Isolation, Identification And Thermodynamics Of Lead - Resistant Bacteria In Lead - Contaminated Soil

With the rapid development of global economy, heavy metal pollutants into the soil through various channels that lead to the accumulation of heavy metals in the soil. Heavy metal pollution mainly exists in sewage irrigation, solid waste, pesticide and fertilizer application and settlement of atmospheric pollutants, etc. A lot of heavy metals into the soil would cause soil composition, function and structure change, that adverse effects on the soil biological properties and microbial community structure. At the same time, harmful substances or breakdown products will gradually accumulated in the soil, through the "soil to plants, human body" indirect absorbed by human body, ultimately endanger human health. Compared with the traditional physical and chemical measures, bioremediation has become a research hotspot in recent years. On the one hand, the cost is low, little pollution to environment, simple operation. On the other hand, microbes have many kinds, multiply quickly and has strong fast adaptability for all kinds of pollutants, etc.Heavy metal lead as a kind of can’t natural degradation elements, that will directly affect the water quality, soil quality and crop growth. And eventually accumulated through the cycle of food chain to the human body, endanger human body health. In this experiment, taking a lead in shaanxi processing lead pollution of the soil as the research object, screened strains have high resistance of bacteria to heavy metal. Through Sherlock Microbial Identification System(MIS) automation System identified the bacteria; Adopt the method of flat line tested the resistance of bacteria to heavy metals and organic matter; Through adsorption kinetics and adsorption thermodynamic, the bacterial adsorption process and mechanism of heavy metal lead is studied.Describe the results of using microbial remediation of lead pollution and engineering management science and practical significance. The main research conclusions are as follows:(1) PLFA measured microbial diversity of samples in soil samples, the results indicate:Pollution of the soil samples contain a lot of different kinds of microorganisms. The ratio of the actinomycetes the maximum is 70.44%, the ratio of the actinomycetes the minimum is 0.81%.(2) Lead resistance bacteria B1 is circular、slightly raised、with a white、margin rules、opaque、easy to start、for long rod bacteria、spores. Through the MIS with automatic identification system screen lead resistance bacteria B1 is Bacillus-cereus.(3) Lead resistance bacteria B1 optimal growth conditions:optimal growth pH 6.0 or so; optimal growth temperature of 35℃ or so; optimal growth osmotic pressure at around 0.5%. At the same time, lead resistance bacteria organic pollutants of low dose with patience. The Resistant bacteria to lead, chromium, manganese, lead, zinc, copper is a certain resistance and a certain concentration of zinc and manganese lead against the growth of bacteria and promote the role. Lead resistance bacteria resistant up to 1200 mg/L of Pb2+ that is much higher than ordinary strains to lead.(4) The lead-resistant bacteria explored best heavy metal adsorption condition, the results indicate:when the concentration of lead ion in the solution of 200 mg/L, pH value of 6.0, temperature of 35℃, biological adsorption effect is best. Through adsorption kinetics and adsorption thermodynamic model can simulate the process of biosorption, explore the mechanism of biosorption. Adsorption kinetics model used Pseudo first-order equation and pseudo second order equation to fit respectively. Concluded lead resistance bacteria Pb2+ adsorption process can use secondary dynamic equation is described. This shows that the adsorption process is given priority to with chemical adsorption. According to Intra-particle diffusion, adsorption process is mainly controlled by the diffusion and liquid film diffusion in the granules. At the same time, application of Langmuir and Freundlich adsorption isotherm, the Freundlich adsorption isotherm adsorption process is more suitable for simulation of the strain.