Physiological and Biochemical Characteristics,Identification and Preliminary Evaluation of Some Bacterial Strains for MEOR

8 strains of bacteria are isolated from oil and water samples of Karamay as condidate bacteria for MEOR.The results of physiological and biochemical tests state that bacteria D are Saccharomyces spp.,I are Bacillus spp.,and others are Pseudomonas spp..Bacterial population and optic density determinations show that the growth of all these bacteria is vigorous at 35℃ and at salinity ≤5%,growth of bacteria D stops and of other bacteria decreases in different degree at salinity 8% and 10%;all these bacteria can grow at 35℃ and at pH in range 4—10 and vigorous growth is observed in acidic media for bacteria D,in neutral media for bacteria A,B,and C and in neutral and alkaline media for bacteria E,F,H,and I;all these bacteria grow well at 40℃ and 45℃ and the temperature at which the growth ceases is of 50℃ for bacteria A,55℃ for bacteria B and E,and 60℃ for all the others.For viscous crude oils from 2 wells in Karamay treated by these bacteria at 35℃,their apparent viscosity at 25℃ is decreased by 25.2—70.6% and high viscosity reduction rate is observed for both 2 crude oils treated by bacteria B,E,and F.The variation in pertroleum compound groups of a crude oil treated by 3 strains of bacteria is discussed briefly.