An Imaging Mass Spectrometry Study on the Formation of Conditioning Films and Biofilms in the Subsurface (Äspö Hard Rock Laboratory, SE Sweden)

Conditioning films and biofilms forming on surfaces of solid materials exposed to aqueous media play a key role in in the interaction between the geo- and biospheres. In this study, time-of-flight secondary ion mass spectrometry and scanning electron microscopy were used to investigate the time scale, mode of formation, and chemistry of conditioning films and biofilms that formed on Si substrates exposed to aquifer water in the subsurface Äspö Hard Rock Laboratory, SE-Sweden. The detection of fragment ions of amino acids, carbohydrates, and carboxylic acids revealed that different types of organic compounds had adhered to the Si surface already after 10 min of exposure to the aquifer fluids, whereas the attachment of microbial cells was first observed after 1000 min. The organic compounds first formed isolated μm-sized accumulations and subsequently started to distribute on the wafer surface more homogenously. Simultaneously further microorganisms attached to the surface and formed biofilm-like cell accumulations after 3 months of exposure to aquifer water.

暴露于水介质的固体材料表面所形成的条件膜（Conditioning films）与生物膜，在地球圈层与生物圈的相互作用中发挥关键作用。本研究采用飞行时间二次离子质谱（Time-of-Flight Secondary Ion Mass Spectrometry, TOF-SIMS）与扫描电子显微镜（Scanning Electron Microscopy, SEM），对瑞典东南部阿斯普奥硬岩实验室地下含水层水中硅衬底表面形成的条件膜与生物膜的形成时间尺度、形成模式及化学组成进行了研究。研究检测到氨基酸、碳水化合物与羧酸的碎片离子，结果表明：暴露于含水层流体仅10分钟后，便已有不同类型的有机物质附着于硅表面；而微生物细胞的附着现象则在暴露1000分钟后才首次被观测到。上述有机物质最初以微米级孤立聚集体的形式存在，随后逐渐在硅片表面更均匀地分布。与此同时，更多微生物附着于表面，并在暴露于含水层水中3个月后形成类生物膜的细胞聚集体。