Shrimp farming is considered a fundamental activity in food security programs in many countries. White shrimp (Litopenaeus
vannamei ) is one of the most cultivated species worldwide. One of the alternatives to reduce the problem of diseases caused by vibrios and increase sustainability in the aquaculture sector is the use of probiotic bacteria.
Therefore, the objective of the present investigation was to evaluate the growth, survival and immune system challenged with Vibrio parahaemolyticus IPNGVE 16 in L . vannamei . 50 µL of B. licheniformis were inoculated in 100 mL of trypticasein soy broth at 2.5% NaCl and the culture was incubated for 72h at 32ºC. The microcapsules of B.
licheniformis were obtained by the spray-drying method using maltodextrin (15%) as an enveloping material, which were added to commercial feed as an additive. Shrimp (L. vannamei ) were collected in commercial postlarvae laboratories in the state of Sinaloa.
The shrimp were transported to the CIIDIR-IPN Aquaculture Laboratory. Shrimp of 40-60 mg were used in tubs (20 L) with 10 L of filtered seawater (20 µm), at 30 ‰ salinity, constant aeration and fed twice a day. The bioassay lasted 36 d and consisted of 4 treatments (triplicate), I): Negative control, Commercial feed (AC); II): AC + microencapsulated B. licheniformis (1.0 g/kg of food), III): AC + microencapsulated B.
licheniformis (2.0 g/kg of food), IV): AC + microencapsulated B. licheniformis (3.0 g/kg feed). For the expression of the immune system, the activity of prophenoloxidase , intracellular superoxide anion concentration and hemocyte count were determined.
The LD50 was 780,000 CFU/mL. Regarding growth, it was observed that the TII (2.08 ± 0.083g) presented the highest growth with respect to the control (1.94 ±0.083 g), there were no significant differences (P > 0.05). Survival after challenge with V.
parahaemolitycus was: Control (52.38%), TII (47.61%), TIII (76.19%) and TIV (76.19%). Being the TIII and TIV where the highest survival was presented (Fig. 1).
For the hemocyte count, TI (positive control) was presented with 2.039 x 106 ± 0.31 x 106
hemocytes/mL, T II with 1.84 x 106 ± 0.17 x 106
hemocytes/mL, T III with 1.72 x 106 ± 0.22 x 10 6 hemocytes/mL, T IV with 1.49 x106 ± 0.30 x 106
hemocytes/mL.
The generation of intracellular superoxide anion, the activity of prophenoloxidase and phenoloxidase in the treatments did not present significant differences between the treatments with respect to the control (P > 0.05).