BACTERIAL COMMUNITY DYNAMICS AND ECOTOXICOLOGICAL ASSESSMENT DURING BIOREMEDIATION OF SOILS CONTAMINATED BY BIODIESEL...

Area of Science:

• Environmental Science
• Microbiology
• Ecotoxicology

Background:

• Biodiesel use is increasing in Brazil via blends like B20 and B5.
• The environmental impact and ecotoxicity of biodiesel-contaminated soils are not well understood.

Purpose of the Study:

• Assess soil ecotoxicity and microbial dynamics after contamination with pure biodiesel (EXPB100) and a low-level blend (EXPB5).
• Investigate the biodegradation potential of soil microbiota on biodiesel and its blends.

Main Methods:

• Laboratory microcosms with clay loam soil contaminated with EXPB100 and EXPB5.
• Most-probable-number (MPN) for bacterial enumeration, dehydrogenase assays, and Eisenia fetida ecotoxicity tests.
• Analysis at different soil depths over 60 days of incubation.

Main Results:

• Ecotoxicity decreased significantly: EXPB100 mortality reduced from 63% to 0%; EXPB5 from 100% to 53-90%.
• Dehydrogenase activity increased in EXPB100 and EXPB5 treated soils compared to pristine soil.
• Aerobic bacteria grew at the top, while anaerobic bacteria grew at various depths in both treatments.

Conclusions:

• Soil indigenous microbiota likely play a role in the biodegradation of biodiesel and its blends.
• Further analysis (GC-FID, 16S rRNA sequencing) is needed to understand biodegradation mechanisms and microbial profiles.