Choose the best answer among the given options.
In \(1928\), a scientist was studying bacterial cultures in his laboratory. After returning from a vacation, he noticed that some of the cultures had been contaminated by a green mould. Surprisingly, he observed unusual effects on the bacterial growth near the mould. He studied this further and published his findings, which later became a breakthrough in treating bacterial infections.
1. The microorganism that caused the unusual effect on bacteria belonged to which group?
2. Which field of medicine benefited the most from this discovery?