Microbial polyester inclusions have previously been demonstrated to be applicable as versatile beads outside the bacterial
cell. Engineering of proteins selectively binding to the polyester inclusions was conceived to produce polyester beads simultaneously
displaying two protein-based functions suitable for applications in, for example, fluorescence activated cell sorting (FACS).
The polyester synthase and the phasin protein were fused to the green fluorescent protein (GFP) and the murine myelin oligodendrocyte
glycoprotein (MOG), respectively, or GFP and MOG were fused to the N- and C-terminus, respectively, of only the phasin. In both cases, fusion proteins were found to be attached to isolated polyester
inclusions while displaying both functionalities per bead. Functionalities at the bead surface were assessed by ELISA, FACS
and fluorescence microscopy. The respective double fusion protein was identified by peptide fingerprinting using MALDI-TOF/MS.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Carotenoids are important natural pigments produced by many microorganisms and plants. Traditionally, carotenoids have been used in the feed, food and nutraceutical industries. The recent discoveries of health-related beneficial properties attributed to carotenoids have spurred great interest in the production of structurally diverse carotenoids for pharmaceutical applications. The availability of a considerable number of microbial and plant carotenoid genes that can be functionally expressed in heterologous hosts has opened ways for the production of diverse carotenoid compounds in heterologous systems. In this review, we will describe the recent progress made in metabolic engineering of non-carotenogenic microorganisms for improved carotenoid productivity. In addition, we will discuss the application of combinatorial and evolutionary strategies to carotenoid pathway engineering to broaden the diversity of carotenoid structures synthesized in recombinant hosts. 相似文献
The branched chain amino acid l-valine is an essential nutrient for higher organisms, such as animals and humans. Besides the pharmaceutical application in parenteral nutrition and as synthon for the chemical synthesis of e.g. herbicides or anti-viral drugs, l-valine is now emerging into the feed market, and significant increase of sales and world production is expected. In accordance, well-known microbial production bacteria, such as Escherichia coli and Corynebacterium glutamicum strains, have recently been metabolically engineered for efficient l-valine production under aerobic or anaerobic conditions, and the respective cultivation and production conditions have been optimized. This review summarizes the state of the art in l-valine biosynthesis and its regulation in E. coli and C. glutamicum with respect to optimal metabolic network for microbial l-valine production, genetic strain engineering and bioprocess development for l-valine production, and finally, it will shed light on emerging technologies that have the potential to accelerate strain and bioprocess engineering in the near future. 相似文献
Over the last years, several methods for the phenotype simulation of microorganisms, under specified genetic and environmental conditions have been proposed, in the context of Metabolic Engineering (ME). These methods provided insight on the functioning of microbial metabolism and played a key role in the design of genetic modifications that can lead to strains of industrial interest. On the other hand, in the context of Systems Biology research, biological network visualization has reinforced its role as a core tool in understanding biological processes. However, it has been scarcely used to foster ME related methods, in spite of the acknowledged potential.
Results
In this work, an open-source software that aims to fill the gap between ME and metabolic network visualization is proposed, in the form of a plugin to the OptFlux ME platform. The framework is based on an abstract layer, where the network is represented as a bipartite graph containing minimal information about the underlying entities and their desired relative placement. The framework provides input/output support for networks specified in standard formats, such as XGMML, SBGN or SBML, providing a connection to genome-scale metabolic models. An user-interface makes it possible to edit, manipulate and query nodes in the network, providing tools to visualize diverse effects, including visual filters and aspect changing (e.g. colors, shapes and sizes). These tools are particularly interesting for ME, since they allow overlaying phenotype simulation results or elementary flux modes over the networks.
Conclusions
The framework and its source code are freely available, together with documentation and other resources, being illustrated with well documented case studies.
Electronic supplementary material
The online version of this article (doi:10.1186/s12859-014-0420-0) contains supplementary material, which is available to authorized users. 相似文献
Isoflavonoids are a diverse group of secondary metabolites derived from the phenylpropanoid pathway. These compounds are distributed
predominantly in leguminous plants and play important roles in plant–environment interactions and human health. Consequently,
the biosynthetic pathway of isoflavonoid compounds has been widely elucidated in the past decades. Up to now, most of the
structural genes and some of the regulatory genes involved in this pathway have been isolated and well characterized. Nowadays,
the protective effects of the legume isoflavonoids against hormone dependent cancers, cardiovascular disease, osteoporosis,
and menopausal symptoms have generated considerable interest within the genetic and metabolic engineering fields to enhance
the dietary intake of these compounds for disease prevention. Subsequently, there are some great progresses in genetic and
metabolic engineering to improve their yields in leguminous and non-leguminous plants and/or microorganisms. Because of the
field of flavonoid biosynthesis has been reviewed fairly extensively in the past, this review concentrates on the more recent
development in the isoflavonoid branch of phenylpropanoid pathway, including gene isolation and characterization. In addition,
we describe the state-of-the-art research with respect to genetic and metabolic engineering of isoflavonoid biosynthesis. 相似文献
Advances in metabolic engineering have led to the synthesis of a wide variety of valuable chemicals in microorganisms. The key to commercializing these processes is the improvement of titer, productivity, yield, and robustness. Traditional approaches to enhancing production use the “push–pull-block” strategy that modulates enzyme expression under static control. However, strains are often optimized for specific laboratory set-up and are sensitive to environmental fluctuations. Exposure to sub-optimal growth conditions during large-scale fermentation often reduces their production capacity. Moreover, static control of engineered pathways may imbalance cofactors or cause the accumulation of toxic intermediates, which imposes burden on the host and results in decreased production. To overcome these problems, the last decade has witnessed the emergence of a new technology that uses synthetic regulation to control heterologous pathways dynamically, in ways akin to regulatory networks found in nature. Here, we review natural metabolic control strategies and recent developments in how they inspire the engineering of dynamically regulated pathways. We further discuss the challenges of designing and engineering dynamic control and highlight how model-based design can provide a powerful formalism to engineer dynamic control circuits, which together with the tools of synthetic biology, can work to enhance microbial production. 相似文献
Resveratrol, an interesting plant phenolic compound, is found in red wine but is not widely distributed in other common food sources. Health benefits of resveratrol include prevention of cardiovascular diseases and cancers, and--as discovered more recently--promotion of longevity in several animal systems. The pathway and enzymes for resveratrol biosynthesis are well characterized. Furthermore, metabolic engineering of this compound has been achieved in plants, microbes and animals. This review attempts to summarize current understanding of resveratrol pathway-engineering in various systems, to outline the challenges in commercial applications and to identify future opportunities for resveratrol bioengineering. 相似文献
Curdlan is a water-insoluble β-(1,3)-glucan produced by Agrobacterium species under nitrogen-limited condition. Its heat-induced gelling properties render curdlan to be very useful in the food
industry initially. Recent advances in the understanding of the role curdlan plays in both innate and adaptive immunity lead
to its growing applications in biomedicine. Our review focuses on the recent advances on curdlan biosynthesis and the improvements
of curdlan fermentation production both from our laboratory and many others as well as the latest advances on the new applications
of curdlan and its derivatives particularly in their immunological functions in biomedicine. 相似文献
Folates (vitamin B9) are essential micronutrients which function as cofactors in one-carbon transfer reactions involved in the synthesis of nucleotides and amino acids. Folate deficiency is associated with important diseases such as cancer, anemia, cardiovascular diseases, or neural tube defects. Epidemiological data show that folate deficiency is still highly prevalent in many populations. Hence, food fortification with synthetic folic acid (i.e., folic acid supplementation) has become mandatory in many developed countries. However, folate biofortification of staple crops and dairy products as well as folate bioproduction using metabolically engineered microorganisms are promising alternatives to folic acid supplementation. Here, we review the current strategies aimed at overproducing folates in microorganisms, in view to implement an economic feasible process for the biotechnological production of the vitamin.
Plant tetrapyrrole metabolism is located in two different organelles and distributes end products into the whole cell. A complex regulatory network is involved to prevent metabolic imbalance and inefficient allocation of intermediates as well as to correlate the metabolic activities with organelle development. This review presents new findings about the control of tetrapyrrole biosynthesis and addresses the question of which regulatory principles are involved in controlling the expression of the participating enzymes and the metabolic flow in the entire pathway. It is suggested that functional organelles are required for nuclear gene expression and that metabolic signals participate in a signalling cascade transferring information from plastids to the nucleus. Recent reports about plastid-localised control mechanisms for plant tetrapyrrole metabolism are summarised and compared with results obtained in experiments on nucleus-plastid communication. 相似文献
Polyols are sugar alcohols largely used as sweeteners and they are claimed to have several health-promoting effects (low-caloric,
low-glycemic, low-insulinemic, anticariogenic, and prebiotic). While at present chemical synthesis is the only strategy able
to assure the polyol market demand, the biotechnological production of polyols has been implemented in yeasts, fungi, and
bacteria. Lactic acid bacteria (LAB) are a group of microorganisms particularly suited for polyol production as they display
a fermentative metabolism associated with an important redox modulation and a limited biosynthetic capacity. In addition,
LAB participate in food fermentation processes, where in situ production of polyols during fermentation may be useful in the development of novel functional foods. Here, we review the
polyol production by LAB, focusing on metabolic engineering strategies aimed to redirect sugar fermentation pathways towards
the synthesis of biotechnologically important sugar alcohols such as sorbitol, mannitol, and xylitol. Furthermore, possible
approaches are presented for engineering new fermentation routes in LAB for production of arabitol, ribitol, and erythritol. 相似文献
Biofuel from renewable biomass is one of the answers to help solve the problems associated with limited fossil resources and climate change. Butanol has superior liquid-fuel characteristics, with similar properties to gasoline, and thus, has the potential to be used as a substitute for gasoline. Clostridia are recognized as a good butanol producers and are employed in the industrial-scale production of solvents. Due to the difficulty of performing genetic manipulations on clostridia, however, strain improvement has been rather slow. Furthermore, complex metabolic characteristics of acidogenesis followed by solventogenesis in this strain have hampered the development of engineered clostridia strains with highly efficient and selective butanol-production capabilities. In recent years, the butanol-producing characteristics in clostridia have been further characterized and alternative pathways discovered. More recently, systems-level metabolic engineering approaches were taken to develop superior strains. Herein, we review recent discoveries of metabolic pathways for butanol production and the metabolic engineering strategies being developed. 相似文献