Efficiency of the transfer of a pSAM2-derivative plasmid between two strains of Streptomyces lividans in conditions ranging from agar slants to non-sterile soil microcosms

Abstract

The aim of this work was to determine the efficiency of the conjugative plasmid pTSl30 to transfer in various environmental conditions between two strains of Streptom_vces lividuns.This plasmid is a derivative of the conjugative and integrative plasmid pSAM2 isolated originally from Streptomyces ambofuciens and capable of transfer to a large range of bacteria.Our results demonstrate the high frequency of the conjugation mechanism since more than 60% of the recipient cells developed on agar slants harbored the plasmid pTS 130 (as evidenced by Southern hybridization with a pSAM2 derivative plasmid probe).When donor and recipient strains were inoculated into sterile and non-sterile soil microcosms, transconjugants were detected after two days of incubation in both cases.However, the number of donor, recipient and transconjugant cells were established at a lower level in the non-sterile soil than in the sterile soil experiments.Moreover, nutrient amendment of the sterile soil was found to increase the population levels of parental strains and transfer frequencies both significantly and simultaneously.On the other hand, modifying water potential of the soil microcosms did not result in affecting the establishment of the Streptomyces liuiduns cells or the transfer rate.