Which of following statements regarding antibiotics is not correct?
(i) Antibiotics are attenuated microorganisms which in small concentration can kill or retard growth of or harmful microorganisms.
(ii) Penicillin was first antibiotic discovered by Alexander Fleming (1928) while working on bacterium Staphylococcus aureus.
(iii) The full potential of penicillin as an effective antibiotic was established by Ernest Chain and Howard Florey.
(iv) Fleming, Chain and Florey were awarded Nobel Prize in 1945.