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animals appears to be a property of Isolates of human or animal origin 
but not of plant origin. The strains to be used in this experiment were 
Isolated from healthy plants. Oue to Its Ice nucleating properties, 
E_. herblcola contributes to frost damage to plants. (I) 
5.2.2 Construction of INA Deletion Mutants 
The purpose of the experiment Is to evaluate the efficacy of INA’ deletion 
mutants of selected prototype strains of P_. syrlnqae pv. syrlnqae and _E. 
herblcola as biological competitors of epiphytic components of INA* 
populations occurring naturally. The construction of INA’ deletion mutants 
from INA* isolated bacteria does not add new or exotic properties which would 
make the mutant more competitive than its parent bacteria. The mutation only 
deletes functions from the treated bacteria. The advantages of such 
constructed mutants compared to chemically-induced equivalents are genetic 
stability and the absence of silent mutations which may adversely affect 
competitive fitness. 
The strategy for constructing such mutants will involve: 
(I) Construction of deletions covering all or part of the INA region 
carried on recombinant plasmid inserts. 
(II) Introduction of the above derived plasmids in the homologous strain 
.or closely, related strains of the same species or pathovar via conjugation or 
transformation. The regions of DNA homology flanking the deletion cn the 
cloned Insert are expected to promote reciprocal exchange of DNA between the 
plasmid and the chromosome so that the deletion will be transferred to the 
chromosome and the wild type region to the vector plasmid. 
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