Showing papers in "Fems Microbiology Letters in 1981"

Nitrogen-fixing nodules induced by Rhizobium on the stem of the tropical legume Sesbania rostrata

Abstract: The only recorded instances of legume, species with aerial nodules are for Neptunia oleracea [ 11 and Aeschynomene indica [2,3 J . This latter, which grows in flooded soils, has two types of nodules: root nodules like other legumes, and stem nodules. Stem , nodules of A. indica usually are distributed sparsely along the lower stem and look more like small swellings than conventional Rhizobium nodules. We report here on a tropical legume, Sesbania 2.1. Techniques for structural studies

Escherichia coli cells containing the plasmid ColV produce the iron ionophore aerobactin

Abstract: The first colicin to be described (colicin V) in 1925 was the product of a virulent Escherichia coli strain [1]. Since then studies have been performed with the aim of identifying the virulence factor associated with the ability to produce colicin V. ' Such a relationship has been established for humans, domestic animals and in experimental animal systems infected with pathogenic E. coli strains [2-7]. To date it is clear that several virulence enhancing factors are encoded by ColV plasmids. Synthesis of colicin V seems not to be essential for virulence enhancement [2,3] although it has been reported that colicin V inhibits macrophages [8]. E. coli strains harbouring ColV plasmids show an enhanced resistance to the bactericidal effects of serum [3,9], and their growth is supported by a new iron sequestering system [7,10,11]. It was shown that the iron ligand was of the hydroxamate type but ferrichrome, the only known ferric hydroxamate complex to be actively taken up by E. coli, was excluded [11 ]. In this paper it is reported that aerobactin is the new iron ligand produced by ColV-bearing E. coli strains. The search for the iron ligand was guided by the fact that other Enterobacteriaceae, Aerobacter aerogenes [12], Shigella flexneri [13] and Enterobacter cloacae [14] produce aerobactin. A new rapid isolation procedure was developed which is different from the one described by the discoverers of aerobactin, F. Gibson and D.I. Magrath [12], and which allows the isolation of large quantities in highly pure form.

SDS polyacrylamide gel electrophoresis and serological analysis of pili from Escherichia coli of different pathogenic origin

Abstract: The presence of non-flagellar filamentous appendages of bacteria is known since about 30 years [1-4] and different types of such structures termed fimbriae [5] or pili [6] have been recognized. The commonest one called the common type 1 pilus has recently been characterized [7,8]. During the last 7-10 years a number of bacterial pili have been described in more detail and their role in host-parasite interactions has been discussed. This has especially been the case with the CFA/ I [9] and CFA/ I I antigens [10], the pilus from Escherichia coli 018ac [11] as well as with the pilus-like antigens K88 and K99 [12-14]. Another pilus preparation, termed F7 []5] has recently been reported to be a mixture of 3 components [16]. The presence of pili on certain bacteria may also be correlated with their capacity to agglutinate erythrocytes from different animal species [17] or yeast cells [18,19]. In these pili-mediated agglutinations distinct patterns can be obtained which may be used in the characterization of pilated bacteria and their pili [17]. It has further been shown that pili mediate the adhesion to uroepithelial cells of E. coli which cause acute pyelonephritis [20,21]. The adhesion of E. coli to intestinal epithelium causing diarrhea has also been demonstrated [22]. In view of the potential importance of pili in bacterial infections we have now studied the pili of a number of E. coli strains from pathogenic origin in SDS-polyacrylamide gel electrophoresis and compared the results with the serological properties of the respective pili.

Evidence for two haemolytic activities from Aeromonas salmonicida

Abstract: Aeromonas salmonicida is the aetiological agent of furunculosis, an economically important disease of fish, particularly salmonids reared under intensive conditions [1]. There has been much interest recently in the investigation of toxins and other pathogenic mechanisms with a view to producing effective vaccines. A factor having leukocytolytic activity has been partially characterized [2]; proteolytic activity may be responsible for the necrosis of tissue seen in infected fish [3,4]. However, the anaemic response of infected fish [5] and the presence of extensive haemosiderin deposits in haemopoietic tissue [6] have resulted in the suggestion that haemolysins may play a role in pathogenesis. Extracellular products obtained by the agar overlay technique have been shown to be toxic and contain haemolytic activity against trout erythrocytes [7]. However, the complex nature of such material is likely to make it difficult to purify the factors responsible. We report here the first detailed study of haemolysin production by A. salmonicida and present evidence for the existence of two distinct haemolytic activities.