Phenylethanol as a quorum sensing molecule to promote biofilm formation of the antagonistic yeast Debaryomyces nepalensis for the control of black spot rot on jujube

•D. nepalensis significantly reduced black spot of jujube caused by A. alternate.•The formation of biofilms was an important biocontrol mechanism of D. nepalensis.•Release of QSMs was critical for cell growth and biofilm formation of D. nepalensis.•Phenylethanol improved biocontrol effect by promoting biofilm formation. Microbial biocontrol agents have become an effective way to inhibit post-harvest diseases of fruits and vegetables, where antagonistic yeast with antimicrobial properties are often employed. In this study, Debaryomyces nepalensis, isolated from the leaves of jujube and identified with internal transcribed spacer sequences, can effectively control the post-harvest black spot of jujube caused by Alternaria alternate, even though it showed no direct inhibitory effects on A. alternate. Phenylethanol, as a quorum sensing molecule, was identified by HPLC to be one of the major metabolites during the culture of D. nepalensis. Phenylethanol could promote the biofilm formation ability of D. nepalensis and increase its adhesion to the surface of jujube fruit, and the control effect of 2 mmol L−1 phenylethanol combined with D. nepalensis on jujube fruit black spot was increased by 15 % compared with D. nepalensis alone. In conclusion, the results of this work provided a new perspective for improving the biological control efficiency of D. nepalensis.