Fungus-be-gone: polymers that block fungi

Scientists from the University of Nottingham have developed a material that stops fungi from growing on surfaces. Welcome news for those who have ever had to clean black mould out of their bathroom! They use polymers that can be 3D printed, and that are designed to tackle a wide variety of damaging fungi - from human pathogens to crop diseases. Unlike fungicides, which can be toxic, these materials appear to be safe at least for plant use - and given that fungal infections are responsible for around a million and a half human deaths worldwide every year, could end up being much more widely useful. Simon Avery helped lead the research, and spoke to Chris Smith...

Simon - Well one of the problems with fungicides or antifungals is these can kick around for a long time, and there are environmental concerns around that. There are tight regulations - and the regulations are not easing, they're tightening - about the use of these fungicides. And also fungi, like bacteria with antibiotics, they can develop resistance.

Chris - And therefore you wanted something that was safe for widespread use, would surmount the problem of growing resistance, and could be easily used?

Simon - Well yes, we were interested in developing a method that didn't involve killing action, because that's where this toxicity and environmental concern comes in. We were interested in actually blocking what is usually the first step of most of the problem that fungi cause, and that is attachment. To cause disease, or even to grow between tiles and grouting in bathrooms, they need to attach to a surface first. If you can block that, then in principle you can block the subsequent problem.

Chris - So is this antifungal equivalent of Teflon, nonstick surfaces, then? You've got something you can put onto a surface, and it just means that if any fungus did try to land on that surface, it can't gain a toehold and therefore it can't start to proliferate or grow?

Simon - I quite like that analogy.

Chris - What is the actual chemical itself? How have you done this, and will this work on a slice of bread as well as it will work on a bathroom tile?

Simon - Well, the chemical... we have a few of these polymers which appear to be very effective. A slice of bread presents a more challenging surface. And also of course, then it's directly onto food, and so there are other challenges there. But we've tested plant surfaces, and they work effectively on those; and glass; plastic surfaces; 3D printed parts we've made as well...

Chris - And does this work against the whole repertoire of fungi that a bathroom tile,, right through to the ear of barley or wheat, might encounter; or is it horses for chemical courses, we're going to need different types of treatment for different indications?

Simon - We've been testing about five different types of fungi: human pathogens, crop pathogens, and the types of fungi you find around the house. The same material won't necessarily work for all types, but then you wouldn't want the material to be usable in that way. There's no reason if you're using it on a crop for it also to give resistance to human pathogens. But we have found materials which work against two or three of the five fungi that we've tested. So that's particularly promising

Chris - What's to stop the microbial world doing what it does best and evolving to just sidestep the blockade imposed by your new chemicals?

Simon - Yeah, it's a good question. If with an antibiotic the bacterium doesn't develop resistance, it will die. So there's a strong, strong pressure on the bacteria to develop resistance. With this, because we're not killing, there's a much lower pressure. And so we anticipate - and we've started these sorts of tests - that the evolution of resistance will be much, much slower, if it happens at all.

Chris - And safety? Because one of the other major considerations is safety in terms of, if you're going to put this on something people are going to eat, that's a major consideration; but also environmental safety, if we're going to be spraying this sort of thing on crops, can you reassure us that these are potentially safe treatments?

Simon - We don't expect, and indeed we've not seen, significant toxicity. And in fact, in humans these have a long track record of safety. One of the advantages in humans, if they're used in humans, is that they don't degrade, and so they don't release potentially toxic products; but in the environment of course, ultimately you would want them to degrade. Modifications can be made, and we've been planning some of those to make these more biodegradable if it's needed for a particular application, such as crop sprays.