Exploration of bacteria associated with Nudibranchs to control Vibrio spp.

Abstract

Shrimp culture process of Litopenaeus vannamei could not be separated from the disease threats. Vibriosis is the main cause of a decrease in aquaculture production. Vibrio harveyi is a pathogenic bacteria that can caused high mortality and Vibro parahaemolyticus can also cause massive financial losses in shrimp culture. The use of antibiotics to control vibriosis, however, has a negative impact. For example, it resulted in the shrimp resistance to pathogenic bacteria. The potential of bacteria that are symbiotic with nudibranchs as anti Vibrio spp. has not been reported yet. The aim of this experiment was to examine the presence of bacterial symbiont in a nudibranch to inhibit or stop the growth of V. harveyi. Antibacterial activity test was done by the overlay method. The tested pathogenic bacteria were used V. harveyi and V. parahaemolyticus. Then the active bacteria were identified by morphological and molecular using 16S rRNA gene sequence. Isolation of bacterial symbiont in Nudibranch revealed 144 isolates. From those isolates only one isolate (SM-N-3(2)/7) was identified as having the ability against V.harveyi and V. parahaemolyticus. The isolate was gram negative rod bacteria. Based in molecular identification using 16S rRNA it was closely related to Pseudoalteromonas piscicida strain NBRC (99%).