CSIR-CCMB Experts Find Why Fungi Turns Harmful

Hyderabad: Scientists at CSIR-Centre for Cellular and Molecular Biology, Hyderabad, have figured out how fungi become harmful inside the human body, according to a study. The finding comes against the backdrop of fungal infections are emerging as a serious but often ignored health threat across the world.

While bacteria and viruses get more attention, fungi are increasingly causing severe infections, leading to hospitalisation and deaths. They are also damaging crops, affecting food production. At the same time, treatment options are limited, as antifungal drugs are few, often toxic, and losing effectiveness due to resistance said scientists.`

A CCMB research team led by Dr Sriram Varahan found that fungi turn dangerous by changing their shape, and this change is controlled not just by genes, but also by how fungi use sugar for energy.

Dr Varahan explained to Deccan Chronicle, “Fungi loves sugar. The study we have done at this point is restricted to fungal infections although we talk about sugar metabolism. The need for antifungal is very high. So, this is a step closer to identifying effective antifungals.”

He said the pathways his team had identified were conserved and this could be possible happening in fungal species. “The morphogenesis that we have worked on is also conserved in animal pathogens, plant pathogens. It is important because plant fungal pathogens are a huge problem,” he added.

Fungi mainly exist in two forms — a small, round yeast form and a long, thread-like filament form. The yeast form helps fungi move and survive, but once inside the human body, fungi often change into the filament form. This filament form is harder for the immune system and medicines to remove and is linked to severe infections.

Dr Varahan’s study shows that this shape change depends on the fungus’s metabolism — especially how it breaks down sugar. When fungi break down sugar rapidly, it affects the production of certain sulphur-based amino acids, which act like a switch that allows fungi to become invasive.

During laboratory experiments, when scientists slowed down sugar breakdown, fungi stayed in the harmless yeast form. But when sulphur-containing amino acids were added, the fungi quickly regained their ability to change shape. This confirmed that these nutrients play a key role in fungal infection.

The team also studied Candida albicans, a common fungus that causes infections in humans. When its sugar metabolism was disrupted, the fungus struggled to change shape, survive immune attacks, and cause disease. In mouse studies, this weakened strain led to much milder infections.

According to Dr Varahan, targeting fungal metabolism could open a new way to treat infections. Since these processes are essential for fungal survival, they may be harder for fungi to resist.

With drug-resistant fungal infections on the rise globally, the study suggests that cutting off fungi’s energy supply could help prevent them from turning harmful — offering hope for safer and more effective antifungal treatments in the future.