Abstract
Campylobacter jejuni and Campylobacter coli were previously considered asaccharolytic, but are now known to possess specific saccharides metabolization pathways, including L-fucose. To investigate the influence of the L-fucose utilization cluster on Campylobacter growth, survival and metabolism, we performed comparative genotyping and phenotyping of the C. jejuni reference isolate NCTC11168 (human isolate), C. jejuni Ca1352 (chicken meat isolate), C. jejuni Ca2426 (sheep isolate), and C. coli Ca0121 (pig manure isolate), that all possess the L-fucose utilization cluster.
All isolates showed enhanced survival and prolonged spiral cell morphology in aging cultures up to day seven in L-fucose-enriched MEMα medium (MEMαF) compared to MEMα. HPLC analysis indicated L-fucose utilization linked to acetate, lactate, pyruvate and succinate production, confirming the activation of the L-fucose pathway in these isolates. Highest consumption of L-fucose by C. coli Ca0121, is conceivably linked to its enhanced growth performance up to day 7, reaching 9.3 log CFU/ml compared to approximately 8.3 log CFU/ml for the C. jejuni isolates. Genetic analysis of their respective L-fucose clusters revealed several differences, including a 1 bp deletion in the Cj0489 gene of C. jejuni NCTC11168, causing a frameshift in this isolate resulting in two separate genes, Cj0489 and Cj0490, while no apparent phenotype could be linked to the presumed frameshift in the NCTC11168 isolate. Additionally, we found that the L-fucose cluster of C. coli Ca0121 was most distant from C. jejuni NCTC11168, but confirmation of links to L-fucose metabolism associated phenotypic traits in C. coli versus C. jejuni isolates requires further studies.
Importance Campylobacter is the leading cause of gastroenteritis in humans worldwide, with increasing incidence and prevalence in recent years. The most prevalent species are Campylobacter jejuni and C. coli with 83% and 10% of all Campylobacter cases, respectively. Previously it was found that the majority of Campylobacter isolates are able to metabolize L-fucose (fuc+ isolates), a sugar that is widely present in the human gut. Putative roles for L-fucose in fuc+ C. jejuni isolates were found in growth, biofilm formation and virulence. Despite this, relatively little is known about L-fucose metabolism and the impact on growth and survival in fuc+ Campylobacter isolates. The results from our comparative genotyping and phenotyping study demonstrate that L-fucose, in both C. jejuni and C. coli fuc+ isolates, is involved in enhanced survival, prolonged spiral cell morphology and changes in the general metabolism. Possible links between phenotypes and differences in respective L-fucose gene clusters are discussed.
