ACCESS NUMBER: 30660-19921 

STUDY TITLE: Survival of a hydrocarbon-utilizing bacterium when introduced into 

native and foreign environments 

REPORT TITLE: Survival of a hydrocarbon-utilizing bacterium when introduced into 

native and foreign environments 

CONTRACT NUMBERS: 14-35-001-30660-19921 

SPONSORING OCS REGION: Gulf of Mexico OCS Region 

APPLICABLE PLANNING AREA: Gulf of Mexico 

FISCAL YEAR(S) OF PROJECT FUNDING: 1994 - 2001 

COMPLETION DATE OF REPORT: December 2001 

COST: FY 1994; $167,774: CUMULATIVE PROJECT COST: $167,774 

PROJECT MANAGERS: Paul A. LaRock and Lisa S. Donovan 

AFFILIATION: Louisiana State University 

ADDRESS: Department of Oceanography and Coastal Sciences, School of the Coast 

and Environment, Baton Rouge, LA 70803 

PRINCIPAL INVESTIGATORS: Paul A. LaRock and Lisa S. Donovan 

KEYWORDS: bioremediation, hydrocarbon degradation, PCR probe, PCR primer, 

fluorescence, bacteria 

BACKGROUND: Bioremediation is emerging as an attractive means to restore 

inaccessible or environmentally sensitive areas. The degradation of spilled 

hydrocarbons is one application where the seeding of bacteria is particularly attractive 

since it is the microbes who ultimately consume and remove these materials, whether 

they occur naturally (as in marsh plant cuticles) or as an anthropogenic input. 

Increasingly we are seeing technological developments in which fluids of diverse origins 

are brought together, either by design or by accident. We are seeing renewed interest 

in the use of bioremediation for the purpose of remediating spilled oil. 

OBJECTIVES: Methods used by the molecular biologist were utilized to, 1) 

quantitatively amplify the DNA of target species, and 2) develop molecular probes that 

would unequivocally and rapidly identify the test species. The upshot of these efforts 

was the development of a methodology that may be used to assess changes in any 

microbial assemblage as a result of changes in the ecosystem, or for tracking 

introduced microbial species during bioremediation efforts. 
ACCESS NUMBER: 30660-19921 

DESCRIPTION: In general, bioremediation consists of either seeding bacteria that 

have been adapted in the laboratory to rapidly degrade the material in question, or 

modification of the environment with ‘fertilizers” to promote the development of natural 

microbial assemblages that are associated with the contaminant. The seeded bacteria 

might begin the degradation process immediately and more efficiently, whereas fertilizer 

addition might entail a relatively long lag period before effects are seen. The critical 

question, however, is whether the seeded microbes can compete and survive against 

native species in a foreign environment. 

SIGNIFICANT CONCLUSIONS: A new species of Acinetobacter that is capable of 

using hexadecane as its sole carbon source was isolated from coastal wetlands in 

Louisiana. When laboratory grown cultures of the Acinetobacter were re-introduced to 

an experimental flow-through marsh environment and hexadecane added, the microbe 

quickly displaced all other bacteria and represented essentially 99% of the microbial 

community. When Acinetobacter was added to Mississippi River water supplemented 

with hexadecane in a chemostat, it was completely displaced after six days at which 

time an indigenous microflora developed that reached a community density of 2 x 10 6

CFU per ml. One of the controls in tis experimen was simply the addition of 

hexadecane to a chemostat that had only river water passed through it, and a microbial 

community of approximately 106 developed right from the start. 

STUDY RESULTS: The results are that 1) Seed bacteria may readily be introduced 

back into the environment from which they originated, 2) Seed bacteria do not 

necessarily survive in foreign environments, and 3) Seeded bacteria may actually inhibit 

the development of normal microflora capable of utilizing the contaminating material. A 

methodology was developed that may be used to assess changes in any microbial 

assemblages as a result of changes in the ecosystem, or for tracking introduced 

microbial species during bioremediation efforts. 

STUDY PRODUCTS: LaRock, P.A. and L.S. Donovan. 2001. Survival of a 

hydrocarbon-utilizing bacterium when introduced into native and foreign environments. 

US Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, 

New Orleans LA. OCS Study MMS 2001-094. 70 pp.