磷脂脂肪酸技术及其在土壤微生物研究中的应用

PLFAs technique and it's application in the study of soil microbiology

以复杂群落形式存在的土壤微生物是C等养分的生物地球化学循环的主要参与者,而存在于活体微生物细胞膜的磷脂脂肪酸(PLFAs)分布广泛、含量相对恒定、周转迅速、对环境因素的变化敏感、分析方法较简单,因此该技术已广泛应用于土壤微生物学研究。阐述了PLFAs概念、命名、种类、意义、提取方法及操作过程中应注意的问题,介绍了MIDI、GC-MS和HPLC-ESI-MS等鉴定手段。概述PLFAs技术应用途径和目的,及其在土壤微生物量、结构、代谢状态、不同农业措施对土壤微生物影响以及土壤生物修复等研究领域的应用。同时,讨论了PLFAs技术的不足。例如,对原位土壤微生物群落特定菌种指征有时不够明确;估算真菌生物量时不够准确;不能用于分析古菌;不同提取法结果区别较大且易受土壤腐殖酸等有机质干扰;供试土样必须-80℃或冻干保存。因此,利用PLFAs技术研究土壤微生物时,应辅以其他生物标识物及相应分析手段,才能更准确地反映土壤微生物群落组成、代谢途径与机理。

The soil microorganisms as complex communities are the leading participants of the bio-geochemistry cycling of C and other nutrients. And phospholipids fatty acids （PLFAs） can serve as an important indicator of the viable microorganisms since they exist in all types of microbial membranes with constant quantity and fast turning-over rate, and they can respond promptly to the variations in environmental factors. Therefore, the relative simple and valuable PLFAs techniques have been utilized widely to investigate the characteristics of soil microorganisms. The conception, nomenclatures, types, and characteristics of PLFAs are introduced in this paper. Different extraction processes for PLFAs and total soil fatty acid methyl esters （TSFAMEs） are sketched. At the same time, the comparison of extraction procedures between PLFAs and TSFAMEs is drawn. The possible problems that are likely to occur during the extraction processes are discussed in detail. The PLFAs-associated techniques such as the MIDI, GC-MS and HPLC-ESI-MS are also recommended here for the interpretation of PLFAs implications. In addition, this paper specifies the practical applications of PLFAs to the studies of soil microbial biomass, microbial communities and microbial metabolic conditions, as well as the effect of agricultural management on the microbial charactereristics. Some other applications are also summed up, for instantce, ecosystem recovery study and ^13C-labeling technique. Meanwhile, some limitations by using PLFAs as an indicator are figured out as well. For example, PLFAs can＇t be used to distinguish the specific microbial communities in the native soils clearly in some cases. Nor can they be used to evaluate the fungal biomass correctly due to the uncertain structures of different microorganisms. PLFAs analysis can do nothing about Archaea either. Moreover, the results from different PLFAs extraction methods vary significantly and are easily interfered by other organic compounds in soil matrix. The soil samples for PLFAs analysis must be stored at - 80℃ or lyophiled because of oxidation effects. It is thereby suggested that in order to elucidate clearly the metabolic pathway and the structure of native microbial consortiums, PLFAs techniques should be employed together with other molecular biological techniques when necessary.