维生素B7和B12对细菌生物被膜形成及厚壳贻贝幼虫变态的影响

Effects of VB7 and VB12 on biofilm formation and larval metamorphosis of the mussel Mytilus coruscus

关键词:  B族维生素  海洋细菌  厚壳贻贝  生物被膜  变态

Key words:  B vitamins  Marine bacteria  Mytilus coruscus  Biofilm  Larval metamorphosis

摘要:

为探究B族维生素对海洋细菌生物被膜形成、海洋贝类幼虫变态所产生的作用，本研究首先使用维生素B7 (VB7)和B12 (VB12)直接刺激厚壳贻贝(Mytilus coruscus)幼虫，观察其对变态的直接诱导活性；然后通过添加VB7和VB12，与海假交替单胞菌(Pseudoalteromonas marina)共同形成生物被膜，分析B族维生素对生物被膜形成及其生物学特性的影响；同时检测生物被膜变化对厚壳贻贝幼虫变态发育的影响。研究结果显示，0.02 mmol/L浓度VB7和VB12可以直接诱导厚壳贻贝幼虫的变态，且效果最为显著(P<0.05)；0.02 mmol/L浓度VB7和VB12处理后的海假交替单胞菌生物被膜对幼虫附着变态的诱导作用均显著提高(P<0.05)；进一步通过细菌密度计数、膜厚度分析、可拉酸染色和定量等方法，揭示VB7和VB12处理后生物被膜细菌密度、膜厚度以及胞外多糖、蛋白和脂质均显著增加(P<0.05)。研究结果证实，VB7和VB12可能通过改变海洋细菌生物被膜的生物学特性，进而调控厚壳贻贝幼虫变态发育。本研究为探究厚壳贻贝幼虫附着变态的分子机制提供了新的理论依据和创新思路，同时为B族维生素在提高厚壳贻贝人工育苗技术、改善厚壳贻贝养殖产业问题和促进海洋牧场生态修复建设等方面的应用提供了理论基础。

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.