Abstract
Heavy metal pollution in Antarctic is serious by anthropogenic emissions and atmospheric transport. To dissect the heavy metal adaptation mechanisms of sea‐ice organisms, a basidiomycetous yeast strain AN5 was isolated and its cellular changes were analyzed. Morphological, physiological, and biochemical characterization indicated that this yeast strain belonged to Rhodotorula mucilaginosa AN5. Heavy metal resistance pattern of Cd > Pb = Mn > Cu > Cr > Hg was observed. Scanning electron microscopic (SEM) results exhibited altered cell surface morphology under the influence of copper metal compared to that with control. The determination of physiological and biochemical changes manifested that progressive copper treatment significantly increased antioxidative reagents content and enzymes activity in the red yeast, which quench the active oxygen species to maintain the intercellular balance of redox state and ensure the cellular fission and growth. Comparative proteomic analysis revealed that, under 2 mM copper stress, 95 protein spots were tested reproducible changes of at least 10‐fold in cells. Among 95 protein spots, 43 were elevated and 52 were decreased synthesis. After MALDI TOF MS/MS analysis, 51 differentially expressed proteins were identified successfully and classified into six functional groups, including carbohydrate and energy metabolism, nucleotide and protein metabolism, protein folding, antioxidant system, signaling, and unknown function proteins. Function analysis indicated that carbohydrate and energy metabolism‐, nucleotide and protein metabolism‐, and protein folding‐related proteins played central role to the heavy metal resistance of Antarctic yeast. Generally, the results revealed that the yeast has a great capability to cope with heavy metal stress and activate the physiological and protein mechanisms, which allow more efficient recovery after copper stress. Our studies increase understanding of the molecular resistance mechanism of polar yeast to heavy metal, which will be benefitted for the sea‐ice isolates to be a potential candidate for bioremediation of metal‐contaminated environments.
Highlights
Copper (Cu) is an indispensable micronutrient and act as key roles as catalytic cofactor in cellular redox reactions and metal homeostasis (Burkhead, Reynolds, Abdel-Ghany, Cohu, & Pilon, 2009)
At 2 mM Cu2+ treatment, MDA content was rapidly accumulated and reached a maximum of 0.43 mmol/g fresh weight (FW) at day 1, and downregulated swiftly to 0.21 mmol/g FW at day 8 but still significantly higher than the control group (p > 0.01). These findings demonstrated that a high rate of lipid peroxidation and loss of cell membrane integrity occurred in cells inoculated with copper ion
Heavy metals cause a significant threat to public health because of the accumulation in body throughout the food chains
Summary
Copper (Cu) is an indispensable micronutrient and act as key roles as catalytic cofactor in cellular redox reactions and metal homeostasis (Burkhead, Reynolds, Abdel-Ghany, Cohu, & Pilon, 2009). Understanding the metabolism response of microorganisms induced by heavy metals, including copper, is nowadays the dominating goal of scientific research on metal detection and removal. A cold-active yeast strain was identified by sequencing of the 26S rDNA as Rhodotorula mucilaginosa strain NA5. It is the first report demonstrating high tolerance toward heavy metals and morphological and physiological changes of the yeast cells induced by copper. This work provides information regarding ecological response of cold-active yeast under heavy metal conditions and lays foundation for bioremediation to remediate the heavy metal-contaminated areas
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