOEB, she values the work she is doing with her students. “The highlight of my career was when my first group of BScHons students in Forensic Genetics graduated and were shortly thereafter appointed by the Forensic Sciences Laboratory as DNA analysts,” she says. 

News Archive

Research eradicates bacteria from avocado facility
2017-01-17

 Description: Listeria monocytogenes Tags: Listeria monocytogenes

Listeria monocytogenes as seen under an electron
microscope. The photo was taken with a transmission
electron microscope at the microscopy unit of the UFS.
Bacteriophages (lollipop-like structures) can be seen
next to the bacterial cells.
Photo: Supplied

“The aim of my project was to identify and characterise the contamination problem in an avocado-processing facility and then to find a solution,” said Dr Amy Strydom, postdoctoral fellow in the Department of Microbial Biochemical and Food Biotechnology at the University of the Free State (UFS).

Her PhD, “Control of Listeria monocytogenes in an Avocado-processing Facility”, aimed to identify and characterise the contamination problem in a facility where avocados were processed into guacamole. Dr Strydom completed her MSc in food science in 2009 at Stellenbosch University and this was the catalyst for her starting her PhD in microbiology in 2012 at the UFS. The research was conducted over a period of four years and she graduated in 2016. The research project was funded by the National Research Foundation.

The opportunity to work closely with the food industry further motivated Dr Strydom to conduct her research. The research has made a significant contribution to a food producer (avocado facility) that will sell products that are not contaminated with any pathogens. The public will then buy food that is safe for human consumption.


What is Listeria monocytogenes?

Listeria monocytogenes is a food-borne pathogenic bacterium. When a food product is contaminated with L. monocytogenes, it will not be altered in ways that are obvious to the consumer, such as taste and smell. When ingested, however, it can cause a wide range of illnesses in people with impaired immune systems. “Risk groups include newborn babies, the elderly, and people suffering from diseases that weaken their immune systems,” Dr Strydom said. The processing adjustments based on her findings resulted in decreased numbers of Listeria in the facility.

The bacteria can also survive and grow at refrigeration temperatures, making them dangerous food pathogens, organisms which can cause illnesses [in humans]. Dr Strydom worked closely with the facility and developed an in-house monitoring system by means of which the facility could test their products and the processing environment. She also evaluated bacteriophages as a biological control agent in the processing facility. Bacteriophages are viruses that can only infect specific strains of bacteria. Despite bacteriophage products specifically intended for the use of controlling L. monocytogenes being commercially available in the food industry, Dr Strydom found that only 26% of the L. monocytogenes population in the facility was destroyed by the ListexP100TM product. “I concluded that the genetic diversity of the bacteria in the facility was too high and that the bacteriophages could not be used as a control measure. However, there is much we do not understand about bacteriophages, and with a few adjustments, we might be able to use them in the food industry.”

Microbiological and molecular characterisation of L. monocytogenes

The bacteria were isolated and purified using basic microbiological culturing. Characterisation was done based on specific genes present in the bacterial genome. “I amplified these genes with polymerase chain reaction (PCR), using various primers targeting these specific genes,” Dr Strydom said. Some amplification results were analysed with a subsequent restriction digestion where the genes were cut in specific areas with enzymes to create fragments. The lengths of these fragments can be used to differentiate between strains. “I also compared the whole genomes of some of the bacterial strains.” The bacteriophages were then isolated from waste water samples at the facility using the isolated bacterial strains. “However, I was not able to isolate a bacteriophage that could infect the bacteria in the facility.

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