Aerobic Biodegradation of Hopanes and Other Biomarkers by Crude Oil-Degrading Enrichment Cultures

Abstract

The degradation of petroleum biomarkers was examined using mixed cultures of microorganisms enriched from surface soils at four different hydrocarbon-contaminated sites. These cultures degraded C30 17alpha(H),21beta(H)-hopane and the C31-C34 extended hopanes in Bonny Light crude oil after 21 days of incubation at 30 degrees C. The C35 extended hopanes were conserved, and no 25-norhopanes were detected during the incubation. Denaturing gradient gel electrophoresis (DGGE) analysis of the enrichment cultures demonstrated distinct microbial community profiles. Additional studies with the LC culture demonstrated a consistent biomarker degradation pattern after growth on three crude oils: a Nigerian Bonny Light crude, a Venezuelan crude oil, and Alaskan North Slope 521. The onset of biomarker degradation was observed between days 14 and 21 but only at 30 degrees C and at oil concentrations below 6 mg/mL. The biomarker profiles following degradation by these enrichment cultures are similar to numerous field observations and may represent the dominant biodegradation pattern found in many hydrocarbon-contaminated aerobic surface environments.

Persistence and biodegradation of oil at the ocean floor following Deepwater Horizon

“…However, hopane is relatively persistent (95% remaining after 4 y) in the highly contaminated samples, supporting its use a conservative marker in heavily contaminated environments. These results add to other studies (39,40,49,50) that redefine views on hopane's fidelity and utility as an internal standard. In light of the research community's crucial public role in assessing the damage wrought by past and future spills, this mounting evidence strongly suggests that best practices are due for revision.…”

Effect of Pyocyanin on a Crude-Oil-Degrading Microbial Community

“…However, it has also been demonstrated that the presence of P. aeruginosa isolates in crude oil-degrading enrichment cultures decreases microbial diversity and aromatic degradation (21). In the later study, two oil-degrading microbial communities were initiated with soil from a polycyclic aromatic hydrocarbon (PAH)-contaminated site (20,21). One community was enriched in the laboratory on oil containing n-alkanes, while the second was enriched on oil lacking n-alkanes.…”

“…For example, the production of rhamnolipid biosurfactants by Pseudomonas aeruginosa has been shown to enhance the rates of octadecane (46) and hexadecane (1) uptake and degradation. However, it has also been demonstrated that the presence of P. aeruginosa isolates in crude oil-degrading enrichment cultures decreases microbial diversity and aromatic degradation (21). In the later study, two oil-degrading microbial communities were initiated with soil from a polycyclic aromatic hydrocarbon (PAH)-contaminated site (20,21).…”

“…Individual microorganisms are capable of degrading only a limited number of crude oil components; thus, more extensive degradation of oil depends on the presence of metabolically diverse microbial communities (2,8,18,21,29,39). However, microbial communities are not static, and factors affecting the composition of the community will alter their degradation potential.…”

Depositional History of Polycyclic Aromatic Hydrocarbons: Reconstruction of Petroleum Pollution Record in Peninsular Malaysia

“…Hopanes are relatively involatile, resist biodegradation, geologically mature and relatively stable in the environment (Simoneit et al, 1988) however there are chemical characteristics and properties among hopanes that compounds with higher number of carbon (e.g. C 35 ) shows bigger resistibility against biodegradation than lower numbered such as C 31 (Frontera et al, 2002) (Fig. 5).…”