The effect of Lactobacillus plantarum administration on the intestinal microbiota of whiteleg shrimp Penaeus vannamei

Along with the intensification of culture systems to meet the increasing global demands, there is an elevated risk of disease outbreak and substantial loss for shrimp farmers. Probiotics, e.g., Lactobacillus plantarum, are among the most promising feed supplements for controlling or treating microbial diseases in shrimp aquaculture. The maintenance of live and viable probiotic bacterial culture during storage is, however, quite challenging. This study investigated the paraprobiotic potential of L. plantarum on whiteleg shrimp (Penaeus vannamei), specifically on the intestinal microbiota. Four different experimental diet preparations of L. plantarum (fermentation supernatant (FS), live bacteria (LB), dead bacteria (DB), and cell-free extract (CE)) were used in the 15-day feeding trial. Subsequently, 16S rDNA gene sequencing technology was applied to analyze and characterize the whiteleg shrimp intestinal microbiota. Results showed that Proteobacteria was the most prevalent phylum in whiteleg shrimp gut microbiota, independent of the diet. Other phyla, including Bacteroidetes, Verrucomicrobia, Tenericutes, and Euryarchaeota were also recorded and independent of the diet. The microbiota of the whiteleg shrimp fed with the L. plantarum CE diet showed the highest abundance of Acidobacteria, with a 70-fold increase compared to that of the animals on the control diet. The abundance of Verrucomicrobia was the highest in the whiteleg shrimp fed with L. plantarum DB diet. Moreover, the abundance of Cyanobacteria, Crenarcheota, and Euryarchaeota in the microbiota of animals fed with L. plantarum FS diet were more than 10-fold higher, compared to that of the whiteleg shrimp fed with the control diet. An increased number of the potential beneficial bacteria from the genera Demequina, Rubritalea, Tenacibaculum, Marinicella and Phaeobacter versus a significantly decreased amount of the potential pathogenic genus Synechococcus were encountered in the microbiota of the CE diet-fed animals. There were 382 operational taxonomic units (OTUs) shared among all gut samples. The microbiota of the shrimps on the CE diet had the most unique OTUs, followed by those included in the FS and DB diet groups. These results demonstrated that P. vannamei fed with L. plantarum CE and FS diets had a significantly altered gastrointestinal microbiota. In conclusion, L. plantarum CE and FS diets have the potential to be used as paraprobiotics, due to the capacity to positively modulate the gastrointestinal microbiota in P. vannamei.