Kinetics of soil dehydrogenase in response to exogenous Cd toxicity.
Soil dehydrogenase plays a role in the biological oxidation of soil organic matter and can be considered a good measure of the change of microbial oxidative activity under environmental pollutions. However, the kinetic characteristic of soil dehydrogenase under heavy metal stresses has not been investigated thoroughly. In this study, we characterized the kinetic characteristic of soil dehydrogenase in 14 soil types, and investigated how kinetic parameters changed under spiked with different concentrations of cadmium (Cd). The results showed that the Kmand Vmaxvalues of soil dehydrogenase was among 1.4-7.3mM and 15.9-235.2μMh-1in uncontaminated soils, respectively. In latosolic red soil and brown soil, the inhibitory kinetic mechanism of Cd to soil dehydrogenase was anticompetitive inhibition with inhibition constants (Ki) of 12 and 4.7mM, respectively; in other soils belonged to linear mixed inhibition, the values of Kiwere between 0.7-4.2mM. Soil total organic carbon and Kiwere the major factors affecting the toxicity of Cd to dehydrogenase activity. In addition, the velocity constant (k) was more sensitive to Cd contamination compared to Vmaxand Km, which was established as an early indicator of gross changes in soil microbial oxidative activity caused by Cd contamination.
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China; Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, CAS 723 Xingke Rd., Tianhe District, Guangzhou 510650, China.
Xiangping
X
Tan
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Ziquan
Z
Wang
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Guannan
G
Lu
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China; Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling, 712100, Shaanxi, China. Electronic address: wenxianghe@nwafu.edu.cn.
Wenxiang
W
He
College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Gehong
G
Wei
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, CAS 723 Xingke Rd., Tianhe District, Guangzhou 510650, China.
Feng
F
Huang
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, CAS 723 Xingke Rd., Tianhe District, Guangzhou 510650, China.
Xinlan
X
Xu
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, CAS 723 Xingke Rd., Tianhe District, Guangzhou 510650, China.
Weijun
W
Shen
D002104:Cadmium / Q000633:toxicity*; D007700:Kinetics; D010088:Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*
D012987:Soil; D002104:Cadmium; D010088:Oxidoreductases
Cadmium; Dehydrogenase; Inhibition constant; Kinetic