AimsStudy the response of microbial communities and selected petroleum hydrocarbon (PH)-degrading genes on simulated PH spills in soils/sediments from different geographic locations. Methods and ResultsA microcosm experiment was conducted by spiking mixtures of petroleum hydrocarbons (PHs) to soils/sediments collected from four different regions of China, including the Dagang Oilfield (DG), Sand of Bohai Sea (SS), Northeast China (NE) and Xiamen (XM). Changes in bacterial community and the abundance of PH-degrading genes (alkB, nah and phe) were analysed by denaturing gradient electrophoresis (DGGE) and qPCR, respectively. Degradation of alkanes and PAHs in SS and NE materials were greater (P<005) than those in DG and XM. Clay content was negatively correlated with the degradation of total alkanes by 112days and PAHs by 56days, while total organic carbon content was negatively correlated with initial degradation of total alkanes as well as PAHs. Abundances of alkB, nah and phe genes increased 10- to 100-fold and varied by soil type over the incubation period. DGGE fingerprints identified the dominance of -, - and -Proteobacteria (Gram -ve) and Actinobacteria (Gram +ve) bacteria associated with degradation of PHs in the materials studied. ConclusionThe geographic divergence resulting from the heterogeneity of physicochemical properties of soils/sediments appeared to influence the abundance of metabolic genes and community structure of microbes capable of degrading PHs. Significance and Impact of the StudyWhen developing practical in-situ bioremediation approaches for PHs contamination of soils/sediment, appropriate microbial community structures and the abundance of PH-degrading genes appear to be influenced by geographic location.