Sodium Chloride

The object of the work is to evaluate whether rhizobacteria populating dry salty environments can increase resistance in tomato to salt stress. Seven strains of plant growth-promoting bacteria that have 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were isolated from soil samples taken from the Arava region of southern Israel. Following growth of these seedlings in the presence of 43 mM NaCl for 7 weeks, the bacterium that promoted growth to the greatest extent was selected for further study. DNA analysis of the 16S RNA indicated that the selected bacterium was Achromobacter piechaudii. This bacterium significantly increased the fresh and dry weights of tomato seedlings grown in the presence of up to 172 mM NaCl salt. The bacterium reduced the production of ethylene by tomato seedlings, which was otherwise stimulated when seedlings were challenged with increasing salt concentrations, but did not reduce the content of sodium. However, it slightly increased the uptake of phosphorous and potassium, which may contribute in part to activation of processes involved in the alleviation of the effect of salt. In the presence of salt the bacterium increased the water use efficiency (WUE). This may suggest that the bacterium act to alleviate the salt suppression of photosynthesis. However, the detailed mechanism was not elucidated. The work described in this report is a first step in the development of productive agricultural systems in saline environments.

The antibacterial effect of 0.5 percent sodium hypochlorite solution as root canal irrigant was studied in fifteen single-rooted teeth. Each tooth was treated at five appointments, and the presence of bacteria in the root canal was studied on each occasion. No antibacterial intracanal dressings were used between the appointments. When 0.5 percent hypochlorite was used no bacteria could be recovered from twelve of fifteen root canals at the fifth appointment. This should be compared with eight of fifteen root canals when saline solution was used as irrigant. These results suggest that 0.5 percent sodium hypochlorite solution is more effective than saline solution as a root canal irrigant.