Impact of biodiesel on biodeterioration of stored Brazilian diesel oil

Alternative fuels are receiving considerable attention, especially biodiesel, which is recognized for its environmental benefits. One advantage is its biodegradability. However, biodegradability may allow the fuel to be more susceptible to microbial contamination, especially during storage. The susceptibility to biodeterioration of biodiesel, diesel, and diesel containing 5, 10, and 20% biodiesel was evaluated using fungi isolated from contaminated oil systems. Paecilomyces sp. produced the highest biomass in 20% and 100% biodiesel, while Aspergillus fumigatus grew best in pure biodiesel. Yeasts had the highest rates of degradation, especially Candida silvicola, with 100% degradation of all esters. Rhodotorula sp. showed greatest activity for C18:3 (linolenic acid), at 39.4%, followed by C18:1 (oleic acid) and C16 (palmitic acid), at 21% and 15%, respectively, after 7 days of incubation. The results are relevant for the resolution of the decade-long debate on the increase in diesel biodegradability due to the addition of biodiesel.