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29 January 2024 | Story Igno van Niekerk | Photo Igno van Niekerk
Prof Jannie Pretorius
Prof Jannie Pretorius uses an engaging and humorous teaching style that keeps his Life Science and Natural Science students fascinated and engaged.

Once upon a time, there was a monotonous teacher: the students did not like his lectures. Nothing interesting ever happened. The teacher grew old and retired. The end. Or not? According to research, teaching can be a humorous, fun, and enjoyable experience if you do it differently.

Mr Bean videos and Trevor Noah in the class

Prof Jannie Pretorius, a lecturer in the School of Mathematics, Natural Sciences, and Technology, uses an engaging and humorous teaching style that keeps his Life Science and Natural Science students fascinated and engaged. When starting out at the UFS, Prof Jannie wondered about using humour in a “serious tertiary environment.” He soon discovered that students, like most other people, also enjoy appropriate humour.

Using humour in education turned into a research project, and Prof Pretorius found himself showing Mr Bean videos and watching Trevor Noah shows to develop a lesson where the impact of using intentional humour was studied by measuring students’ reactions. An example from the transcription of his class on the mating habits of the praying mantis, where the female often bites the male’s head off to eat him for nourishment, shows how fun can be integrated into learning:

So, it seems that the praying mantis is like – praying; the male is saying: ‘Please don’t eat me, Sylvia, please!’… (laughter) … and she would pray back and say, ‘Please, Ronnie, I can’t resist you.’ (laughter).

Sensitive to their learners’ preferences

Despite the classes being fun, Prof Pretorius also cautions that it is important for teachers to be sensitive to their learners’ preferences and cultural backgrounds when using humour. “There is always an element of risk in the use of humour. As such, humour should always be used in a respectful and inclusive manner to ensure that all learners feel comfortable and included in the classroom.”

Prof Pretorius recognises that the use of humour depends on educators’ personal preferences. Ultimately, it is about what the students learn.

Listen to Prof Jannie Pretorius talk about his research. 

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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