Effects of Bacterial Motility on Dynamic Succession of Biofilms and Settlement of the Mussel Mytilus coruscus

Abstract

To study the regulatory role of marine bacterial motility on biofilm formation and settlement of marine bivalves, this study used the economically important marine mussel Mytilus coruscus as the research target, and investigated the wild-type strain and ΔcheW strain of Pseudoalteromonas marina. These bacteria have different motility; thus, the motility analysis of these strains was carried out at various time points, and the differences in the biofilm thickness and composition and bacterial density were also analyzed at different time points. Finally, their effects on dynamic biofilm succession and settlement of M. coruscus were evaluated. This study found that the motility of the wild-type strain and the ΔcheW strain at 6 h, 12 h, 24 h, 48 h, 72 h, and 96 h was significantly different (P < 0.05). It was found that both bacterial circle radii increased with time and reached their maximum at 96 h. Overall, the wild-type strain formed a larger bacterial circle than the ΔcheW strain. The two strains' bacterial density and biofilm thickness increased with time and reached their maximum at 48 h, begging to spread after 72 h. At all time points, the mussel settlement rates on the wild-type strain biofilm were higher than on the ΔcheW biofilm. Initially, the mussel settlement rates increased, but after 72 h a decreasing tendency was observed, reaching the highest value at 48 h. These settlement results were consistent with the changes in the biofilm composition under different time points. Therefore, this study concluded that bacterial motility affects biofilm formation, mainly biofilms thickness, bacterial density, and extracellular compounds during the dynamic succession of biofilms, thereby regulating the settlement of the mussel M. coruscus. This study provides novel insights into the interaction between bacterial motility, biofilm formation, and the settlement of M. coruscus, which may help optimize the production and breeding of economically important marine animals.

Keywords

• pseudoalteromonas marina
• bacterial motility
• biofilms
• dynamic succession
• mytilus coruscus settlement