Study On Endophytic Bacteria In Rice And Construction Of Pesticide Engineering Bacteria

Many bacterial populations were screened from rice plant D-you 527 planted mainly in Sichuan. Three strains were certain to be dominant positions. The endophytic characters of three strains were tested by the nodulation transferring pud 8 plasmid vector. The classification statuses in microbiology of 3 strains were deduced through the research of physiological and biochemical characters. A Delta-endotoxin gene Cry I Ac from B. thuringiensis was transformed to SR-15 strain. The result showed that the transformed gene strain expressed toxin protein, and strong toxicity to Chilo suppressalis.1 One hundred and two bacteria were isolated from roots, stems, leaves and seeds of healthy rice plant D-you 527. Among them, 77 strains were G+, 25 strains were G-. 41 strains were isolated from roots, 37 strains were isolated from leaves and 24 strains were isolated from stems. Bacterial strains were tested different by ERIC-PCR.2 SR-15, SR-25, SL-37 strains were tested to be the dominant position through c distribution curves and characters. Quantity of SR-15 strain was biggest.3 Distribution curves of isolated population in different stages of roots, stems, and leaves were deduced. The result showed that distribution quantity of the dominant bacteria SR-15, SR-25, SL-37 in different stages of roots, stems, and leaves, or different organs were different.4 From the growth curves of three strains, they were consistent with the characters of normal bacteria, those were: lag phase, exponential phase, stationary phase and decline phase. Biological characters of three strains were different in conditions of different pH, temperature and culture media. These characters are similar to the endophytic bacteria reported.5 Efficiency transferring puclS plasmid vector into dominant bacteria in different voltage and plasmid concentration was tested. Transformation frequency in 1500 voltage was highest, but same in different plasmid concentration.6 Bacterial strains transformed puclS plasmid vector were nodulated into the rice plants and screened again through antibiotic plates. The strains screened were tested to be same to original strains through ERIC-PCR. It showed that three strains colonizatied in rice by elect-microscope observation, and were tested that they were all rice endophytic bacteria.7 SR-15, SR-25, SL-37 were identified as Bacillus halmapalus, Micrococcus sedentarius and Aureobacterium flavesnes respectively through chemical components of cell wall, physiological and biochemical characters observed by tests -, microscope and elect-microscope.8 A transformed of SR-15 strain carrying a delta-endotoxin gene from B. thuringiensis subsp. Probe into the express of crystal preliminarly.9 The result showed that SR-15 strain transformed a delta-endotoxin gene Cry I AC from B. thuringiensis subsp could produce toxic protein. Experiment of insect bioassay was that the fermentation production was toxic to the Chilo suppressalis.