Metagenomics in bioflocs and their effects on gut microbiome and immune responses in Pacific white shrimp. Issue 106 (November 2020)

• Record Type: Journal Article
• Authors: Tepaamorndech, Surapun; Nookaew, Intawat; Higdon, Shawn M.; Santiyanont, Pannita; Phromson, Metavee; Chantarasakha, Kanittha; Mhuantong, Wuttichai; Plengvidhya, Vetthachai; Visessanguan, Wonnop
• Is Part Of: Fish & shellfish immunology. Issue 106(2020)
• Page Start: 733
• Page End: 741
• Publication Date: 2020-11
• Subjects: Metagenomics -- Bioflocs -- Pacific white shrimp -- Gut microbiome -- And immunity; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2020.08.042
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Biofloc systems generate and accumulate microbial aggregates known as bioflocs. The presence of bioflocs has been shown to change gut bacterial diversity and stimulate innate immunity in shrimp. The microbial niche of bioflocs may therefore have the potential to drive shifts in the shrimp gut microbiota associated with stimulation of innate immunity. We performed shotgun metagenomic analysis and 16S rRNA-based amplicon sequencing to characterize complex bacterial members in bioflocs and the shrimp digestive tract, respectively. Moreover, we determined whether biofloc-grown shrimp with discrete gut microbiomes had an elevation in local immune-related gene expression and systemic immune activities. Our findings demonstrated that the bacterial community in bioflocs changed dynamically during Pacific white shrimp cultivation. Metagenomic analysis revealed that Vibrio comprised 90% of the biofloc population, while Pseualteromonas, Photobacterium, Shewanella, Alteromonas, Bacillus, Lactobacillus, Acinetobacter, Clostridium, Marinifilum, and Pseudomonas were also detected. In the digestive tract, biofloc-grown shrimp maintained the presence of commensal bacteria including Vibrio, Photobacterium, Shewanella, Granulosicoccus, and Ruegeria similar to control shrimp. However, Vibrio and Photobacterium were significantly enriched and declined, respectively, in biofloc-grown shrimp. The presence of bioflocs upregulated immune-related genes encoding serine proteinase and prophenoloxidase in digestive organs which are routinely exposed to gut microbiota. Biofloc-grown shrimp also demonstrated a significant increase in systemic immune status. As a result, the survival rate of biofloc-grown shrimp was substantially higher than that of the control shrimp. Our findings suggested that the high relative abundance of vibrios in bioflocs enriched the number of vibrios in the digestive tract of biofloc-grown shrimp. This shift in gut microbiota composition may be partially responsible for local upregulation of immune-related gene expression in digestive organs and systemic promotion of immune status in circulating hemolymph. Highlights: Bacterial community in bioflocs dynamically changed during Pacific white shrimp cultivation. Metagenomic analysis revealed that Vibrio was the major bacterial population in bioflocs. Bioflocs maintained the presence of shrimp gut bacteria, but shifted the bacterial proportions. Alteration of gut microbiome was associated with promotion of both local and systemic immunity.