Chickens are the main reservoir of Campylobacter jejuni, the most common bacterium that causes diarrhea worldwide. This study investigated the effects of serial truncations of lipooligosaccharide (LOS), a major component of the outer membrane of C. jejuni, on its bile resistance and intestinal colonization ability in chickens. Genes encoding manno-heptose synthetases or glycosyltransferases were inactivated to generate isogenic mutants. Serial truncation of the LOS core oligosaccharide caused a stepwise increase in the susceptibility to bile acids of two C. jejuni strains, NCTC 11168 and 81-176. Inactivation of hldE, hldD, or waaC caused a severe truncation of the core oligosaccharide, which greatly increased susceptibility to bile acids. Both wild-type strains grew normally in chicken intestinal extracts, whereas the mutants with severe oligosaccharide truncation were not detected 12 h after inoculation. These mutants attained viable bacterial counts in the bile acid-free extracts 24 h after inoculation. The wild-type strain 11-164 was present in the cecal contents at >107 CFU/g 5 days post-challenge, whereas its hldD mutant was present at <103 CFU/g throughout the experimental period. Mutants with a shorter LOS had higher hydrophobicities. Thus, the length of the LOS core oligosaccharide affected the surface hydrophobicity and bile resistance of C. jejuni as well as its ability to colonize chicken intestines.
(Bacterial and Parasitic Disease Research Division)
References:
Iwata T. et al (2013) PLoS ONE 8(2):375-381
