Biosynthesis of Natural Rubber: Current State and Perspectives.

Natural rubber is a kind of indispensable biopolymers with great use and strategic importance in human society. However, its production relies almost exclusively on rubber-producing plants Hevea brasiliensis, which have high requirements for growth conditions, and the mechanism of natural rubber biosynthesis remains largely unknown. In the past two decades, details of the rubber chain polymerization and proteins involved in natural rubber biosynthesis have been investigated intensively. Meanwhile, omics and other advanced biotechnologies bring new insight into rubber production and development of new rubber-producing plants. This review summarizes the achievements of the past two decades in understanding the biosynthesis of natural rubber, especially the massive information obtained from the omics analyses. Possibilities of natural rubber biosynthesis in vitro or in genetically engineered microorganisms are also discussed.

Enhancing thermal conductivity and chemical protection of bacterial cellulose/silver nanowires thin-film for high flexible electronic skin.

Silver nanowires (AgNWs) thin films have emerged as a promising next-generation flexible electronic device. However, the current AgNWs thin films are often plagued by high AgNWs-AgNWs contact resistance and poor long-term stability. Here, to enhance the AgNWs stability on the surface of bacterial cellulose (BC), a novel flexible high conductivity thin-film was prepared by spin-coating a layer of polyvinyl alcohol (PVA) on the BC/AgNWs (BA) film. Firstly, BC film with high uniformity to better fit the AgNWs was obtained. It is observed that inadequately protected AgNWs can be corroded when AgNWs together with PVA were attached to the BC surface (BAP film), Yet, a layer of PVA was spin-coated on the surface of BA film, the BC/AgNWs/spin-coated 0.5 % PVA (BASP) thin-film (10.1 µm) exhibits that the PVA interfacial protective layer effectively mitigated the intrinsic incompatibility of BC with AgNWs as well as external corrosion (Na2S for 3 h) and immobilization of AgNWs, thus having a low conductive sheet resistance of 0.42 Ω/sq., which was better than most of the AgNWs-containing conductive materials reported so far. In addition, the resistance of the BASP thin-film changed little after 10,000 bending cycles, and the conductivity remained stable over BC directly immersed in 0.5 % PVA/AgNWs. This "soft" conductive material can be used to manufacture a new generation of electronic skin.

In Situ Fermentation of an Ultra-Strong, Microplastic-Free, and Biodegradable Multilayer Bacterial Cellulose Film for Food Packaging.

Cellulose-based food packaging has a significant importance in reducing plastic pollution and also ensuring our safety from microplastics. Nonetheless, lignocellulose necessitates sophisticated physical and chemical treatments to be fashioned into a satisfactory food packaging, thus leading to extra consumption and operations. Here, we present a gel-assisted biosynthesis approach for the in situ production of bacterial cellulose (BC) that can be directly applied to food packaging. Komagataeibacter sucrofermentans is homogeneously distributed in the gellan gum (GG)-assisted culture system, and the BC/GG film with an even surface is attained. Then, the BC/GG film is integrated with an antibacterial layer containing a quaternary ammonium chitosan microsphere (QM) through an in situ spray biosynthesis method. The resulting BC/GG/QM multilayer film combines the barrier properties and antibacterial activity. The method for in situ biosynthesis is green, efficient, and convenient to endow the multilayer film with excellent barrier capacity (1.76 g·mm·m-2·d-1·KPa-1 at RH 75%), high mechanical properties (strength 462 MPa), and antibacterial activity (>90% against Escherichia coli O157:H7 and Staphylococcus aureus). In terms of food preservation, the overall performance of the BC/GG/QM multilayer film is better than the commercial petroleum-based film and lignocellulose-derived film. This work proffers a novel strategy to produce a more beneficial and eco-friendly multilayer film via in situ biosynthesis, which manifests great utility in the field of food packaging.

Purified PEGylated porcine glucagon-like peptide-2 reduces the severity of colonic injury in a murine model of experimental colitis.

The rapid degradation of porcine glucagon-like peptide-2 (pGLP-2) by the enzyme dipeptidyl peptidase-IV (DPP-IV) is the main impediment in the development of pGLP-2 as a potential therapeutic agent for intestinal dysfunction and damage. In this study, one mono-modified Lys(30)-polyethylene glycol (PEG)-pGLP-2 was prepared using mPEG-succinimidyl propionate. To determine the optimized condition for PEGylation, the reactions were monitored by RP-HPLC and MALDI-TOF-MS. Stability was tested in purified DPP-IV in vitro. In vivo, the protective effects for colonic injury were measured in dextran sulfate sodium (DSS)-induced colitis in mice. The monoPEGylated products reached the maximum yield at 4:1 ratio of mPEG5k-SPA to pGLP-2. An effective method of successfully separating PEGylated pGLP-2 from mPEG-SPA5kD using CM Sepharose Fast Flow resin was established. The half-life of Lys(30)-PEG-pGLP-2 was 16-fold longer than that of pGLP-2 in DPP-IV. The DSS mice exhibited marked weight loss), which was significantly reduced by Lys(30)-PEG-pGLP-2 therapy. DSS treatment significantly increased colonic damage score, which was significantly reduced by administration of Lys(30)-PEG-pGLP-2 in DSS-mice. DSS-induced colitis clearly induced Myeloperoxidase activity in the colon, which was significantly reduced by treatments with 3% DSS-pGLP-2 or 3% DSS-PEG-pGLP-2. These results showed that site-specific Lys(30)-PEG-GLP-2 was resistant to degradation and reduced the severity of colonic injury in murine colitis. The enhanced biological potency of this product highlighted its potential as a therapeutic agent for intestinal diseases.