Structure and function of microbial communities during the early stages of revegetation of barren soils in the vicinity of a Pb/Zn Smelter

Microbial community structure (expressed as phospholipid fatty acids) and function (expressed as enzyme activities) were studied in an industrial barren resulting from smelting activities, and three revegetated sites dominated by native plant Paulownia fortunei under the subtropical conditions of Southern China in order to determine whether microbial community structure and function can be used as indicators of changes in abiotic environment during the revegetation process. An adjacent area under natural vegetative cover was used as a control. The revegetation did not lead to consistent shifts of individual phospholipid fatty acids (PLFAs) and enzyme profiles with time. However, the levels of some signature PLFAs, such as Gram negative bacteria (16:1ω9c), arbuscular mycorrhizal (AM) fungi (16:1ω5c), fungi (18:2ω6c), actinomycetes (10Me16:0 + 10Me17:0 + 10Me18:0), saturated fatty acid (18:0), monounsaturated fatty acids (16:19c + 16:1ω7c + 16:1ω5c + 17:1ω8c + 18:1ω7c + 18:1ω9c), algae (20:5ω3c), protozoa (20:2ω6c + 20:3ω6c), PLFA ratios including fung/bact and monounsat/sat fatty acids, and enzyme activities including protease, CM-cellulase and β-glucosidase consistently increased with time after revegetation, corresponding to the increase in total N, pH and porosity in the revegetated soils. Moreover, cyclopropyl fatty acids/monoenoic precursors (cy17:0/16:1ω7c and cy19:0/18:1ω7c) significantly decreased during time after revegetation and was inversely correlated with the above soil physico-chemical parameters. Principal component analysis (PCA) indicated that the three revegetated sites were separated from the control sites with time after revegetation based on either the PLFA or enzyme activity data. Canonical correlation analysis (CCA) confirmed that the microbial community structure was closely linked to its function during the revegetation. Our data showed that the revegetative cover dominated by P. fortunei had considerably improved the structure and function of the soil microbial community, and was thus effective for remediation of industrial barrens contaminated with heavy metals. Of the biotic and abiotic factors determined in the present study, soil physico-chemical parameters (except for available P and WHC) may be more important factors in determining the structure and function of soil microbial community than heavy metal contents during the revegetation.