Xin Meng

Bio: Xin Meng is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Chemistry & Medicine. The author has an hindex of 4, co-authored 4 publications receiving 1319 citations.

Biosynthetic pathways for 3-hydroxypropionic acid production

Abstract: Biobased platform chemicals have attracted growing interest recently. Among them, 3-hydroxypropionic acid receives significant attention due to its applications in the synthesis of novel polymer materials and other derivatives. To establish a biotechnology route instead of the problematic chemical synthesis of 3-hydroxypropionic acid, biosynthetic pathway is required, and the strategies of how to engineer a microbe to produce this product should be considered. In the present review, we summarize and review all known pathways, which could be potentially constructed for 3-hydroxypropionic acid production. Mass and redox balances are discussed in detail. Thermodynamic favorability is evaluated by standard Gibbs free energy. The assembly of pathways and possible solutions are proposed. Several new techniques and future research needs are also covered.

Production of extracellular fatty acid using engineered Escherichia coli.

Abstract: As an alternative for economic biodiesel production, the microbial production of extracellular fatty acid from renewable resources is receiving more concerns recently, since the separation of fatty acid from microorganism cells is normally involved in a series of energy-intensive steps Many attempts have been made to construct fatty acid producing strains by targeting genes in the fatty acid biosynthetic pathway, while few studies focused on the cultivation process and the mass transfer kinetics In this study, both strain improvements and cultivation process strategies were applied to increase extracellular fatty acid production by engineered Escherichia coli Our results showed overexpressing ‘TesA and the deletion of fadL in E coli BL21 (DE3) improved extracellular fatty acid production, while deletion of fadD didn’t strengthen the extracellular fatty acid production for an undetermined mechanism Moreover, the cultivation process controls contributed greatly to extracellular fatty acid production with respect to titer, cell growth and productivity by adjusting the temperature, adding ampicillin and employing on-line extraction Under optimal conditions, the E coli strain (pACY-‘tesA-ΔfadL) produced 48 g L−1 extracellular fatty acid, with the specific productivity of 002 g h−1 g−1dry cell mass, and the yield of 44% on glucose, while the ratios of cell-associated fatty acid versus extracellular fatty acid were kept below 05 after 15 h of cultivation The fatty acids included C12:1, C12:0, C14:1, C14:0, C16:1, C16:0, C18:1, C18:0 The composition was dominated by C14 and C16 saturated and unsaturated fatty acids Using the strain pACY-‘tesA, similar results appeared under the same culture conditions and the titer was also much higher than that ever reported previously, which suggested that the supposedly superior strain did not necessarily perform best for the efficient production of desired product The strain pACY-‘tesA could also be chosen as the original strain for the next genetic manipulations The general strategy of metabolic engineering for the extracellular fatty acid production should be the cyclic optimization between cultivation performance and strain improvements On the basis of our cultivation process optimization, strain improvements should be further carried out for the effective and cost-effective production process

Increasing fatty acid production in E. coli by simulating the lipid accumulation of oleaginous microorganisms

Abstract: Unlike many oleaginous microorganisms, E. coli only maintains a small amount of natural lipids in cells, impeding its utility to overproduce fatty acids. In this study, acetyl-CoA carboxylase (ACC) from Acinetobacter calcoaceticus was expressed in E. coli to redirect the carbon flux to the generation of malonyl-CoA, which resulted in a threefold increase in intracellular lipids. Moreover, providing a high level of NADPH by overexpressing malic enzyme and adding malate to the culture medium resulted in a fourfold increase in intracellular lipids (about 197.74 mg/g). Co-expression of ACC and malic enzyme resulted in 284.56 mg/g intracellular lipids, a 5.6-fold increase compared to the wild-type strain. This study provides some attractive strategies for increasing lipid production in E. coli by simulating the lipid accumulation of oleaginous microorganisms, which could aid the development of a prokaryotic fatty acid producer.

Discovery of Thieno[2,3-e]indazole Derivatives as Novel Oral Selective Estrogen Receptor Degraders with Highly Improved Antitumor Effect and Favorable Druggability.

Abstract: Endocrine therapies in the treatment of early and metastatic estrogen receptor α positive (ERα+) breast cancer (BC) are greatly limited by de novo and acquired resistance. Selective estrogen receptor degraders (SERDs) like fulvestrant provide new strategies for endocrine therapy combinations due to unique mechanisms. Herein, we disclose our structure-based optimization of LSZ102 by replacing 6-hydroxybenzothiophene with 6H-thieno[2,3-e]indazole. Subsequent acrylic acid degron modifications led us to identify compound 40 as the preferred candidate. In general, compound 40 showed much better pharmacological profiles than the lead LSZ102, exhibiting growth inhibition of wild-type or tamoxifen-resistant MCF-7 cells, potent ERα degradation, together with superior pharmacokinetic properties, directional target tissue distribution including the brain, and robust antitumor efficacy in the mice breast cancer xenograft model. Currently, 40 is being evaluated in preclinical trials.

Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products

Abstract: Sustainability is a key principle in natural resource management, and it involves operational efficiency, minimisation of environmental impact and socio-economic considerations; all of which are interdependent. It has become increasingly obvious that continued reliance on fossil fuel energy resources is unsustainable, owing to both depleting world reserves and the green house gas emissions associated with their use. Therefore, there are vigorous research initiatives aimed at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. However, alternate energy resources akin to first generation biofuels derived from terrestrial crops such as sugarcane, sugar beet, maize and rapeseed place an enormous strain on world food markets, contribute to water shortages and precipitate the destruction of the world's forests. Second generation biofuels derived from lignocellulosic agriculture and forest residues and from non-food crop feedstocks address some of the above problems; however there is concern over competing land use or required land use changes. Therefore, based on current knowledge and technology projections, third generation biofuels specifically derived from microalgae are considered to be a technically viable alternative energy resource that is devoid of the major drawbacks associated with first and second generation biofuels. Microalgae are photosynthetic microorganisms with simple growing requirements (light, sugars, CO 2 , N, P, and K) that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and valuable co-products. This study reviewed the technologies underpinning microalgae-to-biofuels systems, focusing on the biomass production, harvesting, conversion technologies, and the extraction of useful co-products. It also reviewed the synergistic coupling of microalgae propagation with carbon sequestration and wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation. It was found that, whereas there are outstanding issues related to photosynthetic efficiencies and biomass output, microalgae-derived biofuels could progressively substitute a significant proportion of the fossil fuels required to meet the growing energy demand.

Review of biodiesel composition, properties, and specifications

Abstract: Biodiesel is a renewable transportation fuel consisting of fatty acid methyl esters (FAME), generally produced by transesterification of vegetable oils and animal fats. In this review, the fatty acid (FA) profiles of 12 common biodiesel feedstocks were summarized. Considerable compositional variability exists across the range of feedstocks. For example, coconut, palm and tallow contain high amounts of saturated FA; while corn, rapeseed, safflower, soy, and sunflower are dominated by unsaturated FA. Much less information is available regarding the FA profiles of algal lipids that could serve as biodiesel feedstocks. However, some algal species contain considerably higher levels of poly-unsaturated FA than is typically found in vegetable oils. Differences in chemical and physical properties among biodiesel fuels can be explained largely by the fuels’ FA profiles. Two features that are especially influential are the size distribution and the degree of unsaturation within the FA structures. For the 12 biodiesel types reviewed here, it was shown that several fuel properties – including viscosity, specific gravity, cetane number, iodine value, and low temperature performance metrics – are highly correlated with the average unsaturation of the FAME profiles. Due to opposing effects of certain FAME structural features, it is not possible to define a single composition that is optimum with respect to all important fuel properties. However, to ensure satisfactory in-use performance with respect to low temperature operability and oxidative stability, biodiesel should contain relatively low concentrations of both long-chain saturated FAME and poly-unsaturated FAME.

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

Abstract: The demand for petroleum dependent chemicals and materials has been increasing despite the dwindling of their fossil resources. As the dead-end of petroleum based industry has started to appear, today's modern society has to implement alternative energy and valuable chemical resources immediately. Owing to the importance of lignocellulosic biomass being the most abundant and bio-renewable biomass on earth, this critical review provides insights into the potential of lignocellulosic biomass as an alternative platform to fossil resources. In this context, over 200 value-added compounds, which can be derived from lignocellulosic biomass by various treatment methods, are presented with their references. Lignocellulosic biomass based polymers and their commercial importance are also reported mainly in the frame of these compounds. This review article aims to draw the map of lignocellulosic biomass derived chemicals and their synthetic polymers, and to reveal the scope of this map in today's modern chemical and polymer industry.