Phenylalanine Promotes Biofilm Formation of Meyerozyma caribbica to Improve Biocontrol Efficacy against Jujube Black Spot Rot

Abstract

During storage and transportation after harvest, the jujube fruit is susceptible to black spot rot, which is caused by <i>Alternaria alternata</i>. The present study aimed to evaluate the effectiveness of the yeast <i>Meyerozyma caribbica</i> in controlling <i>A. alternata</i> in postharvest jujube fruits, and to explore the biofilm formation mechanism. The results showed that <i>M. caribbica</i> treatment significantly reduced the <i>A. alternata</i> decay in jujube fruits. <i>M. caribbica</i> could rapidly colonize jujube fruit wounds, adhering tightly to hyphae of <i>A. alternata</i>, and accompanied by the production of extracellular secretions. In <i>in vitro</i> experiments, we identified that <i>M. caribbica</i> adhered to polystyrene plates, indicating a strong biofilm-forming ability. Furthermore, we demonstrated that <i>M. caribbica</i> can secrete phenylethanol, a quorum sensing molecule which can affect biofilm development. Phenylalanine (a precursor substance for phenylethanol synthesis) enhanced the secretion of phenylethanol and promoted the formation of <i>M. caribbica</i> biofilms. Meanwhile, phenylalanine enhanced the biological control performance of <i>M. caribbica</i> against jujube black spot rot. Our study provided new insights that enhance the biological control performance of antagonistic yeast.