Chemical signaling in the microbial world facilitates the regulation of gene expression as a function of cell population density. This is especially true for the Gram-negative bacterial signal N-acyl homoserine lactone (AHL). Lactonases that deactivate AHLs have attracted a lot of attention because of their antibacterial potential. However, the involvement of these enzymes in inhibiting fungal pathogens and the potential role of these enzymes in bacterial-fungal interactions are unknown. Here, we find that a bacterial enzyme involved in the degradation of AHLs is also induced by and degrades the fungal lactone mycotoxin, patulin. This work supports the potential use of bacterial enzymes and/or the producing bacteria in controlling the post-harvest fruit disease caused by the patulin-producing fungus Penicillium expansum.