Bioaugmentation and biostimulation of hydrocarbon degradation and the microbial community in a petroleum-contaminated soil

• Biostimulation and bioaugmentation achieved 60% and 34% oil hydrocarbon degradation.
• Degradation plateau occurred in the seventh week.
• Biostimulation with nitrogen and phosphorus enhanced microbial growth and activity.
• The inoculants, Acinetobacter SZ-1 strain KF453955, survived in oil-polluted soil.

Nutrient additions can stimulate petroleum hydrocarbon degradation, but little is known about how these additions affect the microbial community involved in that degradation. A microcosm study was conducted to assess the impact of bioaugmentation with Acinetobacter SZ-1 strain KF453955 and biostimulation with nutrients nitrogen and phosphorus on petroleum hydrocarbon degradation efficiency and microbial community dynamics during bioremediation of an oil-contaminated soil. Soils were incubated without shaking at room temperature for 10 weeks, and petroleum hydrocarbon degradation efficiency, catalase activity, petroleum hydrocarbon degrader population, and bacterial community diversity were determined. Results showed biostimulation and bioaugmentation, respectively, promoted 60% and 34% degradation of the total petroleum hydrocarbons (TPH) after six weeks of incubation. A degradation plateau occurred in the seventh week. Catalase activity and the populations of oil degraders in soil were generally greater for biostimulation than for bioaugmentation. The inoculants survived into the seventh week for the bioaugmentation treatment, and bacterial diversity did not increase by biostimulation. The populations of TPH-degraders in soil were positively related to TPH degradation efficiency during bioremediation of petroleum-polluted soils.