脂多糖对细菌生物被膜形成及厚壳贻贝幼虫变态的影响

为探究脂多糖(LPS)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,本研究使用不同浓度的LPS直接刺激厚壳贻贝幼虫,观察其对幼虫附着变态的直接作用；同时在海假交替单胞菌形成生物被膜的过程中添加不同浓度的LPS,通过分析生物被膜生物学特性的变化,及变化后的生物被膜对厚壳贻贝幼虫附着变态的影响。研究结果显示,3种浓度的LPS均可直接诱导厚壳贻贝幼虫的变态；10 mg/L浓度LPS处理后的生物被膜其细菌密度、膜厚明显降低(p<0.05),胞外产物中多糖(如可乐酸)、脂类显著增加(p<0.05),同时其对幼虫变态的诱导作用也显著提高(p<0.05),因此推测,在厚壳贻贝幼虫的附着变态过程中,LPS具有直接诱导作用；除此之外,脂多糖还可以通过调控生物被膜胞外物质,特别是可乐酸的生成,从而间接影响厚壳贻贝幼虫的附着变态。

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

To explore the effects of lipopolysaccharide (LPS) on the formation of marine bacteria biofilm and the metamorphosis of mussel larvae, this study used different concentrations of LPS to directly stimulate the larva of Mytilus coruscus to observe the direct effect of LPS on larval metamorphosis. In addition, the biofilm was formed by adding different concentrations of LPS and Pseudoalteromonas marina, to analyze the changes in biological characteristics of the biofilm and the influence of the changed biofilm on the attachment metamorphosis of the mussel larva. The results showed that LPS at three concentrations could directly induce metamorphosis of Mytilus coruscus larvae. The bacterial density and membrane thickness of biofilm treated with 10 mg/L LPS were significantly decreased (P <0.05), the polysaccharides (such as colonic acid) and lipids in extracellular products were significantly increased (P <0.05), and the induction of larval metamorphosis was also significantly increased (P <0.05). It is speculated that LPS has a direct effect on the settlement and metamorphosis of Mytilus coruscus larvae, and LPS might indirectly affect the settlement and metamorphosis of Mytilus coruscus larvae by regulating the production of extracellular substances in the biofilm, especially colonic acid.