Survival of Ralstonia solanacearum and Ralstonia pseudosolanacearum in drain water

Abstract

The survival in drain water of two strains of Ralstonia solanacearum and three strains of Ralstonia pseudosolanacearum, including two strains able to cause wilt in roses, was determined. Water draining from drip‐irrigated rock wool mats on which roses were grown was supplemented with the pathogen and survival was monitored at 4, 12, 20 and 28°C for up to 112 days. All strains were able to survive for at least 112 days in drain water at 12 and 20°C, but at 4°C maximum survival was 56 days. At 28°C, the survival period was strain dependent, but was at least 56 days. Populations declined gradually in non‐sterile drain water to a low level (maximum 100 cfu mL−1 after 112 days). In sterile drain water (autoclaved prior to addition of populations), no or only a limited decline in populations was found at 112 days, dependent on strain and temperature. Drain water that tested negative for Ralstonia in the dilution plating assay was tested for the presence of cells in a viable but non‐culturable state (VBNCs). Tomato plants were inoculated, but no symptoms developed, and plants sampled 22 days post‐inoculation were negative in a plating assay. Therefore, no indications were found that VBNCs were present.

Die-off of plant pathogenic bacteria in tile drainage and anoxic water from a managed aquifer recharge site

“…Whereas for the SRP, we observed a faster decline within 4 days at a higher temperature (25˚C) and a better persistence at the lower temperature in natural TDW. Nevertheless, the temperature effect on the die-off of the SRP was negligible in autoclaved TDW microcosms, when comparing the inactivation curves at 10 and 25˚C (see S1 Fig) . The long-term persistence in sterile aquatic microcosms, where the indigenous microbiota was absent, has been shown earlier for the SRP [25,51], as well as for R. solanacearum [22][23][24]. In addition, our results demonstrated that D. solani can persist in sterile autoclaved water for a prolonged time which seem to contrast with the findings of van Doorn et al [25] where Dickeya spp.…”

“…Few studies investigated the die-off of R. solanacearum in natural water types such as river water [22], agricultural drainage water [23], or drainage water leaching from rock wool in a rose-growing greenhouse [24]. The results of these studies showed that temperature and the natural microbiota have a significant effect on the die-off of R. solanacearum in non-sterile microcosms compared with sterile conditions.…”

Low Temperature Induces Infectious Nonresuscitatable VBNC Cells in Ralstonia Pseudosolanacearum

“…The percentage of nonresuscitatable VBNCs were calculated by comparing the16S rRNA copy number against the control by the formula: [(RNA copies of N th day/sample treatments X 100)/ RNA copies of N th day/control].ResultsCon rmation of VBNCs after psychrophilic stressThe formation of VBNC is genus, strain and stress dependent. Microcosms of RSSC incubated at psychrophilic temperatures lose their culturability within 150 days(van Overbeek et al 2004;Stevens et al 2018). In this investigation, the total loss of culturability was noticed on 180 th day in both the strains.…”

Detection of Ralstonia pseudosolanacearum in drain water based on concentration, enrichment and the use of a duplex TaqMan PCR test

“…If a symptomatic tomato plant is positioned between healthy tomato plants in an aquaponic culture, neighbouring pathogen‐free plants became symptomatic after 8 days (Jenkins & Averre, 1983). Additionally, RSSC strains can persist in water for varying periods of time from a week to months and this persistence is affected by various environmental conditions such as temperature, light, salinity and the composition of the microflora, including lytic bacteriophages, protozoa and other bacteria (Van Overbeek et al ., 2004; Álvarez et al ., 2007; Stevens et al ., 2018).…”