Complex sentence: Florey credited Dubos pioneering approach to deliberately, systematically search for antibacterial compounds which lead to the discovery of gramicidin which revived his research in penicillin.
Split into simpler sentences: Florey credited Dubos with pioneering the approach of deliberately, systematically searching for antibacterial compounds. Such a methodology had led to the discovery of gramicidin, which revived Florey's research in penicillin.