%0 Journal Article %A Said, A. A. %A Livermore, D. M. %A Williams, Rosamund J. %T Expression of H1 outer-membrane protein of Pseudomonas aeruginosa in relation to sensitivity to EDTA and polymyxin B %D 1987 %J Journal of Medical Microbiology, %V 24 %N 3 %P 267-274 %@ 1473-5644 %R https://doi.org/10.1099/00222615-24-3-267 %I Microbiology Society, %X Summary. During growth in magnesium (Mg++)-deficient mineral media, Pseudomonas aeruginosa cells synthesise large amounts of H1 outer-membrane protein and are resistant to polymyxins and EDTA. It has been suggested that H1 protein replaces Mg++ as an outer-membrane-stabilising component in Mg++ -deprived cells, thereby removing the EDTA target and blocking an adsorption site for polymyxins. Induction of H1 protein synthesis also occurred in P. aeruginosa cells grown in Antibiotic No. 3 Broth (Ab3B), although this medium is not Mg++ -deficient. Generally, significant induction of H1 protein did not occur in P. aeruginosa cultures grown in other complex media such as Proteose Peptone and Nutrient Broth, which contained less Mg++ than Ab3B, nor in Isosensitest Broth or Mueller Hinton Broth, which contained higher Mg++ concentrations. H1-protein-induced P. aeruginosa cells from Ab3B cultures, unlike those from Mg++ -deficient mineral-broth culture, remained fully sensitive to polymyxin B and, with one exception, to EDTA. It is concluded that induction of H1 protein does not itself confer resistance to polymyxin B, and has no more than a minor role in EDTA resistance. Other cell-wall changes, such as phospholipid modifications and the absence of Mg++, probably account for the resistance of Mg++ -deprived cells. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-24-3-267