培养基对微生物被膜形成和厚壳贻贝附着的影响

为探讨微生物被膜生物学特性、培养基以及大型生物附着三者之间的相互关系,本实验通过微生物分子生态学和海洋贝类生态学等方法调查了不同培养基对海洋细菌所形成微生物被膜的影响及其对厚壳贻贝幼虫附着的影响。结果显示,厚壳贻贝稚贝率与培养基类型和细菌初始密度显著相关,进一步分析表明,Zo Bell 2216E和Seawater Luriabertani(SWLB)条件下分别有6株和9株细菌形成的微生物被膜密度与稚贝率显著相关。扫描电镜结果显示,Staphylococcus sp.3在Zo Bell 2216E培养基条件下形成微生物被膜的细菌分布较为紧密,Pseudoalteromonas sp.8则在SWLB培养基条件下微生物被膜细菌分布较为紧密,且形态变为短杆状。SDS-PAGE结果显示,相比Zo Bell 2216E培养基,Staphylococcus sp.3在SWLB培养基条件下9条条带蛋白显著下降,其中2个条带完全消失;Pseudoalteromonas sp.8则在SWLB培养基条件下明显增加5条蛋白条带。研究表明,微生物被膜的形成受到培养基的影响,培养基的不同导致微生物被膜的形态结构、分布和蛋白有所差异,最终导致微生物被膜诱导厚壳贻贝幼虫附着变态的活性差异,本研究为后续开展厚壳贻贝附着的分子机制奠定良好基础。

Effects of culture media on the biofilm formation and subsequent settlement of Mytilus coruscus

In order to determine the interactions among the biofilm characteristics, culture media and settlement of marine invertebrate, the present study investigated the effects of the biofilm formation in two types of culture media, and the subsequent effects of bacterial biofilms on the settlement and metamorphosis of Mytilus coruscus larvae. The biofilm inducing activities on larval settlement and metamorphosis were correlated to the bacterial density with exception of one and four species in culture media Zobell 2216E and Seawater Luria-bertani (SWLB), respectively. The inducing activity of the bacterial biofilms was correlated to the culture medium type and initial cell density of bacteria. Scanning electron microscope showed that a thick Staphylococcus sp. 3 biofilm comprising of a stack of bacterial cells under the condition of 2216E compared to SWLB. In contrast, patchy monolayer was found under 2216E in Pseudoalteromonas sp. 8 biofilm, and short rod was observed under SWLB. SDS-PAGE showed that protein profiles of both Staphylococcus sp. 3 and Pseudoalteromonas sp. 8 biofilms changed distinctly in two different culture media. In Staphylococcus sp. 3 biofilm, eight protein bands decreased significantly and two protein bands disappeared under SWLB compared to 2216E. In Pseudoalteromonas sp. 8 biofilms, five protein bands appeared under SWLB. Thus, the culture media impacted the development of bacterial biofilms such as distribution, morphology and phenotypes, and changes in biofilm characteristics may contribute to the variability in the inducing activity on larval settlement and metamorphosis.