AUTHOR=Karki Anand B. , Marasini Daya , Oakey Clark K. , Mar Kaitlin , Fakhr Mohamed K. 

TITLE=Campylobacter coli From Retail Liver and Meat Products Is More Aerotolerant Than Campylobacter jejuni

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02951

DOI=10.3389/fmicb.2018.02951

ISSN=1664-302X

ABSTRACT=<p>Aerotolerance in the microaerophilic species <italic>Campylobacter</italic> was previously reported and could increase bacterial survival and transmission in foods during stressful processing and storage conditions. In this study, 167 <italic>Campylobacter</italic> isolates (76 <italic>C. jejuni</italic> and 91 <italic>C. coli</italic>) were screened for aerotolerance; these strains were previously isolated from retail chicken meat, chicken livers, chicken gizzards, turkey, pork, and beef liver samples. Bacterial cultures were incubated aerobically in Mueller Hinton broth with agitation and viable cell counts were taken at 0, 6, 12, and 24 h. Approximately 47% of the screened <italic>Campylobacter</italic> isolates were aerotolerant (viable after a 12-h aerobic incubation period), whereas 24% were hyper-aerotolerant (viable after a 24-h aerobic incubation). A greater prevalence of aerotolerant strains (80%) was found among <italic>C. coli</italic> isolates as compared to <italic>C. jejuni</italic> isolates (6%). Differences in the oxidative stress response related genes were detected among <italic>C. jejuni</italic> and <italic>C. coli</italic> isolates when comparative genomics was used to analyze 17 Whole Genome Sequenced (WGS) strains from our laboratory. Genes encoding putative transcriptional regulator proteins and a catalase-like heme binding protein were found in <italic>C. coli</italic> genomes, but were absent in the genomes of <italic>C. jejuni</italic>. PCR screening showed the presence of a catalase-like protein gene in 75% (68/91) of <italic>C. coli</italic> strains, which was absent in all tested <italic>C. jejuni</italic> strains. While about 79% (30/38) of the hyper-aerotolerant <italic>C. coli</italic> strains harbored the catalase-like protein gene, the gene was also present in a number of the aerosensitive strains. The Catalase like protein gene was found to be expressed in both aerobic and microaerobic conditions with a 2-fold higher gene expression detected in aerobic conditions for an aerosensitive strain. However, the exact function of the gene remains unclear and awaits further investigation. In conclusion, aerotolerant <italic>Campylobacter</italic> strains (especially <italic>C. coli</italic>) are prevalent in various retail meats. Further studies are needed to investigate whether the genes encoding catalase-like heme binding protein and putative transcriptional regulators in <italic>C. coli</italic> strains are involved in stress response.</p>