High cell density fermentation of Saccharomyces cerevisiae GS2 for selenium-enriched yeast production

Tianwei Tan,Zheng Wang,Liyang Zhang 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

This paper describes a fed-batch fermentation protocol about production of selenium-enriched yeast. Saccharomyces cerevisiae GS2 was selected because of its high tolerance to selenium. The strain GS2 was tested and 122±0.5 g·l−1 dry cell weight was obtained after 30 h cultivation through feed back control of feed rate of glucose according to the concentration of ethanol and dissolved oxygen. Furthermore, the optimal pattern of Na2SeO3 addition was 9 mg Na2SeO3 against 1 g DCW at late exponential phase. With the combination of glucose feeding and Na2SeO3 addition,the final dry cell biomass reached 102±0.4 g·l−1 and a Se uptake level of 2,020±13 mg·Kg−1 was achieved in a 5 l fermentor after 38 h cultivation.

The influence of Trace TiO₂ on Adsorption of Ag+-imprinted Adsorbents Made from Chitosan and Mycelium

Hongyan Huo,Tianwei Tan,Haijia Su 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1

The complex technology of molecular imprinting with a photocatalytic reaction introduces novel ways of treating industrial and living sewage. This paper deals with the effects of trace TiO2 on Ag+-imprinted or non-imprinted adsorbents. NanoTiO2 was added during the preparation of the adsorbents. The performance of these adsorbents was compared with other common adsorbents, such as activated carbon and chitosan. TiO2 loading improved the adsorption ability for Ag+ of adsorbents. Adsorption equilibrium could be rapidly achieved at an initial Ag+ concentration of 200 mg/L under different light conditions (UV, visible light, and dark). After TiO2 loading, the maximal adsorption capacity of Ag+-imprinted and non-imprinted adsorb-ents was 25.0% higher, at 155.0 and 134.3 mg/g, respectively, at the initial Ag+ concentration of 1,000 mg/L. In order to understand the binding state of Ag, Ti on the adsorbents surface, FTIR, XPS were measured. The FTIR analysis, before and after adding TiO2, indicated that TiO2 bound with adsorbents through hydrogen bonding. XPS analysis, before and after adsorption, indicated Ag+ was reduced to Ag0 on the adsorbent surface, leading to an increased adsorption of Ag+.

Simultaneous separation of three isoflavones on oligo-β-cyclodextrin substituted polystyrene-based medium and evaluation adsorption characteristics using AutoDock

Li Yang,Tianwei Tan,Jinyi Luan,Xin Wei,Yongqiang Yang,Wenqing Huang,Zhi Guo,Yujie Wang 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2

The adsorption characteristics between three isoflavones in crude soybean sample and styrene-β-cyclodextrin (S-CD) were studied by molecular mechanics calculations with AutoDock. The discriminatory ability exhibited by S-CD against glycitin, daidzin, and genistin through the differences in the interaction energies and complex geometries could potentially serve for the chromatographic separation. The chromatographic elution order of the three analytes on oligo-β-cyclodextrin substituted polystyrene-based medium (PS-CDP) was predicted depending on the binding free energy values obtained from molecular docking simulations. The experimental results of chromatographic evaluation on PS-CDP were consistent with the simulation prediction. The three isoflavones in sample can be simultaneously separated in one-step under the optimized mobile phase, which consisted of methanol/0.1mM NH4AC=65.0/35.0 (v/v) by PS-CDP column chromatography. A glycitin purity of 95.1% with a recovery of approximate 86.3% was achieved by proper peak cutting, and that of daidzin and genistin was 95.8%, 95.4% and 96.2%, 95.7%, respectively.

A novel sintered metal fiber microfiltration of bio-ethanol fermentation broth

Qian Kang,Jan Baeyens,Tianwei Tan,Raf Dewil 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.8

In bio-ethanol fermentation, the broth consists of mainly water and ethanol, together with particulate residues of unreacted feedstock and additives (mostly yeast). Prior to further processing (distillation), and to avoid fouling of heat exchangers and distillation columns, the solids residues of the broth need to be removed to as low a concentration as possible. The current mechanical separation (belt filter or centrifuge) can only remove +10 μm particles representing about 90% of the total solids content. The remaining 10% is usually recovered in the bottom stream of the first distillation column, and forms the stillage that is further treated. To avoid fouling and even eliminate the first distillation column where the ethanol fraction is only increased from 12% (feed) to 16% (top), a better particulate removal is required. Novel sintered metal fiber (SFM) fleeces are highly efficient for microfiltration, and the removal of suspended solids largely exceeds 99%. The paper (i) positions microfiltration in the overall bio ethanol process; (ii) describes the novel sintered metal fiber microfiltration application; (iii) experimentally determines the major operating characteristics of SFM and (iv) predicts the up-scaled operation by using a simplified filtration model. At an ambient feed temperature, the flux of permeate exceeds 5m3/m2h for a TMP of 1.5 bar and a yeast concentration of 15 g/l, as commonly encountered in the fermenter broth.

Studies on Purification of 1,3-propanediol by Molecular Distillation

Zhe Wang,Zhe Wu,Tianwei Tan 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.4

The separation of 1,3-propanediol using molecular distillation has been studied. The effects of operating temperature and feed flow rate through a sequential distillation strategy were investigated. The optimal experimental temperature was at 70oC for separating 1,3-propanediol and the by-product 2,3-butanediol. Meanwhile, the volume flow rate was 10 mL/min. As a result, the recovery of 1,3-propanediol and 2,3-butanediol were 87.6 and 87.5%,respectively. Furthermore, the integrated separation characteristic of 1,3-propanediol was evaluated through macrolevel and micro-level models. The separation factors of 1,3-propanediol versus 2,3-butanediol and glycerol were 0.11 and 1.07, respectively, affirming that the separation of 1,3-propanediol by molecular distillation was feasible.

Synthesis and characterization of a novel soil stabilizer based on biodegradable poly(aspartic acid) hydrogel

Jun Yang,Fang Wang,Tianwei Tan 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.5

A novel soil stabilizer based on poly-amino acid - polyaspartic acid (PASP) and its copolymer which modified by xanthan gum (XG) was studied to increase soil particle compressive strength and resistance to wind erosion. Due to its unique property, the stabilizer aggregated individual soil particles and formed crust. The sample compressive strength increased from 0.175 to 0.612MPa and the wind erosion modulus reduced from 22.43 to 10.56 g·m−2·min−1 after the 1% PASP hydrogel was applied by 1.67 Lm−2 (1 cm of crust). The soil water content was higher than the control due to the polymer’s excellent water-retaining property. The polymer had no negative influence on seed germination and growth. The biodegradability experiment showed that PASP was easy to biodegrade and therefore it was safe to apply in the field.

Adsorption behaviors of the aminated chitosan adsorbent

Su Haijia,Zhao Yan,Tan Tianwei 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.6

Antibacterial and anti-mildew behavior of chitosan/nano-TiO2 composite emulsion

Haijia Su,Lei Shi,Yan Zhao,Tianwei Tan,Xiaodong Zhang 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6

A novel chitosan/nano-TiO2 composite emulsion (CTCE) was prepared by inverse suspension technology, and its multi-function properties were studied. As can be seen from the results, the gauze treated with chitosan/ nano-TiO2 composite emulsion showed excellent antibacterial activities against Escherichia coli, Aspergillus niger and Candida albicans that the bactericidal ratios could reach 99.96%, 100% and 78.3% after 24 h, respectively. At the same time, the chitosan/nano-TiO2 composite emulsion could really kill the bacteria, not just inhibit its growth, and the bactericidal ratio for E. coli could reach 70.3% after 1 h. The bactericidal ratio for E. coli reached 98.8% at 27 oC compared with 58.7% at 18 oC after 8 h due to the activity of bacteria being weakened at low temperature. Furthermore, the antibacterial ability of antibacterial gauze was hardly influenced with the increase of storage time, which could be reused for up to 8 times without loss of antibacterial ability.