Signatures Science and Technology Division, National Security Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
Environ Microbiol Rep. 2014 Dec;6(6):786-91. doi: 10.1111/1758-2229.12211. Epub 2014 Oct 27.
Microbial mats are characterized by extensive metabolic interactions, rapidly changing internal geochemical gradients, and prevalent microenvironments within tightly constrained physical structures. We present laser ablation isotope ratio mass spectrometry (LA-IRMS) as a culture-independent, spatially specific technology for tracking the accumulation of (13) C-labelled substrate into heterogeneous microbial mat communities. This study demonstrates the novel LA-IRMS approach by tracking labeled bicarbonate incorporation into a cyanobacteria-dominated microbial mat system. The spatial resolution of 50 μm was sufficient for distinguishing different mat strata and the approach effectively identified regions of greatest label incorporation. Sample preparation for LA-IRMS is straightforward and the spatial selectivity of LA-IRMS minimizes the volume of mat consumed, leaving material for complimentary analyses. We present analysis of DNA extracted from a sample post-ablation and suggest pigments, lipids or other biomarkers could similarly be extracted following ablation. LA-IRMS is well positioned to spatially resolve the accumulation of any (13) C-labelled substrate provided to a mat, making this a versatile tool for studying carbon transfer and interspecies exchanges within the limited spatial confines of such systems.
微生物垫的特征是广泛的代谢相互作用、快速变化的内部地球化学梯度以及在紧密受限的物理结构内普遍存在的微环境。我们提出激光烧蚀同位素比质谱 (LA-IRMS) 作为一种非培养、空间特异性的技术，用于跟踪（13）C 标记底物在异质微生物垫群落中的积累。本研究通过跟踪标记的碳酸氢盐掺入蓝藻占主导地位的微生物垫系统，展示了新型的 LA-IRMS 方法。50 μm 的空间分辨率足以区分不同的垫地层，并且该方法有效地确定了最大标记掺入的区域。LA-IRMS 的样品制备简单，LA-IRMS 的空间选择性最小化了消耗的垫材料量，为补充分析留下了材料。我们提出了从烧蚀后样品中提取的 DNA 分析，并建议在烧蚀后可以类似地提取色素、脂质或其他生物标志物。LA-IRMS 非常适合空间解析提供给垫的任何（13）C 标记底物的积累，使其成为研究此类系统有限空间内碳转移和种间交换的多功能工具。
