Analysis of different processes of gene transfer in aquatic ecosystems using the Aquatron

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1 Bacterial DNAs which were released from their cells by phage infection are potential resources for gene transfer by natural transformation. Number of bacteria which took a dissolved plasmid with GFP gene in their cells by natural transformation is 100 times as great as that of bacteria which expressed GFP gene. This indicates natural transformation might take place in natural environments with a higher frequency than we have regarded so far.2 Tetrahymena thermophila, a bacteriovore, inhibited a conjugal transfer from Escherichia coli to Pseudomonas stutzeri by predation on them, and the coexistence of T. thermophila with Microcystis aeruginosa, a producer, enhanced the inhibition.3 A mini tranposon (mini Tn) was constructed by the transposon Tn MERI1 coding the mercury resistance genes. The mini Tn was introduced into a non-conjugal plasmid. Then this plasmid was transferred into Eshericia coli DH1with conjugal plasmid R338. It was observed the mini Tn transposed into R338 and then the mini Tn on R338 was transferred to Eshericia coli HB101 by conjugation. This suggested the possibility a conjugal transfer through transposition among replicon in a bacterial cell.4 DNA sequences of the Tn MERI1 type transposon, IR and DR reiterated sequences on mercury resistance bacterial chromosome were analyzed. This analyses revealed that worldwide gene transfer by transposon took place among bacteria.5 A community dominated with Microcystis aeruginosa, cyanobacteria, in the Aquatron reduced an infectivity of phage EC 10.