Archaeal biofilms: Composition of extracellular polymeric substances, exopolysaccharide synthesis and transport in Sulfolobus acidocaldarius

生物膜代表了地球上绝大多数微生物的共同生活方式。细菌和真核微生物（真菌、藻类）及其胞外聚合物（EPS）形成的生物膜已被广泛研究。生命的第三个领域的成员，古生菌，已经获得了特殊的研究兴趣，因为他们适应极端环境。然而，关于古细菌生物膜的研究相对较少。在本项目中，将利用绿古菌中嗜热嗜酸的好氧成员Sulfolobus acidocalarius研究古菌生物膜的形成和结构、EPS的组成以及作为EPS主要成分的外多糖（PS）的生物合成和运输。S. acidocalarius被认为是一种模式生物，因为形成生物膜的能力已被证明，它很容易在实验室条件下生长，并且在遗传上易于处理。在S. acidocalarius基因组中鉴定出一个包含11个糖基转移酶和8个膜蛋白的基因簇，对两个缺失菌株的初步研究证实了编码蛋白在PS合成和运输中的预测功能。目的是结合最先进的生物膜表征技术，EPS分析和突变/生化方法来揭示PS合成和运输以及响应环境条件下EPS组成的变化。该项目将为古细菌生物膜的组成和形成以及生物技术兴趣的新极端酶（gt）提供新的见解。

Biofilms represent the common mode of life for the vast majority of microorganisms on earth. Biofilms formed by bacteria and eukaryotic microorganisms (fungi, algae) and their extracellular polymeric substances (EPS) have been intensively studied. Members of the third domain of life, Archaea, have gained special research interest due to their adaptation to extreme environments. However, there exists comparatively little information on archaeal biofilms. In the current project, Sulfolobus acidocaldarius, a thermoacidophilic, aerobic member of the Crenarchaeota, will be used to study archaeal biofilm formation and architecture, EPS composition and the biosynthesis and transport of exopolysaccharides (PS) as the major EPS components. S. acidocaldarius qualifies as a model organism, because the ability to form biofilms was demonstrated, it is easy to grow under laboratory conditions and it is genetically tractable. In the S. acidocaldarius genome a gene cluster with 11 glycosyltransferases and 8 membrane proteins was identified and initial studies with two deletion strains confirmed the predicted function of the encoded proteins in PS synthesis and transport. The aim is to combine state of the art techniques for biofilm characterisation, EPS analysis and a mutational/biochemical approach to unravel PS synthesis and transport and changes of EPS composition in response to environmental conditions. This project will provide new insights into composition and formation of archaeal biofilms as well as new extremozymes (GTs) of biotechnological interest.