弧菌生物被膜的动态演替对厚壳贻贝附着的影响

为探讨生物被膜动态演替过程中如何影响海洋无脊椎动物附着,实验选取了对厚壳贻贝附着具有不同诱导活性的弧菌Vibrio cyclitrophicus、V. chagasii和Vibrio sp. 22形成单一生物被膜,观察弧菌动态演替中生物被膜细菌密度、膜厚度和胞外产物等生物学特性变化,探究其对厚壳贻贝稚贝附着的影响。结果显示,弧菌生物被膜动态演替过程中,被膜细菌随着时间推移出现聚集现象,细菌密度和膜厚度也随着时间变化呈先增多后减少。除了Vibrio sp. 22,V. cyclitrophicus和V. chagasii生物被膜细菌密度和膜厚度与稚贝附着均有不同程度的相关性。所测弧菌生物被膜胞外产物的显微激光共聚焦结果分析发现,胞外多糖随着时间先增多,然后开始下降。相对比而言,胞外蛋白和胞外脂质无显著性变化。因而,胞外多糖变化规律与稚贝在被膜上附着变化相一致,表明胞外多糖是生物被膜动态演替过程中调控厚壳贻贝附着的重要因素。本实验初步探讨了生物被膜动态演替特征及其对厚壳贻贝稚贝附着的影响,对于后续进一步在海区开展生物被膜的动态演替与海洋底栖动物附着相互关系研究具有重要的学术价值,同时对于人工鱼礁礁体生物附着机理的研究具有重要的实践价值。

Effects of dynamic succession of Vibrio biofilms on settlement of the mussel Mytilus coruscus

Vibrio, which are widely distributed in marine environments, have ability to form biofilms for the purpose of adaptation to harsh environmental conditions. Although biofilms formed by Vibrio have been known to promote larval and plantigrade settlement of the mussel Mytilus coruscus, how the dynamics succession of these biofilms during the formation impacts mussel settlement remains unknown. In this study, V. cyclitrophicus, V. chagasii and Vibrio sp. 22 with different settlement-inducing activities on plantigrades of the mussel M. coruscus were used to observe the changes of biofilm characteristics such as bacterial density, biofilm thickness and extracellular polymeric substances during the dynamic succession, and to explore subsequent effects of biofilm characteristics on mussel plantigrade settlement. The results showed that during the dynamic evolution of three Vibrio species, the bacteria on the biofilm were aggregated over time. The bacterial density and thickness of the Vibrio biofilms firstly increased with time and finally decreased. Except for Vibrio sp. 22, the bacterial density and biofilm thickness of V. cyclitrophicus and V. chagasii were correlated to the settlement of plantigrades. During the dynamic succession of Vibrio biofilms, the extracellular polysaccharides increased first with time and then began to decrease. In contrast, there was no change in the proteins and lipids on biofilms. The change trend of extracellular polysaccharide was similar to the settlement-inducing activity of biofilms, suggesting that extracellular polysaccharides play an important role in succession of biofilms regulating mussel settlement. Thus, the present finding is important to understand the interaction between biofilms and marine invertebrate settlement, and to clarify settlement mechanism of micro- and macro-organisms on artificial reefs.