THE DEVELOPMENT AND VIABILITY OF COCCAL CAMPYLOBACTER JEJUNI CELLS IN CHEMICALLY DEFINED MEDIA

Abstract

Campylobacter jejuni for near a decade is the most leading cause of gastrointestinal infections in humans worldwide (Colles et al 2008).In spite of increasing incidence of illnesses caused by C. jejuni as a food-borne pathogen there are quite many areas of the physiology of C. jejuni that is still poorly defined. The study of some aspects of physiology of C. jejuni is vital in understanding mechanisms of pathogenicity of C. jejuni and how the bacterium survives in the environment. The objective of the experiment was to investigate how long it took for spiral C. jejuni cells in chemically defined medium under microaerophilic condition to transform to coccal cells and to find out if coccal C. jejuni cells were viable. The experiment was carried out at the University of Reading, United Kingdom. C. jejuni NCTC 11168 culture was inoculated in both chemically defined medium and complex medium (Bolton broth Oxoid CM983 + 5 % v/v laked horse blood Oxoid SR48) and incubated under microaerophilic conditions at 37oC for 3 – 12 days. Viable cells of C. jejuni were estimated by making spread plates on Bolton broth agar and Nutrient agar (Oxoid CM3). The turbidity of C. jejuni in media was measured with a spectrophotometer. Microscopic enumeration in a counting chamber and Most Probable Number were used to estimate total cells counts whereas PC_Image Analysis and scanning electron microscopy were used to record changes in morphology. It took 9 days for spiral C. jejuni cells in chemically defined medium and Bolton broth + laked horse blood under microaerophilic condition to transform to coccal cells. Nine days old C. jejuni coccal cells formed colonies on selective agar media. Viable counts by Most Probable Number method were identical to total counts obtained by microscopical counting indicating that all the cells were viable. The coccal C. jejuni cells were viable.