Microbial community analysis of water, foregut, and hindgut during growth of Pacific white shrimp, Litopenaeus vannamei, in closed-system aquaculture

In closed recirculating systems, a particulate matter consisting of bacteria, algae, fungi, and detritus develops spontaneously. This microbial floc can serve as a high-protein food source for finfish and shellfish and has the potential to supplement the protein required in shrimp feed. To advance the use of microbial floc as a feed supplement, it is necessary to manipulate its microbial components, which requires thorough characterization of the bacterial components. Pacific white shrimp, Litopenaeus vannamei, were raised in a closed recirculating system, and water was compared to the contents of shrimp foreguts and hindguts. Water consistently contained less microbial biomass than did shrimp guts, but 16S rDNA sequences indicated that water was more diverse than shrimp guts. Phylogenetic analysis of 16S rDNA sequences retrieved from water and shrimp foregut grouped these sequences into various unrelated generic clusters. Fatty acid analysis demonstrated that shrimp feed was not a major contributor of microbial fatty acids to shrimp tanks, as the feed mostly contained polyunsaturated fatty acids, which are typically found only in eukaryotes. It is hoped that elucidating more details about the various components of microbial floc will help in understanding its development and will lead to its use as a high-protein feed supplement.