Kinetics of Conjugative Transfer: A Study of the Plasmid pXO16 fromBacillus thuringiensissubsp.israelensis

摘要: Abstract The aggregation-mediated conjugation system ofBacillus thuringiensissubsp.israelensis,encoded by the 200-kb plasmid pXO16, is highly potent in transferring itself and efficient mobilizing other nonconjugative plasmids. present study reveals some salient features of this system. Our observations can be summarized as follows: (i) conjugative transfer takes about 3 1 2 to 4 min. For a corresponds kb per second. (ii) ability seems evenly distributed among donors. (iii) Functionally, mating complex was found consist one donor recipient cell, even though aggregates comprising thousands interconnected cells are formed. (iv) Having donated plasmid, needs “period recovery” 10 min before it redonate plasmid. (v) Secondary transfer, i.e., from newly formed transconjugants, delayed 40 This maturation time exceeds generation time, may indicate that display activity, surface protein (the aggregation substance) has uniformly incorporated into cell wall. Lastly, we when experiments were sufficiently short excess compared with donors, process could reasonably described kinetic model analogous Michaelis–Menten for enzyme catalysis. allowed us estimate (vi) maximal rate 0.05 transconjugant minute, (vii) theKmvalue, concentration results half rate, × 106recipients/ml.