Kowalczyk, Agnieszka (2013) Role of microbial adaptation in the biodegradation of chemical pollutants : extrapolation from laboratory to rivers. PhD thesis, University of Warwick.

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Abstract

The Organisation for Economic Cooperation and Development (OECD) established
standardized tests to predict the chemical behaviour in the environment. Difficulties
exist in the extrapolation of data from laboratory OECD tests into the environment,
and prediction of possible scenarios regarding environmental pollution is not
accurate. The current project aimed to increase the realism of OECD tests and to
investigate the microbial populations involved in the biodegradation of paranitrophenol
(PNP). River water, sediment and biofilms were sampled from a stretch
of River Dene with an effluent discharge point (Wellesbourne WWTP), and were
used as microbial inocula in biodegradation studies. The effect of light, PNP
concentration and inoculum preparation on PNP biodegradation was determined.
Culture dependent techniques were used for isolation of PNP-degrading bacteria
while culture independent techniques; including 16S rRNA Terminal Restriction
Fragment Length Polymorphism, QPCR, and high throughput sequencing targeting
the PNP functional genes (pnpA and mar), enabled detection and characterization of
PNP-degrading bacteria. Light incubation lead to increased river water pH which
inhibited PNP degradation. A threshold PNP concentration was determined around
42 μg/L. Application of biofilm inocula improved the reproducibility of PNP
biodegradation at a concentration of 2 mg/L, and increased the amount of microbial
biomass in test systems. Pseudomonas syringae was identified as a key PNPdegrader.
Additional groups of PNP-degrading bacteria were detected based on the
analysis of pnpA and mar functional markers. It was shown that location of sampling
site for inoculum collection had no impact on biodegradation test outcome but
variation of microbial inocula between sampling dates may affect the biodegradation
of PNP. Core and satellite taxa analysis demonstrated that ‘biodegradation lottery’ is
not the major process which determines the successful chemical biodegradation, and
that probably microbial interactions within inoculum affect proliferation of PNPdegraders,
and therefore impact on test results. This project revealed the lack of
consideration of microbial inocula in the OECD biodegradation test guidelines.
Further experimental work was suggested to expand current studies to different
chemicals and rivers, and to develop more predictable approaches for better chemical
risk management by Industry and Regulatory bodies.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QH Natural history > QH301 Biology Q Science > QP Physiology
Library of Congress Subject Headings (LCSH):	Organisation for Economic Co-operation and Development, Pollutants -- Biodegradation, Adaptation (Physiology), Microbial ecology, Microorganisms -- Physiology
Official Date:	March 2013
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bending, G. D. (Gary D.); Schäfer, Hendrik; Price, Oliver R.; van Egmond, Roger; Finnegan, Chris
Sponsors:	Unilever (Firm)
Extent:	xx, 293 leaves : charts, illustrations.
Language:	eng

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