title: The influence of culture conditions on the susceptibility of Salmonella typhimurium in the Salmonella mutagenicity test.
abstract: To determine the variability of tester strain susceptibility in the Salmonella mutagenicity assay and to optimize the culturing procedure we examined the influences of the overnight culture period (12-16 h), the use of an additional short-term culturing procedure (1-4 h) and the Salmonella density (cfu/plate) on the rate of revertants per plate. As tester strains we used Salmonella typhimurium TA97, TA98, TA100 and TA102. As shown previously for other microbial genotoxicity short-term tests (i.e. with Escherichia coli PQ37), we observed the highest susceptibility of the Salmonella strains, i.e. the highest amounts of revertants per plate, when using a 12 h overnight culture followed by a 2 h short-term culturing procedure. We calibrated the bacterial count to 100 x 10(6) cfu per assay by photometric measurement (600 nm). Initially, we used 0-1 nmole 2,4,7-trinitro-9-fluorenone with S. typhimurium TA97, 0-15 nmole daunomycin with strain TA98, 0-25 nmole sodium azide with strain TA100 and 0-15 nmole methylmethanesulfonate with strain TA102 as reference compounds in the standard plate incorporation test. Subsequently, to evaluate the results of the culturing procedure variations we examined 22 well-known mutagenic and direct-acting (-S9-mix) compounds out of different chemical classes using both the standard and a modified culturing procedure. The comparison of these results showed a 64% (for 4-nitroquinoline-N-oxide) to 421% (for sodium azide) increased amount of revertants for the modified test protocol.
authors: Institute of Medical Microbiology and Hygiene, Faculty of Clinical Medicine Mannheim, University of Heidelberg.
authors: V
authors: V
authors: Mersch-Sundermann
authors: H
authors: H
authors: Krämer
mesh_terms: D015169:Colony Count, Microbial; D008741:Methyl Methanesulfonate / Q000633:toxicity; D009152:Mutagenicity Tests; D009153:Mutagens / Q000633:toxicity*; D015203:Reproducibility of Results; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development; D013997:Time Factors
chemical_list: D009153:Mutagens; D008741:Methyl Methanesulfonate