Efficiency of indigenous and inoculated cold-adapted soil microorganisms for biodegradation of diesel oil in alpine soils

Abstract

Biodegradation of diesel oil (5 g · kg [soil dry weight]-1) was investigated in five alpine subsoils, differing in soil type and bedrock, in laboratory experiments during 20 days at 10°C. The biodegradation activities of the indigenous soil microorganisms and of a psychrotrophic diesel oil- degrading inoculum and the effect of biostimulation by inorganic fertilization (C/N/P ratio = 100:10:2) were determined. Fertilization significantly enhanced diesel oil biodegradation activity of the indigenous soil microorganisms. Biostimulation by fertilization enhanced diesel oil biodegradation to a significantly greater degree than bioaugmentation with the psychrotrophic inoculum. In none of the five soils did fertilization plus inoculation result in a higher decontamination than fertilization alone. A total of 16 to 23% of the added diesel oil contamination was lost by abiotic processes. Total decontamination without and with fertilization was in the range of 16 to 31 and 27 to 53%, respectively.