| Crown gall disease , caused by Agrobacterium tumefaciens, has been a problem with economical losses for extensive damage all over the word. Enhances unceasingly along with the human environmental protection consciousness and to the quality of life, the environment question and chemistry agricultural chemicals question more and more arouses people' s interests. Thereupon, the people then attempt to seek to the method, these methods not only can suppress the bacterium, moreover also can is harmless to the humanity and the natural environment. After practice, the people discovered biological preventing and controlling is the quite ideal method. Preventing and controlling crown gall disease applied the early biological controls strain K84, itself did not have the pathogenicity, its plasmid may synthesize one kind of bacteriocin Agrocin84, may suppress many pathogenic strains, but did not have pathogenicity to non-pathogenic strain . Moreover, it also may through adhere to the position spot competed with the pathogen but to control the pathogen' s invasion. But its bacteriostasis effect is not very obvious, also the stability is low.This research taked Agrobacterium rhizogenes Kl as original strain, Based on the means of mutations with UV, stochastic screening, obtained K3, the strrain had strong inhibitory action to C58, and to its physical and chemcal nature, stability and the fermentative condition's optimization has carried on the preliminary analysis. The result indicated that: Drilling a hole through the plate , the K3 bacterium suspension had the obvious inhibitory action to the C58 strain, compared with the other antagonistic strains, the bacteriostasis effect is best, and the inhibitory action increased with the concentration. The thermostability is durable, after proteinase processing, antimicrobial activity is invariable. Also this strain had the strong stability, After subculturing for 20 times , it still maintained the original antimicrobial activity. Through... |
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