The Sylcauga native, who was a draft-eligible sophomore, was the 21st pick in the round and the 1092nd overall pick in the draft.
Zylstra made nine appearances this season, but missed almost six weeks after leaving the Murray State game during the opening weekend of Ohio Valley Conference play. He posted a 1-2 record with a 4.55 earned run average with 18 strikeouts.
It marks the second time over the last three years the Gamecocks had two players drafted in the same season and the fourth time since 2000. Junior Ben Tootle was selected during the third round on Tuesday, also by the Minnesota Twins.