Isolation And Reduction Characterization Of Humic-reducing Bacteria From Chaohu Lake

With the development of industrialization and urbanization of Chaohu region, a range of issues had been promoted, especially in environmental pollution, such as Heavy metals, azo dyes, nitro-substitutde aromatic compounds, refractory material and so on. In2010, the environment departments warned that plenty of industrial waste and the sanitary sewage with high density of ammonia nitrogen pour into water bodies, which caused the drop of water source’s quality, eutrophication of water body and serious environmental pollution. Some studies reported that a number of microorganisms which can reduce humus were found in sediments abundant of organic materials, contaminated soils and so on, which are able to use humic substances and its model compounds to support growth. The thesis tries to screened a high effective microbe with the function of degradating cyanobacteria content, nitropheneol and heavy metals.Strains of FH-1with the capable of cyanobacteria-degradating and Fe(III)-reducing were isolated from the sediment of Chaohu lake in anaerobic conditions by traditional microbiological screening methods. FH-1was identified as Klebsiella pneumoniae by16SrDNA sequence. It was a short rod Gram-negative bacteria in facultative anaerobic incubated and the colony surface smooth, translucent, neat edge, the colony size of1.5-3.0mm after incubated for24h on LB solid medium plate. The studies of humus-reducing single factor results indicated that the optimal condition for the humus-reducing bacterium were at25℃and pH8.0, respectively. Then we studied the electron donor spectrum of this bacteria. Result showed that: this strains could use glucose, maltose, fructose and lactose as electron donors for anaerobic respiration in which lactose was the best. The heavy metal reduced test of humus-reducing bacteria showed that:FH-1reduced ferric citrate easily with the maximum reduction rate up to80%, while the reduction rate of Fe(OH)3was42%. The reduction rate of low concentrations of Cr(Ⅵ)(0.1-1.0mmol/L) by the bacteria were highly, while the reduction rate of concentration of5mmol/L of Cr(Ⅵ), up to 98%in the16th d. The strains could reduce p-nitrophenol and the rate was up to80%in the15th d.Tests were finished and thermal simulation test indicated:the humus-reducing bacteria with AQDS can promote the use of cyanobacteria polysaccharide and promote the release of lipids in the cyanobacteria, indirectly promote the release of the protein. Overall, AQDS and the humus-reducing bacteria had a positive role in humification of cyanobacteria. The heavy metal was release firstly then adsorption and to stabilize the last in the humification process, Fe was very active throughout the process.The release and adsorption of heavy metal in cyanobacteria added AQDS was more active than not added AQDS.