Further studies on the detection of mutagenic and genotoxic activity in @entity1 faeces: aerobic and anaerobic fluctuation tests with XXXX and @entity526 , and the SOS Chromotest.

@entity1 @entity2491 @entity3793 @entity20720 @entity2340 @entity717 @entity526
The product of six @entity717 were collected from one @entity1 (consuming a normal western diet) over a period of 5 months. Aqueous faecal extracts were prepared (0.75 g wet wt./ml water) under aerobic and anaerobic conditions. Graded doses were assayed aerobically and anaerobically for mutagenicity in replicate microtitre fluctuation tests employing @entity3793 reversion in @entity2491 TA100 and @entity2340 reversion in @entity526 WP2uvrA(pKM101), and in aerobic SOS Chromotests, using @entity526 PQ37. The @entity3793 and @entity2340 content of each extract was determined by (i) pre-column derivatisation with @entity20720 followed by reverse-phase h.p.l.c. and (ii) by aerobic and anaerobic bioassays employing appropriate auxotrophic strains of @entity2491 and @entity526 . All six faecal samples contained enough @entity3793 and @entity2340 or their precursors to compromise the interpretation of fluctuation tests. The h.p.l.c. technique, though quantitatively detecting free @entity2340 added to faecal extracts, did not account for growth-enhancing effects of faecal extracts detected by bioassay using bacteria with a requirement for @entity2340 . However, h.p.l.c. detected @entity3793 more efficiently than bioassays. A combination of reconstruction experiments and bioassays enabled construction of 'growth windows' within which, in fluctuation tests, dose-related increases in numbers of positive wells could be ascribed to mutation rather than to feeding of auxotrophic bacteria. Under aerobic conditions of extraction and assay, five out of six samples were mutagenic to @entity2491 TA100, and all six were mutagenic to @entity526 WP2uvrA(pKM101). None of the samples extracted and assayed anaerobically was mutagenic to @entity2491 , but all six were positive in @entity526 WP2uvrA(pKM101). There was an increase both in faecal @entity3793 and @entity2340 and in mutagenicity during the period of collection, the association between faecal @entity2340 and faecal mutagenicity being statistically significant. All the samples were negative in the SOS Chromotests. We conclude that this donor regularly excretes faeces which contain at least two classes of water-soluble directly-acting mutagens which are not detected in SOS Chromotest at doses five times those giving positive effects in fluctuation tests.
