Oil & Natural Gas Projects
Exploration and Production Technologies
Biological Upgrading of Heavy Oils for Viscosity Reduction/Biocatalytic
P-52 (FEW ESD98-040)
This project was funded through DOE's Natural Gas and Oil Technology Partnership
Program. The Partnership Program establishes alliances that combine the resources
and experience of the nation's petroleum industry with the capabilities of the
national laboratories to expedite research, development, and demonstration of
advanced technologies for improved natural gas and oil recovery.
The goal is to investigate the production of linear alcohols and other intermediates
using novel bacteria that transform long-chain alkanes without degrading aliphatic
hydrocarbons of C8 or less.
Lawrence Berkeley National Laboratory
This research targeted the terminal oxidation of alkanes to alcohols as a specific
mechanism for development. Biological conversion of alkanes to alcohols was
carried out by alkane monooxygenase (AlkMO), an enzyme found in bacteria able
to grow on alkanes. The most well-understood AlkMO is a diiron enzyme, AlkB,
coded by the alkB gene.
For biocatalytic viscosity reduction to be economic, the process will need
to incorporate an "open," non-sterile bioreactor design and use whole-cell
biocatalysts. This precludes the use of genetically engineered organisms and
requires that the process be controlled to maintain desirable biocatalytic agents
and favorable kinetics in the presence of competing bacteria. Additionally,
biocatalytic agents must target longer-chain alkanes (C8 and above) without
oxidizing gasoline range alkanes of C7 or less.
Alkane-oxidizing bacteria are promising biocatalysts for crude oil bioprocessing.
Five bacteria were developed with NGOTP funding that might be useful as biocatalysts,
and two of them may harbor novel enzyme systems for alkane transformation.
The goal of this project is to reduce viscosity in heavy crude oil. This will
reduce the difficulty, and therefore the cost, of both transporting and processing
heavy crude oil. This is important because much of U.S. oil production is heavy
crude oil. Since heavy crude is difficult to transport and process, it sells
at a discount to light, sweet crudes. Reducing viscosity could help increase
profitability and production of this National resource.
The U.S. petroleum industry is increasingly dependent on heavy crude oil to
meet domestic demand for gasoline and distillate fuels. Biocatalytic viscosity
reduction (bioprocessing) uses bacteria to partially transform less-valuable
crude oil components to surface-active compounds (alcohols and carboxylic acids)
that reduce crude oil viscosity. Bioprocessing could be used to lowering heavy
oil viscosity before introduction into a pipeline, thereby reduce pumping costs.
Bacteria were isolated from contaminated environments and evaluated for their
biocatalytic potential. A series of phylogenic, physiologic, and genetic assays
were developed and applied to the strains and reference cultures from other
laboratories. Biocatalysts showing novel or unique activity or genetic profiles
were further evaluated. Using this approach, a "menu" of biocatalytic
agents was developed for chemical processing and environmental applications.
A biocatalyst was identified that has a higher specificity for low-value alkanes
than the higher-value light alkanes. Kinetic modeling of reaction processes
using this biocatalyst indicates that the proper selection of catalyst will
overcome a major challenge to crude oil bioprocessing's unintentional degradation
of gasoline-range alkanes.
The project team selected 32 biocatalytic agents for evaluation. Initial evaluation
identified specific strains as promising agents for the processing of crude
oils and alkane mixtures. The majority of the selected strains have a broad
substrate specificity encompassing C6-C16 alkanes. Some strains oxidize only
alkanes of C8 and above.
The research has focused on completing evaluations of 11 strains selected as
priorities from the complete culture collection. Each of these strains has been
screened for fatty acid methyl ester (FAME) profile. Genomic DNA has been isolated
for 16-DNA analysis. These strains have been tested for homology with known
alkB gene sequences, and the results of the genetic analysis have been correlated
with physiological tests measuring alkane oxidation profiles. Kinetic evaluation
of these strains is in progress.
The results of the researchers' evaluation have demonstrated that the majority
of the bacteria in their collection have homology with known alkB gene sequences.
This sequence is correlated with the ability to transform low-molecular-weight
(C8 and less) alkanes. Two strains that oxidize only select longer-chain alkanes
do not show homology with alkB genes by project protocols. The lack of homology
with alkB suggests that these strains may contain novel enzymes. One strain
has a high specificity in target substrates and is considered of high potential
value as a biocatalytic agent. Invention disclosure forms for this strain are
Current Status (October 2005)
This project is completed.
Project Start: January 15, 1999
Project End: March 15, 2004
Anticipated DOE Contribution: $732,000
Performer Contribution: $300,000 (29% of total)
NETL -Kathleen Stirling (email@example.com or 918-699-2008)
LBNL - William Stringfellow (firstname.lastname@example.org or 510/486-7903)