Biodegradation of commercial gasoline (24% ethanol added) in liquid medium by microorganisms isolated from a...

Isolation of soil microorganisms from a landfarming site with a 19-year history of petrochemical residues disposal was carried out. After isolation, the bacteria behavior in mineral medium with 1% commercial gasoline (24% ethanol) was evaluated. Parameters employed for microorganism evaluation and selection of those with the greatest degradation potential were: microbial growth; biosurfactant generation and compound reduction in commercial gasoline. Starting from bacteria that presented the best degradation results, consortiums formed by 4 distinct microorganisms were formed. A microbial growth in the presence of commercial gasoline was observed and, for most of the bacteria, degradations of compounds such as benzene, toluene and xylenes (BTX) as well as biosurfactant production was observed. Ethanol was partially degraded by the bacterial isolates although the data does not allow affirming that it was degraded preferentially to the aromatic hydrocarbons investigated. The analyzed consortiums present an efficiency of 95% to 98% for most of the commercial gasoline compounds and a preferential attack to ethanol under the essay condition was not observed within 72 h.