Comparison of Survival of Campylobacter jejuni in the Phyllosphere with That in the Rhizosphere of Spinach and Radish Plants

Abstract

Campylobacter jejuni has been isolated previously from market produce and has caused gastroenteritis outbreaks linked to produce. We have tested the ability of this human pathogen to utilize organic compounds that are present in leaf and root exudates and to survive in the plant environment under various conditions. Carbon utilization profiles revealed that C. jejuni can utilize many organic acids and amino acids available on leaves and roots. Despite the presence of suitable substrates in the phyllosphere and the rhizosphere, C. jejuni was unable to grow on lettuce and spinach leaves and on spinach and radish roots of plants incubated at 33°C, a temperature that is conducive to its growth in vitro. However, C. jejuni was cultured from radish roots and from the spinach rhizosphere for at least 23 and 28 days, respectively, at 10°C. This enteric pathogen also persisted in the rhizosphere of spinach for prolonged periods of time at 16°C, a temperature at which many cool-season crops are grown. The decline rate constants of C. jejuni populations in the spinach and radish rhizosphere were 10-and 6-fold lower, respectively, than on healthy spinach leaves at 10°C. The enhanced survival of C. jejuni in soil and in the rhizosphere may be a significant factor in its contamination cycle in the environment and may be associated with the sporadic C. jejuni incidence and campylobacteriosis outbreaks linked to produce.

Phenotypic and Genotypic Evidence for l -Fucose Utilization by Campylobacter jejuni

“…No growth was observed in the basal defined medium (BDM) (no additional carbon source added) for any of the strains tested, allowing for the detection of carbon utilization deficiencies. High cell densities (ϳ10 8 …”

“…In vitro binding of C. jejuni to ␣1,2-fucosylated glycans has been demonstrated previously (11,42), and free fucose reduces adherence to intestinal cells (10), suggesting recognition of this oligosaccharide by the bacterium. In addition, respiratory activity can be detected with fucose as a carbon source (8,15), although the assay identified other sugars believed to be false positives (29). In this report, we provided evidence of strain-specific utilization of fucose for Campylobacter growth.…”

Internalization of enteropathogenic human bacteria in lettuce and coriander plant tissue

“…Survival of C. jejuni in faecal contaminated soil has also been reported by Brandl et al (2004), who demonstrated C. jejuni in soil and roots rhizosphere, long after leaves internalization had stopped. The low oxygen tension resulting from both roots and bacteria respiration at the rhizosphere supports survival of Campylobacter cells.…”

“…Brandl et al (2004) demonstrated C. jejuni in spinach roots and leaves upto 30 days post-inoculation, when temperatures were maintained at 10 to 16°C. Injured plants were shown to support survival of Campylobacter relative to healthy plants, implying post-harvest contamination of vegetables and fruits which play key role in food-safety.…”

Hygienic characteristics of radishes grown in soil contaminated with Stenotrophomonas maltophilia

“…Radishes (approximately 10 g) were first subjected to the removal of the soil adhering to the surface as described by Brandl et al [34] and then homogenised in Ringer's solution by a stomacher (BagMixer ® 400, Interscience, Saint Nom, France) at the maximum speed for 2 min. The decimal serial dilutions of both soil and radishes continued in Ringer's solution.…”