Interception of quorum sensing signal molecule by furanone to enhance shelf life of fermented milk

Fermented milk prepared by culturing the probiotic culture Leuconostoc mesenteroides, is a nutritious drink but at the same time a large number of spoilage microorganisms can grow in it when stored for a long time. The spoilage bacterial cultures are known to communicate with each other by release of signaling molecule which is described as quorum sensing. In the present work, the predominant bacterial culture, Pseudomonas was found to be responsible for spoiling the fermented milk. The signal molecule was identified as hexanoyl homoserine lactone by TLC, GC, and GCMS method. Two furanones namely 2(5H)-furanone and bromofuranone were used to reduce the virulence of Pseudomonas sp. Results showed that 2(5H)-furanone has inhibitory activity against Pseudomonas. This was supported with data of reduced motility, reduced acyl homoserine lactone (HHSL and BHSL), low rhamnolipid content and reduced exoprotease activity of Pseudomonas sp. when furanone was supplemented. With addition of 2(5H)-furanones the shelf life was increased up to 9 days by reducing the spoilage bacterial cultures.