Effects of commercial feeds and natural diets on the culture performance and gut microbiota of Scylla paramamosain

This is the authors' abstract. We don't add key points for this paper.

In this study, we systematically investigated how different feed combinations affect the growth performance and gut microbiota composition of the mud crab Scylla paramamosain in both indoor cement tanks and outdoor earthen ponds. We employed high-throughput 16S rRNA sequencing to profile the bacterial communities, placing particular emphasis on correlations between feed nutritional components and key microbial taxa. Firmicutes, Proteobacteria, Bacteroidetes, and Cyanobacteria emerged as the predominant phyla. Crabs fed locally sourced natural feeds from Dongying showed relatively minor shifts in community structure, whereas those receiving artificial formulated feed exhibited significant divergences, as evidenced by principal coordinate analysis (PCoA) and non-metric multidimensional scaling (NMDS). In indoor cement tank trials, no significant differences were found in Chao1 among groups. However, the combination of Mactra chinensis + Synechogobius hasta + Trachypenaeus curvirostris group significantly elevated Pielou_e and Shannon diversity indices ( P < 0.05), while the Simpson index was higher in both this group and the S. hasta + T. curvirostris + corn + soybean meal combination ( P < 0.05). Similar trends were observed in outdoor earthen pond trials, where the M. chinensis + S. hasta + T. curvirostris group and the S. hasta + T. curvirostris + corn + soybean meal group exhibited significantly higher diversity indices ( P < 0.05). Moreover, several indicator genera (e.g., OM190, Terrisporobacter , Paraclostridium ) were positively correlated with specific nutritional components, implying that balanced feed formulas can promote beneficial bacteria, potentially supporting molting and growth. Collectively, the M. chinensis + S. hasta + T. curvirostris feed combination yielded the most favorable results, highlighting its potential for enhancing both crab growth and gut microbiota diversity. These findings advance our understanding of how feed composition shapes the gut microbiota in S. paramamosain and offer a theoretical basis for optimizing feed formulations, thereby contributing to sustainable aquaculture in Dongying and similar regions. • Firmicutes, Proteobacteria, Bacteroidetes and Cyanobacteria are the predominant phyla of gut microbiota in mud crab. • Artificial formulated feed lead more significant divergences in community structure than locally sourced natural feeds. • Balanced feed formulas can promote beneficial bacteria, potentially supporting molting and growth of mud crab. • M. chinensis + S. hasta + T. curvirostris is the preferred feed combination for mud crab.