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New study finds emerging pathogen inside brown locusts

17 February 2025 | Story Andre Damons | Photo Supplied

Prof Carolina Pohl-Albertyn — Prof Carlien Pohl-Albertyn is the NRF SARChI Research Chair in Pathogenic Yeasts at the UFS.

A new study by researchers from the University of the Free State (UFS), the National Health Laboratory Service, and the University of Venda has confirmed for the first time that common brown locusts are carriers of pathogenic yeasts that can cause severe infections in humans – especially in people with compromised immune systems or who are seriously ill.

The study, ‘South African brown locusts, Locustana pardalina, hosts fluconazole resistant, Candidozyma (Candida) auris (Clade III)’, highlights for the first time the presence of the pathogenic (disease-producing) fungal yeast C. auris in the digestive tract of the locusts, and shows their potential in disseminating this emerging pathogen. The research started in April 2022, when 20 gregarious (swarming) adult locusts were collected during a large locust outbreak which occurred from September 2021 to May 2022 in the semi-arid Eastern Karoo region in the Eastern Cape. The study is still under peer review.

According to Prof Carlien Pohl-Albertyn, National Research Foundation (NRF) SARChI Research Chair in Pathogenic Yeasts, three C. auris strains were isolated from three different adult locusts, two of which also harboured strains of another potentially pathogenic yeast, Candida orthopsilosis. “The fact that we were able to isolate C. auris from 15% of the sampled locusts, using non-selective media and a non-restrictive temperature of 30°C, may indicate that C. auris is abundant in the locusts and that specific selective isolation is not mandatory,” Prof Pohl-Albertyn said.

“Interestingly, C. auris was isolated from the fore- and hindgut of the locusts. Isolation from the foregut, which is dedicated to food intake and storage, filtering and partial digestion, indicates that C. auris was probably obtained by the locusts via feeding activities. Isolation from the hindgut confirms that C. auris can survive the digestive processes in the midgut and is likely to be released back into the environment via faeces.”

Healthy humans are not at great risk

One of the C. auris strains was studied in more detail. This strain was not resistant to disinfectants but showed decreased susceptibility to the common antifungal drug fluconazole. This is a characteristic of this yeast species and thus not surprising. Most of the emerging pathogenic yeasts show this intrinsic resistance. This highlights the urgent need to discover and develop new antifungal drugs.

Prof Pohl-Albertyn, also a Professor of Microbiology in the UFS Department of Microbiology and Biochemistry, says, “Healthy humans are not at great risk for infection by this yeast and there is currently no proof that ingestion may be harmful to them. This is unfortunately not the case for people with compromised immune systems or who are seriously ill. However, few susceptible people come into direct contact with the locusts in South Africa.”

She added that there are treatment options available, using other antifungal drugs, but C. auris can become resistant to all the currently available antifungal drugs.

Importance of the study

“The fact that locusts are a food source for other animals, such as birds, could lead to eventual distribution of the yeast to people. In other countries, wild locusts are a food source for humans and there more direct transmission may be possible,” Prof Pohl-Albertyn said.

She explained that this study tries to answer questions regarding the natural hosts of this emerging pathogen and how it may facilitate the spread of the pathogen to the rest of the environment. The study is one part of the puzzle regarding how new pathogens may emerge from the environment and spread to people.

“One of the questions in the field of pathogenic yeasts is how C. auris was able to emerge as a pathogen in several different countries in a relatively short period. It is well known as a hospital-acquired pathogen, but it is not known where in the environment it occurs naturally, and which environmental factors may have shaped its evolution and ability to cause human infections. This has implications for the prevention of the spread of this specific yeast species, as well as our preparedness for new pathogenic yeasts that may be emerging from the environment.”

News Archive

Researcher part of project aimed at producing third-generation biofuels from microalgae in Germany

2016-05-09

Some of the researchers and technicians among the tubes of the Novagreen bioreactor (Prof Grobbelaar on left)

A researcher from the University of the Free State (UFS), Prof Johan Grobbelaar, was invited to join a group of scientists recently at the Institute for Bio- and Geo-Sciences of the Research Centre Jülich, in Germany, where microalgae are used for lipid (oil) production, and then converted to kerosene for the aviation industry.

The project is probably the first of its kind to address bio-fuel production from microalgae on such a large scale.

“The potential of algae as a fuel source is undisputed, because it was these photoautotrophic micro-organisms that were fixing sunlight energy into lipids for millions of years, generating the petroleum reserves that modern human civilisation uses today. However, these reserves are finite, so the challenge is marrying biology with technology to produce economically-competitive fuels without harming the environment and compromising our food security. The fundamental ability that microalgae have to produce energy-rich biomass from CO2, nutrients, and sunlight through photosynthesis for biofuels, is commonly referred to as the Third-Generation Biofuels (3G),” said Prof Grobbelaar.

The key compounds used for bio-diesel and kerosene production are the lipids and, more particularly, the triacylglyserols commonly referred to as TAGs. These lipids, once extracted, need to be trans-esterified for biodiesel, while a further “cracking” step is required to produce kerosene. Microalgae can store energy as lipids and/or carbohydrates. However, for biofuels, microalgae with high TAG contents are required. A number of such algae have been isolated, and lipid contents of up to 60% have been achieved.

According to Prof Grobbelaar, the challenge is large-scale, high-volume production, since it is easy to manipulate growth conditions in the laboratory for experimental purposes.

The AUFWIND project (AUFWIND, a German term for up-current, or new impetus) in Germany consists of three different commercially-available photobioreactor types, which are being compared for lipid production.

Manipulated Chlorella with high lipid contents (yellow) in the Novagreen bioreactor

The photobioreactors each occupies 500 m2 of land surface area, are situated next to one another, and can be monitored continuously. The three systems are from Novagreen, IGV, and Phytolutions. The Novagreen photobioreactor is housed in a glass house, and consist of interconnected vertical plastic tubes roughly 150 mm in diameter. The Phytolutions system is outdoors, and consists of curtains of vertical plastic tubes with a diameter of about 90 mm. The most ambitious photobioreactor is from IGV, and consists of horizontally-layered nets housed in a plastic growth hall, where the algae are sprayed over the nets, and allowed to grow while dripping from one net to the next.

Prof Grobbelaar’s main task was to manipulate growth conditions in such a way that the microalgae converted their stored energy into lipids, and to establish protocols to run the various photobioreactors. This was accomplished in just over two months of intensive experimentation, and included modifications to the designs of the photobioreactors, the microalgal strain selection, and the replacement of the nutrient broth with a so-called balanced one.

Prof Grobbelaar has no illusions regarding the economic feasibility of the project. However, with continued research, optimisation, and utilisation of waste resources, it is highly likely that the first long-haul flights using microalgal-derived kerosene will be possible in the not-too-distant future.

Prof Grobbelaar from the Department of Plant Sciences, although partly retired, still serves on the editorial boards of several journals. He is also involved with the examining of PhDs, many of them from abroad. In addition, he assisted the Technology Innovation Agency of South Africa in the formulation of an algae-biotechnology and training centre. “The chances are good that such a centre will be established in Upington, in the Northern Cape,” Prof Grobbelaar said.

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