EFFICIENCY OF INDIGENOUS AND INOCULATED COLD-ADAPTED SOIL-MICROORGANISMS FOR BIODEGRADATION OF DIESEL OIL IN ALPINE SOILS

Biodegradation of diesel oil (5 g.kg [soil dry weight](-1)) was invest igated in five alpine subsoils, differing in soil type and bedrock, in laboratory experiments during 20 days at 10 degrees C. The biodegrada tion activities of the indigenous soil microorganisms and of a psychro trophic 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 activit y of the indigenous soil microorganisms. Biostimulation by fertilizati on enhanced diesel oil biodegradation to a significantly greater degre e than bioaugmentation with the psychrotrophic inoculum. In none of th e five soils did fertilization plus inoculation result in a higher dec ontamination than fertilization alone. A total of 16 to 23% of the add ed diesel oil contamination was lost by abiotic processes. Total decon tamination without and with fertilization was in the range of 16 to 31 and 27 to 53%, respectively.