title: Standard inocula preparations reduce the bacterial diversity and reliability of regulatory biodegradation tests.
abstract: 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.
authors.affiliation: Sartorius Mechatronics UK Limited, Longmead Business Centre, Blenheim Road, Epsom, Surrey, KT19 9QQ, UK.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Goodhead
authors.forename: Ian M
authors.initials: IM
authors.lastname: Head
authors.forename: Jason R
authors.initials: JR
authors.lastname: Snape
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Davenport
mesh_terms: D001419:Bacteria / Q000145:classification*; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring / Q000379:methods; D009596:Nitrophenols; D015203:Reproducibility of Results; D012722:Sewage / Q000382:microbiology
chemical_list: D009596:Nitrophenols; D012722:Sewage; C024836:4-nitrophenol
references.citation: Ecotoxicol Environ Saf. 1984 Oct;8(5):410-22
references.pmid: 6386433
references.citation: Ecol Lett. 2006 Jul;9(7):805-12
references.pmid: 16796570
references.citation: Chemosphere. 2003 May;51(6):501-8
references.pmid: 12615102
references.citation: Ecotoxicol Environ Saf. 1992 Apr;23(2):161-72
references.pmid: 1374324
references.citation: Annu Rev Microbiol. 1976;30:327-49
references.pmid: 791071
references.citation: Ecotoxicol Environ Saf. 2000 Mar;45(3):274-83
references.pmid: 10702347
references.citation: Ecotoxicol Environ Saf. 1995 Aug;31(3):218-23
references.pmid: 7498059
references.citation: Ann Ist Super Sanita. 2008;44(1):13-5
references.pmid: 18469371
references.citation: Nucleic Acids Res. 2001 Jan 1;29(1):181-4
references.pmid: 11125085
references.citation: Front Microbiol. 2011 Aug 01;2:164
references.pmid: 21863143
references.citation: Appl Environ Microbiol. 2000 Mar;66(3):1158-66
references.pmid: 10698786
references.citation: Genome Biol. 2010;11(5):210
references.pmid: 20441597
references.citation: Appl Environ Microbiol. 1990 May;56(5):1392-6
references.pmid: 2339892
references.citation: Chemosphere. 2006 Jun;63(11):1953-60
references.pmid: 16297427
references.citation: ISME J. 2012 Aug;6(8):1621-4
references.pmid: 22402401
references.citation: Risk Anal. 1999 Dec;19(6):1193-204
references.pmid: 10765456
references.citation: Microb Ecol. 1998 Jan;35(1):1-21
references.pmid: 9459655
references.citation: Ecotoxicol Environ Saf. 1979 Jun;3(2):159-73
references.pmid: 120246
references.citation: Proc Natl Acad Sci U S A. 2002 Aug 6;99(16):10494-9
references.pmid: 12097644
references.citation: Methods Enzymol. 1990;183:63-98
references.pmid: 2156132
references.citation: Appl Environ Microbiol. 1998 Apr;64(4):1220-5
references.pmid: 16349535
references.citation: Appl Environ Microbiol. 1993 Mar;59(3):695-700
references.pmid: 7683183
references.citation: Ecotoxicol Environ Saf. 1984 Oct;8(5):451-70
references.pmid: 6489241
references.citation: Ecotoxicol Environ Saf. 2001 May;49(1):40-53
references.pmid: 11386714
references.citation: Ecotoxicol Environ Saf. 1981 Mar;5(1):45-55
references.pmid: 7472255
references.citation: Environ Sci Technol. 2009 Apr 15;43(8):2950-6
references.pmid: 19475976
references.citation: Ecotoxicol Environ Saf. 1995 Apr;30(3):274-82
references.pmid: 7541341