Effect of iron limitation on protein composition and ultrastructure of Haemophilus ducreyi

Abstract

Protein profiles of whole cells of Haemophilus ducreyi grown in the presence or absence of the iron chelator desferal, were compared by polyacrylamide gel electrophoresis. Each of four strains produced novel proteins in the range 43-160 kDa when cultured under conditions of reduced iron availability. At some sub-inhibitory concentrations, desferal produced enhanced growth, possibly due to it functioning as an exogenous siderophore. Organisms grown under conditions of reduced iron availability ultrastructurally showed also large periplasmic spaces between cytoplasm and outer membrane.

Selective Bioaccumulation of Mixed Heavy Metals by a Range of Brackish Water Bacteria

“…4). This is attributed to the well-known role of both Zn and Fe in the metabolic activity of the bacterial cells (Abeck et al, 1990) especially as cofactors in the enzymatic activities (Lim, 1989). The tested bacteria also showed tolerant property against Co (Fig.…”

“…Some microorganisms Survive the presence of elevating levels of heavy metals by employing detoxification mechanisms and developing tolerance (Timoney, 1989;Rouch et al, 1989;Schreiber et al, 1990). Examples of positive and negative effects of some of the investigated heavy metals on metabolic activities of microbial cells were discussed including Fe (Abeck et al, 1990;Nakajima and Sakaguchi, 1986;Paerl et al, 1994), Cu (Erardi et al, 1987;Harwood-Sears and Gordon, 1990;Collins et al, 1991), Zn and Ni (Fang and Hui, 1994) and Pb (Leborans et al, 1998). The present study is a continuation of a series of studies on the bioremediation of heavy metals from contaminated effluents using naturally occurring bacteria isolated from brackish water.…”

Identification and purification of a conserved heme-regulated hemoglobin-binding outer membrane protein from Haemophilus ducreyi

“…Certain pathogenic bacteria, including H. ducreyi (1,14), do not secrete siderophores but rather have evolved receptors and transport systems to obtain iron directly from host iron-binding proteins (21,25). Examples of such systems are found in the pathogenic Neisseria spp.…”