Microbial Population Dynamics Associated with Crude-Oil Biodegradation in Diverse Soils

Abstract

Soil bacterial population dynamics were examined in several crude-oil-contaminated soils to identify those organisms associated with alkane degradation and to assess patterns in microbial response across disparate soils. Seven soil types obtained from six geographically distinct areas of the United States (Arizona, Oregon, Indiana, Virginia, Oklahoma, and Montana) were used in controlled contamination experiments containing 2% (wt/wt) crude oil spiked with [1-14 C]hexadecane. Microbial populations present during hydrocarbon degradation were analyzed using both 16S rRNA gene sequence analysis and by traditional methods for cultivating hydrocarbon-oxidizing bacteria. After a 50-day incubation, all seven soils showed comparable hydrocarbon depletion, where >80% of added crude oil was depleted and approximately 40 to 70% of added [ 14 C]hexadecane was converted to 14 CO 2 . However, the initial rates of hydrocarbon depletion differed up to 10-fold, and preferential utilization of shorter-chain-length n-alkanes relative to longer-chain-length n-alkanes was observed in some soils. Distinct microbial populations developed, concomitant with crude-oil depletion. Phylogenetically diverse bacterial populations were selected across different soils, many of which were identical to hydrocarbon-degrading isolates obtained from the same systems (e.g., Nocardioides albus, Collimonas sp., and Rhodococcus coprophilus). In several cases, soil type was shown to be an important determinant, defining specific microorganisms responding to hydrocarbon contamination. However, similar Rhodococcus erythropolislike populations were observed in four of the seven soils and were the most common hydrocarbon-degrading organisms identified via cultivation.

Plant litter and soil type drive abundance, activity and community structure of alkB harbouring microbes in different soil compartments

“…These shifts as well as the increased abundance were most pronounced in the litter layer likely indicating that significant parts of the available alkanes were readily degraded. This fact is supported by data from earlier studies, where extensive community structure changes of alkB harbouring bacteria in nutrient-enriched soils as compared with control plots over time has been described in several field studies (Rö ling et al 2004;Hamamura et al 2006;Vázquez et al, 2009).…”

Comparison of archaeal and bacterial community structures in heavily oil-contaminated and pristine soils

“…in Gammaproteobacteria and high G+C gram-positive Rhodococcus spp. in Actinobacteria are commonly detected bacteria in various oil-contaminating environments (28). In the present study, Pseudomonas-or Rhodococcuslike clones were not detected in the oil-contaminated soil, whereas those affiliated with hydrocarbon-degrading Halomonas, Marinobacter, and Alcanivorax were in abundance.…”

Field performance of alder-Frankia symbionts for the reclamation of oil sands sites

“…The DGGE technique has been used extensively in the characterization of microbial communities (Hadwin et al, 2006), and to monitor shifts in microbial populations during bioremediation studies (Hamamura et al, 2006;Miyasaka et al, 2006) or phytoremediation trials (Phillips et al, 2006;Siciliano et al, 2003). This technique has proven to be useful in the study of complex microbial communities over time and space.…”