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31 March 2020 | Story Leonie Bolleurs | Photo Gerhard de Jager
Prof Linda Basson recently returned from a three-month research expedition in Antarctica. Here she is, relaxing on the ice with the ever-inquisitive Adelie penguins having a gander at these strangers in their snowy world.
Prof Linda Basson recently returned from a three-month research expedition in Antarctica. Here she is, relaxing on the ice with the ever-inquisitive Adelie penguins having a gander at these strangers in their snowy world.

Very little is known about the parasites of Antarctica, which is a highly productive part of the oceans. These small organisms can be used very successfully to determine the health of this fragile ecosystem.

“Our research data can make significant contributions to the biodiversity of parasites, for a start. The data can also be very valuable to indicate the overall health of this large ecosystem – an ecosystem that drives many of the life-giving processes on our planet.” This is the belief of Prof Linda Basson from the Department of Zoology and Entomology at the University of the Free State (UFS). 

She is an aquatic parasitologist who concentrates on various parasites from a wide range of hosts, including vertebrates (fish and amphibians) and invertebrates (plankton, urchins, starfish, sea cucumbers and red-bait).

Prof Basson, together with PhD student Gerhard de Jager, was invited by Prof Isabelle Ansorge, Head of the School of Oceanography, University of Cape Town, to join her research team on the South African National Antarctic Programme (SANAE) Voyage 59 to Antarctica. 

Widen the scope of research 
“Our aim on this trip was to determine how we can collaborate with the various oceanographers to widen the scope of research normally performed on these voyages, in order to also include parasitological aspects. Once we arrived on the continent of Antarctica, we worked to collect a range of hosts from the Southern Ocean to screen these for the whole array of parasites,” she explains. 

No research of any kind on aquatic parasites has ever been done in Penguin Bukta and Akta Bukta, the specific areas where Prof Basson was based with other scientists and the rest of the Agulhas crew.

She adds: “Our research will contribute to the wider knowledge of parasites in marine environments, but specifically in this area where little to nothing is known.”

A chance of a lifetime 
“Antarctica was literally one of the top research destinations on my bucket list. Travelling to and working in Antarctica is a lifelong dream of mine. It was a chance of a lifetime that I could not miss out on,” says Prof Basson. 

Sharing her experience, she says a typical day on board the SA Agulhas II in Antarctica will start with a cup of good, quality coffee and a look at the prevailing weather on the stern of the ship. 

“One would always be amazed by the beautiful, ceaselessly changing water, the restless sea ice and the impressive ancient ice shelf in very invigorating temperatures, while an ethereal Snow Petrel swirls past and the occasional Adelie penguin comes to gaze and contemplate the presence of this large red structure floating in their habitat and obscuring their view. After tearing yourself away from this, the rest of the day would be spent either in the well-equipped laboratory working through collected samples, or else planning the next exciting collection in the intensely cold water.”

Remarkable journey 
To eternalise memories of this unique experience of almost three months, Prof Basson says that, “One cannot go without a fully charged camera with a large SD card, ready to capture the many facets of this exceedingly fragile but enchanting world of ice and sky, ever changing and all in innumerable shades of white”.

“This truly remarkable journey will forever be associated with a myriad of brilliant highlights.”

Finding it extremely difficult to single out a specific highlight, she listed a long list of memorable events, but as a scientist she will always remember “realising the wealth and cornucopia of microscopic life present in the southernmost of our oceans and seeing this first-hand under the microscope”.

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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