Histopathological and intestinal microbial changes in crayfish (Procambarus clarkii) after exposure to polyethylene nanoparticles (PE-NPS) and their remediation by Spirulina platensis

Nanoplastics (NPs) pass through biological barriers and bioaccumulate, negatively affecting cell morphology and function. Therefore, this work investigated the remediation potential of Spirulina platensis in mitigating the harmful effects of polyethylene nanoparticles (PE-NP) on Procambarus clarkii, with emphasis on histopathological alterations and changes in intestinal microbiota. The crayfish individuals were allocated into four groups: Groupe 1: control, Groupe 2: PE-NP (10 mg/L), Groupe 3: PE-NP (10 mg/L) + S. platensis (2.5 and 5.0 g/kg diet), and Groupe 4: S. platensis (2.5 and 5.0 g/kg diet). After 14 days, PE-NPs treatment induced notable histopathological alterations, including cell disarrangement and swelling, as well as evident vacuolization in the cells of the digestive duct. Conversely, co-administration of S. platensis in group three has indicated rearrangement of epithelial cells and a decrease in the number of vacuoles in the gastrointestinal system. In microbial analysis, molecular and morphological identification methods were employed, revealing the presence of five fungal genera (comprising ten fungal species) and four bacterial species in the experimental treatments. Fungal isolates HAG1 and HAG2 exhibited 99.67 % to 100 % identity, and 96 % to 100 % coverage with multiple strains of the same species; On the other hand, bacterial isolate HAG3 showed 99.22 % to 100 % identity and 98 % to 100 % coverage with similar strains. In conclusion, S. platensis effectively alleviated the toxic effects of PE-NPs on crayfish digestive and microbial systems, although the ability of PE-NP to penetrate the crayfish tissue caused histological damage and defects in the intestinal microbial system.