Isolation, Purification And Identification Of Sulfate Reducing Bacteria And Achromatium

In this research, desulfuration bacteria from waste water samples in sewage treatment plants anaerobic reactors, aeration tank and Bayannaoer copper were isolated and purified, and seven strains of desulfuration bacteria were obtained. All of them were identified by morphological, physiological, biochemical and molecular biological methods. Then the effects of environmental elements on their growth were investigated in order to procure optimum living environment. The results are as follows:1. Anaerobic plate sandwich method, pyrogallic acid method and Hungat roll tube method were used to screen the water samples from sewage treatment plants anaerobic reactors and Bayannaoer copper, and then liquid enrichment method and solid purification method were combined to isolate and purify the strains. Six individual strains were obtained and named SRB-1, SRB-2, SRB-3,SRB-4,SRB-5 and SRB-6 separately.2. The morphological characteristics of these six individual strains were rhabditiform, single arrangement, gram-negative, without spore and capsule. The precipitation of FeS and the gas H2S were produced in liquid medium.They had the typical taxonomic features of sulfate reducing bacteria. The colonies were white in solid medium without Fe2+,but black in solid medium with Fe2+.The diameters of the colonies with Fe2+ in solid medium were larger than that of diameters without Fe2+.The results of V-P test, methyl red test and indole test showed negative. All of them used glucose, saccharine and lactose to produce gas. They also had the catalase activities. 3. The six SRB strains were mesophilic bacteria, and their optimum growth temperature were among 30-35℃,and the optimum pH value were between 7.0-8.0.The concentration of salt tolerance was 7.5%.All these six SRB strains treated organics like sodium lactate, glucose and sodium acetate as their electron donors, while they treated sulfate, sulfite and thiosulphate as electron acceptors.4. Aerobic culture method was utilized to isolate and screen one strain of colorless sulfur bacteria, which was named CSB-1.These colonies were white and round,and their surfaces were smooth and moist, and bulge in their centres. The colors of colonies were turned yellow when extending the culture time.the centres of colonies became brown. The surface of these colonies produced precipitation sulfur and made the colonies dry.CSB-1 was gram-negative bacteria, short rod, without spore but with capsule.CSB-1 was mesophilic bacterica, whose optimum growth temperature was 30℃.Its optimum pH value was 7.0.The CSB-1bacteria can not survive without oxygen.5. Through analyzing the 16SrDNA gene sequences, the phylogenetic tree was constracted. The morphological characteristics, physiological and biochemical characteristics were integrated to do further research. SRB-2,SRB-3 and SRB-4 were considered to belong to Citrobacter, while SRB-1 and SRB-6 to Shigella.SRB-5 belonged to Clostridium,and CSB-1 belonged to Thiobacillus.