Bioremediation of an aged and heavily contaminated soil was performed using microbial remediation,
phytoremediation, and microbial/phytoremediation. The removal efficiency of polycyclic
aromatic hydrocarbons (PAHs) was in the order microbial/phytoremediation > microbial remediation
≈ phytoremediation > control. The removal percentage of microbial/phytoremediation (69.6%) was
twice that of control. Kocuria sp. P10 significantly enhanced PAH removal (P < 0.05) and ryegrass growth
(P < 0.01). Dehydrogenase activity increased steadily and was negatively correlated with total PAH content.
Successional changes in soil microbial communities were also detected by pyrosequencing. The
results indicated that biodiversity of the soil bacterial community gradually increased with time and was
slightly lower in control, as indicated by operationaltaxonomic unit(OTU) numbers and Shannon–Wiener
indices. Proportions of Betaproteobacteria and Gammaproteobacteria were consistently high in all
groups. Actinobacteridae were initially predominant (>37.8%) but rapidly decreased to