A protocol for the combined biochemical and serological identification of the Ames mutagen tester strains as Salmonella typhimurium

Abstract

Previously published reports have noted biochemical reactions atypical of Salmonella among the Ames tester strains of Salmonella typhimurium, and an inability to assign the strains to a specific Salmonella O (heat-stable cell wall) antigen group. We studied the biochemistry and serology of strains TA97, 98, 100, 102, 104, 1535, 1537, and 1538 in an attempt to develop a protocol to correctly speciate the strains. Biochemical reactions of all eight strains using standard media supplemented with histidine and biotin were consistent with those of the genus Salmonella. Strains TA100, 104, and 1535 were assigned to Salmonella O groups using bacteria treated with hot ethanol (White schema). H (flagellar) antigen assignments were performed successfully with seven of the eight strains. Two H antigen assignments required the use of the Craigie tube test for selection of motile revertants. Combining our biochemical and serological results obtained by this protocol, we were able to correctly speciate TA100, 104, and 1535 as Salmonella typhimurium. Our results demonstrate that representatives of the tester strains can be correctly speciated provided that procedures are followed that allow for the unusual nutrient requirements, the deep rough cell wall mutation, and the variably deficient motility of these organisms.

Presence and measurement of sample histidine in the ames test: Quantification and possible elimination of a source of false‐positive mutagenicity test results

“…Salmonella typhimurium strains NS1135 and TAlOO were the generous gifts of Dr. Kristien E. Mortelmans (SRI International, Menlo Park, CA) and Dr. Bruce N. Ames (University of California, Berkeley), respectively. The biochemical behavior of these strains has been previously reported (Busch et al, 1986b).…”

Salmonella Serotypes Isolated and Identified From Locally White Soft Cheese

“…one large colony inoculated into 5 ml 0.85% NaCl solution to inoculate the API strip according to the API 20E miniaturized identification system for Salmonella SPP. for biotyping (12,13). The isolated Salmonella strains were transferred simultaneously to Triple Sugar Iron agar by stabbing and streaking and incubated at 37°C for 24 hour to undergone stereotyping at the Institute of Public Health,Baghdad,Iraq.…”

Enhanced mutagenesis of Salmonella tester strains due to deletion of genes other than uvrB

“…Five different DuvrB alleles, formally called chl (bio uvrB gal), were isolated independently for inclusion in the main tester strains [Busch et al, 1986;Popkin et al, 1989]. Because of the methods used to introduce these and other mutations, as well as the pKM101 plasmid, strains containing the same histidine allele are not isogenic [Popkin et al, 1989].…”