Risk of dissemination of Clavibacter michiganensis ssp. sepedonicus with potato waste

Effect of Temperature Treatments on the Viability of Clavibacter sepedonicus in Infected Potato Tissue

“…Our results contrast with the observations of Steinmöller et al (2013), who reported a remarkable heat resistance of the bacterium for 6 d at maximum temperatures at 70°C…”

“…Our results clearly show that Cs inside its natural environment of potato tissue is relatively vulnerable to composting temperatures. However, considering the results of Steinmöller et al (2013), which were obtained with artificially inoculated experimental objects, it remains to be answered whether the composting process is able to kill Cs inside naturally colonised potato tissue as efficiently as the water baths in our experimental set-up.…”

“…Therefore, experiments 4, 5 and 6 were performed with Cs-colonised potato stem tissue that had been crushed and deaerated (experimental objects 1), simulating macerated and deaerated stem tissue in the compost heap. In addition, temperature treatments were tested on non-infected stem tissue that had been crushed, deaerated, and artificially inoculated (spiked) with a freshly prepared Cs-suspension (experimental objects 2), thus partly imitating the experimental objects used by Steinmöller et al (2013). They exposed encapsulated potato plant material spiked with freshly prepared Cs suspension to elevated temperatures by burying the filled capsules in compost heaps.…”

“…Heat transfer during composting occurs via water, moistened air and organic and inorganic materials. In a study on the viability of Cs during composting, Steinmöller et al (2013) exposed encapsulated potato plant material spiked with freshly prepared Cs suspensions at a final concentration of 10 6 cfu/g of substrate to elevated temperatures by burying the filled capsules in compost heaps, and showed that composting for 6 days at maximally 70°C and for 13 days at maximally 55°C, or 90 min of pasteurisation at 55°C, did not fully eradicate the bacterium.…”

“…Literature suggests that the efficacy of temperature treatments depends highly on the physical and chemical environment of the bacterium during temperature exposure; in particular, the presence of an organic matrix may provide significant protection to relatively high temperatures (Fatmi et al 1991;Downer et al 2008;Raviv et al 2011;Steinmöller et al 2013;Howard et al 2015). The natural environment of Cs inside potato plants is constituted by their self-produced biofilm attached to the walls of xylem vessels (Marques et al 2003).…”