Dinotefuran exposure alters biochemical, metabolomic, gut microbiome, and growth responses in decapoda pacific white shrimp Penaeus vannamei

Dinotefuran, a neonicotinoid insecticide, may impact nontarget organisms such as Decapoda P. vannamei shrimp with nervous systems similar to insects. Exposing shrimp to low dinotefuran concentrations (6, 60, and 600 μg/L) for 21 days affected growth, hepatosomatic index, and survival. Biomarkers erythromycin-N-demethylase, alanine aminotransferase, and catalase increased in all exposed groups, while glutathione S-transferase is the opposite; aminopyrin-N-demethylase, malondialdehyde, and aspartate aminotransferase increased at 60 and 600 μg/L. Concentration-dependent effects on gut microbiota altered the abundance of bacterial groups, increased potentially pathogenic and oxidative stress-resistant phenotypes, and decreased biofilm formation. Gram-positive/negative microbiota changed significantly. Metabolite differences between the exposed and control groups were identified using mass spectrometry and KEGG pathway enrichment. N-acetylcystathionine showed potential as a reliable dinotefuran metabolic marker. Weighted correlation network analysis (WGCNA) results indicated high connectivity of cruecdysone in the metabolite network and significant enrichment at 600 μg/L dinotefuran. The WGCNA results revealed a highly significant negative correlation between two key metabolites, caldine and indican, and the gut microbiota within co-expression modules. Overall, the risk of dinotefuran exposure to non-target organisms in aquatic environments still requires further attention.

Toxic effect of chronic waterborne copper exposure on growth, immunity, anti-oxidative capacity and gut microbiota of Pacific white shrimp Litopenaeus vannamei

Copper can be accumulated in water through excessive sewage discharge or residual algaecide to generate toxic effect to aquatic animals. In this study, the juvenile of Pacific white shrimp, Litopenaeus vannamei was exposed to 0 (control), 0.05, 0.1, 0.2, 0.5 or 1 mg Cu²⁺ L^-1 for 30 days. Growth, immune function, anti-oxidative status and gut microbiota were evaluated. Weight gain and specific growth rate of L. vannamei were significantly decreased with the increase of ambient Cu²⁺. Enlarged lumen and ruptured cells were found in the hepatopancreas of shrimp in the 0.5 or 1 mg Cu²⁺ L^-1 treatment. Total hemocyte counts of shrimp in 0.5 or 1 mg Cu²⁺ L^-1 were significantly lower than in the control. The hemocyanin concentration was also significantly increased in 0.2 or 0.5 mg Cu²⁺ L^-1. Lysozyme contents were reduced in shrimp when Cu²⁺ exceeded 0.2 mg L^-1. Meanwhile, activities of superoxide dismutase and glutathione peroxidase were increased in the hepatopancreas and the activity of Na⁺-K⁺ ATPase was decreased in the gills with increasing Cu²⁺. The mRNA expressions of immune deficiency, toll-like receptor and caspase-3 were all significantly higher in the hepatopancreas in 0.05 mg Cu²⁺ L^-1 than in the control. For the diversity of intestinal microbes, Bacteroidetes significantly decreased in 1 mg Cu²⁺ L^-1 at the phylum level. KEGG pathway analysis demonstrates that 1 mg L^-1 Cu²⁺ can significantly alter metabolism, cellular processes and environmental information processing. This study indicates that the concentration of 1 mg L^-1 Cu can negatively impact growth, hemolymph immunity, anti-oxidative capacity and gut microbiota composition of L. vannamei.

Aliiroseovarius pelagivivens gen. nov., sp. nov., isolated from seawater, and reclassification of three species of the genus Roseovarius as Aliiroseovarius crassostreae comb. nov., Aliiroseovarius halocynthiae comb. nov. and Aliiroseovarius sediminilitoris comb. nov

A Gram-stain-negative, non-motile, aerobic and ovoid or rod-shaped bacterium, designated GYSW-22T, was isolated from seawater off Geoje Island in the South Sea, South Korea. Strain GYSW-22T grew optimally at 25 °C, at pH 7.0–8.0 and in the presence of 1.0–2.0 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences showed that strain GYSW-22T and the type strains of Roseovarius crassostreae, Roseovarius halocynthiae and Roseovarius sediminilitoris form a coherent cluster, independent of phylogenetic lineages or clusters comprising the type strains of other species of the genus Roseovarius. Strain GYSW-22T exhibited 16S rRNA gene sequence similarities of 97.2, 96.6 and 96.3 % to R. halocynthiae MA1-10T, R. crassostreae CV919-312T and R. sediminilitoris M-M10T, respectively, and of 92.6–94.7 % to the type strains of other species of the genus Roseovarius. Strain GYSW-22T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The major polar lipids were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain GYSW-22T was 59.0 mol% and its mean DNA–DNA relatedness value with R. halocynthiae MA1-10T was 15 %. On the basis of the data presented, we propose strain GYSW-22T represents a novel species of a new genus, Aliiroseovarius pelagivivens gen. nov., sp. nov. The type strain of the type species is GYSW-22T ( = KCTC 42459T = CECT 8811T). In this study, it is also proposed that Roseovarius crassostreae, Roseovarius halocynthiae and Roseovarius sediminilitoris be reclassified into the new genus as Aliiroseovarius crassostreae comb. nov. (type strain CV919-312T = ATCC BAA-1102T = DSM 16950T), Aliiroseovarius halocynthiae comb. nov. (type strain MA1-10T = KCTC 23462T = CCUG 60745T) and Aliiroseovarius sediminilitoris comb. nov. (type strain M-M10T = KCTC 23959T = CCUG 62413T), respectively.