Figure 2.

Determination of optimal conditions to produce L. casei-immunized H. illucens larvae (HIL) with highest antimicrobial activity. (A) Evaluation of antimicrobial activities at different L. casei concentrations. We infected HIL with 10¹ to 10⁹ cfu/mL of L. casei to determine the optimal concentration for the mass production of AMPs. The activity in L. casei-immunized HIL hemolymph increased in a concentration-dependent manner. The values of column graphs are presented as the mean ± S.D. (B) Evaluation of antimicrobial activities at different incubation times after L. casei infection. Highest hemolymph activity of L. casei-immunized HIL occurred at 24 h. (C) Assessment of HiCec1 and HiDef1 mRNA expressions. HiCec1 and HiDef1 gene expressions in L. casei-immunized HIL hemolymph were evaluated at 2, 4, 8, 16, 24, 48 and 72 h after infection. (A,B) Radial diffusion assay (RDA) was performed with E. coli. (B,C) The values of column graphs are presented as the mean ± S.D. *, **, ***, # and ## indicate p < 0.05, p < 0.01, p < 0.005, p < 0.001 and p < 0.00001 vs. normal control (N), respectively.