Reassembly and biotic sources of carapace bacterial community of Portunus trituberculatus after host molting

Crustaceans molt repeatedly during their development, which leads to frequent reassembly of their associated microbial communities. However, the reassembly of the carapace bacterial community (CBC) and its sources remain largely unclear. Here, these concerns were explored by investigating the succession pattern, assembly processes, and biotic sources of CBC of the swimming crab Portunus trituberculatus after host molting. Rhodobacteraceae, significantly discarded with the molted hard shell, was recruited during the 72 h postmolt. The early colonists such as Pseudoalteromonadaceae and Oeanospirillaceae had the higher physiological functional potentials for colonization, mainly via homogeneous selection. By contrast, the late colonists such as Flavobacteriaceae and Pseudomonadaceae had higher metabolic potentials and their colonization was governed by drift first and dispersal limitation later. The CBC was primarily shaped by multiple colonist pools, especially preceding carapace bacteria. Seawater had a higher contribution for CBC at the early stage than the late stage via providing the key bacteria mainly Rhodobacteraceae. These findings advance our understanding of the CBC and its reassembly pattern and sources, highlighting the importance of seawater bacteria for the early colonists. We also suggest the possibility and potential timing of using probiotics in the rearing water for the management of carapace microbiota in the aquaculture practice.