The 31-year-old, who lived in nearby Offenbach, suffered severe head and neck injuries during the early Monday morning incident at the U60311 club in the city centre. He died on Wednesday at a Frankfurt hospital.
Police said four of those arrested are suspected of manslaughter. The fifth is being investigated for failing to assist the injured man.
It was not entirely clear what sparked the brutal beating, but police said that the man at some point got in a dispute with the club's staff.
Nobody answered the phone Wednesday at U60311, but a statement on the club's website apologized for unspecified “mistakes” that were made.
The statement said two guests involved in a dispute Monday had been approached by club personnel. One of the bouncers was then allegedly attacked with a bottle, the statement said, without elaborating further.
But Frankfurt police spokesman Karlheinz Wagner told The Local on Wednesday that speculation the man had first threatened the bouncers with a bottle was unfounded. He also said alcohol played no role in his death.