Researchers from the University of the Free State (UFS) hope their research into the environmental presence of potential pathogenic yeasts in plastic pollution in freshwater sources in Bloemfontein will increase people’s understanding of the impact human activity can have on their health and that of the environment.

Given the increasingly recognised threat of yeast infections, according to Prof Carolina Pohl-Albertyn from the UFS Department of Microbiology and Biochemistry, it is important to investigate the environmental presence of potential pathogenic yeasts on possible vehicles that may contribute to their distribution.

Pollution of aquatic environments is a concern and poses a health risk to aquatic and terrestrial life. Plastic pollutants can harbour biofilms containing various potential pathogens, including bacteria and fungi. These pollutants can flow along freshwater sources to different environments, spreading pathogens along the way. The risk not only affects aquatic life, but also human health and people should be aware of this.

In this study, the fungi present in the biofilms on various types of plastic collected from freshwater sites in Bloemfontein (i.e., Loch Logan and two separate parts of the Bloemspruit, flowing through Ooseinde) were investigated by a team led by Prof Pohl-Albertyn. These areas are considered to be polluted, containing pollutants such as food packaging, plastic gloves, and even clothing in some instances.

Possible pathogenic yeasts on plastic pollutants

Prof Pohl-Albertyn’s colleagues in the Department of Microbiology and Biochemistry, Profs Olihile Sebolaia and Jacobus Albertyn, together with Tyla Baker, a student of Prof Pohl-Albertyn and Armand Bester from the UFS School of Pathology, were also part of the study. The aim of this research was to investigate and contribute to our knowledge of the habitats fungal pathogens can occur in and or colonise.

The presence of yeasts known to be able to cause disease was detected on all the plastic surfaces tested. These yeasts included many Candida species, such as the emerging pathogen, Candida auris. What is overly concerning is that some of these strains were resistant to the most commonly used antifungal drug, fluconazole.

Pollution should always be a concern

According to Prof Pohl-Albertyn, who holds the NRF SARChI Research Chair in Pathogenic Yeasts, the two sites of the Bloemspruit were littered with plastic pollutants and often had people living next to the stream or cattle drinking from it, which contributed to human and animal waste deposition into this stream.

“Loch Logan does not necessarily have a lot of plastic pollutants but there are high levels of human activity in the area from the shops and restaurants surrounding the pond. Humans have different microbiomes (microbial communities living in and on our bodies) which can be shed into this water source giving rise to new concerns,” says Prof Pohl-Albertyn.

Pollution in general should always be a concern for both human, animal and environmental health. Previously the main concern was on how pollution in water could affect the health of aquatic animals and water quality but as time and research progressed, new threats and concerns surrounding water pollution have come to light, explains Prof Pohl-Albertyn. Plastic pollutants act as surfaces that fungi and other microorganisms can adhere to and grow on to form biofilms (slimy layers) of mixed microorganisms.

Fungi in these layers can potentially be pathogenic, considering that pathogens are shed from humans into water sources directly or through sewage spilling into freshwater sources. People living close to these polluted water sources and those who come into contact with these pollutants stand the risk of coming into contact with these potential fungal pathogens. Pathogenic fungi affect the health of immunocompromised or suppressed individuals and considering the high rates of HIV-positive people in South Africa, they stand a higher risk of developing potentially dangerous fungal infections. There is also the added concern of biofilm-forming fungal species being resistant to currently available antifungal drugs which complicate treatment of these infections even more. 

“The research broadens our understanding of how fungal infections can be acquired and areas that may act as a hub for pathogens. This information can aid in the effort made to combat fungal infection and its associated severity. Research on fungi and how they interact with their surrounding environment can also shed light on the epidemiology and origin of acquired resistance observed in several fungal species,” says Prof Pohl-Albertyn.

Greater effort needed to keep water sources clean

There is also hope that the research inspires other researchers and entities to develop strategies to mitigate the harmful effects of pollution. Spreading information regarding fungal infections is also essential, considering that these infections are becoming increasingly frequent with an estimated annual death of 3.8 million, according to a 2024 review.

Prof Pohl-Albertyn says greater effort needs to be put into keeping water sources clean. Local businesses or municipalities could initiate clean-up initiatives to remove plastic pollutants from water sources. Municipalities need to ensure that waste removal services cover problem areas where large amounts of waste are being produced to prevent weather events from depositing waste into freshwater sources. Hopefully, by initiating these initiatives it will aid in decreasing pollution and increasing job creation in the Mangaung area.