title: Effects of nitrogen sources and metal ions on ethanol fermentation with cadmium-containing medium.
abstract: This study evaluated ethanol fermentation and its correlation with glutathione (GSH) synthesis under various cadmium-conditions with different metal ions and nitrogen sources. We found that corn steep liquor (CSL) and yeast extract have differential roles to play in GSH accumulation in cell even though both of them could alleviate the inhibition by cadmium. The different GSH accumulation in cell resulted from the different contents of metal ions in CSL and yeast extract. Intracellular GSH decreased with increasing calcium concentrations, and high calcium concentrations rendered the yeast more tolerant to cadmium stress than the nitrogen sources did. When the mole ratio of calcium to cadmium was 100:1, yeast tolerated 1000 µmol/L cadmium with no decrease in efficiency in ethanol production. As a result, the use of calcium allowed a significant saving of high-cost nutrient yeast extract with an efficient ethanol production, making the bioconversion of cadmium-containing biomass into ethanol possible.
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, China.
authors.forename: Qingyun
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, China.
authors.forename: Mengnan
authors.initials: M
authors.lastname: Wu
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, Shanghai, China.|Energy Research Institute of Shandong Academy of Sciences, Jinan, China.
authors.forename: Min-Tian
authors.initials: MT
authors.lastname: Gao
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002104:Cadmium / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002412:Cations / Q000737:chemistry / Q000378:metabolism; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*
chemical_list: D002412:Cations; D003470:Culture Media; D008670:Metals; D002104:Cadmium; D000431:Ethanol; D005978:Glutathione; D005947:Glucose; D009584:Nitrogen; D002118:Calcium
keywords: Cadmium; Calcium; Detoxification; Ethanol fermentation; Saccharomyces cerevisiae