RESUMO
Acute hepatopancreatic necrosis (AHPND) is a severe bacterial disease affecting farmed shrimp. Although various pathogenic bacteria associated with AHPND-affected shrimp have been described, little is known about the bacterial signatures in the stomachs and intestines when the disease occurs naturally. In this study, we characterized the microbiome of P. vannamei by high-throughput sequencing (HTS). Shrimp samples were collected from a commercial farm and divided into two groups: healthy and affected by AHPND, confirmed by PCR. Stomach and intestine samples were subjected to microbiome analysis targeting the V3-V4 region of the 16S rRNA gene. PERMANOVA analysis revealed a significant disparity in the bacterial diversity between the stomach and intestine microbiomes of these two health conditions. Our results suggest that the significant abundance of Vibrio brasiliensis and V. sinaloensis in the intestines of affected shrimp plays a role in AHPND infection. This imbalance could be mitigated by the presence of Pseudoalteromonas, Gilvimarinus, and other members of the phylum Pseudomonadota such as Cellvibrionaceae, Psychromonadaceae, and Halieaceae, which showed significant abundance in healthy intestines. This study highlights the significance of the microbial community in the differentiation of specific microbial signatures in different organs of P. vannamei. These findings offer a deeper understanding of the intricate dynamics within the shrimp microbiome under these conditions, enriching our view of AHPND progression and paving the way toward future identification of probiotics tailored for more efficient management of this disease.
RESUMO
Vibriosis is caused by some pathogenic Vibrio and produces significant mortality in Pacific white shrimp Penaeus (Litopenaeus) vannamei larvae in commercial hatcheries. Acute hepatopancreatic necrosis disease (AHPND) is an emerging vibriosis affecting shrimp-producing countries worldwide. Zoea 2 syndrome is another type of vibriosis that affects the early stages of P. vannamei larvae. Although the pathogenesis of AHPND and zoea 2 syndrome is well known, there is scarce information about microbial composition and biomarkers of P.vannamei larvae affected by AHPND, and there is no study of the microbiome of larvae affected by zoea 2 syndrome. In this work, we characterized the microbiome of P. vannamei larvae collected from 12 commercial hatchery tanks by high-throughput sequencing. Seven tanks were affected by AHPND, and five tanks were affected by zoea 2 syndrome. Subsequently, all samples were selected for sequencing of the V3-V4 region of the16S rRNA gene. Similarity analysis using the beta diversity index revealed significant differences in the larval bacterial communities between disease conditions, particularly when Vibrio was analyzed. Linear discriminant analysis with effect size determined specific microbial signatures for AHPND and zoea 2 syndrome. Sneathiella, Cyclobacterium, Haliea, Lewinella, among other genera, were abundant in AHPND-affected larvae. Meanwhile, Vibrio, Spongiimonas, Meridianimaribacter, Tenacibaculum, among other genera, were significantly abundant in larvae affected by zoea 2 syndrome. The bacterial network at the phylum level for larvae collected from tanks affected by AHPND showed greater complexity and connectivity than in samples collected from tanks affected by zoea 2 syndrome. The bacterial connections inter Vibrio genera were higher in larvae from tanks affected by zoea 2 syndrome, also presenting other connections between the genera Vibrio and Catenococcus. The identification of specific biomarkers found in this study could be useful for understanding the microbial dynamics during different types of vibriosis.