湖泊底泥中17β-雌二醇的生物代谢机制研究

研究了湖泊底泥微生物在好氧、厌氧环境条件下对17β-雌二醇(17β-estradiol, E2)的生物降解特性,探讨了其相应地生物代谢机制.结果表明,好氧条件,反应24h后约99%的E2从液相中消失,中间产物雌激素酮(estrone, E1)随反应进行浓度先增加后从液相中逐渐消失;厌氧条件,96h后约4%的E2仍存在于液相中, E1浓度先增加后降低后又逐渐增加,再降低直至从液相中完全消失.综合分析E2和E1的浓度经时变化认为,好氧条件下, E2被脱氢酶氧化成E1, E1再被体系中存在的其它生物酶氧化,直至被完全矿化;厌氧条件下, E1和E2二者之间存在一种相互转换关系:E2被脱氢酶氧化成E1,同时E1被还原酶还原成E2,在相互转化的过程中,体系中的其它生物酶会逐渐降解E2、E1,直至最终将其完全矿化.与E2相比较, E1更易积累于天然水域中的微生物体内.

Biodegradation mechanisms of 17beta-estradiol (E2) by lake sediment

Batch experiments using lake sediment mud liquors spiked with E2 were performed under aerobic and anaerobic conditions. The catabolic mechanisms of E2 were also induced. The results indicate that under aerobic condition, 99% of E2 can be removed from aqueous phase after as short as 24 h. Concentration of estrone (E1) firstly increase and then decrease slowly until to vanish from aqueous phase; Under anaerobic condition, 4% of E2 still be in aqueous phase after 96 h of reaction. Concentration profile of E1 show that E1 firstly increase then decrease, then increase and then decrease to vanish from aqueous phase finally. Analyzing the concentration profiles of E2 and E1, we draw a conclusion that E2 is oxidized to E1 by dehydrogenase and then E1 was oxidized by other enzymes within sediment to mineralization completely under aerobic condition. Under anaerobic condition, there is a mutual translation relation between E2 and E1. E2 was oxidized to E1 by dehydrogenase and synchronously E1 is reduced to E2. During this mutual translation course, E2 and E1 can be degraded gradually to finally mineralization completely by other enzymes within the reaction system. Comparing with E2, E1 can accumulate more easily within biosolid in natural waters.