Search

Designing efficient plastic-digesting microorganisms is necessary to accelerate the decomposition of biodegradable plastics leaking into outer environments. However, screening of microorganisms for hydrophobic plastics is labor-intensive and time-consuming. Herein, a high-throughput, straightforward micro-spray-based screening system is presented; the whole process only takes 1–5 days using a minimal amount of polymers. Bioplastic microparticles sprayed on an agar plate share a large interface with microorganisms, and therefore their discovery is readily recognizable. This method inspires finding new microorganisms that digest conventional plastics known as non-degradable plastics.

Current sustainable bioplastics need dramatic improvement to become competitive. Herein, we prepared poly(butylene succinate-co-carbonate) nanocomposites with citric acid and cellulose nanocrystals (CNCs). The dimethyl carbonate co-monomer lowers crystallinity and increases elongation; citric acid increases the strength, and the CNCs maximize mechanical performance. Accelerated biodegradation is also favorable for sustainable tough bags.

The control of viral outbreaks requires nucleic acid diagnostic tests that are sensitive, simple and fast. Here, we report a highly sensitive and specific one-pot assay for the fluorescence-based detection of RNA from pathogens. The assay, which can be performed within 30–50 min of incubation time and can reach a limit of detection of 0.1-attomolar RNA concentration, relies on a sustained isothermal reaction cascade producing an RNA aptamer that binds to a fluorogenic dye. The RNA aptamer is transcribed by the T7 RNA polymerase from the ligation product of a promoter DNA probe and a reporter DNA probe that hybridize with the target single-stranded RNA sequence via the SplintR ligase (a Chlorella virus DNA ligase). In 40 nasopharyngeal SARS-CoV-2 samples, the assay reached positive and negative predictive values of 95 and 100%, respectively. We also show that the assay can rapidly detect a range of viral and bacterial RNAs., A one-pot enzymatic assay for the fluorescence detection of RNA accurately and rapidly detects specific viral and bacterial pathogens, as shown for SARS-CoV-2 RNA in clinical samples.

Polyhydroxybutyrate (PHB) is a natural polyester synthesized by several microorganisms. Moreover, it has excellent biodegradability and is an eco-friendly material because it converts water and carbon dioxide as final decomposition products. However, the applications of PHB are limited because of its stiffness and brittleness. Because cellulose nanocrystals (CNCs) have excellent intrinsic mechanical properties such as high specific strength and modulus, they may compensate for the insufficient physical properties of PHB by producing their nanocomposites. In this study, natural polyesters were extracted from Cupriavidus necator fermentation with CNCs, which were well-dispersed in nitrogen-limited liquid culture media. Fourier-transform infrared spectroscopy results revealed that the additional O–H peak originating from cellulose at 3500–3200 cm−1 was observed for PHB along with the C=O and –COO bands at 1720 cm−1. This suggests that PHB–CNC nanocomposites could be readily obtained using C. necator fermented in well-dispersed CNC-supplemented culture media.

In article number 2003155, Jeyoung Park, Dongyeop X. Oh, Sung Yeon Hwang, and co‐workers report a biodegradable, moisture‐resistant, highly efficient, and breathable face mask filter based on easy‐to obtain poly(butylene succinate) coated with chitosan nanowhiskers. Integrated microfiber/nanofiber mats present a particulate matter removal efficiency as high as the commercial N95 filter due to a combination of physical sieving and electrostatic adsorption. [Image: see text]

Aluminum-coated polypropylene films are commonly used in food packaging because aluminum is a great gas barrier. However, recycling these films is not economically feasible. In addition, their end-of-life incineration generates harmful alumina-based particulate matter. In this study, coating layers with excellent gas-barrier properties are assembled on polypropylene films through layer-by-layer (LbL) deposition of biorenewable nanocellulose and nanochitin. The coating layers significantly reduce the transmission of oxygen and water vapors, two unfavorable gases for food packaging, through polypropylene films. The oxygen transmission rate of a 60 μm-thick, 20 LbL-coated polypropylene film decreases by approximately a hundredfold, from 1118 to 13.10 cc m−2 day−1 owing to the high crystallinity of nanocellulose and nanochitin. Its water vapor transmission rate slightly reduces from 2.43 to 2.13 g m−2 day−1. Furthermore, the coated film is highly transparent, unfavorable to bacterial adhesion and thermally recyclable, thus promising for advanced food packaging applications.

Biodegradable aliphatic polyesters need to be tough for commodity-plastic applications, such as disposable bags. Herein, we show that chitosan nanowhiskers (CsWs) prepared from naturally abundant chitin is an effective nanofiller that reinforces the strength and toughness of poly(butylene succinate) (PBS). In-situ polycondensation of an aqueous solution of processed CsWs led to a PBS nanocomposite with the highest tensile strength (77 MPa) and elongation at break (530%) reported to date for all PBS types at a minimal nanofiller content of 0.2 wt%. The observed 3.2-fold increase in toughness of the CsW/PBS composite compared to neat PBS is superior to those of composites prepared using cellulose nanocrystals, chitin nanowhiskers, and unstably dispersed CsWs in 1,4-butanediol monomer. Interestingly, CsWs efficiently overcome the disadvantages of the PBS film that easily tears. The highly polar surfaces of the CsWs strongly bind to polymer chains and promote a fibrillar and micro-void structure, thereby maximizing the chain-holding ability of the nanofiller, which resists external tensile and tear stress. This sustainable all-organic nanocomposite is a promising candidate for biodegradable disposable commodities.

The recent outbreaks of Ebola, Zika, MERS, and SARS-CoV-2 (2019-nCoV) require fast, simple, and sensitive onsite nucleic acid diagnostics that can be developed rapidly to prevent the spread of diseases. We have developed a SENsitive Splint-based one-step isothermal RNA detection (SENSR) method for rapid and straightforward onsite detection of pathogen RNAs with high sensitivity and specificity. SENSR consists of two simple enzymatic reactions: a ligation reaction by SplintR ligase and subsequent transcription by T7 RNA polymerase. The resulting transcript forms an RNA aptamer that induces fluorescence. Here, we demonstrate that SENSR is an effective and highly sensitive method for the detection of the current epidemic pathogen,severe acute respiratory syndrome-related coronavirus2 (SARS-CoV-2). We also show that the platform can be extended to the detection of five other pathogens. Overall, SENSR is a molecular diagnostic method that can be developed rapidly for onsite uses requiring high sensitivity, specificity, and short assaying times.

Recently (R)-selective ω-transaminase ((R)-ω-TAMV) from Mycobacterium vanbaalenii was discovered and utilized for the asymmetric synthesis of (R)-amines from its corresponding ketones. In this study, (R)-ω-TAMV was used for the kinetic resolution of racemic amines to produce (S)-amines. (R)-ω-TAMV showed very low product inhibition by ketone product (acetophenone), which is beneficial for carrying out the kinetic resolution of racemic amines with high concentration. 100 mM racemic amines were successfully resolved into (S)-amines (>99% ee) by (R)-ω-TAMV with pyruvate. In addition, the kinetic resolution of α-MBA was successfully carried out by using acetone as an amino acceptor which is cheaper than pyruvate.

Recently, ω-transaminases have been increasingly used to synthesize amine compounds by reductive amination of prochiral ketones which are of high pharmacological significance. However, the conventional methods for evaluating these enzymes are time consuming and have often been regarded as a bottle neck in developing these enzymes as industrial biocatalysts. In the past few years, several high throughput screening methods have been developed for fast evaluation and identification of ω-transaminase. This review summarizes the various methodologies developed for rapidly screening ω-transaminases.

A novel thermostable ω-transaminase from Thermomicrobium roseum which showed broad substrate specificity and high enantioselectivity was identified, expressed and biochemically characterized. The advantage of this enzyme to remove volatile inhibitory by-products was demonstrated by performing asymmetric synthesis and kinetic resolution at high temperature.

In this study, we successfully synthesized enantiomerically pure (R)- and (S)-γ-amino acids (>99% ee) using ω-transaminase (ω-TA) through kinetic resolution and asymmetric synthesis respectively. The present study demonstrates the high potentiality of ω-TA reaction for the production of chiral γ-amino acids.

In this study, we developed a one-pot one-step deracemization method for the production of various enantiomerically pure amines using two opposite enantioselective ω-TAs. Using this method, various aromatic amines were successfully converted to their (R)-forms (>99%) with good conversion.