遺伝子操作微生物の環境中での生残性に関する基礎的研究 第二報 富栄養ミクロコズムと貧栄養ミクロコズムにおける外来遺伝子の消長

Abstract

Survival behavior of a genetically engineered microorganism (GEM) was investigated by using an eutrophic microcosm and an oligotrophic microcosm. E.coli HB101 was transformed with recombinant plasmid pBK9 (pBR322 inserted with kanamycin resistant gene (kan) from plasmid pUC4K at the Eco RI site). The logarithmical decrease of the GEM was observed after introduction of the engineered E.coli into the eutrophic microcosm. The decay in the microcosm was expressed as follows: log (n) = -0.211 (x) + 6.21 (correlation coefficient= 0.901, n=viable cell number of GEM/ml, and x=time in days), when nutrient was not fed to the microcosm after the introduction of the GEM. The same phenomenon was also observed in the oligotrophic microcosm when nutrient was not fed, and the equation of the decay of the GEM was as follows: log (n) = -0.272 (x) + 5.72 (correlation coefficient=0.931). In the microcosms in which nutrient broth for the GEM was continuously fed after GEM introduction, long term survival of the GEM was observed, despite eutrophic or oligotrophic. however, the GEM existed in higher viable number in the eutrophic microcosm fed with rich nutrient about 3X105cell/ ml than the oligotrophic microcosm fed with poor nutrient (about 103 cell/ml). From these results, it was elucidated that nutritional condition for introduced GEM was an important factor for GEM's survival in mixed microbial ecosystems.