Microbial Functional Diversity in Facilities Cultivation Soils of Nitrate Accumulation

There are increasing concerns over facilities cultivation soils of nitrate accumulation in China. Nitrate pollution in secondary salinization soil is regarded as having potential effects on soil microbial communities. Our study was conducted to evaluate effects of secondary salinization on soil microbial functional diversity with the BIOLOG method. The results showed that Average well-color development (AWCD) values declined with the rising of nitrate concentrations to some extent. The results also exhibited that the accumulation of nitrate in soil decreased the carbon sources utilization rates and the microbial species diversity indices. It indicated that nitrate has significantly negative effects on the sole-carbon-source metabolic ability of soil microbial communities. The cluster analysis intuitively demonstrated the distance and relationship between each sample: soil samples with high nitrate content were more close to each other, while soil samples with low were more similar in distances. The principal component analysis (PCA) result further validated that nitrate was inversely correlated to microbial carbon sources utilization intensity and microbial diversity. The four carbon substrates, Carbohydrates, Miscellaneous, Amino acids and Polymers, could reflect most of the information about carbon sources utilization. Microorganisms preferred these four carbon substrates were more vulnerable to nitrate. Thus, these four carbon substrates could be one of the prioritized microbe carbon sources in soil bioremediation.