Fate of organophosphate flame retardants (OPFRs) in the "Cambi® TH + AAD" of sludge in a WWTP in Beijing, China.

Organophosphate flame retardants (OPFRs) are emerging environmental pollutants that cause endocrine disruption, neurotoxicity, and reproductive toxicity. Sewage sludge is an important source of tri-OPFRs that are released into the environment. The occurrence, distribution, and ecological risk of OPFRs in the full-scale "Cambi® thermal hydrolysis (TH) + advanced anaerobic digestion (AAD) + plate-frame pressure filtration" sludge treatment process is closely related to the application of sewage sludge. We tested sludge samples from a wastewater treatment plant in Beijing, China. Nine tri-OPFRs were detected in the sludge samples collected at different treatment units during four seasons. The ΣOPFRs decreased from 1,742.65-2,579.68 ng/g to 971.48-1,702.22 ng/g. The mass flow of tri-OPFRs in treated sludge decreased by 61.4%, 48.9%, 42.4%, and 63.9% in spring, summer, autumn and winter, respectively, effectively reducing the corresponding ecological risk. The ecological risk of tri-OPFRs in sludge in forestland utilization mainly lies in chlorinated tri-OPFRs, especially TCPP and TCEP. No >42.20 t/hm2 of sludge could be used continuously for one year to prevent tri-OPFRs from exceeding the low ecological risk level, indicating that the current commonly applied proportion of sludge (1.6-30 t/hm2) will likely not raise the ecological risk of tri-OPFRs.

Review of available "extraction + purification" methods of natural ceramides and their feasibility for sewage sludge analysis.

Natural ceramide, a biologically active compound present in plants, has been used widely in food, cosmetics, and pharmaceutical industries. Abundant ceramide has been detected in sewage sludge, which has inspired the idea to recycle ceramide from it. Therefore, the methods of extracting, purifying, and detecting ceramides from plants were reviewed, with the aim to establish methods to get condensed ceramide from sludge. Ceramide extraction methods include traditional methods (maceration, reflux, and Soxhlet extraction) and green technologies (ultrasound-assisted, microwave-assisted, and supercritical fluid extraction). In the past two decades, more than 70% of the articles have used traditional methods. However, green extraction methods are gradually improved and showed high extraction efficiency with lower solvent consumed. The preferred technique for ceramide purification is chromatography. Common solvent systems include chloroform-methanol, n-hexane-ethyl acetate, petroleum ether-ethyl acetate, and petroleum ether-acetone. For structural determination of ceramide, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry are used in combination. Among quantitative analysis methods for ceramide, liquid chromatography-mass spectrometry was the most accurate. This review concludes that with our prilemenary experiment results it is feasible to apply the plant "extraction + purification" process of ceramide to sludge, but more optimization need to be performed to get better results.

The function of "Cambi® thermal hydrolysis + anaerobic digestion" on heavy metal behavior and risks in a full-scale sludge treatment plant based on four seasons investigation.

The environmental risk of heavy metals in sewage sludge from a full-scale "Cambi® thermal hydrolysis + anaerobic digestion" sludge treatment plant was discussed based on four seasons' data. Results showed that the order of heavy metal concentration in sludge was Zn > Cu > Cr > Ni > As > Pb > Hg > Cd, which all increased significantly due to the "enrichment effect" caused by the degradation of organics. Nevertheless, the mass of heavy metals except for Cd decreased. Chemical fractions of different heavy metals in raw sludge varied greatly. The proportion of their residual fraction all increased slightly after treatment. Thermal hydrolysis and anaerobic digestion led to the transformation of some heavy metal fractions. Deep dehydration process reduced the mass of heavy metals from sludge (less than 10%). Potential ecological risk of heavy metals was low (RI <150) when sludge is applied 0.75 kg/m2 to soil according to GB 4284-2018, in which the risk of Hg and Cd was highest. Furthermore, the accumulation amounts of heavy metals in test soil and rural soil with the annual sludge application amount of 0.75 kg/m2 for 15 years were calculated, which did not exceed GB 36600-2018 and GB 15618-2018 respectively.

Study on the reduction of chlorine and heavy metals in municipal solid waste incineration fly ash by organic acid and microwave treatment and the variation of environmental risk of heavy metals.

Municipal solid waste incineration (MSWI) fly ash usually needs to undergo dechlorination or heavy metal stabilization pretreatment for further treatment, recycling or disposal. In this paper, the removal effect of chlorine in fly ash by water washing, lactic acid, citric acid and microwave treatment was studied, and XANES was used to analyze chlorine chemical form in fly ash. In addition, the heavy metals in fly ash were also checked. The results indicated that double washing and triple washing could remove 88.0 % and 95.5 % of chlorine from fly ash respectively. The "double water washing + microwave/organic acid" could remove about 96.6 % of chlorine, and 42.9 % and 47.2 % of insoluble chloride respectively. The microwave treatment could maximize the stabilization of heavy metals with a BI value of 39.1 %, 0.11 %, 1.65 %, 15.4 % and 3.98 % for Cd, Cr, Cu, Pb and Zn. The elution of heavy metals by citric acid was obvious. "Double water washing + citric acid" removed 87.0 % of Cd, 17.2 % of Cr, 11.9 % of Cu, 39.6 % of Pb and 43.6 % of Zn, but the environmental risk of Cu and Cr increased about 2-3 % after the treatment. The results of this study provide guidance for the pretreatment of fly ash before resource utilization.

Immobilization of Cytochrome C by Benzoic Acid (BA)-Functional UiO-66-NO2 and the Enzyme Activity Assay.

Recently, metal-organic frameworks (MOFs) are considered to be the moderate hosts for the bio-enzymes owing to their unique 3D pores and controllable surface affinity to the target molecules. In this work, the benzoic acid (BA)-modulated UiO-66-NO2 was introduced, and cytochrome c (Cyt C) was chosen as the target enzyme to evaluate the immobilization efficiency of the resulting UiO-66-NO2-BA. The immobilization conditions including pH, adsorption time, and temperature and the initial concentrations of BA were optimized. The adsorption kinetics and thermodynamics were analyzed to further explore the enhanced adsorption mechanism. It is worth noted that all the UiO-66-NO2-BA exhibited evidently enhanced adsorption capacities in comparison with the unmodified UiO-66-NO2 due to the formation of the chemical bonds between the UiO-66-NO2-BA and cytochrome C, indicating the positive roles of BA modification. Finally, the activities of the immobilized cytochrome C were assessed by using the catalytic oxidation of ABTS in the presence of H2O2, which reactions were also conducted over the free cytochrome C for comparison. The evidently improved stability under definite pH range, prolonged durability against the organic solvents, and the good reusability of the immobilized cytochrome C highlight the prospect applications of functional MOF immobilized enzymes in the practical catalytic reactions.

Integrated passive sampling and fugacity model to characterize fate and removal of organophosphate flame retardants in an anaerobic-anoxic-oxic municipal wastewater treatment system.

It is crucial to deeply understand the fate and removal mechanism of various organophosphate flame retardants (PFRs) in specified wastewater treatment processes. However, concentration fluctuation and matrix effect in wastewater challenge quantification of PFR flux for both field observation and model validation. We present measured seasonal distribution profiles of time-weighted average (TWA) concentrations by in situ hydrophobic and polar passive samplers and modeled mass transport and transformation by means of fugacity for 11 PFRs with varied structures in an anaerobic-anoxic-oxic (A-A-O) municipal wastewater treatment system, and provided a systematic approach to characterize fate and removal mechanism of PFRs in major compartments via various treatment processes. We find evidence that PFRs have a unique structural-dependent fate and removal in the A-A-O system. Hydrophilic chlorinated-PFRs present persistent in all major compartments and dominate in effluents with significant variations; alkyl-PFRs are majorly reduced by biodegradation; whereas hydrophobic aryl-PFRs have the highest removal percentage, contributed by both sorption on solids and biotransformation. Sensitive analysis shows the most influential operation parameters on removal efficiency varied among the PFRs with different properties. We also conclude passive sampling can be effectively applied to estimate TWA wastewater concentrations and to validate fugacity model prediction.

Seasonal concentration variation and potential influencing factors of organophosphorus flame retardants in a wastewater treatment plant.

Organophosphate flame retardants (OPFRs) in both of water and sludge phase of influent and effluent of the STP were investigated in Beijing of China in five seasons. Total OPFRs concentrations in water phase of influent in five seasons were between 600 and 838 ng/L, where total OPFRs concentration was the lowest in summer of 2018. In water phase of influent and effluent, two chlorinated OPFRs (TCEP and TCPP) were major. Alkyl OPFRs decreased the most in water phase from influent to effluent. In sludge phase, the OPFRs amounts in winter were the lowest. The main OPFRs in sludge phase were TEHP and EHDP, which can be explained by the two OPFRs properties (log Kow and log Koc). Higher the values of the log Kow and log Koc of OPFRs, more amounts in sludge phase. The mass flow of OPFRs in influent were analysed by Principal Component Analysis (PCA), indicating that the influent amounts of TCEP, TDCP, TCPP and DCP were main OPFRs in four seasons to influence the characteristics of influent. Compared to OPFRs reduction in some STPs in other countries, alkyl and aryl OPFRs reduction rates were higher than chlorinated OPFRs. TBEP, TEHP and TPHP can always be effectively removed in different seasons and different STPs. The analysis methods of Pearson correlation and linear correlation were processed to check the possible factors affecting OPFRs reduction in STP. OPFRs reduction was related to some STP working parameters. Significant correlation also was found between OPFRs properties and reduction.

A mini-review of heavy metal recycling technologies for municipal solid waste incineration fly ash.

This mini-review article summarizes the available technologies for the recycling of heavy metals (HMs) in municipal solid waste incineration (MSWI) fly ash (FA). Recovery technologies included thermal separation (TS), chemical extraction (CE), bioleaching, and electrochemical processes. The reaction conditions of various methods, the efficiency of recovering HMs from MSWI FA and the difficulties and solutions in the process of technical development were studied. Evaluation of each process has also been done to determine the best HM recycling method and future challenges. Results showed that while bioleaching had minimal environmental impact, the process was time-consuming. TS and CE were the most mature technologies, but the former process was not cost-effective. Overall, it has the greatest economic potential to recover metals by CE with scrubber liquid produced by a wet air pollution control system. An electrochemical process or solvent extraction could then be applied to recover HMs from the enriched leachate. Ongoing development of TS and bioleaching technologies could reduce the treatment cost or time.

The influence of an upgrade on the reduction of organophosphate flame retardants in a wastewater treatment plant.

The appearance of an increased amount of organophosphate flame retardant (OPFRs) in natural water is related the treated effluents from wastewater treatment plants (WWTPs) and thus understanding the OPFRs concentration and reduction variation in WWTPs would provide valuable insight into OPFR management and reduction. In this study, we have analyzed OPFRs (10 kinds: tris(chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), tris(1,3-dichloropropyl) phosphate (TDCP), tris(phenyl) phosphate (TPhP), tris(2-ethylhexyl) phosphate (TEHP), diphenylcresylphosphate (DCP), tris(methylphenyl) phosphate (TCP), tris(2-butoxyethyl) phosphate (TBEP), 2-ethylhexyl diphenyl phosphate (EHDP), and tris(butyl) phosphate (TBP)) in both water and sludge samples collected from different phases of a WWTP upgrading. The results show that TCPP and TCEP were mainly present in the aqueous phase, whereas TEHP dominated in the solid phase. The overall OPFR reduction efficiencies were above 40% through whole treatment processes by all the phases. More OPFRs reduction efficiency in primary sedimentation tanks was higher mainly because of bigger tank volume. The anaerobic zone in all cases could decrease OPFRs by over 13%. The removal of OPFRs in the oxic zone highly varied under the influence of the aeration pipe, water temperature, and aeration amount. Compared with chlorinated OPFRs, aryl and alkyl OPFRs were easier to reduce and less affected by the upgrading. Because OPFRs have been widely used in plastic materials such as pipes, WWTP upgrading - which usually requires more aeration and addition of reagents and instruments and the aim of which is normally to reduce more COD, N and P -- has introduced more OPFRs into the water within the WWTP.

Heavy metal behavior in "Washing-Calcination-Changing with Bottom Ash" system for recycling of four types of fly ashes.

The Washing-Calcination-Changing with Bottom Ash (WCCB) system, effective at reducing chloride, was proposed to treat fly ash (FA) from a municipal solid waste incinerator (MSWI) before recycling FA in cement kiln as raw material. This study analyzed the behavior of heavy metals in four types of FA during WCCB treatment via Tessier and X-ray absorption fine structure (XANES) method. One FA was from the bag filter of a typical MSWI in Beijing, China (CFA), and the other three were from Japan (RFA, CaFA, and NaFA). All the metals were reduced especially Pb, Cd, and Hg (38.4-82.4%, 21.8-34.7%, and 100%, respectively). Besides Cr almost all heavy metals were stabilized according to Tessier analysis. Cr should be given more attention in WCCB as the formation of exchangeable Cr in the final residue. XANES result indicated that PbCl2 could be the main species of Pb in FA, while CaFA contains some PbO. The treated FAs contain PbCO3 and PbO besides PbCl2. The Tessier results of Ni, Pb, Cd, Cr, and Cu showed that NaFA was better at heavy metal stabilization than the other FA, so NaHCO3 is a more suitable neutralizer in WCCB.

Lipid profiling in sewage sludge.

High value-added reutilization of sewage sludge from wastewater treatment plants (WWTPs) is essential in sustainable development in WWTPs. However, despite the advantage of high value reutilization, this process must be based on a detailed study of organics in sludge. We used the methods employed in life sciences to determine the profile of lipids (cellular lipids, free fatty acids (FFAs), and wax/gum) in five sludge samples obtained from three typical WWTPs in Beijing; these samples include one sludge sample from a primary sedimentation tank, two activated sludge samples from two Anaerobic-Anoxic-Oxic (A2/O) tanks, and two activated sludge samples from two membrane bioreactor tanks. The percentage of total raw lipids varied from 2.90% to 12.3%. Sludge from the primary sedimentation tank showed the highest concentrations of lipid, FFA, and wax/gum and the second highest concentration of cellular lipids. All activated sludge contained an abundance of cellular lipids (>54%). Cells in sludge can from plants, animals, microbes and so on in wastewater. Approximately 14 species of cellular lipids were identified, including considerable high value-potential ceramide (9567-38774 mg/kg), coenzyme (937-3897 mg/kg), and some phosphatidylcholine (75-548 mg/kg). The presence of those lipid constituents would thus require a wider range of recovery methods for sludge. Both cellular lipids and FFAs contain an abundance of C16-C18 lipids at high saturation level, and they serve as good resources for biodiesel production.

Comparison of biodiesel production from sewage sludge obtained from the A²/O and MBR processes by in situ transesterification.

The potential of two types of sludge obtained from the anaerobic-anoxic-oxic (A(2)/O) and membrane bioreactor (MBR) processes as lipid feedstock for biodiesel production via in situ transesterification was investigated. Experiments were conducted to determine the optimum conditions for biodiesel yield using three-factor and four-level orthogonal and single-factor tests. Several factors, namely, methanol-to-sludge mass ratio, acid concentration, and temperature, were examined. The optimum yield of biodiesel (16.6% with a fatty acid methyl ester purity of 96.7%) from A(2)/O sludge was obtained at a methanol-to-sludge mass ratio of 10:1, a temperature of 60°C, and a H2SO4 concentration of 5% (v/v). Meanwhile, the optimum yield of biodiesel (4.2% with a fatty acid methyl ester purity of 92.7%) from MBR sludge was obtained at a methanol-to-sludge mass ratio of 8:1, a temperature of 50°C, and a H2SO4 concentration of 5% (v/v). In this research, A(2)/O technology with a primary sedimentation tank is more favorable for obtaining energy from wastewater than MBR technology.

[Pretreatment technology for fly ash from MSWI and the corresponding study of chloride behavior].

The introduced pretreatment technology, WCCB (Washing + Calcination), was effective to reduce chlorides in fly ash by consuming relatively low energy for recycling fly ash as the raw material for cement industry. The washing conditions are: twice-washing, liquid/solid = 3, mixing speed = 150 r x min(-1), 1st mixing time = 5 min, and 2nd mixing time = 10 min. The original incinerator was used for the calcination process, 1 000 degrees C, 10% O2 and dwelling time of 1 hour were adopted. By adopting X-ray absorption near edge structure and X-ray diffraction, the behavior of chlorides was explained and NaCl, KCl and CaCl2 are the main form of chlorides existing in fly ash. The reagent used in the air pollution control system to neutralize the acid component in the discharged gas surely acted a very important role in the formation of chlorides. The insoluble chlorides in fly ash had a very similar structure as that of Friedel's salt, which was related with CaCl2.

Environmental and economic assessment of municipal sewage sludge management - a case study in Beijing, China.

A case study was conducted in Beijing to identify municipal sewage sludge (SS) management systems appropriate for a sound material-cycle society. The environmental and economic impacts of four realistic SS-handling scenarios were investigated: stabilization by thermal drying, increased inclusion of SS in cement manufacture, and using either dried or carbonized SS as substitute fuel for coal-fired power generation plants. The results showed that the current sludge management system had the lowest operating cost but higher greenhouse gas (GHG) emissions and a low recycling rate. The case with the use of carbonized SS reused in coal-fired power plants had higher energy consumption and almost the same GHG emissions as the current system. On the other hand, the case including more SS in cement manufacture had the same level of energy consumption with much lower GHG emissions. The case with the use of dried SS in coal-fired power plants also resulted in lower energy consumption and lower GHG emissions than at present. Furthermore, sensitivity analysis showed that drying SS with surplus heat from cement plants used less energy and emitted less GHG compared to the other two drying methods.

Optimization of soluble human interferon-γ production in Escherichia coli using SUMO fusion partner.

Interferon-γ (IFN-γ) is a broad-spectrum antiviral glycoprotein that produced by lymphatic T cells and natural killer cells those who had stimulated by antigen. Human IFN-γ (hIFN-γ) often used in clinical research and practice because of its bioactivity, for example, antivirus, antitumor, controlling cell apoptosis, and the strict selectivity. However, due to the difficulties of Escherichia coli expression system meet in protein folding, the hIFN-γ often existed as inclusion body. The production of soluble hIFN-γ can be developed to shorten the production cycle and decrease the cost. In this study, small ubiquitin-related modifier fusion technology was used to express and purify recombinant hIFN-γ. Expression induced by adding 50 mM arginine and 1 % (w/v) glycerol into the culture at 24 °C existed as a soluble form of 70 % in total protein. Finally, about 62 mg recombinant hIFN-γ was obtained from 1 L fermentation culture with no less than 96 % purity. Determined by cytopathic effect inhibition assay, the specific activity of the recombinant hIFN-γ achieved at 7.78 × 10(5) IU/mL.

The calcination process in a system for washing, calcinating, and converting treated municipal solid waste incinerator fly ash into raw material for the cement industry.

Calcination is the second step in a washing-calcination-conversion system in which treated municipal solid waste incinerator fly ash and bottom ash can be reused as raw material in the cement industry and can decompose or stabilize hazardous compounds, reduce residue amounts, and alter residue characteristics. In this research, only fly ash is discussed. Chloride reduction is important if treated fly ash is to be reused in cement; however, the relationship between washed fly ash properties and chloride reduction by calcination is not well understood. This study used washed residues of three types of fly ash-raw fly ash (RFA) from the boiler or economizer of an incineration system, fly ash collected in a bag filter injected with calcium hydroxide (Ca(OH)2) for acid removal (CaFA), and fly ash collected in a bag filter injected with sodium bicarbonate (NaHCO3) for acid removal (NaFA)-in calcination experiments with varying temperature (400-1100 degrees C) and atmosphere (100% nitrogen [N2] at 25 mL/min or 10% oxygen [O2] [90% N2] at fluxes of 25, 50, and 75 mL/min). From the perspective of chloride reduction, heating to 1000 degrees C with 1-hr heating time, 1-hr holding time, and an atmosphere of 10% O2/90% N2 was most suitable for calcination. Under these conditions, chloride levels were reduced by 91, 52, and 96% in washed residues of RFA, CaFA, and NaFA, respectively. Among the washed residues, the weight of the washed residue of NaFA decreased the most.

Expression and purification of antimicrobial peptide buforin IIb in Escherichia coli.

A novel production method in Escherichia coli for an antimicrobial peptide of 21 amino acids, buforin IIb, which is a synthetic analog of buforin II, has been developed. The buforin IIb gene was cloned into the vector pET32a to construct an expression vector pET32a-buforin IIb. The fusion protein Trx-buforin IIb, purified by nickel nitrilo-triacetic acid (Ni-NTA) resin chromatography, was cleaved by hydroxylamine hydrochloride to release recombinant buforin IIb. Purification of recombinant buforin IIb was achieved by HPLC: about 3.1 mg/l active recombinant buforin IIb with purity >99% was obtained. The recombinant buforin IIb showed antimicrobial activities that were similar to the synthetic one.

Arctigenin enhances chemosensitivity of cancer cells to cisplatin through inhibition of the STAT3 signaling pathway.

Arctigenin is a dibenzylbutyrolactone lignan isolated from Bardanae fructus, Arctium lappa L, Saussureamedusa, Torreya nucifera, and Ipomea cairica. It has been reported to exhibit anti-inflammatory activities, which is mainly mediated through its inhibitory effect on nuclear transcription factor-kappaB (NF-κB). But the role of arctigenin in JAK-STAT3 signaling pathways is still unclear. In present study, we investigated the effect of arctigenin on signal transducer and activator of transcription 3 (STAT3) pathway and evaluated whether suppression of STAT3 activity by arctigenin could sensitize cancer cells to a chemotherapeutic drug cisplatin. Our results show that arctigenin significantly suppressed both constitutively activated and IL-6-induced STAT3 phosphorylation and subsequent nuclear translocation in cancer cells. Inhibition of STAT3 tyrosine phosphorylation was found to be achieved through suppression of Src, JAK1, and JAK2, while suppression of STAT3 serine phosphorylation was mediated by inhibition of ERK activation. Pervanadate reversed the arctigenin-induced downregulation of STAT3 activation, suggesting the involvement of a protein tyrosine phosphatase. Indeed, arctigenin can obviously induce the expression of the PTP SHP-2. Furthermore, the constitutive activation level of STAT3 was found to be correlated to the resistance of cancer cells to cisplatin-induced apoptosis. Arctigenin dramatically promoted cisplatin-induced cell death in cancer cells, indicating that arctigenin enhanced the sensitivity of cancer cells to cisplatin mainly via STAT3 suppression. These observations suggest a novel anticancer function of arctigenin and a potential therapeutic strategy of using arctigenin in combination with chemotherapeutic agents for cancer treatment.

Changes in quality of life during biofeedback for people with puborectalis dyssynergia: generic and disease-specific measures.

AIM: The aim of the study was to evaluate the changes in symptoms and quality of life in people with puborectalis dyssynergia after biofeedback by using Short Form-36 and Patient Assessment of Constipation Quality of Life Questionnaire. BACKGROUND: Biofeedback is an effective treatment in clinical symptoms for puborectalis dyssynergia. However, little is known about the degree of the variation in the quality of life for these people after biofeedback. METHOD: Thirty-six people with puborectalis dyssynergia were studied between June 2006 and March 2008. A bowel symptom record, a generic quality of life measure - the Short Form-36 and a disease-specific measure - the Patient Assessment of Constipation Quality of Life Questionnaire were recorded before and after biofeedback. FINDINGS: Thirty-one people rated their satisfaction with behavioural treatment as 'major' or 'fair' and substantial symptom improvements occurred. Before treatment, seven of Short Form-36 subscales (except bodily pain) were significantly lower in people with puborectalis dyssynergia than those in healthy individuals. Following treatment, all subcategories except general health showed improvement surpassing pretreatment baseline values and equalling those for normal. The total Patient Assessment of Constipation Quality of Life Questionnaire score also dramatically improved as did all subscales. The nurses continually encouraged the participants, increased participants' motivation and got good outcomes. CONCLUSION: Patient-centred functional status outcomes measured by general and disease-specific instruments give critical data, from which to inform patient management. The nurses should give psycho-social support and increase the participants' motivation during training.

Production of bioactive γ-glutamyl transpeptidase in Escherichia coli using SUMO fusion partner and application of the recombinant enzyme to L-theanine synthesis.

The amino acid L-theanine (γ-glutamylethylamide) has potential important applications in the food and pharmaceutical industries and increased demand for this compound is expected. It is the major "umami" (good taste) component of tea and its favorable physiological effects on mammals have been reported. An enzymatic method for the synthesis of L-theanine involving recombinant Escherichia coli γ-glutamyltranspeptidase (GGT) has been developed. We report here the application of small ubiquitin-related modifier (SUMO) fusion technology to the expression and purification of recombinant Escherichia coli γ-GGT. In order to obtain γ-GGT with high theanine-forming activity, safety, and low cost for food and pharmaceutics industry, M9 (consisting of glycerol and inorganic salts) and 0.1% (w/v) lactose were selected as culture medium and inducer, respectively. The fusion protein was expressed in soluble form in E. coli, and expression was verified by SDS-PAGE and western blot analysis. The fusion protein was purified to 90% purity by nickel-nitrilotriacetic acid (Ni-NTA) resin chromatography with a yield of 115 mg per liter fermentation culture. After the SUMO/γ-GGT fusion protein was cleaved by the SUMO protease, the cleaved sample was reapplied to a Ni-NTA column. Finally, about 62 mg recombinant γ-GGT was obtained from 1 l fermentation culture with no less than 95% purity. The recombinant γ-GGT showed great transpeptidase activity, with 1500 U of purified recombinant γ-GGT in a 1-l reaction system, a biosynthesis yield of 41 g of L-theanine was detected by paper chromatography or high pressure liquid chromatography (HPLC). Thus, the application of SUMO technology to the expression and purification of γ-GGT potentially could be employed for the industrial production of L-theanine.