Microbial catabolic diversity in soils contaminated with hydrocarbons and heavy metals

Understanding indigenous microbial function in contaminated soil is crucial to the successful development and use of bioremediation technologies. We measured the catabolic diversity of indigenous microbial communities in soils with a 30-yr history of Pb, Cr, and hydrocarbon (HC) contamination using a modified substrate-induced respiration method. There were characteristic differences of microbial respirations in the response of highly versus less contaminated soils to the range of organic substrates used. The catabolic response to glucose as compared to succinic acid was approximately 1:5 in less contaminated soils, but 1:25 in highly contaminated soils. In contrast, the response ratio to glucose versus aromatics was about 1:0.4 in less contaminated soils and 1:1 in highly contaminated soils. Principal components analysis (PCA) of the responses confirmed that catabolic diversity differed between highly and less contaminated soils. Univariate analysis also indicated that catabolic diversity was reduced in highly contaminated soils. This catabolic difference was strongly associated with the alteration of microbial community composition. Statistical analyses suggested that the variation in microbial community catabolic diversity was attributed to HCs more than to Pb and Cr.