title: Microbial degradation of gasoline in soil: Effect of season of sampling.
abstract: In cases where fire debris contains soil, microorganisms can rapidly and irreversibly alter the chemical composition of any ignitable liquid residue that may be present. In this study, differences in microbial degradation due to the season in which the sample is collected was examined. Soil samples were collected from the same site during Fall, Winter, Spring and Summer and the degradation of gasoline was monitored over 30 days. Predominant viable bacterial populations enumerated using real-time PCR and reverse transcriptase polymerase chain reaction (RT-PCR) enumeration revealed the predominant viable bacterial genera to be Alcaligenes, Bacillus, and Flavobacterium. Overall, the compounds most vulnerable to microbial degradation are the n-alkanes, followed by the mono-substituted alkylbenzenes (e.g., toluene, ethylbenzene, propylbenzene and isopropylbenzene). Benzaldehyde (a degradation product of toluene) was also identified as a marker for the extent of biodegradation. Ultimately, it was determined that soil collected during an unusually hot and dry summer exhibited the least degradation with little to no change in gasoline for up to 4 days, readily detectable n-alkanes for up to 7 days and relatively high levels of resilient compounds such as o-xylene, p-xylene and 1,3,5-trimethylbenzene. These results demonstrate, however, that prompt preservation and/or analysis of soil evidence is required in order to properly classify an ignitable liquid residue.
authors: Department of Chemistry and Chemical Biology, Forensic and Investigative Sciences Program, Indiana University Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD 326, Indianapolis, IN 46202, United States.
authors: D A
authors: DA
authors: Turner
authors: Department of Natural Resources and Environmental Management, Ball State University, Muncie, IN 47306, United States.
authors: J
authors: J
authors: Pichtel
authors: Department of Biology, Ball State University, Muncie, IN 47306, United States; Department of Natural Resources and Environmental Management, Ball State University, Muncie, IN 47306, United States.
authors: Y
authors: Y
authors: Rodenas
authors: Department of Biology, Ball State University, Muncie, IN 47306, United States.
authors: J
authors: J
authors: McKillip
authors: Department of Chemistry and Chemical Biology, Forensic and Investigative Sciences Program, Indiana University Purdue University Indianapolis (IUPUI), 402 North Blackford Street, LD 326, Indianapolis, IN 46202, United States. Electronic address: jvgoodpa@iupui.edu.
authors: J V
authors: JV
authors: Goodpaster
mesh_terms: D001673:Biodegradation, Environmental; D002274:Carcinogens, Environmental / Q000032:analysis*; D004269:DNA, Bacterial; D005742:Gasoline / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D002274:Carcinogens, Environmental; D004269:DNA, Bacterial; D005742:Gasoline; D012987:Soil
keywords: Fire debris; Ignitable liquids; Principal components analysis; Soil