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By: Annie Labrecque / Québec Science

In an arid landscape in the centre of the Mornag region in Tunisia, there is an experimental chicken farm. Despite the oppressive heat — already registering above 35 °C on this September morning — researcher Karim Ben Slama, the photographer and I had to put on white lab coats, shoe covers and hairnets. Our guide, Nciri Achref, an engineer and technical controller, said that these precautions are taken to prevent the chicks from becoming contaminated by any microbes from outside the farm.

This is where the AviBiocin experiment is being carried out, led by a scientific team from the Université de Tunis El Manar and Université Laval. The goal of the project is to reduce the use of antibiotics in poultry farming. “In Tunisia, as in a number of other countries, farmers make extensive use of antibiotics, sometimes in an unsupervised way, particularly on semi-industrial farms. They use them preventively because they’re afraid of getting certain diseases on their farms,” explained Karim Ben Slama, head of department at the Institut Supérieur des Sciences Biologiques Appliquées de Tunis at the Université de Tunis El Manar. The use of antibiotics is also to stimulate animal growth, and this has been a widespread practice around the world for decades.

Yet we know that excessive use contributes to antibiotic resistance in pathogens. According to the World Health Organization, infections, whether in animals or humans, that are increasingly difficult to treat have been placed among the top 10 threats to public health. Moreover, antibiotic resistance knows no borders and gets transmitted from one living being to another, whether human or animal. “If we can limit the use of antibiotics in poultry farming, we may be able to obtain meat that contains fewer resistant bacteria and, namely, fewer traces of antibiotics,” added Karim Ben Slama.

While the chicks I would see were adorable, the stars of this research project are the bacteriocins. Produced by bacteria to resist or eliminate other bacterial strains, these small proteins could replace antibiotics without producing any side effects. While antibiotics destroy a wide range of both good and bad bacteria in the intestinal flora, bacteriocins have a more targeted spectrum of activity. They constitute a promising solution for chicken production in Tunisia and elsewhere.

In fact, every year, some 100,000 tonnes of antibiotics are given to farm animals worldwide, and the trend is increasing. Specialists are unanimous: this needs to change!

From left to right: technical controller Nciri Achref; the journalist, Annie Labrecque ; researcher Karim Ben Slama.
Noureddine Ahmed
At the experimental farm, chickens are divided into several separate pens and fed specific diets. From left to right: technical controller Nciri Achref; the journalist, Annie Labrecque ; researcher Karim Ben Slama.

Sad record

While the overuse of antibiotics on farm animals is a problem in Tunisia, human consumption is, too. People there have unfortunately been categorized as the world’s second-largest consumer of antibiotics, behind Turkey, according to a 2018 article in the journal Proceedings of the National Academy of Sciences (PNAS).

In Tunisia, it is very easy to get hold of these drugs, as a medical prescription or care of a specialist are not required. The inappropriate use of treatments — against viruses rather than bacteria, for example, or for too short or too long a period — contributes to the rise in antibiotic-resistant bacteria.

The PNAS study has raised awareness in Tunisia of the seriousness of the situation. Following the publication of that study, at a conference held last May at the Congrès de l’Acfas in Montréal, microbiology researcher Rym Ben Sallem, from Université Sainte-Anne in Nova Scotia, stressed that Tunisian scientists had “set up monitoring tools to assess antibiotic resistance in various bacteria of human, animal and environmental origin.” Previously, little data were available on the phenomenon.

Bacteriocins as preservatives

Although people have known about bacteriocins since the 1920s, they were relegated to the background by the formidable effectiveness of antibiotics. “There are now a number of teams, including one in Ireland at University College Cork, that are working on the basic science, isolation and identification of bacteriocins,” said Ismail Fliss, full professor in the Department of Food Science at Université Laval in Québec.

This bacteriocin expert carried out research that led to the approval of the first bacteriocin to be used for food preservation in Canada, Bac M35. It is used to prevent contamination by Listeria monocytogenes bacteria in smoked salmon and trout.

The next step was to determine whether this type of protein could have uses other than in food preservation, such as in farming. The professor at Université Laval, who spent part of his university career in Tunisia and is a regular guest researcher there, was a natural choice to manage the AviBiocin project with Karim Ben Slama. “Our team is especially interested in practical applications,” he said.

In their laboratory at Université Laval, Ismail Fliss’s team selected several bacteriocins by analyzing the contents of healthy poultry intestines. Produced by the Escherichia coli bacterium naturally present in poultry, Microcin J25 was chosen. Tests have confirmed its effectiveness in inhibiting the growth of certain pathogens, such as salmonella, which infect chickens. “This bacteriocin showed conclusive results, which is why we then did in vivo testing,” stressed Karim Ben Slama.

The bacterial strains studied in Québec were placed in a 200-litre fermenter (bioreactor) to produce large quantities of bacteriocins. These were then transported to Tunisia, where they were ground into powder and incorporated into a soft mixture.

On all fronts

In the “One Health” approach, which is being promoted by the World Health Organization (WHO) to combat antibiotic-resistant bacteria, action must be taken at all levels to improve health worldwide — in humans, animals and the environment. In its guidelines published in 2017, the WHO warned that “if no action is taken today, by 2050, almost all current antibiotics will be ineffective in preventing and treating human disease.” In fact, similar antibiotics are used in animals and humans.

Nciri Achref
Noureddine Ahmed
Nciri Achref explains how the water-cooling system keeps the farm at a comfortable temperature.

A promising trial

Once suited up, we entered the building where, fortunately for us, the temperature was much cooler. This poultry building belongs to the Poulina Group, the largest producer of chickens for human consumption in Tunisia. The company, which operates in a number of poultry sectors, including production, butchery and processing, sees commercial interests in this research project because an antibiotic-free chicken would be easier to certify for export.

In front of us, over a thousand 19-day-old chicks chirp and roam freely in one of the 32 pens. From their very first days of life, the chicks are raised in ideal conditions, where temperature, light and humidity are rigorously controlled. These variables are progressively changed as their little bodies become increasingly covered in feathers. The chicks, who are the guinea pigs for the first stage of the in vivo project, are given unlimited food and water.

“The chicks don’t all eat the same thing,” explained Karim Ben Slama. The trial compares the four following diets: standard; without additives (control group); with a low dose of bacteriocins; and with a high dose of bacteriocins. “We weighed them for the first time last week. We’re tracking their growth,” said the researcher, gesturing to the various chickens with blue markings on their feathers. They were selected to be weighed weekly by the research team, which hopes that the bacteriocins will not harm their intestinal flora and will effectively prevent infections.

The Tunisian team expects the chickens to reach a weight of between 1.6 and 2 kg, the standard weight for butchery in the industry. Their carcasses will be examined in detail by the scientists. “This in vivo test will enable us to compare the intestinal flora of chickens that were fed standard feed with those fed feed supplemented with bacteriocins. This will enable us to judge whether or not the flora is disrupted,” explained Karim Ben Slama.

The experiment was halfway through at the time of my visit, but engineer Nciri Achref had already observed that “chicks fed with feed containing bacteriocin seemed bigger yet ate less than the others.” He looked at Karim Ben Slama to find the researcher smiling contentedly to hear this update. If bacteriocins promote growth as well as fight infection, they could become an alternative to antibiotics.

However, the scientists are realistic. Pathogenic bacteria can pull a fast one — they could also develop resistance to bacteriocins, just as they do to antibiotics. But maybe they won’t if you use a cocktail of bacteriocins! “The strategy would be to combine several bacteriocins with different mechanisms and spectrums of activity,” stated Ismail Fliss from Université Laval. Bacteria would have more difficulty resisting such a cocktail as opposed to a single bacteriocin.

Within the next year, the scientists hope to publish their results, which are currently being analyzed. This could be the start of a new era in the poultry industry!

Noureddine Ahmed
Chickens eat one of the four diets being compared as part of the research project.

The work described in this article was made possible by support from the UK government’s Global AMR Innovation Fund, which is part of the Department of Health and Social Care, and Canada’s International Development Research Centre. The latter also supported the production of this report.

This article was originally published in the December 2023 issue of Québec Science.

Learn more about this research project

Top photo credit: Noureddine Ahmed