Factors Affecting Conjugative Transfer Rates of Plasmids in Batch and Continuous Cultures

概要

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Factors affecting the rates of plasmid transfer were investigated using Escheriehia coli LC102 bearing a conjugative plasmid R100-1 and E. coli DH1. The rate constant of transconjugant increase, k_<ti>, was used for presenting the degree of plasmid transmissibility instead of the plasmid transfer efficiency (pte). The rate constant was defined as the specific rate of transconjugant increase (srti, the number of transconjugants per donor per h) divided by the recipient cell concentration. The k_<ti> values ranged between 10^<-10> and 10^<-15> ml cells ^<-1> h^<-1>, when estimated under various conditions. Moderate liquid agitation had a favorable effect on k_<ti> but agitation rates higher than 33 s^<-1> (intergrated shear force) greatly decreased the value of k_<ti>. The transconjugant-forming activity of the cells growing in continuous culture did not significantly change with the dilution rate, except those growing at dilutio rates less than 0.1 h^<-1>. The rate constant k_<ti> at temperatures of 10-15℃ was as low as the detection limit (10^<-15> ml cells^<-1> h^<-1>).
社団法人日本生物工学会の論文
1990-04-25