Fed-batch Self-regulated Fermentation of Glucose to Co-produce Glycerol and 1,3-propanediol by Recombinant Escherichia coli

As important bio-chemicals, glycerol and 1,3-propanediol (1,3-PDO) have been widely used in numerous fields, e.g., polymers, cosmetics, foods, lubricants, medicines, and so on. Bio-based 1,3-PDO is generally produced from glycerol or glucose by natural or recombinant strains, during which organic acids are always co-produced. In this work, acetic acid was also co-produced when 1,3-PDO was obtained from glucose by a recombinant strain of E. coli MG1655. Usually, a base was added to adjust the fermentation pH, resulting in the accumulation of organic salts and difficulty in the next down streaming process. Herein, a novel strategy was developed to consume the produced acetic acid by cells self in fed-batch self-regulated fermentation. The recombinant E. coli cells produced 48.33 g/L glycerol and 61.27 g/L 1,3-PDO with a total mass yield of 45.6% and without any other byproducts at the end of 5 fed-batch fermentations. The initial buffer pH, glucose concentration, pulse feeding sugar amount, time for a single batch fermentation and reducing acid were investigated by a series of comparative experiments. This fed-batch self-regulated fermentation has potential for the co-production of 1,3-PDO and glycerol, and will highlight the subsequent modification of recombinant E. coli strain by synthetic biology.

Private Property and Public Commons: Narrowing the Gap

Private property and public commons each represent strongly felt concepts of society but in very different ways. While the protection of private property is at the heart of the capitalist system and deeply embedded in our laws, the protection of the public commons is a mere subset of government policies and often lacks firm regulations. Critically, natural commons such as air, water, biodiversity, and a habitable earth, are hardly protected at all. Environmental laws regulate use and protection of natural “resources” in a strict instrumental fashion, ignoring the intrinsic value of Nature and take Earth’s ecological systems for granted. This article traces the “hidden logic” of environmental law and explores some of the history of property and the commons in the European context. It then shows the fundamental importance of ecological integrity for all efforts towards sustainable societies. The overall thesis is that property and commons must be based on ecological sustainability as a fundamental norm of law.

Comprehensive Landscape of Matrix Metalloproteinases in the Pathogenesis of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, chronic interstitial lung disease with unknown etiology. Matrix metalloproteinases (MMPs) are involved in fibrotic lung tissues, contributing to the initiation, progression, or resolution of chronic inflammatory disease. In present study, comprehensive changes of MMPs expressions were investigated in IPF by integrative analysis of single-cell transcriptome and bulk transcriptome data. 24 of MMPs were altered and the changes could significantly distinguish IPF from normal subjects and other lung diseases. Among them, MMP1, MMP7 and MMP19 were closely associated to lung functions, susceptibility and alveolar surface density. MMP1 and MMP7 as potential diagnostic indicators, MMP1 and MMP19 as prognostic markers in IPF could accurately predict disease progression. Devolution of MMPs at single-cell resolution, MMP19 was highly expressed in macrophages and markedly interfered with TNF signaling pathway which synchronizes fibrotic microenvironment. MMP19+ macrophages were significantly different from MMP19- macrophages in energy metabolism and immune function. The interaction of MMP19+ macrophages with hyperplastic AT2 was mediated by TNFSF12-TNFRSF12A, and further activated the TNFRSF12A receptor to affect cell glucose metabolism and mitochondrial function. In summary, MMPs has great application potential in the diagnosis, treatment, and prognosis of IPF.

Roots of (and Solutions to) Our Ecological Crisis. A Humanistic Perspective

Research into the sources of contemporary ecological crisis as well as ways to overcome it has been conducted for several decades. Rich academic literature provides numerous attempts to identify the causes of the crisis and its solutions. The ecological crisis is extremely complex and variously conditioned. Therefore, I focus on determining only two sources of the crisis and, respectively, two solutions. Since the late 1960s, monotheistic religions, Christianity in particular, have been made responsible for the environmental crisis. Christianity is accused of forwarding two theses which are harmful to the environment: 1. The sole purpose of nature is to serve man. 2. By God’s will, man is endowed with unlimited power over nature. I attempt to overcome this understanding of the source of the crisis by showing the interpretation of the Bible which contradicts the above-mentioned theses. Moreover, I show “the ecological potential” of the Judeo-Christian and Muslim traditions. As the second source of the crisis I indicate modern thought: 1. Man’s alienation from nature as the result of the Cartesian division of reality into res cogitans and res extensa. 2. Francis Bacon’s program: the study of nature is the task of natural sciences alone; nature is devoid of value in itself. 3. The mathematization of nature made it possible for the natural and technical sciences to develop rapidly, which contributed to the industrial revolution. I look for an antidote to this cause of the crisis in Klaus M. Meyer-Abich’s idea of man’s peace with nature which he developed as part of the practical philosophy of nature. I believe that revealing our inseparable bond with nature and showing compassion towards nature may help overcome the destructive consequences of modern thought. 

Development of a New 1,2,4-butanetriol Biosynthesis Pathway in an Engineered Homoserine-producing Strain of Escherichia coli

1,2,4-butanetriol (BT) is a compound of high interest with applications in pharmaceutical and materials. In this work, we designed a novel biosynthetic pathway for BT from glucose via a nonessential amino acid homoserine. This non-natural pathway used an engineered phosphoserine transaminase (SerC_R42W/R77W) to achieve the deamination of homoserine to 4-hydroxy-2-oxobutanoic acid (HOBA). Three consecutive enzymes including a lactate dehydrogenase, a 4-hydroxybutyrate CoA-transferase and a bifunctional aldehyde/alcohol dehydrogenase are used to catalyze HOBA to BT. To enhance the carbon flux to homoserine, a homoserine-producing Escherichia coli was developed by improving the overexpression of two relevant key genes metL and lysC (V339A). The simultaneous overexpression of the genes encoding these enzymes for the homoserine-derived BT pathway enabled production of 19.6 mg/L BT from glucose in the homoserine-producing E. coli.

A High-efficiency Cathode Using Co₃O₄ and Carbon Paper by Electrodeposition for Rechargeable Lithium-oxygen Batteries

The conductivity, microstructure, low cost, eco-friendliness, simple and controllable preparation are key points of the preparation and application of cathode materials for lithium-oxygen batteries. Considering the above-mentioned important factors comprehensively, the Co₃O₄@CP electrode with a three-dimensional structure was prepared by directly growing Co₃O₄ on the surface of carbon paper (CP) using a simple and controllable electrodeposition method. The obtained Co₃O₄ depositing layer has a nanosheet microstructure and can provide abundant catalytic active sites for the oxygen evolution and reduction reactions. The network architecture of electronic transmission is constructed by CP in the cathode, promoting the efficiency of the electrode reaction. It’s worth noting that the binder-free and conductive additive-free cathode is beneficial to reduce side reactions. The lithium-oxygen battery assembled with the obtained Co₃O₄@CP electrode showed satisfactory electrochemical performance. The cell assembled with the obtained Co₃O₄@CP electrode provided a discharge specific capacity of 10954.7 mA·h·g⁻¹ at a current density of 200 mA·g⁻¹, and the voltage profiles of the cell were good under 100 mA·g⁻¹ at a limited capacity of 500 mA·h g⁻¹ based on the mass of Co₃O₄. Therefore, the Co₃O₄@CP composite material is a promising candidate with good application prospects as a cathode material for lithium-oxygen batteries.

Foreword to Resumption

Recent Progress in Modification and Preparations of the Promising Biodegradable Plastics: Polylactide and Poly(butylene adipate-co-terephthalate)

The acquisition of high-performance biodegradable plastics is of great significance in addressing the problem of environmental pollution of plastics. Polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are the most promising biodegradable polymers and have excellent functional properties. However, low elongation at break and impact strength of PLA and low tensile modulus and flexural strength of PBAT hinder their application. A large number of studies focus on improving the performance of PLA and PBAT and broadening their applications. In terms of polymer modification, this paper summarized recent progresses in both chemical and physical modification methods for PLA and PBAT, respectively. The properties of PLA can be improved by co-polymerization, grafting, cross-linking and blending. The properties of PBAT can be improved mainly through blending with other degradable polymers, natural macromolecules and inorganic materials. This review can provide the reference and ideas for the modification of biomass-based biodegradable plastics like PLA and fossil-based biodegradable plastics like PBAT.

Coiled Coils as Versatile Modules for Mammalian Cell Regulation

Synthetic biology is a rapidly growing field that allows us to better understand biological processes at the molecular level, and enables therapeutic interventions and biotechnological applications. One of the most powerful tools in synthetic biology is the small, customizable, and modular protein–protein interaction domains, which is used to regulate a wide variety of processes within mammalian cells. Here we review designed coiled coil dimers that represent a set of heterodimerization domains with many advantages. These dimers have been useful for directing the localization of selected proteins within cells, enhancing chemical or light-regulated transcription, creating fast proteolysis-based responsive systems and protein secretion, genome editing, and cell–cell interaction motifs. Additionally, we will discuss how these building blocks are used in diverse applications, such as CAR T cell regulation and genome editing. Finally, we will look at the potential for future advances in synthetic biology using these building modules.

Waterborne Polyurethane Dispersion Synthesized from CO₂ Based Poly (Ethylene Carbonate) Diol with High Performance

CO₂-based aliphatic polycarbonates (APCs) are not widely commercialized due to the poor performance and high cost, compared to the traditional synthetic materials. In this paper, poly(ethylene carbonate) diol (PECD) was synthesized from CO₂ and ethylene oxide (EO), and the comprehensive properties were characterized. Furthermore, the preparation and properties of waterborne polyurethane dispersion (WPU) derived from PECD were studied. The result showed that PECD had high reactivity, narrow molecular weight distribution index and excellent thermal stability. The obtained WPU exhibited superior tensile performance, adhesion properties and surface hardness. Due to the low cost of EO and CO₂, PECD is expected to be widely used in the preparation of polyurethanes.