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

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.nbsp 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.nbspTruffle 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.nbspThe 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

Endogenous Starter Bacteria Associated to Chanterelle mycelia Enhance Aroma, color and growth of mycelia

Chanterelle (Cantharellus cibarius) mushroom can be cultured from its fruit body on agar medium. The present study showed that the growth rate of chanterelle mycelia in agar medium is slow whereas the pigment of the cultured mycelia was medium dependent. Different mycelia colors were detected in this study: from orange to pink and brown.This study also revealed bacterial growth near mycelia fragments, which appeared only at the initial phase of mycelia growth after which the mycelia continued to grow, blocking bacterial growth in the center of the agar plates. Therefore, we presumed that these bacteria were able to transfer the color to the chanterelle mycelia and may serve as fungal growth helper bacteria. The first step was to isolate these accompanying bacteria in pure culture and relate its phenotypical aspect to the mycelia aspect. The second step consisted of chemically treating the mycelia to suppress bacteria around and verify the myceliarsquos ability to enhance or decrease color production. As a third step, the Chanterelle mycelia were treated separately with different chemical reagents [Sodium nitrate, Potassium phosphate monobasic, Ammonium nitrate, Citric acid, Acetic acid, Boric acid (0.05 g/ml), 1% NaOH, 1% KOH and 0.5%.HCl] followed by incubation in different agar plates. We demonstrated that some treatments killed all bacteria after which the mycelia lost its growth capacity. As a final step, agar plates showing no development of mycelia were inoculated with bacteria. After this inoculation, mycelia growth resumed and obtained the color of the inoculated bacteria.nbspThe results clearly showed that endogenous bacteria present in Chanterelle mycelia serve to initiate mycelial growth and impart color to the Chanterelle mycelia. The isolated bacteria produced aromas, lecithinase, amylase and laccase as well. However, these bacteria were unable to produce oxidase, catalase or protease