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Standard inocula preparations reduce the bacterial diversity and reliability of regulatory biodegradation tests

Lookup NU author(s): Dr Andrew Goodhead, Professor Ian Head, Professor Russell DavenportORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


OECD ready biodegradability tests have been central to understanding the biodegradation of chemicals from a regulatory perspective for many decades. They are not fit for contemporary prioritisation of chemicals based on persistence, however, due to the low concentration of inocula used, short duration and high variability between tests. Two OECD standard inoculum pretreatment methods (settlement and filtration) were investigated to observe their effect on the probability of biodegradation and associated changes in bacterial community structure and diversity of inocula sourced from the activated sludge process of wastewater treatment plants. Both settlement and filtration were shown to dramatically and significantly reduce the probability and increase the variability of biodegradation of 4-nitrophenol compared to the use of unprocessed inocula. These differences were associated with a significant hundred-fold reduction in cell numbers and solids content and a significant shift in bacterial community structure that was sometimes accompanied by significant reductions in detectable operational taxonomic unit richness and evenness. The natural variation (between different environments) and variation due to differential selection of bacterial communities (by different pretreatment methods) is offered as an explanation for the historical high variability in standard OECD ready biodegradability tests.

Publication metadata

Author(s): Goodhead AK, Head IM, Snape JR, Davenport RJ

Publication type: Article

Publication status: Published

Journal: Environmental Science and Pollution Research

Year: 2014

Volume: 21

Issue: 16

Pages: 9511-9521

Print publication date: 01/08/2014

Online publication date: 17/09/2013

Acceptance date: 08/08/2013

Date deposited: 09/10/2013

ISSN (print): 0944-1344

ISSN (electronic): 1614-7499

Publisher: Springer Berlin Heidelberg


DOI: 10.1007/s11356-013-2064-4


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Funder referenceFunder name
Brixham Environmental Laboratory, AstraZeneca, UK
Engineering and Physical Sciences Research Council (EPSRC)
EP/E500501/1RCUK Academic Fellowship
EP/I025782/1EPSRC Challenging Engineering Award