蛋白酶分泌菌对重金属胁迫的反应

Responses of Microorganisms Producing Protease to Heavy Metal Stress

摘要:

本文研究了Pb、Zn、Cu和Cd对3种蛋白酶产生菌：碱性地衣芽孢杆菌2709(Bacillus licheniformis 2709)、中性枯草杆菌1.398(Bacillus subtilis1.398)和酸性宇佐美曲霉537(Aspergillus usamii 537)生长及其酶活性的影响, 并采用生长抑制皿分析(GIPA)方法针对3种菌株在Pb、Zn、Cu、Cd不同胁迫浓度下的生长量进行打分, 分析其耐性与抗性指标(MTC与MIC)。结果表明4种重金属在超过一定临界浓度后, 对3种菌株的生长和蛋白酶活性均产生了较大的抑制作用。碱性蛋白酶对4种重金属均具有较大的适应性, 其次是中性蛋白酶对Zn和Cd具有一定的适应性, 而酸性蛋白酶对4种重金属均表现出被抑制状态。3种菌株对Pb和Zn耐性与抗性最高(2.0 mmol/L~6.0 mmol/L), 其次是对Cd也具有一定的抗性(0.5 mmol/L~0.75 mmol/L)。

Abstract:

Effects of Pb, Zn, Cu and Cd on growth and enzyme activities of microorganisms such as Bacillus licheniformis 2709, Bacillus subtilis1.398 and Aspergillus usamii 537, which can individually produce alkaline, neutral and acid protease, were studied, respectively. By determining growth and enzyme activities of three bacterial species, as well as analyzing their tolerance and resistance indicators (MTC and MIC) using growth inhibition plate analysis (GIPA) under different heavy metal gradients, results showed that four heavy metals under higher than a special concentration level significantly inhibited growth and enzyme activities of three species. The alkaline protease exhibited greatest adaptability to four heavy metals, next the neutral protease also exhibited certain adaptibilty to Zn and Cd, whereas the acid protease was totally inhibited under any levels of heavy metal concentrations. Three species not only showed great potential to tolerate and resist toxicity of lead and zinc (2.0 mmol/L-6.0 mmol/L), but also showed certain resistance to cadmium (0.5 mmol/L-0.75 mmol/L).