Establecimiento de bacterias benéficas en el tracto digestivo y gónada de adultos de Argopecten purpuratus (Lamarck 1819) en cultivo masivo

Abstract

The objective of the present study was to evaluate the feasibility of establishing beneficial (probiotic) bacterial strains 11, C33, and 77 in the digestive tracts of broodstock of the scallop Argopecten purpuratus. Colonization of digestive tract and gonad in the scallops was attempted by feeding them with mix culture of Isochrysis galbana and the benefical bacterial strains. The study was carried out in three experimental stages :1) "in vitro" testing evaluated ingestion of the beneficial bacteria by the scallops; 2) pilot assays in tanks of 200 L and 3) large (production) scale assays in 2000 L commercial culture tanks. Results of ingestion of bacteria by adult A. purpuratus showed 92% ingestion of strains 11 and C33 (P<0.05). Evaluation of colonization of the digestive tract in specimens fed with a diet of I. galbana associated with strains 11, C33, and 77 (Bacterial Probiotic Mixture MBP) showed only the presence of strain 11 (41.8%). Analysis of histological sections showed that scallops exposed to MBP treatment showed large numbers of bacteria adhered to microvilli in the digestive tract. The results of the large scale assays showed settlement of bacterial strain 11 in all specimens fed with the MBP diet, in numbers fluctuating between 34.12 and 75.64 UFC g-1. Similarly, gonadal colonization was detected in scallops examined by means of traditional plate cultures. The results allow the conclusion that it is feasible to use the microalgae as a vector for the introduction of probiotic bacterial strain 11 into the digestive gland and gonad of A. purpuratus. Also. addition of these bacteria did not cause deleterious effects on survival of these broodstock.