Overview
ISO/TS 29843-1:2010 - "Soil quality - Determination of soil microbial diversity - Part 1: Method by phospholipid fatty acid analysis (PLFA) and phospholipid ether lipids (PLEL) analysis" - defines an extended laboratory procedure to extract and quantify membrane lipids that represent viable soil microorganisms. The Technical Specification describes combined extraction, fractionation and instrumental measurement steps (including Bligh–Dyer extraction and GC/MS) to determine both PLFA and PLEL, offering a phenotypic approach to assess soil microbial diversity and biomass.
Key topics and technical requirements
- Scope and purpose: Quantitative determination of phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL) from soil as indicators of viable microbial communities.
- Sampling reference: Soil collection, handling and storage should follow ISO 10381-6 guidance for microbiological assessments.
- Extraction method: Lipid extraction uses the Bligh–Dyer procedure to recover total lipids from soil samples.
- Lipid fractionation: Silica (si) column chromatography separates neutral lipids, glycolipids and phospholipids; further solid-phase columns (NH, SCX) are used to separate FAME classes and non-ester-linked fractions.
- Chemical transformations:
- Mild alkaline hydrolysis to produce fatty acid methyl esters (FAME) from ester-linked PLFA.
- Acidic methylation and specific cleavage (e.g., hydroiodic acid, HI) to analyse ether lipids (PLEL).
- Derivatizations such as DMDS and TMSI for structure elucidation of unsaturated and hydroxy-substituted fatty acids.
- Measurement: Gas chromatography coupled with mass spectrometry (GC/MS) is specified for identification and quantification of FAME and PLEL-derived analytes.
- Analyte classes: Separation and reporting of saturated (SATFA), mono-unsaturated (MUFA), poly-unsaturated (PUFA), hydroxy-substituted (PLOH/UNOH), and non-ester-linked fatty acids (NEL-UNSFA).
- Reagents and apparatus: Lists analytical-grade solvents, standards (e.g., C19:0 FAME), silica and SCX columns, and GC/MS column specifications.
Practical applications
- Soil health and monitoring: Quantify viable microbial biomass and community shifts in agriculture, forestry and land management.
- Environmental assessment: Evaluate effects of contaminants, remediation, fertilization or land-use change on microbial communities.
- Research: Provide phenotypic complement to molecular methods (DNA/RNA) for microbial ecology and biogeochemical studies.
- Indicator use: Detect physiological stress responses (e.g., cyclopropyl fatty acid increases) and shifts among bacteria, fungi and archaea by lipid biomarkers.
Who uses this standard
- Environmental and soil laboratories, ecologists, agronomists, remediation consultants, research institutions and regulatory agencies requiring standardized PLFA/PLEL protocols for comparative, reproducible soil microbial analysis.
Related standards
- ISO/TS 29843-2 - simpler PLFA extraction method (PLFA only).
- ISO 10381-6 - guidance on soil sampling, handling and storage for microbiological analyses.
Keywords: ISO/TS 29843-1:2010, soil quality, PLFA, PLEL, phospholipid fatty acid analysis, Bligh–Dyer extraction, GC/MS, soil microbial diversity, lipid biomarkers.