DETERMINANTS THAT MAY BE INVOLVED IN VIRULENCE AND DISEASE IN Campylobacter jejuni

Growth of autobioluminescent Campylobacter jejuni in response to various environmental conditions

An autobioluminescent Campylobacter jejuni organism generated from the fusion of luxCDABE genes from Xenorhabdus luminescens to the flaA promoter of C. jejuni was used in conjunction with gel-stabilized gradient plates to map the responses of this organism to three environmental factors (pH, NaCl concentration, and temperature) and various concentrations of L-fucose, D-fucose, and sodium desoxycholate. The minimum, optimum, and maximum temperatures for the growth of autobioluminescent C. jejuni ATCC 35921 in solid media were found to be 30, 40, and 45 degrees C, respectively. At its optimum growth temperature, C. jejuni ATCC 35921 was able to grow well at pHs of 5.5 to 8.0 and in the presence of up to 1.70 to 1.75% NaCl. At its minimum growth temperature, however, C. jejuni ATCC 35921 could grow only at pHs of 6.5 to 8.0 and in the presence of up to 0.5% NaCl. L-Fucose, D-fucose, and sodium desoxycholate were shown to inhibit the growth of C. jejuni. Autobioluminescent C. jejuni was also used to determine whether the flaA promoter responds to both environmental conditions and chemical stimulants. While sodium desoxycholate was found to down-regulate C. jejuni flaA promoter activity, L-fucose was found to up-regulate its activity. Sodium chloride, pH, and D-fucose were all shown to exert no significant effects on promoter activity. Bacterial bioluminescence in combination with two-dimensional gradient gels is a powerful tool for studying the behavior of bacteria exposed to various environments.

Genetic and biochemical evidence of a Campylobacter jejuni capsular polysaccharide that accounts for Penner serotype specificity

Campylobacter jejuni, a Gram-negative spiral bacterium, is the most common bacterial cause of acute human gastroenteritis and is increasingly recognized for its association with the serious post-infection neurological complications of the Miller-Fisher and Guillain-Barré syndromes. C. jejuni lipopolysaccharide (LPS) is thought to be involved in the pathogenesis of both uncomplicated infection and more serious sequelae, yet the LPS remains poorly characterized. Current studies on C. jejuni suggest that all strains produce lipooligosaccharide (LOS), with about one-third of strains also producing high-molecular-weight LPS (referred to as O-antigen). In this report, we demonstrate the presence of the high-molecular-weight LPS in all C. jejuni strains tested. Furthermore, we show that this LPS is biochemically and genetically unrelated to LOS and is similar to group II and group III capsular polysaccharides. All tested kpsM, kpsS and kpsC mutants of C. jejuni lost the ability to produce O-antigen. Moreover, this correlated with serotype changes. We demonstrate for the first time that the previously described O-antigen of C. jejuni is a capsular polysaccharide and a common component of the thermostable antigen used for serotyping of C. jejuni.