The Effect of Zinc Exposure on the Bacteria Abundanceand Proteolytic Activity in Seawater
The Effect of Zinc Exposure on the Bacteria Abundanceand Proteolytic Activity in Seawater
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发表时间：
2010-12
影响因子：
4.1
通讯作者：
B. Wei
中科院分区：
文献类型：
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作者：
B. Wei
锌是异养细菌生长和酶活性所必需的微量元素。然而，过量的锌负荷显示出毒性和对微生物过程的抑制。锌对海洋微生物功能的影响还没有研究集中在细菌和酶活性。在这项研究中，我们研究了锌对细菌丰度和各自的蛋白水解活性的短期影响。海水样品通过0.6 μm过滤器过滤以去除颗粒和食草动物，在过滤器中加入不同浓度的Zn（0.01和10 μM）。在0、4和16小时抽取等分试样。使用SYBR Gold染色和落射荧光显微镜计数细菌。用甲基香豆酰胺（MCA）底物测定胞外蛋白酶活性（氨肽酶、胰蛋白酶和胰凝乳蛋白酶型活性）。结果表明，添加锌对细菌丰度没有明显影响。然而，除了锌明显降低氨肽酶活性相比，控制。胰蛋白酶活性在0小时时很高，在有或没有Zn的条件下，沿着16小时孵育期没有观察到变化。胰凝乳蛋白酶活性也不受锌。这表明锌对氨肽酶有直接影响。总的来说，锌污染可能会影响微生物活性和蛋白质的转化。
Zinc (Zn) is an essential trace element for growth and enzyme activities of heterotrophic bacteria. However, excess load of Zn shows toxicity and inhibition to microbial processes. The effect of Zn on marine microbial function has not been studied focusing on bacterial and enzymatic activities. In this study, we examined the short-term effect of Zn on bacterial abundance and respective proteolytic activity. Seawater sample was filtered through 0.6-μm filter to remove particle and grazers, varying concentrations of Zn (0.01 and 10 μM) were added to the filtrates. Aliquots were withdrawn at 0, 4, and 16-hr. Bacteria were enumerated using SYBR Gold staining and epifluorescence microscopy. Extracellular protease activities (aminopeptidase-, trypsinand chmotrypsin-type activities) were measured by methylcoumarylamide (MCA)substrates. Results showed that, the addition of Zn did not cause any significant changes on the bacteria abundance. However, the addition of Zn clearly decreased the aminopeptidase activity compared to control. Trypsin activity was high at 0 hr and no change was observed along the 16 hr incubation period in conditions either with or without Zn. Chymotrypsin activity was also not affected by Zn. This suggests that Zn has direct impact on aminopeptidase. Overall, Zn contamination seems to have effect on the microbial activities and transformation of proteins in aquatic system.