ASM Attends UN General AssemblyASM President, Susan Sharp, Ph.D., joined global leaders at the United Nations General Assembly in New York today in a historical meeting to focus on the commitment to fight AMR.
Some of your work relates to two fungal toxins, aflatoxin and sterigmatocystin. We've all heard of aflatoxin - it can be a problem in peanut butter - but what is the scale of the problem?
That's hard to quantify, but with aflatoxin we can put some dollar amounts on it: in the U.S. every year we have to destroy crops because they're contaminated with aflatoxin. This would range, depending on the weather conditions, from several million even up to a billion dollars [per year].
These compounds are also carcinogenic. Do we have a handle on how many cancer fatalities they cause?
Again, I don't have the numbers, but we do think it is very serious and the people who are most affected by this are in developing countries. We know there's many people effected seriously by this in Africa and Asia. It's a tender situation for governments, too, since you don't want to scare your population. It's a direct health problem in third world countries, whereas here, it's a major economic problem. Aflatoxin directly effects a particular gene in our body called p53 and we can actually do a diagnostic test that indicates whether the person has consumed aflatoxin. There's a lot of data showing that people with liver cancer in Africa and China have this particular mutation.
Your work has shown that in these toxin-producing fungi, sporulation is linked somehow to toxin production. What can you tell me about that work?
That's a complex genetic connection, but there are signaling pathways that connect both processes and many of the proteins in the fungus that are required for making secondary metabolites are also required for making spores. They are linked and it probably has to do with niche securement. One might speculate that once challenged by another organism, a fungus has two major things it can do: it can produce chemicals to try and protect itself, and it can also produce spores so it can escape. And maybe they're coupled together to give the fungus every chance to stay alive, but that's all speculation.
You've also done some work with viruses that infect fungi - mycoviruses - and it turns out Aspergillus has a sort of immune defense against certain viruses. How does that work?
That's really interesting. Aspergillus and other eukaryotes have machinery in their body - it's known as RNA interference machinery - a set of proteins that recognize double stranded RNA (and many of our viruses are dsRNA) and destroy it. We've shown that Aspergillus has this and that Aspergillus can recognize these dsRNAs and destroy them.
What's next for your lab?
An interesting aspect of fungal secondary metabolites is that many of them are very useful. All these regulatory proteins we've found that regulate the bad, undesirable molecules, also regulate the molecules we want to develop as pharmaceuticals. We've started a new area in our lab, where we're also trying to find novel metabolisms from fungi which could be used in a medicinal or pharmaceutical setting.
What do you think is the most understudied microbial system?
Those that are difficult or impossible to culture, like fungi that are obligate symbionts. We know very little about these, they're so hard to work with, but it's a promising area.
What is your favorite microbe? Why?
I'm fond of all microbes, but fungi you can see. I'm a very visual person, in fact I double majored in art and science as an undergrad (I had a hard time deciding which way to go). Fungi are beautiful. They have all sorts of different forms and shapes and colors.
If you could name a new microbe right now, would you name it after yourself? If not, how would you name it?
Most likely, I would name a microbe after its role in the ecosystem. I could see possibly dedicating it to a person who has influenced me very strongly in life.
What advice would you give students about life as a microbiologist working in academia?
In general, you should pursue something you're passionate about.
What is something about you that most people don't know?
Probably most people don't know that I'm equally interested in art as I am in science.