Complete genome sequence of the rifamycin SV-producing Amycolatopsis mediterranei U32 revealed its genetic characteristics in phylogeny and metabolism

Amycolatopsis mediterranei is used for industry-scale production of rifamycin, which plays a vital role in antimyco- bacterial therapy. As the first sequenced genome of the genus Amycolatopsis, the chromosome of strain U32 comprising 10 236 715 base pairs, is one of the largest prokaryotic genomes ever sequenced so far. Unlike the linear topology found in streptomycetes, this chromosome is circular, particularly similar to that of Saccharopolyspora erythraea and Nocardia farcinica, representing their close relationship in phylogeny and taxonomy. Although the predicted 9 228 protein-coding genes in the A. mediterranei genome shared the greatest number of orthologs with those of S. erythraea, it was unexpectedly followed by Streptomyces coelicolor rather than N. farcinica, indicating the distinct metabolic characteristics evolved via adaptation to diverse ecological niches. Besides a core region analogous to that common in streptomycetes, a novel ＇quasicore＇ with typical core characteristics is defined within the non-core region, where 21 out of the total 26 gene clusters for secondary metabolite production are located. The rifamycin biosynthesis gene cluster located in the core encodes a cytochrome P450 enzyme essential for the conversion of rifamycin SV to B, revealed by comparing to the highly homologous cluster of the rifamycin B-producing strain S699 and further confirmed by genetic complementation. The genomic information of A. mediterranei demonstrates a metabolic network orchestrated not only for extensive utilization of various carbon sources and inorganic nitrogen compounds but also for effective funneling of metabolic intermediates into the secondary antibiotic synthesis process under the control of a seemingly complex regulatory mechanism.

Plasma Enhanced Chemical Vapor Deposition Nanocrystalline Tungsten Carbide Thin Film and Its Electro-catalytic Activity

Nanocrystalline tungsten carbide thin films were fabricated on graphite substrates by plasma enhanced chemical vapor deposition （PECVD） at H2 and Ar atmosphere, using WF6 and CH4 as precursors. The crystal phase, structure and chemical components of the films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive spectrometer （EDS）, respectively. The results show that the film prepared at CH4/WF6 concentration ratio of 20 and at 800℃ is composed of spherical particles with a diameter of 20-35 nm. Electrochemical investigations show that the electrochemical real surface area of electrode of the film is large, and the electrode of the film exhibits higher electro-catalytic activity in the reaction of methanol oxidation. The designated constant current of the film catalyst is 123.6 mA/cm^2 in the mixture solution of H2SO4 and CH3OH at the concentration of 0.5 and 2.0 mol/L at 70℃, and the designated constant potential is only 0.306 V （vs SCE）.

Preparation and Electrocatalytic Activity of Tungsten Carbide Nanorod Arrays

High density tungsten carbide nanorod arrays have been prepared by magnetron sputtering （MS） using the aluminum lattice membrane （ALM） as template. Electrocatalytic properties of nitromethane electroreduction on the tungsten carbide nanorod arrays electrode were investigated by electrochemical method, and their electrocatalytic activity is approached to that of the Pt foil electrode.

Elemental sulfur upregulated testicular testosterone biosynthesis by associating with altered gut microbiota in mice

Elemental sulfur has been used as a traditional Chinese medicine to treat the late-onset hypogonadism and impotence without a clarified mechanism for many hundreds of years.In the present study,mice were received sulfur or distilled water for 35 days by daily intragastric gavage at a dose of 250 mg/kg body weight.Then,the serum testosterone level and genes associated with testicular testosterone biosynthesis(TTB)were detected.The gut microbiota was also analyzed by 16S rRNA gene sequencing.Serum testosterone level was significantly increased by 291.1%in sulfur-treated mice.The H2S levels in serum and feces were significantly increased.The expression of genes associated with TTB including StAR,p450c17,3β-HSD,and P450scc in testes were significantly upregulated by Sulfur and NaHS,suggesting that sulfur promotes TTB depending on H2S.In addition,sulfur increased the diversity of gut microbiota and the abundance of several bacteria associated with sulfur metabolism,including genus Prevotella,which might be positively associated with serum level of testosterone in boys.Five pathways including bile secretion,carotenoid biosynthesis,lipid biosynthesis proteins,propanoate metabolism,and biosynthesis of type II polyketide products,were identified to associate with sulfur.Together,our results suggested that sulfur upregulated testicular testosterone biosynthesis via H2S,which was associated with alteration of gut microbiota in mice.Our study highlights a mechanism for the treatment of late-onset hypogonadism and impotence by sulfur.

Amino Acid Biosynthesis and Proteolysis in <i>Lactobacillus Bulgaricus</i>Revisited: A Genomic Comparison

The amino acid biosynthesis and proteolytic system of Lactobacillus bulgaricus (L.Bulgaricus ) is important for its growth in niche-specific environments, as well as for flavour formation in the food industry. Comparative analyses of 4 completed sequences of the L.Bulgaricus strain genome on a genomic scale revealed that genes involved in amino acids synthesis were undergoing reductive evolution. However, the selected industrial strains, namely, L.Bulgaricus 2038 and L.Bulgaricus ND02, retained more complete genes in the amino acid synthesis and proteolytic system category than the laboratory strains, and have some unique genes and pathways for obtaining amino acids that enable these bacteria to adapt to their various environmental niches.

Manganese doping to boost the capacitance performance of hierarchical Co_(9)S_(8)@Co(OH)_(2) nanosheet arrays

Transition metal sulfides(TMSs)have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity.Herein,we report a self-supported hierarchical Mn doped Co_(9)S_(8)@Co(OH)_(2) nanosheet arrays on nickel foam(NF)substrate by a one-step metal–organic-framework(MOF)engaged approach and a subsequent sulfurization process.Experimental results reveal that the introduction of manganese endows improved electric conductivity,enlarged electrochemical specific surface area,adjusted electronic structure of Co_(9)S_(8)@Co(OH)_(2) and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes.The optimal Mn doped Co_(9)S_(8)@Co(OH)_(2) electrode exhibits an ultrahigh specific capacitance of 3745 F g^(-1) at 1 A g^(-1)(5.618 F cm^(-2) at 1.5 mA cm^(-2))and sustains 1710 F g^(-1) at 30 A g^(-1)(2.565 F cm^(-2) at 45 mA cm^(-2)),surpassing most reported values on TMSs.Moreover,a battery-type asymmetric supercapacitor(ASC)device is constructed,which delivers high energy density of 50.2 Wh kg^(-1) at power density of 800 W kg^(-1),and outstanding long-term cycling stability(94%capacitance retention after 8000 cycles).The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices.

Banana Peel Carbon that Containing Functional Groups Applied to the Selective Adsorption of Au(III) from Waste Printed Circuit Boards

This paper reports a kind of banana peel carbon (BPC) containing -OH, -NH2 functional groups which prepared through controlling carbonization temperature and its application on the selective adsorption of gold from waste printed circuit boards (PCBs). The adsorption of BPC for Au(III) reached equilibrium in 30 min and the adsorption of Au(III) was favorable at pH 2.5. Meanwhile, the adsorption isotherm showed the maximum adsorption capacity of 801.7 mg/g for Au(III). The results displayed that BPC had a strong selectivity for Au(III) and a negligible affinity to base metal ions, such as Cu(II), Ni(II), Fe(III) and Pb(II). The BPC adsorbent, which absorbed gold, can be recovered completely by HCl-thiourea solution.

Edge-enriched N, S co-doped hierarchical porous carbon for oxygen reduction reaction

The development of carbon materials with high electrochemical performance for next-generation energy device is emerging, especially N, S co-doped carbon materials have sparked intensive attention. However,the exploration of N, S co-doped carbon with well-defined active sites and hierarchical porous structures are still limited. In this study, we prepared a series of edge-enriched N, S co-doped carbon materials through pyrolysis of thiourea(TU) encapsulated in zeolitic imidazolate frameworks(TU@ZIF) composites,which delivered very good oxygen reduction reaction(ORR) performance in alkaline medium with onset potential of 0.94 V vs. reversible hydrogen electrode(RHE), good stability and methanol tolerance. Density functional theory(DFT) calculations suggested that carbon atoms adjacent to N and S are probable active sites for ORR intermediates in edge-enriched N, S co-doped carbon materials because higher electron density can enhance O_(2)adsorption, lower formation barriers of intermediates, improving the ORR performance comparing to intact N, S co-doped carbon materials. This study might provide a new pathway for improving ORR activity by the integration engineering of edge sites, and electronic structure of heteroatom doped carbon electrocatalysts.

A systematic study of the whole genome sequence of Amycolatopsis methanolica strain 239T provides an insight into its physiological and taxonomic properties which correlate with its position in the genus

The complete genome of methanol-utilizing Amycolatopsis methanolica strain 239T was generated,revealing a single 7,237,391 nucleotide circular chromosome with 7074 annotated protein-coding sequences(CDSs).Comparative analyses against the complete genome sequences of Amycolatopsis japonica strain MG417-CF17T,Amycolatopsis mediterranei strain U32 and Amycolatopsis orientalis strain HCCB10007 revealed a broad spectrum of genomic structures,including various genome sizes,core/quasi-core/non-core configurations and different kinds of episomes.Although polyketide synthase gene clusters were absent from the A.methanolica genome,12 gene clusters related to the biosynthesis of other specialized(secondary)metabolites were identified.Complete pathways attributable to the facultative methylotrophic physiology of A.methanolica strain 239T,including both the mdo/mscR encoded methanol oxidation and the hps/hpi encoded formaldehyde assimilation via the ribulose monophosphate cycle,were identified together with evidence that the latter might be the result of horizontal gene transfer.Phylogenetic analyses based on 16S rDNA or orthologues of AMETH_3452,a novel actinobacterial class-specific conserved gene against 62 or 18 Amycolatopsis type strains,respectively,revealed three major phyletic lineages,namely the mesophilic or moderately thermophilic A.orientalis subclade(AOS),the mesophilic Amycolatopsis taiwanensis subclade(ATS)and the thermophilic A.methanolica subclade(AMS).The distinct growth temperatures of members of the subclades correlated with corresponding genetic variations in their encoded compatible solutes.This study shows the value of integrating conventional taxonomic with whole genome sequence data.