Corwin L M, Fanning G R, Feldman F, Margolin P
J Bacteriol. 1966 Apr;91(4):1509-15. doi: 10.1128/jb.91.4.1509-1515.1966.
Corwin, L. M. (Walter Reed Army Institute of Research, Washington, D.C.), G. R. Fanning, F. Feldman, and P. Margolin. Mutation leading to increased sensitivity to chromium in Salmonella typhimurium. J. Bacteriol. 91:1509-1515. 1966.-Certain deletion mutants including the tryptophan operon in Salmonella typhimurium are unable to utilize several sugars as carbon sources in solid media, although they are able to grow in liquid media with these sugars. The addition of citrate or washing the agar with ethylenediaminetetraacetic acid permits growth on solid media. Analysis of the agar revealed that Fe(3+) and Cr(3+) were present at concentrations of 22 and 75 mum, respectively. The addition of Fe(3+) to liquid media in 0.5 mm concentrations did not inhibit the wild type or the mutants. A similar concentration of Cr(3+) did not inhibit the wild type, but concentrations as low as 0.01 to 0.05 mm inhibited the deletion mutants. Other metals were inhibitory at various concentrations, but none showed any significant differential effects on the mutants and the wild type. The increased sensitivity of the mutants to chromium may be due either to an increased permeability to Cr(3+), resulting in higher effective intracellular concentrations and inhibition of one or more metabolic functions, or to a binding of Cr(3+) to an altered cell wall, resulting in decreased permeability of required substrates.
科温，L.M.（华盛顿特区沃尔特·里德陆军研究所），G.R.范宁、F.费尔德曼和P.马戈林。鼠伤寒沙门氏菌中导致对铬敏感性增加的突变。《细菌学杂志》91:1509 - 1515。1966年。——鼠伤寒沙门氏菌中的某些缺失突变体，包括色氨酸操纵子，在固体培养基中无法利用几种糖作为碳源，尽管它们能够在含有这些糖的液体培养基中生长。添加柠檬酸盐或用乙二胺四乙酸洗涤琼脂可使它们在固体培养基上生长。对琼脂的分析表明，其中铁（Ⅲ）和铬（Ⅲ）的浓度分别为22微摩尔和75微摩尔。在液体培养基中添加浓度为0.5毫摩尔的铁（Ⅲ）不会抑制野生型或突变体。类似浓度的铬（Ⅲ）不会抑制野生型，但低至0.01至0.05毫摩尔的浓度会抑制缺失突变体。其他金属在不同浓度下具有抑制作用，但没有一种对突变体和野生型表现出任何显著的差异效应。突变体对铬敏感性增加可能是由于对铬（Ⅲ）的通透性增加，导致细胞内有效浓度升高并抑制一种或多种代谢功能，或者是由于铬（Ⅲ）与改变的细胞壁结合，导致所需底物的通透性降低。
