The ingestion of microplastics affects the diversity of the gut microbiome and testicular development in Japanese quail

Five Japanese quail Coturnix japonica were administered with powdered microplastics (MPs, test group) while five quail did not receive MPs (control group) to investigate the effect of MPs on gut microbiota. In the MP administration, a powdered form of commercially available polystyrene was mixed with sterile water and orally delivered to the quail's proventriculus using a syringe. After the experiments, all 10 quail were euthanized and dissected to measure the weight of each organ and collect samples. A next-generation sequencing analysis based on the 16S rRNA gene was conducted using DNA extracted from pellets of gut fluid samples to investigate gut microbe diversity. A canonical correspondence analysis using the next-generation sequencing data was conducted to examine the correlation between visceral weight changes induced by MP exposure and alterations in the gut microbiome diversity. The dominant bacterial families showed no significant correlation with gut and testis weights in the test group. However, a correlation was inferred between distinct dominant bacterial families and gut and testis weights in the control group, which differed from those observed in the experimental group. Although the underlying cause of gut microbiota changes due to MP ingestion remains to be elucidated, MP ingestion was demonstrated to have some effect on quail gut microbiota and testis.