This study focused on an endophytic bacterial strain, Pantoea sp. Sd‐1, which can be used to degrade lignin and rice straw. This strain was isolated from rice seeds by an optimized surface ...sterilization method. Pantoea sp. Sd‐1 showed exceptional ability to degrade rice straw and lignin. In rice straw or kraft lignin‐containing medium supplemented with 1% glucose and 0·5% peptone, Pantoea sp. Sd‐1 effectively reduced the rice straw mass weight by 54·5% after 6 days of treatment. The strain was also capable of reducing the lignin colour (52·4%) and content (69·1%) after 4 days of incubation. The findings suggested that the rice endophytic bacterium Pantoea sp. Sd‐1 could be applied for the degradation of lignocellulose biomass, such as rice straw. SIGNIFICANCE AND IMPACT OF THE STUDY: Rice straw, an abundant agricultural by‐product in China, is very difficult to degrade because of its high lignin content. Due to the immense environmental adaptability and biochemical versatility of bacteria, endophytic bacteria are useful resources for biodegradation. In this study, we screened for endophytic bacteria capable of biodegrading rice straw and lignin and obtained one strain, Pantoea sp. Sd‐1, with suitable characteristics. Sd‐1 could be used for degradation of rice straw and lignin, and may play an important role in biodegradation of this agricultural by‐product.
Soy isoflavone metabolites are currently receiving much attention due to the stronger and wider bioactivities than that of isoflavones. Therefore, biosynthesis of isoflavone metabolites by isolated ...isoflavone biotransforming bacteria is important. However, the biosynthesis process must be under obligate anaerobic conditions due to the reduction reactions catalysed by isoflavone biotransforming bacteria. In this study, we cloned the daidzein and genistein reductase gene (dgr) from Slackia sp. AUH‐JLC159. The recombinant Escherichia coli (E. coli) whole‐cell was used for the first time as the biocatalyst for aerobic biosynthesis of dihydrodaidzein (DHD) and dihydrogenistein (DHG) from soy isoflavones daidzein and genistein. Our results indicated that the recombinant E. coli whole‐cell was able to reduce daidzein and genistein to DHD and DHG under aerobic conditions, while the maximal concentration of the substrate daidzein or genistein that the E. coli whole‐cell was able to convert efficiently was only 0·4 mmol l−1. Under the optimized conditions, the maximal concentration of daidzein or genistein that the E. coli whole‐cell was able to convert efficiently was increased to 1·4 mmol l−1. Our results demonstrated that E. coli whole‐cell is an efficient biocatalyst for biosynthesis of isoflavone metabolites under aerobic conditions.
Significance and Impact of the Study
Soy isoflavone metabolites, which are more biologically active than their precursor isoflavones, are currently receiving much more attention. However, the non‐natural isoflavone metabolites are synthesized or biosynthesized under obligate anaerobic conditions. Here, we describe a new approach to the reduction of soy isoflavones daidzein and genistein under aerobic conditions by use of the recombinant Escherichia coli whole‐cell expressing isoflavone reductase. Our study provides the first evidence that isoflavone metabolites, such as dihydrodaidzein and dihydrogenistein, are able to be produced efficiently under aerobic conditions.
Significance and Impact of the Study: Soy isoflavone metabolites, which are more biologically active than their precursor isoflavones, are currently receiving much more attention. However, the non‐natural isoflavone metabolites are synthesized or biosynthesized under obligate anaerobic conditions. Here, we describe a new approach to the reduction of soy isoflavones daidzein and genistein under aerobic conditions by use of the recombinant Escherichia coli whole‐cell expressing isoflavone reductase. Our study provides the first evidence that isoflavone metabolites, such as dihydrodaidzein and dihydrogenistein, are able to be produced efficiently under aerobic conditions.
Abstract Using 2.93 fb −1 of e + e − collision data collected with the BESIII detector at the center-of-mass energy 3.773 GeV, we perform the first amplitude analysis of the decay D + → K S 0 $$ ...{K}_S^0 $$ π + π 0 π 0 and determine the relative magnitudes and phases of different intermediate processes. The absolute branching fraction of D + → K S 0 $$ {K}_S^0 $$ π + π 0 π 0 is measured to be (2.888 ± 0.058stat. ± 0.069syst. )%. The dominant intermediate processes are D + → K S 0 $$ {K}_S^0 $$ a 1(1260)+(→ ρ + π 0) and D + → K ¯ $$ \overline{K} $$ *0 ρ +, with branching fractions of (8.66 ± 1.04stat. ± 1.39syst. ) × 10 −3 and (9.70 ± 0.81stat. ± 0.53syst. ) × 10 −3, respectively.
Highlights • AMPAR, EAAT2 and EAAT3 might be involved in prenatal stress induced offspring depression. • Prenatal stress caused behavioural despair in TST of juvenile rat offspring. • Prenatal stress ...reduced EAAT2 and EAAT3 mRNA levels in the hippocampus, striatum and frontal cortex of juvenile rat offspring. • Prenatal stress differently changed pGluR1 expression in the hippocampus and frontal cortex in juvenile rat offspring.
Aerosol filter samples were collected at a high-elevation mountain observatory (4180 m a.s.l.) in the northeastern part of the Qinghai-Xizang (Tibet) Plateau (QXP) during summer 2012 using a ...low-volume sampler and a micro-orifice uniform deposit impactor (MOUDI). These samples were analyzed for water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and total organic nitrogen (TON) to elucidate the size-resolved chemical composition of free tropospheric aerosols in the QXP region. The average mass concentration of the sum of the analyzed species in PM2.5 (particle matter) (WSIs + OC + EC + TON) was 3.74 mu g sm-3, 36% of which was sulfate, 18% OC, 17 % nitrate, 10% ammonium, 6.6% calcium, 6.4% TON, 2.6% EC, 1.5 % sodium, 0.9% chloride, 0.5% magnesium, and 0.3% potassium. The size distributions of sulfate and ammonium peaked in the accumulation mode (0.32-0.56 mu m), whereas the size distributions of both nitrate and calcium peaked in the range of 1.8-3.2 mu m, suggesting the formation of nitrate on mineral dust. OC, EC and TON were also predominantly found in the accumulation mode. The bulk chemical composition and the average oxidation degree of water-soluble organic matter (WSOM) were assessed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). WSOM was found to be highly oxidized in all PM2.5 samples with an average oxygen-to-carbon atomic ratio (O / C) of 1.16 and an organic mass-to-organic carbon ratio (OM / OC) of 2.75. The highly oxidized WSOM was likely related to active cloud processing during upslope air mass transport coupled with strongly oxidizing environments caused by snow/ice photochemistry. High average ratios of OC / EC (7.6) and WSOC / OC (0.79) suggested that organic aerosols were primarily made of secondary species. Secondary organic aerosol (SOA) was estimated on average accounting for 80% (62-96%) of the PM2.5, indicating that SOA is an important component of free tropospheric aerosols over the northern QXP.
Graphene nanosheets (GNSs) had been considered as the potential reinforcements of the composites. In this study, sponge-like graphene was used as a reinforcement to enhance the dispersity of GNSs in ...the metal matrix. AgCuTi alloy was melted and infiltrated into the sponge-like graphene, which led to the reaction between the GNSs and the AgCuTi alloy. The microstructure on the interface of the GNSs and AgCuTi alloy was characterized. The GNSs reinforced AgCuTi based composite was utilized as an interlayer to braze graphite and Cu, and the dispersity of the GNSs in the brazing seam was discussed. Comparing with the pure AgCuTi interlayer, the shear strength of the graphite and Cu joint was increased by 75% when the GNSs reinforced AgCuTi based composite interlayer was used.
•GNSs reinforced AgCuTi composite was prepared by a melt infiltration method.•The GNSs in the composite were interconnected and free of any agglomeration.•Graphite and Cu were successfully brazed with the addition of the GNSs.•The shear strength was improved by 75% when the interconnected GNSs were added.
Understanding the sources and impact of volatile organic compounds (VOCs) on ozone formation is challenging when the traditional method does not account for their photochemical loss. In this study, ...online monitoring of 56 VOCs was carried out in summer and autumn during high ozone pollution episodes. The photochemical age method was used to evaluate the atmospheric chemical loss of VOCs and to analyze the effects on characteristics, sources, and ozone formation of VOC components. The initial concentrations during daytime were 5.12 ppbv and 4.49 ppbv higher than the observed concentrations in the summer and autumn, respectively. The positive matrix factorization (PMF) model identified 5 major emission sources. However, the omission of the chemical loss of VOCs led to underestimating the contributions of sources associated with highly reactive VOC components, such as those produced by biogenic emissions and solvent usage. Conversely it resulted in overestimating the contributions from VOC components with lower chemical activity such as liquefied petroleum gas (LPG) usage, vehicle emissions, and gasoline evaporation. Furthermore, the estimation of ozone formation may be underestimated when the atmospheric photochemical loss is not taken into account. The ozone formation potential (OFP) method and propylene-equivalent concentration method both underestimated ozone formation by 53.24 ppbv and 47.25 ppbc, respectively, in the summer, and by 40.34 ppbv and 26.37 ppbc, respectively, in the autumn. The determination of the ozone formation regime based on VOC chemical loss was more acceptable. In the summer, the ozone formation regime changed from the VOC-limited regime to the VOC-NOx transition regime, while in the autumn, the ozone formation regime changed from the strong VOC-limited regime to the weak VOC-limited regime. To obtain more thorough and precise conclusions, further monitoring and analysis studies will be conducted in the near future on a wider variety of VOC species such as oxygenated VOCs (OVOCs).
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