[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.

[Elemental analysis and infrared spectra of suspended substance in the effluent from eco-biofilter].

The suspended substance (SS) in the effluent from eco-biofilters was examined by elemental analysis and infrared spectroscopy. The inorganic components of SS in D1 and S1 are more than those in D2 and S2, respectively. The IR spectra of SS is mainly composed of the adsorption of carbohydrates, protein, etc. The domninating bands near 1655, 1542 and 1240 cm(-1) are assigned to amide I, amide II and amide III respectively, and the characteristic IR absorption of protein could be one of the significant components of cell walls. The peak near 1460 cm(-1) is attributable to the bending stretching of CH1-- and CH3--. The strength of adsorption peaks in the region 1720-1200 cm(-1) for D1 is lower than that for D2, but at 1040 cm(-1) the case is reversed.

[Comparison of infrared spectra of native and esterified beer yeast].

The native beer yeast and esterified beer yeast were examined by infrared spectroscopy. The IR spectrum of beer yeast is mainly composed of the adsorption of carbohydrates, protein, etc. The dominating bands near 1652, 1532 and 1240 cm(-1) were assigned to amide I, amide II and amide III, and the characteristic IR absorption of protein could be one of the significant components of cell walls. The peak near 1 454 cm(-1) is attributable to the bending stretching of CH2- and CH3-. A substantial portion of the absorbance at 1160 cm(-1) is attributable to the stretching vibration of C-O on the structure of carbohydrates, the main components of the cell walls. The band present at 1080 cm(-1) was caused by the C-O stretching of carbohydrates and alcohols found in the RNA, the DNA and/or the cell envelop of the yeast. The peaks at 1744 cm(-1) (attributed to the carboxylate stretching) and 1454 cm(-1) confirmed the esterification process of carboxylate groups presented in the cell wall. After esterification with methanol-chloride hydride, the major components and the structures of the biomaterial remained intact.