Reduction of exoprotease production in Aeromonas hydrophila by tomato fruits extract (Lycopersicon esculentum Mill.)

Abstract

Abstract. Aeromonas hydrophila is pathogenic bacteria in fish. One of its virulence factors is exoprotease. A quorum-sensing system controls the production of exoprotease. Quorum sensing is an intercellular communication of bacteria using a signal molecule of C4-HSL. The exoprotease production of A. hydrophila can be blocked using quorum sensing inhibitors. The inhibition of quorum sensing of A. hydrophila can be conducted by C4-HSL analogs molecules. In this research, the molecules predicted as quorum sensing inhibitors and act as C4-HSL analog molecules were furanone from tomato fruits. The inhibition of the quorum sensing of A. hydrophila could be shown by reducing exoprotease production. This research aimed to determine the reduction of exoprotease production of A. hydrophila by extracts of n-hexane, ethyl acetate, and methanol of tomato fruits with the concentrations of 0%, 2%, 4%, 6%, and 8%, respectively. The qualitative exoprotease assay result showed that n-hexane extract of tomato did not affect growth and exoprotease production of A. hydrophila. As much as 4% of ethyl acetate extract of tomato fruits could inhibit exoprotease production but affect A. hydrophilla growth. Meanwhile, 4% methanol extract of tomato fruits could inhibit exoprotease production without affecting A. hydrophilla growth. The quantitative exoprotease assay result showed that 4% of methanol extract could inhibit exoprotease production by 71.68% without affecting the growth of A. hydrophila.