I want to know the answer to the following question:
What also happened in 1939 besides tyrothricin?
All the background I'm provided with is that "In 1939, coinciding with the start of World War II, Rene Dubos reported the discovery of the first naturally derived antibiotic, tyrothricin, a compound of 20% gramicidin and 80% tyrocidine, from B. brevis.". Is that enough to answer the question?
Answer: yes