微量湿式分析による分子レベル同位体比の品質管理と確度向上 : 特に天然存在比の正確な評価とStable Isotope Probing(SIP)法の応用に向けて

抄録

Recent advances in the application of molecular approaches have emphasized our potentially underestimate of microbial diversity in natural environments and have revealed comprehensive biogeochemical processes. One of the biggest challenges for organic geochemists and/or microbial ecologists is to identify which organisms are carrying out a specific set of metabolic processes. To answer this fundamental question, stable isotope probing (SIP) together with compound-specific isotope analysis (CSIA) is a useful technique to understand the microbial ecology and its biogeochemical cycles. The method relies on the incorporation of a substrate that is highly enriched in a stable isotope such as ¹³C and¹⁵N, and the identification of specific molecular targets through active microorganisms in any environment. However, we have to pay attention about highly SI-enriched contamination problems and co-elution problems during pretreatment of chemical analysis and also in chromatographic procedures, which potentially prevent us from performing precise CSIA. Here, we point out quality control by wet chemical pre-treatment for precise compound-specific isotope analysis by isotope-ratio mass spectrometry coupled to gas chromatography and liquid chromatography. Not only in biogeochemical background but also from a scope of common welfare, CSIA technique is also widely useful tools for validation approaches in food material, anti-doping test, and environmental assessment. For further precise CSIA, we also discuss representative optimized analytical conditions of some model compounds including intact polar lipids (IPLs) with its derivatives, n-alkane, and amino acids.