[Study on mechanism of beer yeast adsorbing copper ion by spectroscopy].
Copper ions adsorption by beer yeast was studied by AAS, FTIR, SEM/EDS etc. The quantity of copper biosorption by NaOH-treated yeast and acetone-treated yeast increased significantly, while the esterification of carboxylate functionalities and the methylation of amino group presented in the cell walls of yeast resulted in a marked decrease in copper adsorption. These results show that amino and carboxylate groups in yeast cell wall play a great role in binding copper. According to IR spectra, the dominating bands near 1 652, 1 539 and 1 237 cm(-1) are assigned to amide I , amide II and amide IlI, the characteristic IR absorption of protein which could be one of the significant components of cell walls. The peak near 1 456 cm(-1) is attributable to the bending stretching of CH2- and CH3-. The changes in the spectra of the copper-exposed yeast biomass were in the stretch of hydroxyl groups or amino groups, which shifted from 3 392 to 3 404 cm' , and in the symmetrical stretch of carboxylate groups, which shifted from 1 405 to 1 383 cm(-1). The components and structure of the exposed-copper biomass remain intact. SEM/EDS analysis shows that the main elements of beer yeast are carbon, oxygen, and magnesium, while the surface of yeast is rough, and the copper-loaded yeast only binds little copper.
Han
Run-ping
RP
Department of Chemistry, Zhengzhou University, Zhengzhou 450052, China.
Yang
Guan-yu
GY
Zhang
Jing-hua
JH
Bao
Gai-ling
GL
Shi
Jie
J
D000327:Adsorption; D003300:Copper / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D013054:Spectrophotometry, Atomic; D017550:Spectroscopy, Fourier Transform Infrared
D003300:Copper