The Molecular Mechanisms Of Salt Osmtic Stress Tolerantion Enhancement Of Pseudomonas Putida KT2440 By Betaine And Ectoine

The main purpose of this research encompass on: The salt tolerance characteristic of Pseudomonas putida KT2440 and the environmental factors influenced the salinity tolerance of KT2440, The osmprotection of exogenously supplied compatible solutes to KT2440 and its mechanisms, the feasibility and genetic engineering strategies to promote the salinity tolerance of KT2440. The results show that: (1)The mechanisms of the salinity tolerance promotion of KT2440 by exogenous compatible solutes were that exogenous compatible could reduce the lag time and promote the survival rate under salt osmotic stress. (2)Ectoine provided a temporary osmprotection as an emergency strategy when there were no other compatible solutes available under salt osmotic strass. The gene govern the ectoine degradation were cloned , and the block in ectoine degradation pathway did not promote the osmprotection effect to KT2440. (3)The medium supernatant could promote the salt tolerance of KT2440 under salt osmotic stress, and the presence of glycine betaine in the medium supernatant was the main factor of osmprotection effect of medium supernatant. (4)A genetic engineering strain KT2440dgbtbet were constructed by a new genetic engineering strategy, the salt tolerance of KT2440dgbtbet promoted significantly compared with KT2440.The salinity tolerance characteristic of Pseudomonas putida KT2440 and the environmental factors such as the nourishment, inoculant culture and initial biomass effect the salinity tolerance of KT2440 were studied. The enrichment of culture medium influcenced the growth of KT2440 under high salinity stress. In complete medium KT2440 could survive in higher salinities than in chemically defined medium. Augmentation of initial biomass could reduced the lag time and enhanced the salinity tolerance of KT2440, but no significant effected on the generation time of KT2440. Carbon recourses influcenced the salinity tolerance of KT2440, in chemically defined medium used glucose as sole carbon KT2440 could survive in higher salinities than in chemically defined medium used toluate as sole carbon. The level of nitrogen and potassium influcenced the...