摘要：
Acidithiobacillus thiooxidan is the major microorganism in bioleaching of heavy metal from sewage sludge. The biological oxidation of sulfur by Acidithiobacillus thiooxidan is the committed step of bioleaching of heavy metal. In order to isolate and cultivate efficientAcidithiobacillus thiooxidan, its characteristic of acid production is studied, and then the method of improving the effect of its acid production is selected. An autotrophic sulfur-oxidizing bacterium (strain JJU-1) was isolated from the activated sludge of a sewage plant. According to its colonial morphology, SEM image of strain, physiological-biochemical properties and its16S rRNA gene sequence analysis, the strain was identified as Acidithiobacillus thiooxidan. Sulfur oxidation by JJU-1 was studied from four aspects, such as initial pH, quantity of sulfur, size of sulfur particle and concentration of surfactant agent (Tween 60). The culture mediums with different initial pH were studied and the results indicated that the initial pH of culture medium almost had no effect on growth ofAcidithiobacillus thiooxidanin later stage, more specifically, the pH of culture mediums were almost the same on the 7th day. The experiment results also showed the growth of microorganism was restrained at pH below 1. Considering the influence by different amount of substrate sulfur added into the culture mediums, the rate of sulfate formation by JJU-1 strain was higher when the sulfur amount increased. On the 8th day the maximum difference of the culture mediums pH with different amount of sulfur was 0.54. The rate of sulfate formation by JJU-1strain increased with the decrease in sulfur particle size. The sulfur particles passing through 180μm yielded lower rates of sulfate formation than these of size below 180μm. The addition of Tween 60 had some effect on sulfate formation by JJU-1 strain. When the concentration of Tween 60 was at 0.4~1.6 g·L-1, it would increase the rate of sulfate formation. However, when the concentration of Tween 60 exceeded 2.0 g·L-1, there was a negative effect on the growth of JJU-1 strain on the 8th day. The microfiltration membrane experiment indicated that the Acidithiobacillus thiooxidan must be in direct physical contact with the sulfur particle before oxidation could take place. At the optimal growth conditions (pH=2.5~3.5,θ=28~32°C), the pH of culture media decreased from 3.5 to around 1.5 after 5 days, which indicated that the JJU-1 strain showed efficient in sulfur oxidation and sulfate formation. Therefore, The JJU-1 strain could be widely used in sewage sludge bioleaching%嗜酸性氧化硫硫杆菌是生物淋滤技术去除污泥中重金属的主要菌种,其生物氧化产酸反应是生物淋滤的关键步骤.为筛选、培育出高效的嗜酸性氧化硫硫杆菌.通过研究氧化硫硫杆菌的产酸特性,找出提高其产酸效果的方法,筛选、培育出高效的嗜酸性氧化硫硫杆菌.本研究从某污水处理厂活性污泥中分离、纯化得到一株高效氧化单质硫的菌株JJU-1,通过菌株和菌落形态观察、生理生化试验、16S rDNA序列分析和同源性比较等分析方法,鉴定该菌株为嗜酸性氧化硫硫杆菌(Acidithiobacillus thiooxidan),并从初始pH值、硫粉投加量、单质硫粒度、吐温60浓度等4个方面对JJU-1菌株的产酸特性进行了研究.实验结果表明:培养液初始pH值对后期产酸性能影响较小,当培养到第7天时,各培养液的pH值基本处于同一水平,但初始pH值小于1时,菌株的生长受到抑制;硫粉投加量越大,菌株产酸效率越高,当培养到第8天时,不同硫粉投加量的培养液pH值最大差值达到0.54;菌株产酸速率随单质硫粒度的减小而增大,粒径小于180 μm的硫粉比大于180μm的硫粉产酸速率快;吐温60的投加对氧化硫硫杆菌产酸有一定的影响,当吐温60的浓度为0.4~1.6 g·L-1时,对氧化硫硫杆菌产酸有一定的促进作用,但当吐温60的浓度大于2.0 g·L-1时,培养8 d后氧化硫硫杆菌的生长受到一定的抑制;微滤膜实验表明JJU-1菌株与单质硫表面的直接接触是发生产酸反应的先决条件.在最佳生长条件(初始pH=2.5~3.5、θ=28~32°C)下,JJU-1菌株培养5 d后,培养液pH值从3.5降到1.5左右,由此可见,该菌株具有良好的氧化单质硫产酸性能,在污泥生物淋滤技术中具有一定的应用前景.
