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02 July 2019 | Story Leonie Bolleurs
Edwin Skhosana
Edwin Skhosana is working hard to become a successful and competent actuary one day. With him is his lecturer, Dr Michael von Maltitz.

Edwin Skhosana, an Actuarial Sciences student, was described by his lecturer, Dr Michael von Maltitz of the Department of Mathematical Statistics and Actuarial Science, as ‘very quiet’ in his Causal Inference class. 

This may sound like a compliment, but it’s not.

For Dr Von Maltitz, being quiet is definitely not encouraged – not with the new teaching methods applied in class.

“See, my class is all about engagement – getting the students to watch videos on the topics, read about the methods in question, and then come to class to grill me about things they don’t understand. This change in teaching method is extremely disconcerting for many Mathematical students, who have up until now only been taught in the ‘memorise-regurgitate’ form they had ever since the start of high school,” he explains.

Future success


“My goal is to get the students to a level of understanding where they can sit down with me or with an expert in the field and have a conversation about the Mathematical Statistics topics that I teach. This is a very difficult task in such a technical module, and few students ever feel comfortable enough to engage with me actively in class in this way,” Dr Von Maltitz points out. 

Edwin is working hard towards applying the skills and knowledge he has obtained at university to become a successful and competent actuary one day. 

An important turning point was when it dawned on him how the things discussed in class could find an important practical application in so many fields.  

“This suddenly drove a spontaneous fascination in my mind that led me to engage with Dr Von Maltitz,” the previously quiet Edwin explains.

And everything changed.

Desperate to learn

Dr Von Maltitz explains: “Edwin came to my office to ask some questions. The incredible thing was that he sat down, and a conversation about the Mathematics, the foundations, and the methods just flowed between us. I have seldom had such an insightful chat about my module with a student. It was like a cascade of information just fell into place for Edwin.”

Although he sometimes still experiences his studies as challenging and grapples to adapt to the various styles of lecturing from different lecturers, Edwin now has hope for his class in Causal Inference. 

“I think Dr Von Maltitz’s way of presenting in class is excellent. It is, however, hard to grasp if you are still anchored in the old way of cramming, because he wants you to understand and be able to apply what he teaches,” says Edwin.

“It was just wonderfully refreshing to see someone so desperate to learn something (rather than just wanting to get a degree), and then actually managing to turn around a bad semester mark into such a river of understanding,” Dr Von Maltitz concludes.

Dr Michael von Maltitz
Dr Micheal von Maltitz

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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