Ating Yuniarti, Maftuch, Soemarno, Aulanni’am
Faculty of Agriculture, University of Brawijaya, Malang, Indonesia
Faculty of Fisheries and Marine Science, University of Brawijaya, Malang, Indonesia
Laboratory of Biochemistry, University of Brawijaya, Malang, Indonesia
Key words: Biocontrol, penaeid, quorum sensing, quorum quenching, vibrio.
Vibriosis caused by Vibrio harveyi is still a bottleneck for the development of shrimp culture industry. As quorum sensing (QS) regulates the virulence of V. harveyi, interference of QS might offer opportunity for controling V. harveyi in shrimp culture. The aim of this study was to evaluate the ability of AHL-degrading Bacillus to interfere with the AHL production and the growth of V. harveyi in vitro and in vivo on Penaeus monodon larvae. Based on biochemical and molecular study, the AHL-degrading Bacillus was confirmed as B. subtilis STC. The results showed that AHL-degrading Bacillus affected (P<0.05) the Total Bacterial Count (TBC) and Total Vibrio Count (TVC) within 24 and 48 hours in in-vitro and in-vivo study. The higher the B. subtilis STC was added, the less concentration of viable Vibrio cells in the system. The AHL concentration in in-vitro study were significantly different (P<0.05) between treated group and control. Meanwhile, the AHL concentrations in P. monodon culture were found the same (P>0.05) in all treatments. Yet, there was a trend that the higher of B. subtilis STC given, the smaller number of AHL available in the system. The survival rates of P. monodon larvae were significantly different (P<0.05) among treatments. The use of AHL-degrading bacteria, B. subtilis STC, at the concentration of 1×106 CFU.ml-1 improved the survival rate of P. monodon larvae up to 65.56% when infected by V. harveyi. Therefore, this AHL-degrading bacteria could be used as biocontrol agent against vibriosis in P. monodon larvae culture.