The effects of toxic pollutants on freshwater bacterial communities

Milner, Carl Russell

Abstract

The effects of heavy metals, and phenolic compounds and phenol derivatives, on freshwater bacterial communities was studied. An effluent containing copper, zinc, cadmium and lead was found to have little or no toxic effect on planktonic bacterial communities in the River Aire, except for a localised inhibition of bacterial heterotrophic activity immediately below the discharge. The rapid complexation, adsorption and dilution of metals in the river were thought to account for the absence of bacterial inhibition.

The presence of phenolic compounds and phenol derivatives in a small stream, Sugden Beck, caused major alteration in the planktonic and sediment bacterial communities, although this depended on pH. I.n comparison with a control stream, Stubs Beck, which did not contain phenolic compounds or phenol derivatives, the bacterial community in Sugden Beck had fewer percentage chromogenic bacteria, reduced species diversity and increased viable counts on Pseudomonas-selective-media (PSM agar). A taxonomic study at these two sites showed that the phenolic compounds and phenol derivative~ in Sugden Beck, caused a shift in species composition away from a diverse bacterial community, containing a wide range of Gram-negative and Gram-positive genera, to one comprised of Gram-negative bacteria belonging to the genus Pseudomonas. Major differences were also found between Sugden Beck and Stubs Beck, in the morphology of planktonic bacteria and the ability to mineralize 2,4-dichlorophenoxyacetic acid (2,4D). Bacteria isolated from Stubs Beck and Sugden Beck were shown to have differing sensitivities to phenolic compounds and phenol derivatives. The toxicity of these compounds to bacteria was found to depend on the compound's structure and also on pH.

Citation

Milner, C. R. The effects of toxic pollutants on freshwater bacterial communities. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4224203

• Thesis Type: Thesis
• Deposit Date: Jun 22, 2022
• Publicly Available Date: Feb 24, 2023
• Keywords: Botany
• Public URL: https://hull-repository.worktribe.com/output/4224203
• Additional Information: Department of Botany, University of Hull
• Award Date: Apr 1, 1984