Importance Of Pili Research Articles

Adhesion of Escherichia coli O157:H7 during sublethal injury and resuscitation: Importance of pili and surface properties

Escherichia coli O157:H7 can recover from sublethally injured (SI) state, which causes threat of foodborne illness. Adhesion plays a key role in the carriage of pathogens in food. In this study, we investigated the adhesion ability of SI and recovered E. coli O157:H7 wildtype and its three pili-deficient mutants (curli, type 1 fimbriae, and type IV pili) on six food-related surfaces. Plate counting was used to determine adhesion population after washing and oscillating the surfaces. Spinach exhibited the stronger adhesion population of E. coli O157:H7 than the other fresh produces (p < 0.05). In addition, at least one key pili dominated adhesion on these surfaces, and curli was always included. The adhesion population and contribution of different types of pili were jointly affected by surface and physiological state. This can be attributed to high hydrophobicity and positive charge density on surface and different expression levels of csgB, fimA, fimC and ppdD in SI and recovered cells. Among glucose, mannose, maltose, fructose, lactose, and sucrose, addition of 0.5% mannose could reduce adhesion of cells at all physiological states on stainless steel. Overall, this research will provide support for controlling adhesion of SI and recovered E. coli O157:H7.

Cyanobacteria-bryophyte symbioses

Cyanobacteria are a large group of photosynthetic prokaryotes of enormous environmental importance, being responsible for a large proportion of global CO(2) and N(2) fixation. They form symbiotic associations with a wide range of eukaryotic hosts including plants, fungi, sponges, and protists. The cyanobacterial symbionts are often filamentous and fix N(2) in specialized cells known as heterocysts, enabling them to provide the host with fixed nitrogen and, in the case of non-photosynthetic hosts, with fixed carbon. The best studied cyanobacterial symbioses are those with plants, in which the cyanobacteria can infect the roots, stems, leaves, and, in the case of the liverworts and hornworts, the subject of this review, the thallus. The symbionts are usually Nostoc spp. that gain entry to the host by means of specialized motile filaments known as hormogonia. The host plant releases chemical signals that stimulate hormogonia formation and, by chemoattraction, guide the hormogonia to the point of entry into the plant tissue. Inside the symbiotic cavity, host signals inhibit further hormogonia formation and stimulate heterocyst development and dinitrogen fixation. The cyanobionts undergo morphological and physiological changes, including reduced growth rate and CO(2) fixation, and enhanced N(2) fixation, and release to the plant much of the dinitrogen fixed. This short review summarizes knowledge of the cyanobacterial symbioses with liverworts and hornworts, with particular emphasis on the importance of pili and gliding motility for the symbiotic competence of hormogonia.

SDS polyacrylamide gel electrophoresis and serological analysis of pili fromEscherichia coliof different pathogenic origin

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.