Endogenous Bacteria of Tuber aestivum Ascocarps are Potential Biocontrol Agents of Microbial Post-harvest Deterioration of Truffles

Neila Saidi, Shweta Deshaware, Ilef Ben Romdhane, Matab Nadim, Heikki Ojamo, Robert Kremer, Salem Shamekh

Most previous investigations of microbial interactions with truffle have been conducted within the soil environment and have not considered effects on post-harvested truffles. After harvest, truffles spoil easily and quickly within 4 days.  This study evaluated the efficacy of bacteria isolated from fresh Tuber aestivum fruits ascocarps as biocontrol agents against the bacteria and fungi responsible for spoiling truffle fruit. Effects of acetic acid (12 %-v/v) and citric acid (10%-w/v) as inhibitors of isolated spoilage bacteria were also tested. An antagonism test between microbes extracted from unspoiled truffle microorganisms was performed against microbes responsible for spoilage of truffle fruits. Spoilage bacteria were identified. Truffle fruits immersed in a supernatant from antagonistic bacteria culture medium contributed to non-spoilage and resulting in storage of fruit at room temperature for more than two weeks without spoilage development. In addition, acetic acid (12 %-v/v) inhibited all tested spoilage bacteria. However citric acid (10%-w/v) had no inhibitory effect on spoilage bacteria. The results showed a high rate of antifungal activity among the bacterial isolates, indicating that truffle may be a common source for selection of microorganisms with important biotechnological potential, and may be useful for further biocontrol of food, plant, and soil-borne pathogenic bacteria and fungi.