厚壳贻贝肠道细菌的生物被膜对其幼虫和稚贝附着的影响

Effects of intestinal bacterial biofilms on settlement process of larvae and plantigrades in Mytilus coruscus

为研究肠道细菌在厚壳贻贝(Mytilus coruscus)幼虫和稚贝生长发育过程中的作用,本研究从成体厚壳贻贝肠道中分离出了10株细菌,通过分别形成单一细菌生物被膜,检验其对厚壳贻贝幼虫和稚贝附着的影响和生物被膜特性。实验结果发现,10株肠道细菌所形成的生物被膜均能诱导厚壳贻贝幼虫和稚贝的附着,但不同种类肠道细菌的诱导能力不同,其中Bacillus sp.4对厚壳贻贝幼虫具有高诱导活性,Phaeobacter sp.1具有低诱导活性;Phaeobacter sp.1对厚壳贻贝稚贝具有高诱导活性,Bacillus sp.4具有低诱导活性。通过比较分析Bacillus sp.4和Phaeobacter sp.1生物被膜的生物量及胞外产物发现,肠道细菌被膜细菌密度、膜厚和胞外脂类对厚壳贻贝幼虫的附着变态无影响,而胞外蛋白和胞外多糖可以影响幼虫的附着变态;对于厚壳贻贝稚贝的附着,肠道细菌被膜细菌密度、膜厚和胞外α-多糖均能影响其诱导活性,而胞外脂类和胞外蛋白无影响。本研究成果可为提高厚壳贻贝的健康生态养殖相关技术提供相关的指导,为解析生物被膜调控厚壳贻贝附着机制和该物种生态健康养殖提供理论依据。

Ten strains of bacteria were isolated from the gut of Mytilus coruscus to study its role in the settlement of larvae and plantigrade by forming biofilms.Results showed that the inducing ability of the biofilms formed by ten bacteria were different,although all of them could induce the settlement of larvae and plantigrade.In larvae,Bacillus sp.4 showed high inducing activity,while Phaeobacter sp.1 had low inducing activity.In plantigrades,Phaeobacter sp.1 showed high inducing activity,while Bacillus sp.4 showed low inducing activity.The polysaccharides and proteins from biofilms formed by Bacillus sp.4 and Phaeobacter sp.1 impacted larval settlement and metamorphosis,and the cell density,thickness and extracellular lipids of biofilm showed no effect on inducing activity of larval settlement and metamorphosis.For plantigrades,biofilm’s bacterial density,thickness and extracellularα-polysaccharide could induce plantigrades to the settlement,and the extracellular lipids and proteins of biofilms did not affect the settlement.This study is helpful for improving the healthy ecological culture of M.coruscus and to understand the settlement mechanism of M.coruscus.