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Title: The toxicity of o-cresol and 2,4-dimethylphenol on anaerobic microbial associations
Author: McDowall, Alex
ISNI:       0000 0004 5359 8667
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2014
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The study of anaerobic bacterial growth associations plays an important role in the analysis of the toxicity and effect of pollutants. These associations can be found in the environment, for example in groundwater or wastewater treatment plants or even in the gut of animals. The aims of this study were to compare the toxicity exhibited on anaerobic growth associations by two similar alkylphenolic compounds, o-cresol and 2,4-dimethylphenol (DMP), individually and combined, and examine the specific effect these compounds had on individual bacterial groups within the consortium. Through the use of anaerobic batch cultures, the inhibitory concentrations and effects of o-cresol and 2,4-dimethylphenol on anaerobic processes were analysed. Concentrations of o-cresol = 1.85mM were shown to have an inhibitory effect on sulphate reduction, acetogenesis and methanogenesis. At concentrations = 7.4mM complete inhibition of sulphate reduction was noted and the acetogenic and metha nogenic processes were greatly reduced, concentrations = 9.3mM appear to cause complete inhibition of methane production. 2,4-dimethylphenol inhibited bacterial groups at concentrations =0.41mM; complete inhibition of sulphate production was observed at concentrations of DMP =3.28mM. Although methane production was significantly reduced at the highest concentration (4.1mM) complete inhibition was not observed. It was found that DMP was more toxic to all the bacteria and archaea within the consortium than o-cresol. Use of continuous flow systems allowed for the separation of the microbial groups within the consortium allowing for the analysis of the direct effect of o-cresol and 2,4- Dimethylphenol. Analysis of the results indicated that the compounds inhibited all the microbial groups, although with varying x degrees of success. It was observed that acetoclastic methanogenic bacteria are more resilient to the toxic effect of the compounds than h methanogens and sulphate reducing bacteria. The combined toxicity of these compounds was analysed utilising batch cultures. The combined toxic effect on the growth consortium was observed after addition of both of these compounds to batch cultures. The results showed that, when combined, these compounds exhibited a toxic effect on the consortium, which was synergistic in nature. This study has highlighted the toxic effects of o-cresol and DMP on anaerobic consortia and the importance of the synotrophic relationships between the different bacterial and archaeal groups. It is important that work in this field is carried on to develop a better understanding of the implications of toxic chemical spills and their impact on the groundwater environment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available