Highlights

• The mycelia of Stropharia rugosoannulata have the ability to accumulate cadmium.

• Down regulation of amino acid metabolism-related proteins inhibits mycelial growth.

• Proteins of energy metabolism and antioxidant system contribut to the Cd tolerance.

• Possible application of S. rugosoannulata in bioremediating Cd-contaminated soils.

Soil Cd pollution seriously threatens environment and human health. The mycelia of Stropharia rugosoannulata were proved could absorb and accumulate Cd, suggesting that this macrofungi could be a potential candidate for bioremediation of Cd-contaminated soils. Further, the physiologic and proteomic differences of S. rugosoannulata mycelia under 0.2 mg/L (low) and 2 mg/L (high) Cd stress were investigated via antioxidant system analysis and the TMT technique.

Figure 1 Cd concentrations in mycelia (A) and supernatant (B) of S. rugosoannulata under Cd stress. The mycelia were cultured in PDB with 0, 0.2, 2.0 mg/L Cd for 21 days. Error bars represent±SEM of three replicates. Means with different letters in the same figure differ significantly (Duncan’s test, p < 0.05).

Cd accumulation and mycelial growth inhibition exhibited a concentration-depended trend. Analysis of antioxidant system indicated that SOD, GR, GSH, GSSG and ASA played key roles in resisting the toxic effects of Cd. Via proteome analysis, 24 and 267 differentially expressed proteins (DEPs) were observed under low and high Cd stress, respectively. GO and KEGG analysis found that the mycelial growth inhibition might due to the down-regulation of some DEPs involved in “valine, leucine and isoleucine biosynthesis” and “tyrosine metabolism”; the certain tolerance to high Cd stress might attribute to the regulation of DEPs referred to energy metabolism and antioxidant system-related pathways, maintaining cellular energy homeostasis and removing ROS produced by cells.

Figure 2 Graphic abstract

This study provides a theoretical basis for the application of S. rugosoannulata in remediating Cd-contaminated soils in future.

posted by Dong Qin from Institute of Edible Fungi