Effects of Bacillus licheniformis on the bacterial communities in shrimp zero-water exchange aquaculture system

The effects of Bacillus licheniformis on immune response, disease resistance, and nutrition for the Penaeus vannamei have been extensively studied, but little is known about the effects in intestinal and environmental microbial communities under the zero-water exchange aquaculture system. The effect of Bacillus licheniformis can probably be achieved by influencing the bacterial community of intestinal and environmental. To test this hypothesis, we used 16S rRNA gene amplicon sequencing to investigate both intestinal and environmental bacterial composition in shrimp zero-water exchange aquaculture system after add Bacillus licheniformis to feed or water applied. First of all, shrimp intestinal microbiota had a close correlation to the ambient microbiota in the zero-water exchange aquaculture system. The main phylum is Planctomycetes and Proteobacteria, but their proportion differs greatly in different environments. Then there was significant impact on the abundance of Chlamydia in the intestine and water after adding Bacillus licheniformis to water or feed; while at the genus level, it significantly changes the abundance of Planctomicrobium and Pir4_lineage in the intestinal and sediment. Finally, the results showed that the addition of Bacillus licheniformis to feed and water changed the related pathways, for example, Digestive System, but the change trend was opposite. These above results may be helpful to comprehensively understand the changes in shrimp intestines and environment after Bacillus licheniformis is added through feed and water in the zero-water exchange aquaculture system, thereby providing basic information for choosing the right probiotics and how to add them to sustain shrimp health.