Phage preparation FBL1 prevents Bacillus licheniformis biofilm, bacterium responsible for the mortality of the Pacific White Shrimp Litopenaeus vannamei

Abstract

Recurrent outbreaks of Bacillus licheniformis strain 52 caused high mortality on juvenile and reproducers of the Pacific White Shrimp Litopenaeus vannamei breeders, in a maturation facility in Colombia. This recurrence led to the suspicion of a permanent contamination source within the tanks. It was hypothesized that biofilms could be that source, but there were no previous reports on the ability of B. licheniformis to form biofilms. Consequently, we tested for the biofilm formation capacity of the bacterium. Using a novel method, a complex biofilm was obtained. Then, phage therapy was assayed as an alternative to control the biofilm. The best outcome was obtained when bacteria and phage preparation FBL1 were inoculated simultaneously, resulting in a 44.77% reduction of the biofilm. Our data indicated that the reduction was probably due to a diminished initial inoculum caused by the phage, instead of the removal of the formed biofilm. This work provides new information that contributes to the understanding of the outbreaks caused by the pathogenic strain 52 in aquaculture systems, and presents promising data supporting the future use of phage therapy.