Characterization and Implications of <i>Enterobacter cloacae</i> Strains, Isolated from Italian Table Olives “Bella Di Cerignola”

Abstract

Enterobacter cloacae can be recovered in the spontaneous fermentations of Italian table olives. In this study, the effects of salt (20 to 100 g/L), temperature (10 to 37 degrees C), pH (4 to 5 and 8 to 10), p-coumaric and vanillic acids (0.5 to 2 g/L), and the acidification of the medium through lactic, citric, and ascorbic acids were investigated on 15 strains of E. cloacae, isolated from Italian table olives "Bella di Cerignola." Finally, a confirmatory experiment in synthetic brine was run. The strains were inhibited only by an NaCl amount of 70 to 80 g/L and by p-coumaric acid; on the other hand, they showed the ability to grow also at low temperatures (10 to 15 degrees C). The confirmatory experiment highlighted their ability to survive both at 15 degrees C and at pH 5. Enterobacter cloacae could be a real problem for the fermentation of table olives in southern Italy; some hurdles could be used (salt or brine acidification), but some environmental conditions (for example, the temperature) should be controlled carefully to maintain olive safety at acceptable levels.