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03 May 2021 | Story Leonie Bolleurs | Photo Sonia Small
Prof Robert Bragg recently participated in a live panel discussion with leaders from the food and beverage sector, debating the challenges facing the industry and sharing their lessons and solutions.

Prof Robert Bragg from the Department of Microbiology and Biochemistry at the University of the Free State formed part of a live panel discussion with leaders from the food and beverage sector, debating the challenges facing the industry and sharing their lessons and solutions.

The discussion, part of a week-long virtual event (19-23 April), was attended by more than 1 300 attendees representing 500 food manufacturers, retailers, ingredient companies, and laboratories from 83 countries.

The magazine, New Food, coordinated the initiative that focused on food integrity. Speaking with Prof Bragg at the session that centred around animal welfare, zoonotic disease, and antibiotics, were Catherine McLaughlin, Chair, Responsible Use of Medicines in Agriculture (RUMA); Vicky Bond, UK Managing Director, The Humane League; and Daniela Battaglia, Livestock Development Officer, Food and Agriculture Organization of the United Nations (FAO).

The rise of antibiotic resistance

James Russell, President of the British Veterinary Association (BVA), was the moderator of the discussion that also touched on the issues surrounding animal welfare; how animal welfare can impact meat quality; avoiding future zoonotic disease; the rise of antibiotic resistance; ethical considerations to be mindful of; and the use of pesticides and safety considerations.

Prof Bragg specifically talked about antibiotic resistance. “Mankind has major problems with antibiotics,” he said. 

He asked if animal agriculture can be sustained without the use of antibiotics and stated that it was necessary to look at alternatives. Possible solutions he suggested include improved vaccines, bacteriophages, and phage enzymes. He, however, believes that biosecurity will be the most effective alternative. 

Living in a post-antibiotic area

Disinfectants are one of the biosecurity measures taken to minimise the risk of infectious diseases. “But it is important to be aware of the fact that as resistance to antibiotics increases the resistance to disinfectants also increases,” said Prof Bragg. 

He continued: “An increase in the use of disinfectants increases the resistance to disinfectants. This is also evident in humans, especially now during the COVID-19 pandemic. Much of these disinfectants are also of poor quality,” he said. 

According to Prof Bragg, we are living in a post-antibiotic era. “Although food standards are higher in developed countries such as in Europe – where people can pay more for poultry that were fed diets with reduced antibiotics, it is important to keep in mind that people cannot pay the same for poultry in developing countries. These countries often import poultry from countries where the food standards are not that high and where birds were treated to diets containing more antibiotics. A large supplier of poultry in Africa is small-scale farmers, who also feed their birds food containing higher levels of antibiotics.” 

“We need to look at the antibiotic problem as a global problem; a concern that will be with us for a while,” said Prof Bragg.

One solution provided by the group was for mankind to reduce its meat intake and moving to a more plant-based diet. This will have a significant effect on animal welfare as well as reducing the demand for antibiotics.

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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