Using of lipid biomarkers for assessing soil microbial community structure

The ecological balance of microbial community (MC) is very important as an index of soil ecosystem health due to the pivotal and vital roles of MC. Microbial culture methods are suitable for this purpose because the majority of soil microorganisms unable to grow on synthetic media. DNA- based molecular analyses just provide microbial diversity data. Then a rapid method for the assessment of soil microbial community structure is using phospholipid fatty acid (PLFA) patterns (because they are degraded rapidly after cells death, by the action of phosphatases). Moreover, PLFA provide broad information dealing with microbial diversity, biomass and their nutritional - physiological status. Certain and specific PLFAs, viz. trans/cis ratio (monounsaturated fatty acids (16:1w7t) to 16:1w7c), cy/pre ratio (cyclopropyl (cy17:0 + cy19:0) fatty acids to precursor (16:1ω7+18:1ω7) fatty acids, S/M ratio (saturated to monosaturated fatty acids), G-/G+ ratio (Gram negative bacteria to Gram positive bacteria fatty acids), F/B ratio (saprophytic fungi to bacterial fatty acids) were able as indicators of physiological or nutritional status in different environmental conditions, such as heavy metals polluted soils, changes in pH, depth changes drought, salinity, different agricultural managements and flooding are used for evaluation of soil microbial communities. The method of PLFA analysis in soil and determining microbial diversity, biomass and their physiological status are addressed here.