The role of the dormant-like viable but nonculturable (VBNC) condition in the etiology of bacterial infection was examined using a plant system. The plant-pathogenic bacterium Ralstonia solanacearum was first shown to enter into the VBNC state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. To determine if the VBNC condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plants was determined at different stages of infection. The fraction of in planta bacteria that were VBNC increased during infection and became greater than 99% by the late stage of disease. The possibility that soil-dwelling VBNC bacteria may resuscitate and infect plants was also examined. When tomato seeds were germinated in sterile soil that contained VBNC but no detectable culturable forms of R. solanacearum cells, resuscitation was observed to occur in soil adjacent to plant roots; these resuscitated bacteria were able to infect plants. This is the first report of R. solanacearum entering the VBNC state and of resuscitation of any VBNC plant-pathogenic bacteria and provides evidence that the VBNC state may be involved in explaining the persistent nature of some infections.

During the inception of crown gall tumorigenesis, the traferred DNA (T-DNA) is processed from the Ti (tumor Indc n)

No abstract

No abstract

Xanthomonas campestris pathovar campestris was examined for the ability to enter the viable but non-culturable (VBNC) state. When nutrients were removed from a bacterial culture, the culturability dropped to undetectable levels within 6 weeks while the concentration of viable cells remained above 10(5) cells ml(-1). Addition of cupric sulfate facilitated this process. When bacteria were placed in autoclaved soil, culturability dropped by at least four logs within 5 days of the experiment while the concentration of viable cells remained at least two logs higher. These results indicate that the plant pathogen X. campestris can enter the VBNC condition in sterile soil and in liquid cultures and that cupric sulfate decreases the time for entry into the VBNC condition.