Differences in amino acids utilization between Campylobacter jejuni M1 and 11168H – HILIC-MS and Genome-Scale Metabolic Modelling analysis.

Abstract S10

Presenters: Noemi Tejera (Quadram Institute Bioscience, Norwich, UK)

Authors: Noemi Tejera, Mark Philo, John Wain and Dipali Singh

Campylobacter jejuni is a major cause of food-borne illness worldwide and is recognized as the predominant bacterial infection preceding the peripheral neuropathies Guillain Barré syndrome and Miller Fisher syndrome. Understanding the importance of the metabolic capabilities of this fastidious organism and the existing differences in substrates utilization between isolates is key in defining how C. jejuni is able to survive and adapt to a variety of environmental niches. C. jejuni lacks many of the carbohydrate utilization pathways, with amino acids and tricarboxylic acid (TCA) cycle intermediates playing a central role in its metabolism, acting as major carbon and energy sources for in vitro growth. However, several studies indicate that there are clear differences in amino acids utilization and response, with serine, glutamate, aspartate and proline being shown to have a growth-promoting role, and lysine and arginine described as chemorepellents. In this study, we explore the amino acids utilization preferences of two strains of C. jejuni, M1 and 11168H, using a sensitive and specific hydrophilic interaction liquid chromatography coupled with tandem mass-spectrometry (HILIC-MS) in house implemented method. A genome-scale metabolic modelling approach was also employed to analyse the implications of our results in the metabolism of C. jejuni.
A modification of the defined Gibco Dulbecco’s Modified Eagle Medium DMEM/F-12 media was used to set up our cultures. After 24h, HILIC-MS analysis of the samples indicated that cysteine, cystine, glutamate, glutamine, methionine, proline and serine were consumed in the highest levels by both isolates (expressed as % of present concentrations), and arginine and glycine displayed the lowest utilization percentages. Some differences were observed between strains, with M1 utilizing higher percentages of isoleucine, leucine, phenylalanine and tyrosine, when compared with 11168H. With the obtained results, we were able to optimize our previously published MM1 defined media and achieve high rates of growth at 24h (OD 1.23 ± 0.15 and 0.66 ± 0.13, n=6; for M1 and 11168H respectively). This will translate to improved experimental design for further metabolic studies and sheds light on the preferred amino substrate utilisation for C. jejuni. Restricting access to these substrates could reduce the burden of Campylobacter in the food chain.

Presenting in Speaking session 4 - Survival and application