Jasad renik terekayasa telah banyak dimanfaatkan pada berbagai lingkungan. Informasi tentang penlaku jasad renik terekayasa 1 lingkungan hingga saat ini masih sangat jarang, terutama yang berkaitan dalam kemampuannya berkompetisi dengan jasad renik lain pada lingkungan yang tidak mendukung fungsi khusus bagi gen yang dibawanya (lingkungan spesifik). Penelitian ini bertujuan untuk mempelajari tentang kemampuan kompetisi jasad renik terekayasa pada lingkungan kaya dan miskin nutrisi dengan kondisi lingkungan yang tidak spesifik. Penelitian ini dilakukan dengan menggdan tiga galur Escherichiu coli sebagai jasad model, yaitu E. coli R6.0, E. coli R6.3 dan E. coli R6.4, masing-masing berturut-turut membawa plasmid pEOR, pEOR dengan open reudingJiame (OW) buatan yang dapat diekspresikan dan pEOR dengan ORF yang tidak dapat diekspresikan. Kompetisi dilakukan dengan membiakkan ketiga galur secara bersama-sama pada media Luria-Bertani (LB) dan M9 dengan sistem biakan tertutup. Penambahan isopropiltio-j3-D-galaktopiranosida (IPTG) pada media dilakukan untuk mengaktifkan ekspresi ORF buatan Cuplikan sel untuk analisis koinpetisi diambil pada fase adaptasi (lug phase), pertumbuhan logaritmik (log phuse), stasioner (stationary phuse) dan stasioner yang diperpanjang (prolonged stutionuiy phase). Kemampuan kompetisi diukur dengan menghitung poporsi masing-masing galur. Hasil pengamatan menunjukkan bahwa E. colz R6.3 ineiniliki proporsi terkecil bila dibandingkan dua kompetitornya, yaitu E. colr R6.0 dan E. colr R6.4, baik pada media LB atau M9, dengan atau tanpa penambahan IPTG. Proporsi E. colz R6.4 lebih kecil bila dibandingkan dengan proporsi E. coil R6.0. Proporsi E. colz R6.3 dan R6.4, pada saat ditumbuhkan pada medium M9, lebih kecil bila dibandingakan dengan di medium LB. Hasil tersebut menunjukkan bahwa ukuran plasmid dan ekspresi OW buatan menurunkan daya koinpetisi bag1 jasad renik pembawanya, meskipun ditumbuhkan pada medium kaya nutrisi. Beban energi jasad renik terekayasa tersebut inenjadi lebih besar, ketika jasad renik tersebut ditumbuhkan pada medlum miskin nutrisi

Genetically engineered microorganisms (GEM) have been widely used in various environments. However, there is still limited information regarding the behavior of GEM in environment, particularly in competition with other microorganisms. Previous studies concerning competition of GEM have been established, but most of them have been done in environments which support function of carried genes (specific environments). Accordingly, the objective of this research was to study the competitiveness of GEM in non specific enviro'nments supplied with rich and poor nutrition. Three strains of genetically engineered Escherichia coli were used as GEM models, i.e., E. coli R6.0, R6:3 and R6.4. E. coli R6.0, R6.3 and R6.4 harbor plasmids pEOR, pEOR6.3 and pEOR6.4, respectwely. Plasmid pEOR was constructed in the previous study for expressing chemically synthesized open reading frame (artificial OW). Plasmids pEOR6.3 and pEOR6.4 were constructed from plasmid pEOR inserted with artificial OW in its KpnI-BamHI site. The OW of pEOR6.3 could be expressed, while the ORF of pEOR6.4 could not. Competition experiment was done by co-culturing the three strains of E. coli in batch culture system. The media used in the competition experiment were Luria-Bertani (LB) and M9 for rich and poor environment representative, respectively. The expression of the artificial ORF was induced by adding isoprophylthio-P-D-galactopyranosid(eI PTG) into the culturing media. Samples for competition analysis were taken fiom lag phase, log phase, stationary phase and prolonged stationary phase. Competitiveness was quantified by enumerating the proportion of each strain after co-culturing in the coculture. The results showed that E. co/i R6.3 had the smallest proportion when it was co-cultured with its competitors, i.e. R6.0 and R6.4, whether in LB or M9 media, with or without IPTG addition. The proportion of E. colz R6.4 was smaller than R6.0. However, the proportion of E. coli R6.3 and R6.4 in M9 medium was smaller than in LB me&um. It could be concluded that the size of plasmid and the expression of artificial ORF had reduced the competitiveness of the GEM, although it was cultured in the rich nutrition environment. The energy burden of GEM becomes much higher when it was cultured in poor nutrition environment.

Kata Kunci : Bioteknologi,Jasad Renik Terekayasa,E Coli,Lingkungan Kaya dan Miskin Nutrisi, GEM, competition, plasmid, artificial open reading frame, rich nutrition environment, poor nutrition environment