Membrane lipids and their related acyl and/or alkyl moieties are important biomarkers of the microbial community in environmental samples. Intact polar lipids, which are described by their lipid head groups and fatty acid tails, are major membrane components of living cells only and may therefore provide information about the living soil microbial community. However, the intact polar lipids in soil organic matter may originate from non-microbial organisms (e.g., roots, soil animals) as well as microorganisms. We report on the profiles of more than 300 membrane-derived intact polar lipids in grassland soil organic matter from sites with diverse plant communities and soil properties. The origin of the soil lipid profiles was deduced by comparisons with the intact polar lipids of plant roots, amoebae, collembolans, fungi and bacteria. In addition, we investigated the impact of plant and soil-related drivers on the composition of the intact polar lipids in soil organic matter. Soil organic matter lipid profiles were considerably more diverse and evenly distributed than the profiles of roots and soil organisms (amoebae, bacteria, collembolans and fungi). Moreover, the lipid profiles in soil organic matter had more odd-carbon numbered acyl and alkyl chains, ornithine lipids, and phospholipids with low levels of unsaturation, possibly because they are of bacterial origin. We suggest that most of the intact polar lipids in soil organic matter (45–80%) were derived from bacteria, rather than plants, fungi, or soil animals. The PE (31:0) and PE (32:1) lipids were considered as biomarkers for all bacteria, whereas PE (29:0, 29:2 and 30:0) are specific to Gram (+) bacteria and PG (33; 0, 34:1 and 36:2) and OL (36:0, 37:0, 37:1, 39:1 and 39:2) were used to identify Gram (−) bacteria. Bacterial lipids were differentiated from intact lipids of plant roots that typically contain MGDG (36:4) and MGDG (36:6), while fungi have indicative markers of PC (36:4) and PE (36:4). Thus, intact polar lipid profiles complement and advance other approaches, such as fatty acid-based analysis of soil microbial community composition, and may allow for analysis of soil food web structure.

膜脂质及其相关的酰基和/或烷基部分是环境样品中微生物群落的重要生物标志物。完整的极性脂质（由其脂质头基和脂肪酸尾巴描述）仅是活细胞的主要膜成分，因此可以提供有关活土壤微生物群落的信息。但是，土壤有机质中完整的极性脂质可能源自非微生物生物（例如，根，土壤动物）以及微生物。我们报告了来自具有不同植物群落和土壤特性的地点的草原土壤有机质中300多种来自膜的完整极性脂质的概况。通过与植物根，变形虫，collembolans，真菌和细菌的完整极性脂质进行比较，推导出了土壤脂质谱的起源。此外，我们调查了植物和土壤相关驱动因素对土壤有机质中完整极性脂质组成的影响。与根部和土壤生物（变形虫，细菌，collembolans和真菌）的分布相比，土壤有机质脂质的分布更加多样化，分布均匀。此外，土壤有机质中的脂质分布具有更多的奇碳编号的酰基和烷基链，鸟氨酸脂质和不饱和度较低的磷脂，可能是因为它们是细菌来源的。我们建议土壤有机质中大多数完整的极性脂质（45-80％）来自细菌，而不是植物，真菌或土壤动物。PE（31：0）和PE（32：1）脂质被视为所有细菌的生物标志物，而PE（29：0、29：2和30：0）对革兰氏（+）细菌和PG具有特异性（33 ; 0，34：1和36：2）和OL（36：0、37：0、37：1、39：1和39：2）用于鉴定革兰氏（-）细菌。细菌脂质与通常含有MGDG（36：4）和MGDG（36：6）的植物根的完整脂质区分开来，而真菌则具有PC（36：4）和PE（36：4）的指示性标记。因此，完整的极性脂质谱补充并推进了其他方法，例如基于脂肪酸的土壤微生物群落组成的分析，并且可能允许对土壤食物网结构进行分析。