Isolation and Characterization of a Novel Motility Mutant in SALMONELLA TYPHIMURIUM
type: CreativeWork
description: A new mutant, BT40, isolated from mutagenized cultures of S. typhimurium was deficient in chemotaxis (Che- phenotype) in tryptone semisoft agar, but had random motility with a tumbling frequency (37%) similar to that of the parental strain, ST23 (39%). In spatial assays accumulation of BT40 cells in capillary tubes containing attractants was decreased by 33%-59% compared to ST23, but BT40 had a normal response to attractants in temporal assays. The methylation level of the chemotactic proteins was decreased in BT40. At room temperature, the mean swimming speed was 11 μm/s for BT40 and 20 μm/s for ST23; more BT40 cells wobbled (50%) than ST23 cells (30%), also. The proportion of time that the flagella rotated in the clockwise direction was 5% for BT40 and 28% for ST23. Motile BT40 cells had only 1-3 flagella per cell, and the length of the flagellar filaments was only 40% of the normal. The mutant phenotype was designated as CheG- and conjugational studies located cheG between 12 min and 33 min on the chromosomal map. Transductional crosses with fla mutants indicated that cheG was located in flagellar region I at 23 min, and complementation analysis with recA fla strains mapped cheG in flaFVIII. Transductional analysis of spontaneous revertants indicated that besides intragenic revertants, there were pseudorevertants with at least 4 types of suppressor mutations: type I suppressors, linked to the class I Tn10 by 16%, were located between the Tn10 and cheG; type II suppressors, linked to the class I Tn10. by 7%, were distal to cheG with respect to the Tn10; type III were linked to the class I Tn10 by 1%; type IV suppressors were not linked to the class I Tn10 and included in this type were the suppressor linked by over 60% to the class II Tn10. The CheG- phenotype was due to a defect in a flagellar gene that caused the mutant to have short flagella and fewer flagellar filaments resulting in a decrease in the stability of the flagellar bundle. This instability accounte…
abstract: A new mutant, BT40, isolated from mutagenized cultures of S. typhimurium was deficient in chemotaxis (Che- phenotype) in tryptone semisoft agar, but had random motility with a tumbling frequency (37%) similar to that of the parental strain, ST23 (39%). In spatial assays accumulation of BT40 cells in capillary tubes containing attractants was decreased by 33%-59% compared to ST23, but BT40 had a normal response to attractants in temporal assays. The methylation level of the chemotactic proteins was decreased in BT40. At room temperature, the mean swimming speed was 11 μm/s for BT40 and 20 μm/s for ST23; more BT40 cells wobbled (50%) than ST23 cells (30%), also. The proportion of time that the flagella rotated in the clockwise direction was 5% for BT40 and 28% for ST23. Motile BT40 cells had only 1-3 flagella per cell, and the length of the flagellar filaments was only 40% of the normal. The mutant phenotype was designated as CheG- and conjugational studies located cheG between 12 min and 33 min on the chromosomal map. Transductional crosses with fla mutants indicated that cheG was located in flagellar region I at 23 min, and complementation analysis with recA fla strains mapped cheG in flaFVIII. Transductional analysis of spontaneous revertants indicated that besides intragenic revertants, there were pseudorevertants with at least 4 types of suppressor mutations: type I suppressors, linked to the class I Tn10 by 16%, were located between the Tn10 and cheG; type II suppressors, linked to the class I Tn10. by 7%, were distal to cheG with respect to the Tn10; type III were linked to the class I Tn10 by 1%; type IV suppressors were not linked to the class I Tn10 and included in this type were the suppressor linked by over 60% to the class II Tn10. The CheG- phenotype was due to a defect in a flagellar gene that caused the mutant to have short flagella and fewer flagellar filaments resulting in a decrease in the stability of the flagellar bundle. This instability accounte…
author: Chacko, David Matthew
language: English
keywords: Biochemistry, Microbiology, Salmonella typhimurium.
date published: 1985-09-01T07:00:00Z
date modified: 2026-07-24T02:53:44Z
provider: Loma Linda University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Loma Linda University