Integrated physiologic and proteomic analysis of Antarctic yeast Rhodotorula mucilaginosa AN5 in response to Cd stress at low concentration

In Antarctica, sea ice microorganisms are subjected to principal abiotic environmental stresses, such as low temperature, strong UV radiation and high salinity, but increasingly serious heavy metal pollution might has more grievous implication there. Herein, morphological, physiological and isobaric tag for relative and absolute quantification (iTRAQ)-based proteomic analyses were performed to anatomize the heavy metal adaptation mechanism of Rhodotorula mucilaginosa AN5, a type of basidiomycetous yeast strain isolated from Antarctic sea ice. Morphological observation showed that yeast AN5 could partly alleviate cadmium stress by the increase of cell size. KEGG functional enrichment along with physiological analysis showed that heavy metal tolerance of sea ice yeast might prominently be related to unsaturated fatty acids biosynthesis regulated by peroxisome proliferators-activated receptor (PPAR) signaling pathway, which is the first report in non-animal field. In addition, redox equilibrium, substances metabolism and energy generation also played key roles for yeast acclimation upon Cd stress. In general, Antarctic yeast could cope with heavy metal mainly by morphological alteration, ROS-scavenging capacity improvement and unsaturated fatty acids biosynthesis. This research provided particular insight into the tolerance mechanisms of Antarctic sea ice yeast in response to heavy metal stress.