Abstract:As a growth cofactor, vitamin B (VB) participates in the body's various physiological and biochemical processes in the form of prosthetic groups or coenzymes. Meanwhile, the vitamin B is an essential nutrient in ensuring the regular operation of most biological activities. In this study, pharmacological experiments, confocal microscopy observation, and biofilms staining with mordant were used to understand the effects of vitamins B on marine biofilm formation and metamorphosis of Mytilus coruscus, which is a marine bivalve. VB7 and VB12 were used to investigate its impact on biofilm formation of Pseudoalteromonas marina, which exhibits an induction activity on the metamorphosis of M. coruscus larvae. The direct induction activity of VB7 and VB12 on larval metamorphosis was also detected. Results showed that the VB7 and VB12 at 0.02 and 0.2 mmol/L could directly and significantly increase the larval metamorphosis, and the concentration of VB7 and VB12 at 0.02 mmol/L had the most potent induction. Moreover, VB7 and VB12 at 0.02 mmol/L can also accelerate the growth of P. marina. The biofilm of P. marina formed at 0.02 mmol/L VB7 or VB12 had significant inducting effects on larval metamorphosis. The biofilm thickness, bacterial density, and extracellular polymeric substances (EPS) such as polysaccharides (especially the colonic acid), proteins, and lipids increased significantly after VB7 or VB12 treatment. In summary, VB7 and VB12 can increase the mussel larval metamorphosis directly. At the same time, they can also induce the production of biofilm EPS and further enhance the mussel larval metamorphosis inducing ability of the biofilm, suggesting that VB7 and VB12 can promote the larval metamorphosis of M. coruscus by changing the biofilm EPS composition. The results of this study provide a new theoretical basis and innovative methods for exploring the molecular mechanism of larval metamorphosis. It also provides a solid theoretical basis for the application of vitamin B in improving the artificial breeding technology of M. coruscus, solving the problems of mussel aquaculture industry and ecological restoration.
