Objective  Potential of applying native Xinjiang plants in combination with microbes as a bioagent to treat low concentration oil sludge pollution was explored.

  Method  Three treatments of microbes, plants, and plant-microbe combination that used plant including Cynodon dactylon, Festuca elata, Lolium Perenne, or Sorghum sudanense and the microbes including Candida lipolytica (Microbe A), Bacillus subtilis PL-2 (Bacterium B), and/or B. subtilis XJ-16 (Bacterium C) were conducted along with control in a pot experiment for 120 d. Effects of the treatments on petroleum hydrocarbon residues, and microbial population, as well as biomass and chlorophyll content of the plants, were determined.

  Result  Under the single-factor treatments, C. dactylon, S. sudanense, Bacterium B, or Bacterium C provided relatively similar effect in degrading petroleum hydrocarbons with 31.39%, 34.19%, 33.71%, and 33.39% reductions, respectively, which were significantly higher than control (P＜0.05). The plant-microbe combinations, on the other hand, showed significantly greater pollution remedying effect, such as achieved by incorporating C. dactylon with Bacterium A, B, and C that delivered the hydrocarbon removal rates of 43.02%, 40.20%, and 42.54%, respectively. Meanwhile, the culturable bacteria count increased significantly from 1.50×10⁵ cfu·g⁻¹ to 2.59×10⁵ cfu·g⁻¹ and fungi count from 4.32×10⁴ cfu·g⁻¹ to 5.53×10⁴ cfu·g⁻¹. In addition, the dry weight and total chlorophyll content of C. dactylon rose significantly in the presence of the microbes (P＜0.05).

  Conclusion  In view of petroleum hydrocarbon residue, microbial population, plant biomass, and leaf chlorophyll content, it appeared that the combined applications of Xinjiang native plant C. dactylon with yeast C. lipolytica and bacterium B. subtilis PL-2 or XJ-16 could be feasible for cleaning the environmental pollution caused by low concentration oil sludge in the area.