Alterations in the proteome as a regulating mechanism for patulin stress by the antagonistic yeast Meyerozyma guilliermondii

Meyerozyma guilliermondii is an antagonistic yeast; our research team has recently reported its biocontrol ac-tivities against blue mold decay of pears and strong patulin (PAT) reduction ability in vitro. PAT is a harmful mycotoxin produced by some species of Penicillium, Aspergillus, and Byssochlamys. The PAT degradation process and molecular mechanism(s) of M. guilliermondii remain unclear. The data-independent acquisition (DIA) stra-tegies promise a comprehensive, reproducible, digital, qualitative and quantitative record of the proteins present in a sample. Differentially expressed proteins accompanying PAT degradation in M. guilliermondii were observed to investigate PAT reduction mechanisms. The comparative proteomic analysis of M. guilliermondii showed that 136 proteins were up-regulated and 122 were down-regulated upon PAT degradation. The M. guilliermondii's regulation of PAT response mainly includes the up-regulation of (1) growth and reproduction-related protein expression, (2) transcription and translation-related protein expression, (3) resistance-related protein expression, (4) multidrug transporters, (5) anti-oxidative stress-related proteins, (6) the cell wall and cell membrane production-related proteins, and (7) PAT degradation-related protein expression. This paper analyzed M. guilliermondii's molecular response and regulation upon PAT reduction at the gene and protein expression levels. Our results provide a solid foundation for PAT control in fruits and their products by antagonistic yeasts.