PLA PHB Daphnia transcripto

The impact of bioplastic particles, specifically poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB), on the feeding and behavioural responses, gut microbiome and cephalic transcription of Daphnia magna was investigated. D. magna juveniles were exposed for 72 h to microparticles of two bioplastics, PHB and PLA, at two concentrations (high: 150 mg/L, low: 1.5 mg/L), along with kaolin and control groups, and under starvation conditions. Exposure to high concentrations of PLA and PHB microparticles significantly inhibited feeding and impacted various behavioural responses in D. magna, resembling effects observed under starvation. Microbiome analysis revealed notable shifts in taxonomic composition and functional profiles. Specifically, PLA and PHB microparticle treatments reduced key bacteria like Limnohabitans and increased relative abundance of Enterobacterales (Aeromonas) and Pseudomonadales (Pseudomonas and Acinetobacter) in gut microbiome. Transcriptomic analysis revealed that both PLA microparticles and starvation enhanced catabolic processes related to energy acquisition from sources other than food, while microplastics up-regulated neurological pathways, cell turnover, and differentiation. In contrast, starvation down-regulated these pathways. These transcriptomic responses are likely associated to functional changes in the gut microbiome. Exposure to microplastics resulted in decreased biosynthesis of short-chain fatty acids in the gut, altered neurological pathways in the brain and disrupted behavioural responses, altogether supporting the importance of the microbiota-gut-brain crosstalk