title: Use of a thermoresponsive polymer in ethanol fermentation carried out in a cadmium-containing medium.
abstract: In this study, a new thermoresponsive polymer, PG1-co-PHEDTA, was used as a reagent for the detoxification and recovery of cadmium from ethanol fermentation carried out in a cadmium-containing medium. We found that the polymer, PG1-co-PHEDTA, had an important role in ethanol production. In the absence of PG1-co-PHEDTA, ethanol fermentation was severely inhibited by cadmium. However, the inhibitory effect of cadmium could be significantly alleviated by the addition of PG1-co-PHEDTA, and the rates of glucose consumption and ethanol production were similar to those reported for cadmium-free fermentation processes. The investigation into the key units of PG1-co-PHEDTA showed that HEDTA was the contributing factor for the positive effect on ethanol fermentation. However, the effect of HEDTA that was incorporated into PG1 was higher than that of the free HEDTA. Three-fold higher concentration of free HEDTA was required to obtain similar results as that with PG1-co-PHEDTA additive. Glutathione (GSH) and cadmium assays demonstrated that the transport of cadmium into the cell could be prevented by PG1-co-PHEDTA via the formation of a chelated structure with the HEDTA groups in PG1-co-PHEDTA. By applying the unique phase transition of PG1-co-PHEDTA, cadmium of more than 90% could be removed from fermentation broths with a simple centrifugation step.
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Ruobin
authors.initials: R
authors.lastname: Chen
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Hu
authors.affiliation: School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
authors.forename: Afang
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Energy Research Institute of Shandong Academy of Sciences, Jinan 250014, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China; Energy Research Institute of Shandong Academy of Sciences, Jinan 250014, China. Electronic address: mtgao@shu.edu.cn.
authors.forename: Min-Tian
authors.initials: MT
authors.lastname: Gao
mesh_terms: D018533:Biomass; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D004492:Edetic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D008658:Inactivation, Metabolic; D009566:Nitrates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D013696:Temperature
chemical_list: D009566:Nitrates; C514522:PG1 compound; D011108:Polymers; D002104:Cadmium; D000431:Ethanol; D011092:Polyethylene Glycols; D004492:Edetic Acid; D005947:Glucose; C026060:N-(hydroxyethyl)ethylenediaminetriacetic acid
keywords: Bioprocess design; Cadmium; Ethanol; Fermentation; Thermoresponsive polymer; Yeast