Proteomic response of Euglena gracilis to heavy metal exposure - Identification of key proteins involved in heavy metal tolerance and accumulation

Contamination of the environment by heavy metals is an increasing problem globally. While the mechanisms bacteria and yeasts have developed to tolerate these metals are well covered in the published literature, much less is known about algae. In this study, the wild-type Euglena gracilis (Z-strain) and the sugar loving E. gracilis var. saccharophila (B-strain) were exposed to the heavy metals cadmium (Cd), lead (Pb) and mercury (Hg). Minimum inhibitory concentration (MIC) studies indicated that the heavy metal tolerance of both strains was in the order of Pb > Cd > Hg. Based on microwave plasma atomic emission spectroscopy (MP-AES), the maximum Cd accumulation by Z-strain was 8.1 mg Cd per gram of dry weight (DW), which makes it a Cd hyperaccumulator.