Stability and Activity of the Major Nod Factor Produced by Bradyrhizobium japonicum following Purification, Sterilization, and Storage

Abstract

Nod factors, also known as lipo-chitooligosaccharides (LCOs), are signal molecules produced by rhizobia during rhizobia-legume symbiosis. These Nod factors often must be purified, sterilized, and stored before use in research experiments. Therefore, we evaluated the influence of purification, sterilization, and storage methods on degradation and biological activity of Nod factor comprised primarily of Nod BjV(C18:1 MeFuc). During filter sterilization, various types of filters affected the amount of LCO recovered: polyestersulfone (67.7%), cellulose acetate (54.9%), nylon (48.1%), polytetrafluoroethylene (38.0%), and mixed cellulose ester (31.8%). During autoclaving (durations of 15 to 30 min) ∼30% of the LCO was lost LCO degraded faster when stored at 23 ± 2°C (room temperature) than at 4 ± 1°C (refrigerator); after 16 mo, 74% of the LCO was recovered following room temperature storage and 84% following refrigerator storage. The biological activity (root hair deformation and stimulation of soybean seed germination) of LCO (10 -7 M) obtained from autoclaved and stored samples were not different from that of freshly prepared LCO; no reduction in biological activity was found.