The Antagonistic Effect of 2-Phenylethanol Produced by Serratia liquefaciens Strain JS-239 Against Botrytis cinerea.

Botrytis cinerea is a necrotrophic fungal pathogen responsible for gray mold diseases in economically significant crops. Although conventional fungicides are commonly used to control these diseases, they pose environmental hazards, such as soil and water contamination, harm to nontarget organisms, and ecosystem disruption. Additionally, overuse promotes the development of fungicide-resistant strains, reducing their efficacy. Consequently, finding sustainable alternatives is essential for agriculture. In this study, strain JS-239 was isolated from the Northern Unit of Kettle Moraine State Forest, Wisconsin. Dual-culture plate assays and bioactivity tests using crude metabolites from JS-239 demonstrated strong inhibition against B. cinerea. Phylogenetic analysis based on 16S rRNA and four housekeeping genes identified JS-239 as Serratia liquefaciens. Flash chromatography with a silica gel column was used to fractionate an ethyl acetate extract of the JS-239 culture, with bioactivity assays identifying fraction 34 as the most effective against B. cinerea. Gas chromatography-mass spectrometry revealed the active antifungal compound to be 2-phenylethanol. Control assays on pre- and postharvest gray mold in strawberries showed that 2-phenylethanol significantly reduced disease severity. This is the first report of S. liquefaciens producing the metabolite 2-phenylethanol.