As a lay person, it's not clear to me whether these malacidins were found in mycelium (fungi). I'm inclined to think this is likely. If so, finding them in dirt is not really surprising (30% of dirt is comprised of mycelium - living and dead). It seems like the obvious place to look for new antibiotics.
For anyone that's interested in fungi I can't recommend listening to Paul Stamets talk on the subject more highly. Like a lot of people here on HN I take in a lot of information and his recent interview with Joe Rogan[0] was one of the most fascinating things I've come across in years.
There was a reason all of the indigenous cultures got out in the woods and got to know their plant neighbors -very- well. 4 billion years of evolution produced copious treasures for those humble enough to root around in the woods and swamps. (Favorite example: aspirin)
For anyone that's interested in fungi I can't recommend listening to Paul Stamets talk on the subject more highly. Like a lot of people here on HN I take in a lot of information and his recent interview with Joe Rogan[0] was one of the most fascinating things I've come across in years.
[0] https://www.youtube.com/watch?v=mPqWstVnRjQ