Microbial degradation of xenobiotic chemicals

Colquhoun, KO, 1988. Microbial degradation of xenobiotic chemicals. PhD, Nottingham Trent University.

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Abstract

The inherent biodegradability of eight xenobiotic chemicals which have exhibited aberrant behaviour in degradation tests were investigated. Three of the chemicals investigated; benzene-1,3-disulphonic acid (BDSA), 2-chlorobenzoic acid (2CBA) and cis, cis, cis, cis-1,2,3,4-cyclopentanetetracarboxylic acid (CPTCA) were not found to be inherently biodegradable. t-Butanol was removed in a semi-continuous activated sludge (SCAS) test, but the mechanism was found to be volatilization not biodegradation, a fact overlooked by other workers. Three of the remaining four chemicals, 3-chlorobenzoic acid (3CBA), N-methylaniline (NMA) and tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA) were degraded in SCAS tests after acclimatization.

Hexamethylenetetramine (hexa) was not degraded in the SCAS test, but it was degraded during 28 day die-away tests. It has been demonstrated that hexa can be degraded by unadapted activated sludge and soil at levels as low as 10-sg 1-1 using 14C labelled substrate. The ability of activated sludge to degrade these chemicals found to be inherently biodegradable was not lost during a deacclimatization period of 3 months. None of the chemicals investigated were found to be inhibitory to microbial growth.

Microorganisms have been isolated which can degrade 3CBA, hexa, NMA and THFTCA and growth characteristics investigated. Four microorganisms capable of degrading 3CBA were isolated and identifed as Pseudomonas species. The degradative pathway has been identified as the ketoadipate pathway. NMA and THFTCA were degraded by an Alcaligenes species and a Corynebacterium species respectively, both isolated from activated sludge. Hexa was degraded by two-separate species Methylobacterium isolated from activated sludge by enrichment. The hexa, NMA and THFTCA degrading isolates appear to be the first reported.

The results obtained are discussed in context with what has been reported by other workers, both in relation to biodegradation in general, and biodegradation testing in particular.

Item Type:	Thesis
Creators:	Colquhoun, K.O.
Date:	1988
ISBN:	9781369324174
Identifiers:	Number Type PQ10290168 Other
Rights:	This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without the author's prior written consent.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	10 Nov 2020 16:47
Last Modified:	11 Oct 2023 09:10
URI:	https://irep.ntu.ac.uk/id/eprint/41603

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