Isolation Of Plant Growth Promoting Bacterial And Their Biological Effect On Application

The heavy metal pollution has been received increasing concerns. The microbial enhanced phytoremediation techniques, with their lower cost and environmental friendly nature, have been accepted by enormous researchers. In addition, the use of repaired plant material, has also become a hot issue in recent years.Plant growth promoting strains Y4-4, WTC34 and WK61 were isolated from soils contaminated with Cu. With ammonium sulfate and glucose as the carbon and nitrogen sources of NBRIP culture in a liquid medium, three strains are solutions of inorganic phosphorus with good ability. Tests also found three strains have the ability to produce IAA, siderophore and hydrocyanic acid.PCR amplification, physiological and biochemical characters, homology analysis of 16S rDNA sequence, and characteristics of biologic were focused on three strains in our research. Study results indicate that the Y4-4, WTC34 and WK61, respectively the preliminary identification of Pantoea (Pantoea SP.), Pseudomonas bacteria (Pseudomona SP.) and Cedecea (Cedecea SP.). In addition, strain Y4-4, WTC34 and WK61 all showed the resistance to CHL, AMP, ERY and STR. The optimum growth temperature of Y4-4 is about 25℃, WTC34 can grow well between 20-30℃, the suitable temperature for WK61 is around 30℃; Y4-4 is activity between the pH 4 to 10, WTC34 grow well between the pH6-9, the favoriate initial pH for WK61 is 8. Three strains also have strong ability of lactic acid.By pot experiment, a test was made to investigate the impact of strain Y4-4, WTC34 and WK61 to alfalfa in Tangshan Cu-contaminated soil. The results were that:Y4-4 can survivals in Cu-contaminated soils, vaccination Y4-4 many times significantly promote the shoot and root dry weight of alfalfa, respectively increasing22.6 and 21%.In addition, it significantly higher P content in root of alfalfa by (19%).Inoculated with Y4-4, WTC34 and WK61 on alfalfa to maximize the total accumulation of Cu in the upper range can improve separately by 15%,22% and 18%.Compared with the control, inoculation Y4-4 can improve the growth of alfalfa in qixiashan Pb, Zn pollution soil, enhance the shoot dry weight (23.4%) and the total dry weight (22%).and Zn uptake of alfalfa in Pb, Zn contaminated soils, increase in phytoremediation of heavy metals in soil has a high potential. Inoculation of Y4-4 single or multiple can improve Zn uptake of alfalfa, which strains vaccination Y4-4 many times dramatically improves plant shoot content of Zn, raise up 33%, total Zn accumulation in plants has increased 30.3%.Under laboratory scale, pot experiment of wheat was adopted to screening combining plant residues and microbial effects on the growth of wheat in saline-alkali soil. Results illustrate that the add wet rape significantly increase shoot (150.6%) and root (112.7%) biomass of wheat, plus strain of Y4-4 (the biomass of shoot increased by 16.2%; that of root increased by 6.14%) and dry rape (the biomass of shoot increased by 26.2%; that of root increased by 24.8%) respectively are not notable significantly, but the application of both of them can significantly (the biomass of shoot increased by 70%; that of root increased by 56.4%) increase shoot and root dry biomass of wheat. Compared with the control, add dry rape can significantly increase Cu concentration in wheat, therefore the combination of plant residues and PGPR has a great potential for development as a fertilizer of organic copper.Y4-4 for further study in the growth of heavy metal pollution of soils and saline-alkali soil, include a small amount of soil in the centrifuge tube, inoculation of Y4-4 training for 15 days, determination of pH value of soil sampling at different time and available phosphorus content, quick-acting potassium levels and number of bacteria. Results showed that:following immunization with Y4-4, available phosphorus content first increase and then reduce, it negative correlation with soil pH value. The number of bacteria first increase and then reduce, it illustrated that Y4-4 can survive in heavy metal soil and saline-alkali soil. Inoculating Y4-4 also has a role on the increase of available Cu content in Tangshan soil and available Zn content of Qixia soil.