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命模式。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。第三生命领域的成员，古生代，由于适应极端环境而获得了特殊的研究兴趣。然而，关于古生菌生物膜的信息相对较少。在本项目中，Sulfolobus acidocaldarius将被用于研究古细菌生物膜的形成和结构、EPS的组成以及作为EPS主要成分的胞外多糖(PS)的生物合成和运输。S.acidocaldarius是一种模式生物，因为它具有形成生物膜的能力，很容易在实验室条件下生长，而且遗传上很容易驯化。在酸性链球菌基因组中，鉴定出一个由11个糖基转移酶和8个膜蛋白组成的基因簇，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。其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的合成和运输以及EPS组成随环境条件的变化。该项目将对古生菌生物膜的组成和形成以及生物技术感兴趣的新的极端酶(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.