The experiment studied on the rhizosphere effect in phytoremediation of the petroleum polluted soil by three kinds of grasses which were Pannicum， Eleusine indica(L.) Gaerth and Tall Fescue. After a period of 150 d ,this pot experiment show that the three kinds of plants rhizosphere accelerated the degradation of petroleum in different degrees.The results show that the plant roots improved the soil moisture which increased 5% compared with unplanted control soil .The dehydrogenas activity is 0.61～1.20 times higher.The number of microorganisms in the rhizosphere increased three orders of magnitude.The abduction of plant rhizosphere environment and the coercion of petroleum changed the distribution and activity of microorganisms.The petroleum degradation rates in the rhizosphere are 22.1%～30.3% higher than in the unplanted control soil.The effect of rhizosphere degeneration changed the component of petroleum obviously.It strengthened the degeneration degree of normal hydrocarbons that had low and moderate carbon.The plant rhizosphere environment is favorable to degenerate the high-carbon hydrocarbons into the low-carbon hydrocarbons.At the same time the peak area ratios of Pr/nC ₁₇,Ph/nC ^₁₈ and Pr/Ph have been enhanced 0.99,2.69 and 1.25 respectively.It accelerated the isomerization of normal hydrocarbons.

A strain screened from the waste water of an oilfield can produce insoluble extracellular polysaccharide used in selective plugging which is instrumental in microbially enhanced oil recovery. However this strain is sensitive to high temperature and produces little extracellular polyssacharides above 40 ℃. Therefore pET-ecoRRF, pET-tteRRF and corresponding control plasmids were transformed into the strain. The new strain can grow in 45 ℃, and western-blot indicates that the RRF genes have been expressed noticeably in the transgene strains. It has been showed that the transgene strains are able to bear higher temperature, and the sustainable temperature is higher five to eight degrees than the original strain. Because Enterobacter sp. is related to Escherichia coli, the expression of RRF is better than the gene of Thermus thermophilus in the strain of JD. At last it is successful to get a genetic engineering microbe which can endure the temperature as high as 45 ℃ and produce extracellular polysaccharides.