Comparative analysis of gut bacterial community composition during a single day cycle in Chinese mitten crab (Eriocheir sinensis)

Abstract

Many physiological functions in crustaceans adapt to daily environmental change through circadian changes. However, the daily variation of the gut bacterial community composition has not been reported for crustaceans. In this study, we aimed to identify and elaborate on 24 h dynamic variations in the gut bacterial community of the Chinese mitten crab (Eriocheir sinensis). To this end, we processed gut samples from crabs collected at four time points (6:00, 12:00, 18:00, and 24:00) in a 24 h period and applied 16 S rRNA high-throughput gene sequencing. The gut bacterial community alpha-diversity and richness were highest in the samples collected at 18:00. Vagococcus salmoninarum was the most abundant species in the 12:00 samples, and Vibrio rumoiensis was the most abundant species in the 18:00 samples. Thus, our findings suggest that the daily variation may affect the response of the gut bacterial community to oxidative stress, and even affect the innate immune response of E. sinensis. Firmicutes and Bacteroidetes were identified as the dominant phyla in the gut bacterial community network. To the best of our knowledge, this is the first report describing the daily change in the gut microbiome composition of a crustacean species, E. sinensis. Our findings provide new insight into the 24 h dynamic variations of gut bacteria in crustaceans and may be useful for improving E. sinensis aquaculture.