The curative action of Lactobacillus plantarum FNCC 226 to Saprolegnia parasitica A3 on catfish (Pangasius hypophthalamus Sauvage)

The inhibition of the growth of the parasitic S. parasitica A3 on catfish using L. plantarum FNCC 226 in vivo and in vitro, were examined in this study. To prevent fungal proliferation, different concentration of S. parasitica A3 were employed in a two step approach: to determine the concentration of zoospore suspension count that caused a 50% infection on catfish and concentration of L. plantarum FNCC 226 that inhibits the growth of the S. parasitica A3 on catfish. The design use was the Completely Randomized Design with 4 x4 factorial pattern consisting of 4 infection concentration of S. parasitica A3 suspensions, i.e. 0xIC50, IC50 (Infectious Concentration 50%), 2xIC50, and 4xIC50 and 4 concentrations of L. plantarum FNCC 226 inoculums, i.e. MaxNLC (Maximal Nir Lethal Concentration), ½xMaxNLC, ¼xMaxNLC, and 0xMaxNLC, with 4 times replication. The results obtained showed that the IC50 count for a 50% infectious was 1 x 10^7 zoospore/mL and were dose dependent. L. plantarum FNCC 226 inhibit mycelium of S. parasitica A3 were found to be 7.7 x 10^5 cfu/mL (MaxNLC), 4.0 x 10^5 cfu/mL (½xMaxNLC) and 2.3 x 105 cfu/mL (¼xMaxNLC) and were dependent on the initial number of the infectious S. parasitica A3. The decrement of S. parasitica A3 infection coincide with the increment of L. plantarum FNCC 226 blocked. Thus, this study indicated that L. plantarum has the capacity to inhibit S. parasitica and it would be possible to design new biocontrol of this pathogen in catfish.