Theses and Dissertations

Issuing Body

Mississippi State University


Lynch, F. Leo

Committee Member

Mylroie, John E.

Committee Member

Brown, Lewis R.

Committee Member

Kirkland, Brenda L.

Date of Degree


Document Type

Graduate Thesis - Open Access



Degree Name

Master of Science


College of Arts and Sciences


Department of Geosciences


This study uses scanning electron microscopy (SEM) to examine the occurrence of bacteria and their exopolysaccharide slime layer in microbial enhanced oil recovery experiments. A test of SEM preservation techniques showed that air drying and 10% glutaraldehyde fixation preserved the slime layer but distorted and flattened bacteria. Techniques with ethanol dehydration preserved the bacterial textures but fragmented the slime layer. In sandstones that had been plugged during microbial enhanced oil recovery experiments, bacteria are sparsely distributed. An irregular, confluent slime sheet covers grains and coats pore spaces and is responsible for permeability modification in microbial enhanced oil recovery. The development of the slime layer over time involves several steps: growth of ultramicrobacteria into full-sized bacteria; creation of a slime capsule; growth of globular masses, ropy masses, webs, thin sheets; and growth of a thicker, poreilling mass of slime associated with large balls of slime.