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Growth and Heavy Metal Binding Properties of Transgenic Chlamydomonas Expressing a Foreign Metallothionein Gene

 

作者: Xiao-Hua Cai,   Christopher Brown,   Jagat Adhiya,   SamuelJ Traina,   RichardT Sayre,  

 

期刊: International Journal of Phytoremediation  (Taylor Available online 1999)
卷期: Volume 1, issue 1  

页码: 53-65

 

ISSN:1522-6514

 

年代: 1999

 

DOI:10.1080/15226519908500004

 

出版商: Taylor & Francis Group

 

关键词: bioremediation;cadmium;phytochelatin;phytoremediation.

 

数据来源: Taylor

 

摘要:

We have compared the growth rates and cadmium binding capacity of wild-type and transgenicChlamydomonas reinhardtiicells expressing a foreign class-II metallothionein. We observed that cells expressing metallothionein grew to significantly higher cell densities than wild-type cells in the presence of a toxic cadmium concentration (40 μM). When grown at a low (5 μM) cadmium concentration, cells expressing metallothionein bound twofold more cadmium (0.43 μg Cd)mg Ch1) than wild-type. At cadmium concentrations (40 μM), which induce phytochelatin synthesis in wild-type cells the cadmium binding capacity of both wild-type (79.6 μg Cd)mg Ch1) and transformed cells (86.4 μg Cd)mg Ch1) was similar; however, the transformed cells grew to higher densities than the wild type. These results suggest that under conditions that apparently induce phytochelatin expression, the presence of metallothionein in the cytoplasm reduces heavy metal toxicity. Furthermore, because cells expressing metallothionein grow to higher densities than wild-type cells at a toxic cadmium concentration (40 μM), the transgenic cells sequester more total cadmium (9% of total Cd) from the medium than the wild type (5.5% of total Cd). These results indicate that the trace-metal binding properties of Chlamydomonas can be enhanced through the expression of trace-metal-specific binding proteins.

 

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