Biosynthesis of chiral diols from alkenes using metabolically engineered type II methanotroph.

Methanotrophs are environmentally friendly microorganisms capable of converting gas to liquid using methane monooxygenases (MMOs). In addition to methane-to-methanol conversion, MMOs catalyze the conversion of alkanes to alcohols and alkenes to epoxides. Herein, the efficacy of epoxidation by type I and II methanotrophs was investigated, and type II methanotrophs were observed to be more efficient in converting alkenes to epoxides. Subsequently, three (Epoxide hydrolase) EHs of different origins were overexpressed in the type II methanotroph Methylosinus trichosporium OB3b to produce 1,2-diols from epoxide. Methylosinus trichosporium OB3b expressing Caulobacter crescentus EH produced the highest amount of (R)-1,2-propanediol (251.5 mg/L) from 1-propene. These results demonstrate the possibility of using methanotrophs as a microbial platform for diol production and the development of a continuous bioreactor for industrial applications.

Sustainable biosynthesis of chemicals from methane and glycerol via reconstruction of multi-carbon utilizing pathway in obligate methanotrophic bacteria.

Obligate methanotrophic bacteria can utilize methane, an inexpensive carbon feedstock, as a sole energy and carbon substrate, thus are considered as the only nature-provided biocatalyst for sustainable biomanufacturing of fuels and chemicals from methane. To address the limitation of native C1 metabolism of obligate type I methanotrophs, we proposed a novel platform strain that can utilize methane and multi-carbon substrates, such as glycerol, simultaneously to boost growth rates and chemical production in Methylotuvimicrobium alcaliphilum 20Z. To demonstrate the uses of this concept, we reconstructed a 2,3-butanediol biosynthetic pathway and achieved a fourfold higher titer of 2,3-butanediol production by co-utilizing methane and glycerol compared with that of methanotrophic growth. In addition, we reported the creation of a methanotrophic biocatalyst for one-step bioconversion of methane to methanol in which glycerol was used for cell growth, and methane was mainly used for methanol production. After the deletion of genes encoding methanol dehydrogenase (MDH), 11.6 mM methanol was obtained after 72 h using living cells in the absence of any chemical inhibitors of MDH and exogenous NADH source. A further improvement of this bioconversion was attained by using resting cells with a significantly increased titre of 76 mM methanol after 3.5 h with the supply of 40 mM formate. The work presented here provides a novel framework for a variety of approaches in methane-based biomanufacturing.

Suppressed photocatalytic activity of ZnO based Core@Shell and RCore@Shell nanostructure incorporated in the cellulose nanofiber.

The protection of skin cells against intense ultra-violet (UV) rays is of greater concern and needs immediate attention. Sustainable efforts and strategies are in progress to minimize the factors that adversely affect skin cells. Herein, we synthesized zinc oxide (ZnO) in the form of core-shell (Core@Shell) or reverse core-shell (RCore@Shell) structure where silica was synthesized as a shell or core, respectively on the surface of cellulose nanofiber (CNF). Both cases exhibited much higher UV-blocking performance as well as alleviate the whitening effect because these particles retain their nanoscale dimensions as favored by the cosmetic industry. Significantly, these nanostructures shows the less photocatalysis activity than that of pristine ZnO nanoparticles. And we found that the photocatalytic activity of ZnO in RCore@Shell/CNF was more suppressed that Core@Shell/CNF, showing that it is a proper structure to neutralize or scavenge free radicals prior to their exit from the particles. Our results suggest that, reduction in photocatalysis induced by Core@Shell/CNF and RCore@Shell/CNF nanostructures is a promising strategy for skincare products in cosmetic industry.

Discarded Egg Yolk as an Alternate Source of Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate).

Many poultry eggs are discarded worldwide because of infection (i.e., avian flu) or presence of high levels of pesticides. The possibility of adopting egg yolk as a source material to produce polyhydroxyalkanoate (PHA) biopolymer was examined in this study. Cupriavidus necator Re2133/pCB81 was used for the production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3HHx), a polymer that would normally require long-chain fatty acids as carbon feedstocks for the incorporation of 3HHx monomers. The optimal medium contained 5% egg yolk oil and ammonium nitrate as a nitrogen source, with a carbon/nitrogen (C/N) ratio of 20. Time course monitoring using the optimized medium was conducted for 5 days. Biomass production was 13.1 g/l, with 43.7% co-polymer content. Comparison with other studies using plant oils and the current study using egg yolk oil revealed similar polymer yields. Thus, discarded egg yolks could be a potential source of PHA.

Human umbilical cord blood-derived mesenchymal stem cell transplantation attenuates severe brain injury by permanent middle cerebral artery occlusion in newborn rats.

BACKGROUND: Severe brain injury induced by neonatal stroke causes significant mortality and disability, and effective therapies are currently lacking. We hypothesized that human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) can attenuate severe brain injury induced by permanent middle cerebral artery occlusion (MCAO) in rat pups. METHODS: After confirming severe brain injury involving more than 50% of the ipsilateral hemisphere volume at 1 h after MCAO using diffusion-weighted magnetic resonance imaging (MRI) in postnatal day (P)10 rats, human UCB-derived MSCs were transplanted intraventricularly. The brain MRI was evaluated periodically up to 28 d after MCAO (P38). Sensorimotor function and histology in the peri-infarct tissues were evaluated at the end of the experiment. RESULTS: Severe brain injury induced by permanent MCAO resulted in decreased survival and body weight gain, increased brain infarct volume as measured by MRI, impaired functional tests such as the rotarod and cylinder test, and histologic abnormalities such as increased terminal deoxynucleotidyl transferase nick-end labeling, reactive microglial marker, and glial fibrillary acidic protein-positive cells in the penumbra. All of these abnormalities were significantly improved by MSC transplantation 6 h after MCAO. CONCLUSION: These results suggest that human UCB-derived MSCs are a promising therapeutic candidate for the treatment of severe perinatal brain injury including neonatal stroke.

Intratracheal transplantation of human umbilical cord blood-derived mesenchymal stem cells attenuates Escherichia coli-induced acute lung injury in mice.

BACKGROUND: Human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) attenuate hyperoxic neonatal lung injury primarily through anti-inflammatory effects. We hypothesized that intratracheal transplantation of human UCB-derived MSCs could attenuate Escherichia coli (E. coli)-induced acute lung injury (ALI) in mice by suppressing the inflammatory response. METHODS: Eight-week-old male ICR mice were randomized to control or ALI groups. ALI was induced by intratracheal E. coli instillation. Three-hours after E. coli instillation, MSCs, fibroblasts or phosphate-buffered saline were intratracheally administered randomly and survival was analyzed for 7 days post-injury. Lung histology including injury scores, myeloperoxidase (MPO) activity, and protein levels of interleukin (IL)-1α, IL-1ß, IL-6, tumor necrosis factor (TNF)-α, and macrophage inflammatory protein (MIP)-2 as well as the wet-dry lung ratio and bacterial counts from blood and bronchoalveolar lavage (BAL) were evaluated at 1, 3, and 7 days post-injury. Levels of inflammatory cytokines in the lung were also profiled using protein macroarrays at day 3 post-injury which showed peak inflammation. RESULTS: MSC transplantation increased survival and attenuated lung injuries in ALI mice, as evidenced by decreased injury scores on day 3 post-injury and reduced lung inflammation including increased MPO activity and protein levels of IL-1α, IL-1ß, IL-6, TNF-α, and MIP-2 on day 3 and 7 post-injury. Inflammatory cytokine profiles in the lungs at day 3 post-injury were attenuated by MSC transplantation. MSCs also reduced the elevated lung water content at day 3 post-injury and bacterial counts in blood and BAL on day 7 post-injury. CONCLUSIONS: Intratracheal transplantation of UCB-derived MSCs attenuates E. coli-induced ALI primarily by down-modulating the inflammatory process and enhancing bacterial clearance.