NSRRC Activity Report 2023

Environmental and Earth Sciences 077 Fig. 2 : Proposed mechanisms for Cr(VI) removal by Cyanidiales. [Reproduced from Ref. 1] To investigate the metal interactions associated with Cyanidiales, synchrotron-based Fourier-transform infrared (SR-FTIR) spectroscopy was conducted at TLS 14A1 for determining the alterations in Cyanidiales’ functional groups and protein secondary structure (PSS). In response to Cr(VI) exposure, the α-helix and β-strand components of metallothionein, a family of cysteine-rich proteins that play a role in metal stress, were examined. The α-helix/β-strand ratios showed a linear correlation (R 2 ≥ 0.8337) with sorbed Cr amounts for all samples. However, two contrasting trends emerged at both pH 2.0 ( Fig. 1(i) ) and 7.0 ( Fig. 1(j) ). Gp at pH 2.0 and Cm at pH 7.0 exhibited a negative correlation between the α-helix/β-strand ratios Fig. 1 : 2D images for Cr distributed on Cyanidiales at (a-c) pH 2.0, and (d-f) pH 7.0. The Cr sorbed capacities and related speciation in Cyanidiales were at (g) pH 2.0 and (h) pH 7.0. The ratio of α-helix (1652 cm -1 ) to parallel β-strand (1631 cm -1 ) as a function of sorbed Cr amounts on Cyanidiales at (i) pH 2.0 and (j) 7.0. [Reproduced from Ref. 1]