High-resolution detection of bacterial profile of ocean water, before and after being used by shrimp farms

Bacterial diversity was evaluated in ocean water by next-generation sequencing (16S rRNA gene, V3/V4 regions) before and after being used by several shrimp farms with an operative capacity of >500 Ha and biomass producing of 3.5 t/Ha. A total of 22 bacteria species were identified in water before being incorporated into farm facilities; of these, Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria resulted to be the most abundant phyla. After being used by shrimp farms, water decreased in quality (high concentrations of organic matter and nitrogenous metabolites) and the bacterial profile was modified in the outlet channel (effluent). Herein, beta diversity revealed changes in the bacterial profile of inlet and outlet water; for instance, different bacteria were detected de novo (some non-indigenous) and other were no longer detected; a total of 16 species (5 de novo) were registered in the effluent and Cyanobacteria, Actinobacteria, Proteobacteria, and Planctomycetes were the most abundant phyla. Many of the species thriving in the effluent resulted to be associated to the decomposition and recycling of organic matter and nitrogenous compounds. The farms acted as bioreactors favoring bacteria other than those detected in the inlet channel.