3 research outputs found
Rapid proteolysis of puromycyl peptides in non‐thalassaemic and thalassaemic erythroid cells
No full textGreening textile industry in Vietnam
No full text The textile and garment industry has made a remarkable contribution to the economic development of Vietnam and employs currently a large labor force of 2.5 million people.However, the textile industry is also seen as a most polluting and unsustainable industry due to the use of excessive amounts of materials and the release of large amounts of pollutants into the environment. In order to improve the environmental sustainability and effectiveness of the textile industry in Vietnam this study has looked into preventive measure, reuse/recycling options and improved end-of-pipe technologies, separately and in combination. The end-of-pipe treatment is the last step in the greening production model. Textile wastewater is very difficult to treat, especially regarding the high color intensity. Removal of color from textile wastewater was studied by varying the pH, the application of a biological treatment step, the application of coagulation/flocculation and of Advanced Oxidation Processes (O3, O3/H2O2, Fenton’s reagent). The coagulation process was very effective in color removal of insoluble dyestuffs (98%), but this process is not so suitable for wastewater containing only soluble dyestuffs (12-55%). Of the Advanced Oxidation Processes, the Fenton’s reagent process was the most effective method for color removal (81-98%)for the four types of wastewater tested. The decolorization with the ozone process at low pH (pH 5)showed that direct oxidation by molecular ozone is much more selective in color removal than the oxidation by hydroxyl radicals. The presence of colloidal particles caused a 12-fold increase for ozone needed to obtain the same color removal efficiency as for a wastewater without colloidal particles.Each of the investigated processes could only remove one or a few types of pollutants from the wastewater, with the consequence that effluents could not meet all the discharge regulations. The combination of an activated sludge process, and a coagulation and ozone process yielded the best color (45 Pt-Co) and COD (30 mg O2/L) removal at the lowest costs (0.3 €/m3), compared with all other tested combinations. Separate collection of wastewater streams in a factory can also strongly contribute to the efficiency and sustainability of wastewater treatment. In the wet processes of the textile industry 75% of the total water consumption is for rinsing purposes. Wastewater from most rinsing steps contains low amounts of pollutants and can be reused in other process stages or can be discharged without treatment. An industrial ecology zone model, integrating preventive cleaner production approaches, a waste exchange network for reuse and recycling, and new end-of-pipe technologies, has been developed and assessed in two case studies: the Thanh Cong Company and the Nhon Trach 2 Industrial Zone. The greening production model developed for the Thanh Cong Company, a large-scale textile company in Hochiminh city, included the combination of cleaner production, external waste exchange and end-of-pipe technology. The dyestuffs, auxiliary chemicals, water and energy consumption can be reduced significantly when the proposed cleaner production, the external waste exchange options and the improved end-of-pipe technologies are implemented. Total benefits in savings per day can be more than 1,000 US$. The industrial ecology zone model was designed in three steps. Firstly the greening production model developed for the Thanh Cong Company was applied to all textile enterprises in the industrial ecology zone that was considered. Secondly an outside waste exchange network was designed. The outside network includes reuse of waste plastics, waste paper and waste oil at recycling companies in the neighborhood. The last step is to treat solid waste and polluted air and to treat and reuse wastewater for irrigation (cotton cultivation), for use in sanitary systems and to water plants in the industrial zone. The case studies of the greening production model and of the industrial ecology zone model demonstrated that a successful industrial ecology practice not only depends on the interaction between enterprises inside but also on the interaction with the actor networks outside the industrial system:the economic networks, the social networks and the policy networks. These networks can contribute in different ways to the implementation of the models. In the case study of a large textile company the economic network is very important in the implementation of the greening production model and in the case study of an industrial ecology zone the policy network play the most important role in the implementation of the industrial ecology model. </p
Recombinant expression of fungal oxidases for industrial application
No full textLaccases catalyse the oxidation of a range of organic substrates coupled to the
reduction of molecular oxygen to water. They are members of the ubiquitous blue multi-copper oxidase family. These enzymes are implicated in a wide variety of biological activities. Most of the laccases studied thus far are of fungal origin. Large variety of potential substrates has raised interest in the use of laccases in several industrial applications, such as pulp delignification, textile dye bleaching, effluent detoxification, biopolymer modification and bioremediation. Cloning of the laccase genes followed by heterologous expression may provide higher enzyme yields and may permit to produce laccases with desired properties (different substrate specificities and improved stabilities) for industrial applications.
Heterologous expression of Pleurotus ostreatus laccases POXC and POXA1b in two yeasts and a first approach of directed evolution experiments are reported. The yeasts of choice were Saccharomyces cerevisiae, proven to be success-full in recombinant laccase expression and directed-evolution experiments, and Kluyveromyces lactis, a non-conventional yeast offering significant advantages, such as high-level secretion of non-hyperglycosylated recombinant proteins. Expression vectors were set up cloning the cDNAs under the control of different promoters. Furthermore, the laccase leader peptides (poxc and poxa1b), as well as the yeast derived signal peptides (S. cerevisiae invertase and K. lactis killer toxin), were alternatively used to direct the secretion of active laccase into the culture medium. The laccase signals proved to be more effective to drive the secretion of recombinant proteins in both hosts.
Levels of laccase secreted activity were markedly different: rPOXA1b transformants always gave much higher activity than rPOXC transformants, and production of both laccases in S. cerevisiae was significantly lower than that in K. lactis.
Recombinant laccases from K. lactis were purified to electrophoretic homogeneity and characterized. rPOXA1b specific activity was similar to that of the native protein, whilst rPOXC specific activity was much lower than that of the native POXC. Mass spectrometry analyses of the recombinant proteins allowed to verify their primary structures and to identify post-translational modifications. Our data confirm that K. lactis has a lower tendency, respect to S. cerevisiae, to hyperglycosylate recombinant proteins. The S. cerevisiae laccase expression systems were further used to set off directed evolution experiments. Mutated cDNAs libraries with different mutation rate were created, and homologous recombination experiments were performed, giving rise to libraries of mutated laccase secreting yeasts. Moreover a screening procedure to isolate clones exhibiting desired property was realized.
As a result, this work allowed obtaining the heterologous expression of two P. ostreatus laccases in yeasts, and their purification and characterisation. Moreover, this research work broadened the potentiality of the developed expression system addressing enzymes to such large markets and different industrial application such as pulp and textile bleaching, and enzymatic remediation of waste streams. A new laccase host (K. lactis) has been built on, and its promising performances will lead to further investigate its utilization for further structure-activities studies, as well as for directed evolution. Results obtained demonstrate the potential of the recombinant expression for the study of potential industrial interest
