Early biochemical and physiological studies of C. botulinum indicated that they were distinct physiologically and
could be divided into four groups, which were designated groups I, II, III and IV (Hatheway, 1990). These physiological
groups were based on proteolytic and saccharolytic characteristics, acid and alcohol fermentation end products,
ability to grow at low temperatures, heat resistance of spores, and ability to grow in the presence of acids, alcohols and salts