Supercritical liquid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile. configuration. The prefixes indicate iso branching, anteiso branching and cyclopropyl Cucurbitacin B supplier groups, respectively. For RQ nomenclature, ubiquinones and menaquinones with isoprene units in their side chain were abbreviated as UQ-and MK-is the predicted response; is the number of factor variables; is the linear coefficient; is the quadratic coefficient; is the interaction coefficient; and and are the independent coded variables. Design Expert? software (v8 trial, Stat-Ease Inc., Minneapolis, MN, USA) was used for the regression analysis and visualization of the response surface data. The fit of the regression model was checked by the adjusted coefficient of determination (R2). The statistical significance of the adjusted model was determined by the application of Fishers F-test. Analysis of variance (ANOVA) was performed to evaluate significant differences between independent variables. The adequacy of the Cucurbitacin B supplier model was determined by evaluating the pure error, the lack of fit, the coefficient of determination (p-value) and the Rabbit Polyclonal to C-RAF Fisher test value (F-value). 4. Conclusions We investigated an alternative method for the extraction of microbial lipid biomarkers from anaerobically digested sludge using scCO2 extraction to replace the conventional organic solvent extraction method. Our optimized method simultaneously detected RQ, PLFA, and PLEL. The multiple-response optimization maximized all the dependent variables (total amounts of RQ, PLFA and PLEL extracted) together. Optimal extraction conditions were achieved at 23.6 MPa, 77.6 C and 10.6% (v/v) methanol. Under these conditions, the total amounts of RQ, PLFA, and PLEL were 22.17, 604.61 and 6.78 nmol/g-dry sludge, respectively, with relative standard deviations (RSDs) of 9.02%, 11.04% and 3.68%, respectively. The experimental values agreed with predicted values, and the scCO2 extraction results were comparable with those obtained by conventional organic solvent extraction. Eight menaquinone components, 30 fatty acid components and 1 etherlipid component were identified in the samples, indicating the Cucurbitacin B supplier sensitivity of SFE method for the simultaneous extraction of both bacterial and archaeal lipids from anaerobically digested sludge. The SFE Cucurbitacin B supplier method has the potential to drastically reduce the amount of solvent used and extraction time needed, and could simplify the procedure. This method could be an effective technique for analyzing microbial lipid biomarkers in environmental samples, with the possibility of extended application and automation. Acknowledgment This work was financially supported by a Grant-in-Aid for Scientific Research (B21360252) from the Japan Society for the Promotion of Technology (JSPS)..