Investigation of microbial diversity in an acid tar lagoon and the effect of low pH on two microorganisms isolated from an acid tar lagoon

Acid tar lagoons are heavily polluted, man-made environments found in several
locations around the world, including the United Kingdom, Germany and the United
States of America. Each lagoon is unique due to the different methods of tar production
resulting in a specific waste tar composition. There is also a great deal of heterogeneity
within each lagoon as a result of the viscous and mobile nature of the tar waste,
alongside a combination of attempted remediation efforts and/or illegal fly tipping.
The work presented in this thesis concerns one particular acid tar lagoon situated in the
North West of England which arose as a result of deposition of waste from benzole
refining. The effects on microbial diversity of a combination of low pH and high levels
of organic pollutants were investigated using samples taken from various locations
within this lagoon. A variety of techniques including classical microbiology, DGGE
and T -RFLP, were used to examine the microbial diversity, which was found to be
much lower in lagoon samples than pristine environments and appears to have
similarities with the microbial communities present in the Rio Tinto, Spain.
Following microbial diversity analysis a detailed examination of two specific organisms
isolated from lagoon samples was carried out in order to understand some of the
mechanisms of survival and tolerance to such an extreme environment. An
acidotolerant unicellular alga which appears to form a large biofilm in several areas of
the lagoon, Euglena gracilis G46, and an acidophilic bacterium, Acidocella 29, were the
focus ofthis aspect ofthe work. It appears that E. gracilis G46 maintains a near-neutral
pH under acidic conditions, Acidocella 29 is thought to have an unusually low
intracellular pH.