硫氧化菌种脱除硫化物生成单质硫限制性因素优化

Optimization of restrictive factors during process of removing sulfide into elemental sulfur by sulfur oxidizer

摘要:

【目的】针对硫氧化菌种较为特殊的生化特性，优选其氧化硫化物生成单质硫过程的相关限制性因素，以提高该类菌种生成单质硫效率。【方法】采用一株典型脱硫菌Thermithiobacillus tepidarius JNU-2 (T. tepidarius JNU-2)氧化硫化物生成单质硫。研究该菌株在以Na2S2O3为能源底物时的培养特性和脱硫性能，并结合单因素实验对菌株氧化硫化物生成单质硫的限制性因素进行优选。【结果】T. tepidarius JNU-2在以Na2S2O3为唯一能源底物培养时的μmax为0.207 h?1，最终生物量为4.0×106 cells/mL。98%的Na2S2O3在24 h时被消耗殆尽，此时单质硫产量达到最大值为0.8 g/L。随后单质硫逐渐被氧化利用，最终稳定在0.2 g/L。经过对该过程主要限制性因素进行单因素实验优化，确定最佳碳氮源、MgSO4、FeSO4和能源底物条件分别为：CO2、NH4Cl 0.5 g/L、MgSO4 0.5 g/L、FeSO4 0.1 g/L和Na2S2O3 15.0 g/L。优化后的氧化Na2S2O3生成单质硫过程的最大生物量可达4.8×106 cells/mL，单质硫产量提升至1.14 g/L。相较于未优化之前，单质硫的产量提高了42.5%。【结论】优化该过程主要限制性因素可有效提高化能自养型T. tepidarius JNU-2氧化硫化物生成单质硫效率。

Abstract:

[Objective] Concerning the special biochemical characteristics of sulfur oxidizer, we optimized related restrictive factors during the process of oxidizing sulfide to elemental sulfur for improving productivity of the elemental sulfur. [Methods] A typical desulfurization strain Thermithiobacillus tepidarius JNU-2 (T. tepidarius JNU-2) was used for oxidizing sulfide into elemental sulfur. The culture trait and desulfurization performance was respectively studied with Na2S2O3 as the energy substrate. Then the process of oxidizing sulfide into elemental sulfur related restrictive factor was optimized via single factor experiments. [Results] With Na2S2O3 as the sole energy substrate, μmax of T. tepidarius JNU-2 was 0.207 h?1 and the final biomass was 4.0×106 cells/mL. Nearly 98% Na2S2O3 had been consumed at 24 h and elemental sulfur production reached the maximum value 0.8 g/L. Then elemental sulfur was gradually oxidized and eventually maintained at 0.2 g/L. The optimum conditions of major restrictive factors such as carbon and nitrogen source, MgSO4, FeSO4 and energy substrate was determined through the single factor experiments as follow. CO2, NH4Cl 0.5 g/L, MgSO4 0.5 g/L, FeSO4 0.1 g/L, Na2S2O3 15.0 g/L. After optimization, the maximum biomass reached 4.0×106 cells/mL during the process of oxidizing Na2S2O3 into elemental sulfur and its titer was increased to 1.14 g/L, which was improved by 42.5% compared to the previous non-optimized one. [Conclusion] The efficiency of elemental sulfur from oxidizing sulfide by chemoautotrophic T. tepidarius JNU-2 could be effectively improved via optimization of major restrictive factors.