絮凝酵母吸附Cr(VI) 的机理

Mechanism of Cr(VI) biosorption by flocculating yeast

摘要:

絮凝酵母SPSC01 为酿酒酵母Saccharomyces cerevisiae 和粟酒裂殖酵母Schizosaccharomyces pombe 的融合菌株，用其吸附水溶液中的重金属Cr(VI)，可以大大降低生物吸附的固液分离成本。为了探讨SPSC01 菌体絮凝蛋白对Cr(VI) 还原吸附的影响，对SPSC01 与其亲本菌株的吸附行为进行了比较。结果表明，SPSC01 和其具有絮凝性状的亲本S. pombe 的Cr(VI) 去除速率基本同步，远优于无絮凝性状的亲本S. cerevisiae；达到吸附平衡时，S. pombe、SPSC01和S. cerevisiae 对总Cr 去除率分别达68.8％、48.6％和37.5％；从而证明了絮凝有利于Cr(VI) 的还原、吸附，絮凝蛋白在Cr(VI) 的还原吸附过程中起促进作用。通过化学屏蔽方法和傅立叶变换红外光谱 (FTIR) 分析，对SPSC01 菌体表面吸附Cr(VI) 的机理进行了研究，结果表明SPSC01 菌体表面吸附Cr(VI) 起主要作用的基团是氨基、羧基和酰胺基。

关键词:絮凝酵母; 生物吸附; Cr(VI); 吸附机理

Abstract:

The flocculating yeast strain SPSC01 is a fusant strain of Saccharomyces cerevisiae and Schizosaccharomyces pombe. The use of SPSC01 to absorb Cr(VI) from Cr(VI) containing aqueous solution would greatly reduce the cost of post-adsorption separation, since the superior flocculating property of SPSC01 would allow easy separation of the Cr(VI)-biomass from the solution. In order to investigate the effects of flocculating proteins on Cr(VI) reduction and absorption by SPSC01, the absorption behaviors of SPSC01 and its parental strains were compared. The results showed that Cr(VI) removal rate of SPSC01 was almost the same as that of S. pombe, which also has flocculating ability, but was faster than that of S. cerevisiae, which has no flocculating ability. When the system reached equilibrium, the amount of total Cr adsorbed by S. pombe, SPSC01 and S. cerevisiae were 68.8%, 48.6% and 37.5%, respectively. This showed that flocculation was beneficial to Cr(VI) reduction and adsorption, and suggested that focculating proteins may play a role in enhancing the Cr(VI) adsorption capacity of SPSC01 and S. pombe. We investigated the mechanism of Cr(VI) adsorption by SPSC01 using chemical modification and FTIR. The results indicated that the major functional groups (amino, carboxyl and amide) of surface proteins may contribute to the absorption of Cr(VI).

Key words:flocculating yeasts; biosorption; Cr(VI); mechanisms of adsorption