Uso de bacteriófagos para reducir la carga de vibrios en postlarvas de camarón blanco (litopenaeus vannamei)

Abstract

The present study evaluated the efficacy of a commercial bacteriophage in reducing the bacterial load of Vibrio spp. in white shrimp (Litopenaeus vannamei) postlarvae cultured under two salinity conditions: 20 and 30 ups. Two salinity treatments were used: one with application of the bacteriophage (9mL/kg of feed) and the other without application, for a period of 15 days. Bacterial load, growth, survival and physiological state of the postlarvae were evaluated. The results showed a remarkable reduction of Vibrio parahaemolyticus in the treated groups. At 20 ups, the bacterial load decreased from 1,855,333 to 46,333 CFU/gH (97.5% reduction), while at 30 ups it went from 1,833,667 to 16,800 CFU/gH (99.1% reduction). Growth also improved: at 20 ups, the mean weight was 0.2095 g with bacteriophage versus 0.1080 g without treatment. At 30 ups, treated postlarvae reached 0.2089 g versus 0.1914 g in the control. Survival increased slightly at 20 ups with respect to the control 89% and numerical difference at 30 ups (81% to 94%). In addition, a visible physiological recovery was observed in the treated organisms: improved swimming activity, increased feed consumption, reduction of abnormal pigmentation and clinical signs. Efficacy was more evident at 30 ups, suggesting that this salinity favors the action of the bacteriophage and the recovery of health in infected postlarvae.