AUTHOR=Tejera Noemi , Crossman Lisa , Pearson Bruce , Stoakes Emily , Nasher Fauzy , Djeghout Bilal , Poolman Mark , Wain John , Singh Dipali 

TITLE=Genome-Scale Metabolic Model Driven Design of a Defined Medium for Campylobacter jejuni M1cam

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 11 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01072

DOI=10.3389/fmicb.2020.01072

ISSN=1664-302X

ABSTRACT=Campylobacter jejuni, the most frequent cause of food-borne bacterial gastroenteritis, is a
fastidious organism when grown in the laboratory. Oxygen is required for growth, despite the
presence of the metabolic mechanism for anaerobic respiration. Amino acid auxotrophies are
variably reported and energy metabolism can be through several electron donor/ acceptor
combinations. Overall, the picture is one of a flexible, but vulnerable metabolism. To understand
Campylobacter metabolism, we have constructed a fully curated, metabolic model for the
reference organism M1 (our variant is M1cam) and validated through laboratory experiments. Our
results show that M1cam is auxotrophic for methionine, niacinamide and pantothenate. There are
complete biosynthesis pathways for all amino acids except methionine and it can produce energy,
but not biomass, in the absence of oxygen.

M1cam will grow in DMEM/F-12 defined media but, not in the previously published
Campylobacter specific defined media tested. Using the model, we identified potential
auxotrophies and substrates that may improve growth. With this information, we have designed
a simple defined media containing inorganic salts, the auxotrophic substrates, L-methionine,
niacinamide and pantothenate, and pyruvate and additional amino acids L-cysteine, L-serine and
L-glutamine for growth enhancement. Our defined media supports 1.75-fold higher growth rate
than Brucella broth after 48 hours at 37 ◦ C and sustains growth of other C. jejuni strains. This
media can be used to design reproducible assays that can help to better understand adaptation,
stress resistance and virulence mechanisms of this pathogen.

We have shown that with a well curated metabolic model it is possible to design a media to
grow this fastidious organism. This has implications for the investigation of new Campylobacter
24 species defined through metagenomics, such as C. infans.