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25 July 2019 | Story Leonie Bolleurs | Photo Leonie Bolleurs
Plant Sciences Congress
At a public seminar, Understanding human evolution through the study of past environments in the Free State, presented by the UFS Department of Plant Sciences, were, from the left, front: Kristen Wroth, Britt Bousman; back: Prof Louis Scott, mentor in the UFS Department of Plant Sciences, and Michael Toffolo.

Florisbad, a thermal spring situated 45 km northwest of Bloemfontein on the edge of a large dry saltpan, is a well-known fossil site that used to be a large lake where giant buffalo, blue wildebeest, and hippos roamed thousands of years ago. Today, this fossil-bearing spring is not only a tourist attraction and a venue for weddings, but also an established quaternary research station that has attracted several palaeo-scientists since the 1930s, following the discovery of a remarkable human cranium and other fauna. 

Studies of past environments 

Three international researchers studying different aspects of archaeology at this and other sites in the Free State, recently presented lectures at the UFS to a multidisciplinary group of academics in plant sciences, geology, geography, and environmental management.

These lectures are part of the ongoing collaboration regarding fossil plant (pollen), fauna, and archaeological studies between the University of the Free State (UFS), the National Museum, and universities abroad.

Florisbad, a key site for understanding the appearance of modern environments as well as modern humans in Southern Africa, is the focus of the investigations of all three visiting scientists, aiming to provide a better understanding of past Free State environments where human evolution has taken place.

Michael Toffolo, a junior research chair from the University of Bordeaux Montaigne in France, focuses on the reconstruction of site-formation processes, palaeo-environments, and ancient human activities based on the study of the micro-morphology of archaeological deposits. He has been working in Southern Africa since 2013. The title of his lecture was: Reconstructing Pleistocene environments in the Free State by looking at the microscopic sedimentary record. 

Fluoride-preserved bones

Florisbad is widely known for the discovery of an archaic modern human skull of c. 260 000 years old. According to Toffolo, the human probably died, and the remains was left at the spring by the hyenas. The bones consequently absorbed fluoride from the spring water, which counteracted decomposition and helped to preserve it. 

Britt Bousman talked about middle and late Pleistocene terraces and archaeology in the Modder River Valley. He has worked in Southern Africa for the past 43 years and started his collaboration with researchers from the UFS and the National Museum in 1985. They have worked together at several sites, investigating palaeo-environments. Bousman teaches Archaeology in the Department of Anthropology at the Texas State University. 

While most scientists study early human records in rock shelters, especially those near the coast where seafood was harvested by prehistoric people, he is one of only a few researchers who studies the evolution of early human behaviour in central South Africa in the context of their activities in the open environment. 

“Rock shelters are good spaces for human behaviour,” says Bousman. He believes, however, that the Modder River area is a better space to study how humans have survived on the land under changing climatic conditions in the long term; for example, how they hunted and slaughtered animals. This can be seen from the many artefacts they left, such as spearheads, scrapers, etc. Interesting animal remains were also found, such as the bones of an extinct giant zebra at the Erfkroon site along the Modder River, with a head measuring 63 cm compared to that of a current zebra, which measures 54 cm. The only complete horn core of an extinct giant wildebeest was also found at the site. 

The first chemists

According to Bousman, technology changed in the Stone Age and included the production of more grinding stones, indicating that humans collected plants and grinded them. Observations of modern plant-collecting activities suggested that not many plant foods needed grinding. Bousman proposes that different plant components may have been grinded for medicinal mixtures, therefore these ancestors may have assumed the role of chemists. 

Kristen Wroth, a postdoctoral researcher in the Geoarchaeology Working Group at the University of Tübingen, Germany, presented a lecture on early human-environment interactions and ancient pyro technology. She uses a suite of micro-archaeological techniques such as phytolith (microscopic plant silica) analysis, micromorphology, and FTIR to understand both human and Neanderthal behaviour and to reconstruct how local environments have changed in space and through time.


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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