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

Abstract

Aeromonas hydrophila is pathogenic bacteria in fish. One of its virulence factors is exoprotease. The production of exoprotease is controlled by a quorum sensing system. Quorum sensing is an intercellular communication of bacteria that using a signal molecule of C4-HSL. The exoprotease production of A. hydrophila can be blocked by 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 that predicted as quorum sensing inhibitors and act as C4-HSL analog molecules were furanone from tomato fruits. The inhibition of quorum sensing of A. hydrophila could be shown by a reduction of exoprotease production. The aim of this research was 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 had no effect on 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 affect A. hydrophilla growth. The quantitative exoprotease assay result showed that 4% of methanol extract could inhibit exoprotease production by 71.68% without affect the growth of A. hydrophila.