Chinese liquor is produced from spontaneous fermentation starter (Daqu) that provides the microbes, enzymes and flavors for liquor fermentation. To improve the flavor character of Daqu, we inoculated ...Bacillus licheniformis and studied the effect of this strain on the community structure and metabolic profile in Daqu fermentation. The microbial relative abundance changed after the inoculation, including the increase in Bacillus, Clavispora and Aspergillus, and the decrease in Pichia, Saccharomycopsis and some other genera. This variation was also confirmed by pure culture and coculture experiments. Seventy-three metabolites were identified during Daqu fermentation process. After inoculation, the average content of aromatic compounds were significantly enriched from 0.37mg/kg to 0.90mg/kg, and the average content of pyrazines significantly increased from 0.35mg/kg to 5.71mg/kg. The increase in pyrazines was positively associated with the metabolism of the inoculated Bacillus and the native genus Clavispora, because they produced much more pyrazines in their cocultures. Whereas the increase in aromatic compounds might be related to the change of in situ metabolic activity of several native genera, in particular, Aspergillus produced more aromatic compounds in cocultures with B. licheniformis. It indicated that the inoculation of B. licheniformis altered the flavor character of Daqu by both its own metabolic activity and the variation of in situ metabolic activity. Moreover, B. licheniformis inoculation influenced the enzyme activity of Daqu, including the significant increase in amylase activity (from 1.3gstarch/g/h to 1.7gstarch/g/h), and the significant decrease in glucoamylase activity (from 627.6mgglucose/g/h to 445.6mgglucose/g/h) and esterase activity (from 28.1mgethylcaproate/g/100h to 17.2mgethylcaproate/g/100h). These effects of inoculation were important factors for regulating the metabolism of microbial communities, hence for improving the flavor profile Daqu.
•B. licheniformis inoculation affected the microbial community structure.•B. licheniformis inoculation influenced the enzyme activity of Daqu.•B. licheniformis inoculation enriched pyrazines and aromatic compounds.
The natural product α-cyclopiazonic acid (α-CPA) is a very potent Ca
-ATPase inhibitor. The CPA family of compounds comprise over 80 chemical entities with at least five distinct skeletons. While ...α-CPA features a canonical 6/5/6/5/5 skeleton, the 6/5/6/5 skeleton is the most prevalent among the CPA family. However, the origin of the unique tetracyclic skeleton remains unknown. The 6/5/6/5-type CPAs may derive from a precursor of acetoacetyl-l-tryptophan (AATrp) generated from a hypothetic thioesterase-like pathway. Alternatively, cleavage of the tetramic acid ring would also result in the formation of the 6/5/6/5 scaffold.
HMP-F28 is a marine sponge-associated filamentous fungus known to produce CPAs that act as primary neurotoxins. To elucidate the origin of this subfamily of CPAs, we performed homologous recombination and genetic engineering experiments on strain HMP-F28. Our results are supportive of the ring cleavage pathway through which the tetracyclic 6/5/6/5-type CPAs are generated from 6/5/6/5/5-type pentacyclic CPAs.
To overcome the difficulty in tracking the trajectory of an inspection robot inside a transformer, this paper proposes a distributed model predictive control method. First, the kinematics and ...dynamics models of a robot in transformer oil are established based on the Lagrange equation. Then, by using the nonlinear model predictive control method and following the distributed control theory, the motion of a robot in transformer oil is decoupled into five independent subsystems. Based on this, a distributed model predictive control (DMPC) method is then developed. Finally, the simulation results indicate that a robot motion control system based on DMPC achieves high tracking accuracy and robustness with reduced computing complexity, and it provides an effective solution for the motion control of robots in narrow environments.
Objective This study’s objective was to investigate the diversity of intestinal microorganisms in adult Vespa velutina (Asian hornet) killed by natural causes. This study investigates the composition ...of intestinal fungi and bacteria and predicts the pathogenic pathogen in adult Vespa velutina (Asian hornet). Methods We determined the ITS1 sequence of fungi and the V3–V4 variant region of 16S rRNA of bacteria using Illumina MiSeq technology. Operational taxonomic units (OTU) of gut symbiotic microorganisms were quantified, and the resulting data were subjected to analysis of species abundance, composition, and alpha diversity. OTU function was predicted using PICRUSt2/FUNGuild. In addition, cultured microorganisms from the gut microbiota of adult Vespa velutina were isolated and identified. A number of 3610 (fungi) and 8373 (bacteria) were identified via cluster analysis. A total of 13 strains, 51 classes, 126 orders, 285 families, and 586 genera were identified for fungi and 44 strains, 113 classes, 319 orders, 662 families, and 1394 genera were identified for bacteria. E. shigella, Herbaspirillum, and Aaaia were the most abundant classes of bacteria, and Fusarium, Mortierella, and Starmerella were the most abundant classes of fungi. In addition, 16 community genera of fungi and 11 of bacteria were outlined as core taxa. Species diversity and richness for the gut fungal and bacterial communities with VN were found to be higher than those with VA. Furthermore, bacterial species diversity and richness were found to be higher than those of fungi in VA and VN. Functional analysis revealed that Vespa velutina gut bacteria exhibited 20 functions, while fungi were classified into three types of nutrient modes. Cultivable bacteria were obtained from two phyla and two classes, but no fungi could be cultivated. Conclusion Variations in the species diversity and abundance of both fungi and bacteria in the gut were observed between the VA and the VN. The involvement of bacteria in the death of adult Vespa velutina was found to be significant. In addition, VA1 (the self-named strain) may be a pathogenic bacterium derived from the gut of the VA that exhibits virulence.
Naturally occurring echinocandin B and FR901379 are potent antifungal lipopeptides featuring a cyclic hexapeptide nucleus and a fatty acid side chain. They are the parent compounds of echinocandin ...drugs for the treatment of severe fungal infections caused by the
and
species. To minimize hemolytic toxicity, the native fatty acid side chains in these drug molecules are replaced with designer acyl side chains. The deacylation of the
-acyl side chain is, therefore, a crucial step for the development and manufacturing of echinocandin-type antibiotics. Echinocandin E (ECE) is a novel echinocandin congener with enhanced stability generated via the engineering of the biosynthetic machinery of echinocandin B (ECB). In the present study, we report the discovery of the first echinocandin E acylase (ECEA) using the enzyme similarity tool (EST) for enzymatic function mining across protein families. ECEA is derived from
sp. SY1965 isolated from a sediment collected from the Mariana Trench. It was cloned and heterologously expressed in
TK24. The resultant TKecea66 strain showed efficient cleavage activity of the acyl side chain of ECE, showing promising applications in the development of novel echinocandin-type therapeutics. Our results also provide a showcase for harnessing the essentially untapped biodiversity from the hadal ecosystems for the discovery of functional molecules.
We present IRAM 30 m observations of molecular lines of CO and its isotopologues from the massive spiral galaxy NGC 5908 selected from the CGM-MASS sample. 12CO J = 1 − 0, 12CO J = 2 − 1, and 13CO J ...= 1 − 0 lines have been detected in most of the positions along the galactic disk. The total molecular gas mass of NGC 5908 is and the total cool gas mass adding atomic hydrogen is , comparable to the upper limit of the mass of the X-ray emitting hot gas in the halo. Modeling the rotation curves constructed with all three CO lines indicates that NGC 5908 has a dark matter halo mass of , putting it among the most massive isolated spiral galaxies. The 12CO/13CO J = 1 − 0, 12CO J = 2 − 1/J = 1 − 0 line ratios and the estimated molecular gas temperature all indicate normal but non-negligible star formation in this fairly gas-rich massive isolated spiral galaxy, consistent with the measured star formation intensity and surface densities. The galaxy is probably at an early evolutionary stage after a fast growth stage with mergers and/or starbursts, with plenty of leftover cool gas, relatively high SFR, low hot CGM cooling rate, and low X-ray emissivity.
ABSTRACT
We present 3‐mm observations obtained with the Institut de Radioastronomie Millimétrique (IRAM) 30‐m telescope for 10 nearby gas‐rich active galaxies spanning three orders of magnitude in ...infrared luminosity. Emission lines of HCO+(1–0), HCN(1–0) and C2H(1–0) were simultaneously detected in most galaxies of our sample. We also tentatively detected the rare isotopic species H13CN, HC15N and H13CO+ in up to four galaxies (IC 694, NGC 3690, NGC 4258 and NGC 6240). Our estimation shows that the optical depth of HCN is low to moderate in these galaxies (τ∼ 1–5). After comparing the intensity ratios of different molecular emission lines (HCN/HCO+, C2H/HCN and C2H/HCO+) with the infrared luminosity (LIR), we find that in the infrared luminous sample of five composite (AGN+starburst) galaxies these ratios vary with LIR: the HCN/HCO+ ratio increases with LIR, which is consistent with previous studies, while there is a slight trend in the composite galaxies that both C2H/HCN and C2H/HCO+ ratios decrease with increasing LIR. Although our sample is limited, this trend may possibly imply a relation between the overall gas density and the infrared luminosity of galaxies.
In this paper, a novel miniaturized low-pass waveguide filter with wide stop-band is proposed for the harmonic rejection of Ku-band Very Small Aperture Terminal (VSAT) transmitters. The proposed ...filter consists of a corrugated waveguide low-pass filter and a metal septum in the H -plane at the center of the narrow side wall. Because it does not require additional impedance transformers, the proposed filter achieves a compact size. To estimate the amplitude level of the higher-order modes at the input port of the harmonic reject filter in a RF transmitter, higher-order modes generated by E -plane probe-type microstrip-to-waveguide (M2W) transition are analyzed and calculated using commercial numerical tools. To analyze the response of the proposed filter in higher-order modes, the mode conversions in the structure are also analyzed and calculated. The analysis shows that a wide stop-band free of spurious response in all higher-order modes can be obtained by co-designing M2W transition and filter. To validate the design concept, a Ku-band harmonic reject filter is designed using WR-75 waveguide. Simulation results show that the reflection is less than -23dB between 13~15 GHz, while the suppression stop-band performance in TE 10 mode is better than 35dB in 17.5~29.6 GHz. The effective length of the filter is 29 mm. Simulation results also indicate that the spurious pass-band performance in TE 20 , TE 21 and TM 21 modes is improved by the M2W transition. Finally, to validate the proposed idea, a Ku-band GaN power amplifier is fabricated and measured. The measurements show that the amplifier has a minimum output power of 72.5 W with better than 20 dBc 2 nd harmonic rejection. By using the proposed filter, the measured 2 nd harmonic rejection of the power amplifier is greater than 52 dBc.
Since the discovery that honey bee viruses play a role in colony decline, researchers have made major breakthroughs in understanding viral pathology and infection processes in honey bees. Work on ...virus transmission patterns and virus vectors, such as the mite
, has prompted intense efforts to manage honey bee health. However, little is known about the occurrence of honey bee viruses in bee predators, such as vespids. In this study, we characterized the occurrence of 11 honey bee viruses in five vespid species and one wasp from four provinces in China and two vespid species from four locations in France. The results showed that all the species from China carried certain honey bee viruses, notably
(AmFV),
(DWV), and
(IAPV); furthermore, in some vespid colonies, more than three different viruses were identified. In France, DWV was the most common virus;
(SBV) and
(BQCV) were observed in one and two samples, respectively. Phylogenetic analyses of IAPV and BQCV sequences indicated that most of the IAPV sequences belonged to a single group, while the BQCV sequences belonged to several groups. Additionally, our study is the first to detect
(LSV) in a hornet from China. Our findings can guide further research into the origin and transmission of honey bee viruses in Vespidae, a taxon of ecological, and potentially epidemiological, relevance.
In order to understand the product inhibition of enzymatic lignocellulose hydrolysis, the enzymatic hydrolysis of pretreated rice straw was carried out over an enzyme loading range of 2 to 30 FPU/g ...substrate, and the inhibition of enzymatic hydrolysis was analyzed kinetically based on the reducing sugars produced. It was shown that glucose, xylose, and arabinose were the main reducing sugar components contained in the hydrolysate. The mass ratio of glucose, xylose, and arabinose to the total reducing sugars was almost constant at 52.0 %, 29.7 % and 18.8 %, respectively, in the enzyme loading range. The reducing sugars exerted competitive inhibitory interferences to the enzymatic hydrolysis. Glucose, xylose, and arabinose had a dissociation constant of 1.24, 0.54 and 0.33 g/l, respectively. The inhibitory interferences by reducing sugars were superimposed on the enzymatic hydrolysis. The enzymatic hydrolysis could be improved by the removal of the produced reducing sugars from hydrolysate.
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