Metagenomic profiling of cecal microbiota and antibiotic resistome in rodents.

The rodent gut microbiota is a known reservoir of antimicrobial resistance, yet the distribution of antibiotic resistance genes (ARGs) within rodent cecal microbial communities and the specific bacterial species harboring these ARGs remain largely underexplored. This study employed high-throughput sequencing of 122 samples from five distinct rodent species to comprehensively profile the diversity and distribution of ARGs and to identify the bacterial hosts of these genes. A gene catalog of the rodent cecal microbiome was constructed, comprising 22,757,369 non-redundant genes. Analysis of the microbial composition and diversity revealed that Bacillota and Bacteroidota were the dominant bacterial phyla across different rodent species, with significant variations in species composition among the rodents. In total, 3703 putative antimicrobial resistance protein-coding genes were identified, corresponding to 392 unique ARG types classified into 32 resistance classes. The most enriched ARGs in the rodent cecal microbiome were associated with multidrug resistance, followed by glycopeptide and elfamycin antibiotics. Procrustes analysis demonstrated a correlation between the structure of the microbial community and the resistome. Metagenomic assembly-based host tracking indicated that most ARG-carrying contigs originated from the bacterial family Oscillospiraceae. Additionally, 130 ARGs showed significant correlations with mobile genetic elements. These findings provide new insights into the cecal microbiota and the prevalence of ARGs across five rodent species. Future research on a wider range of wild rodent species carrying ARGs will further elucidate the mechanisms underlying the transmission of antimicrobial resistance.

Meta-analysis of the prevalence of Giardia duodenalis in sheep and goats in China.

Giardia duodenum (G. duodenalis) can cause giardiasis and infect a variety of hosts. So far, there have been no detailed data regarding the positive rate of G. duodenalis in sheep and goats in China. Here, a systematic literature review was carried out to investigate the epidemiology of G. duodenalis in sheep and goats in China. To perform the meta-analysis, the databases CNKI, VIP, WanFang, PubMed, Web of science and ScienceDirect were employed for screening studies related to the prevalence of G. duodenalis in sheep and goats in China. The total prevalence of G. duodenalis in sheep and goats was estimated to be 7.00% (95% CI: 4.00-10.00). In the age subgroup, the prevalence of G. duodenalis in sheep and goats of >12 months (11.29%; 95% CI: 8.08-14.97) was higher than that in sheep and goats of ≤12 months (7.57%; 95% CI: 3.95-12.24). An analysis based on seasons showed that the prevalence of G. duodenalis in sheep and goats was higher in summer (11.90%; 95% CI: 0.50-35.05) than that in other seasons. The prevalence of G. duodenalis in sheep and goats after 2016 was 8.57% (95% CI: 5.34-11.79), which was higher than others. The highest prevalence of G. duodenalis in sheep and goats was 13.06% (95% CI: 6.26-19.86) recorded in Southwestern China. The prevalence of Giardia infection in sheep (7.28%; 95% CI: 2.30-14.73) was higher than that in goats (5.43%; 95% CI: 2.73-8.98). The NOAA's National Center for Environmental Information (https://gis.ncdc.noaa.gov/maps/ncei/cdo/monthly) was used to extract relevant geoclimatic data (latitude, longitude, elevation, temperature, precipitation, humidity, and climate). By analyzing the data of each subgroup, it was shown that region, genetype, and climate were potential risk factors for giardiasis prevalence in sheep and goats. Based on the analysis of common factors and geographical factors, it is recommended to strengthen effective management measures (e.g. ventilation and disinfection in warm and humid areas) and formulate relevant policies according to local conditions. Breeders should strengthen the detection of G. duodenalis in sheep and goats, customize corresponding control measures according to the diet and living habits of sheep and goats, and strengthen the protection of sheep and lamb calves, so as to reduce the incidence rate and reduce the economic loss of China's animal husbandry.

Iterative Synthesis of 2-Deoxyoligosaccharides Enabled by Stereoselective Visible-Light-Promoted Glycosylation.

The photoinitiated intramolecular hydroetherification of alkenols has been used to form C-O bonds, but the intermolecular hydroetherification of alkenes with alcohols remains an unsolved challenge. We herein report the visible-light-promoted 2-deoxyglycosylation of alcohols with glycals. The glycosylation reaction was completed within 2 min in a high quantum yield (ϕ=28.6). This method was suitable for a wide array of substrates and displayed good reaction yields and excellent stereoselectivity. The value of this protocol was further demonstrated by the iterative synthesis of 2-deoxyglycans with α-2-deoxyglycosidic linkages up to a 20-mer in length and digoxin with ß-2-deoxyglycosidic linkages. Mechanistic studies indicated that this reaction involved a glycosyl radical cation intermediate and a photoinitiated chain process.

Enhanced Nitrite Production from the Aqueous Photolysis of Nitrate in the Presence of Vanillic Acid and Implications for the Roles of Light-Absorbing Organics.

A prominent source of hydroxyl radicals (•OH), nitrous acid (HONO) plays a key role in tropospheric chemistry. Apart from direct emission, HONO (or its conjugate base nitrite, NO2-) can be formed secondarily in the atmosphere. Yet, how secondary HONO forms requires elucidation, especially for heterogeneous processes involving numerous organic compounds in atmospheric aerosols. We investigated nitrite production from aqueous photolysis of nitrate for a range of conditions (pH, organic compound, nitrate concentration, and cation). Upon adding small oxygenates such as ethanol, n-butanol, or formate as •OH scavengers, the average intrinsic quantum yield of nitrite [Φ(NO2-)] was 0.75 ± 0.15%. With near-UV-light-absorbing vanillic acid (VA), however, the effective Φ(NO2-) was strongly pH-dependent, reaching 8.0 ± 2.1% at a pH of 8 and 1.5 ± 0.39% at a more atmospherically relevant pH of 5. Our results suggest that brown carbon (BrC) may greatly enhance the nitrite production from the aqueous nitrate photolysis through photosensitizing reactions, where the triplet excited state of BrC may generate solvated electrons, which reduce nitrate to NO2 for further conversion to nitrite. This photosensitization process by BrC chromophores during nitrate photolysis under mildly acidic conditions may partly explain the missing HONO in urban environments.

Secondary Metabolite Production Potential of Mangrove-Derived Streptomyces olivaceus.

Mangroves are intertidal extreme environments with rich microbial communities. Actinobacteria are well known for producing antibiotics. The search for biosynthetic potential of Actinobacteria from mangrove environments could provide more possibilities for useful secondary metabolites. In this study, whole genome sequencing and MS/MS analysis were used to explore the secondary metabolite production potential of one actinobacterial strain of Streptomyces olivaceus sp., isolated from a mangrove in Macau, China. The results showed that a total of 105 gene clusters were found in the genome of S. olivaceus sp., and 53 known secondary metabolites, including bioactive compounds, peptides, and other products, were predicted by genome mining. There were 28 secondary metabolites classified as antibiotics, which were not previously known from S. olivaceus. ISP medium 2 was then used to ferment the S. olivaceus sp. to determine which predicted secondary metabolite could be truly produced. The chemical analysis revealed that ectoine, melanin, and the antibiotic of validamycin A could be observed in the fermentation broth. This was the first observation that these three compounds can be produced by a strain of S. olivaceus. Therefore, it can be concluded that Actinobacteria isolated from the mangrove environment have unknown potential to produce bioactive secondary metabolites.

Stereoselective Electro-2-deoxyglycosylation from Glycals.

We report a novel and highly stereoselective electro-2-deoxyglycosylation from glycals. This method features excellent stereoselectivity, scope, and functional-group tolerance. This process can also be applied to the modification of a wide range of natural products and drugs. Furthermore, a scalable synthesis of glycosylated podophyllotoxin and a one-pot trisaccharide synthesis through iterative electroglycosylations were achieved.

Highly Transparent Poly(vinyl alcohol)(PVA)/TiO2 Nanocomposite Films with Remarkable Photocatalytic Performance and Recyclability.

Titanium dioxide (TiO2) has been regarded as an efficient photocatalyst for degradation of environmental pollutants. However, recovery of TiO2 nanoparticles from suspension limits its practical application. Herein, we reported a novel highly transparent poly(vinyl alcohol)(PVA)/TiO2 photocatalytic film via in-situ growth and solution casting method. TiO2 nanoparticles with average size of 10 nm were uniformly dispersed in transparent PVA matrix. The photocatalytic performance was investigated by photodegradation of methyl orange (MO) aqueous solution under solar light irradiation. PVA/TiO2 photocatalytic film exhibited remarkably high photocatalytic activity and excellent recyclable properties during multi-cycle use. PVA not only acted as a transparent supports for TiO2, but also worked as an efficient holes scavenger. The hydroxyl groups on PVA chains played a key role in separation of photo-generated electrons and holes, thus increased the photodegradation rate of MO. This work gives an easy and reliable way for polymer/TiO2 nanocomposites in practical environmental applications.

In vitro and in vivo evaluation of antibacterial activity and mechanism of luteolin from Humulus scandens against Escherichia coli from chicken.

Resistance of Escherichia coli (E.coli) to antibiotics has steadily increased over time; hence, there is an urgent need to develop safer alternatives to antibiotics. The present study aimed to evaluate the effect of luteolin (Lut) on E. coli from chicken. The bioactive compound Lut from Humulus scandens was selected by network pharmacology and molecular docking analyses. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM) were used to observe the effects of Lut on the morphology and structure of E. coli cells. The data-independent acquisition (DIA) method was used to analyze protein expression level of E. coli before and after Lut treatment. The in vivo evaluation of the antibacterial, anti-inflammatory, and oxidative effects of Lut on E.coli was conducted using E.coli isolated strains infected the SPF chicken model. The network pharmacology analysis revealed 19 distinctive bioactive compounds such as Lut and ß-sitosterol in H. scandens; furthermore, 30 core targets were selected from H. scandens. The KEGG enrichment analysis showed that the PI3K-Akt, TNF, MAPK, IL-17, JAK-STAT, and HIF-1 pathways were related from H. scandens. Based on the results of the network pharmacology analysis, Lut was subjected to screening by molecular docking analysis to determine its antibacterial effect on E. coli and the associated mechanism of action. The minimum inhibitory concentration (MIC) of Lut against E. coli standard strains was 500 µg/mL. SEM, TEM, and CLSM results indicated that Lut damaged the cell wall and cell membrane of E. coli strains and destroyed the cell structure, leading to cell death.The expression level of membrane structure, Phenylalanine metabolism and some other metabolic pathways in E.coli changed after treatment with Lut (P < 0.05). In vivo experiments in the SPF chicken model showed that Lut treatment alleviated the decline in the growth performance of chickens (P < 0.05), prevented pathological changes in the correspond ding organs and suppressed the inflammatory response induced by E. coli infection (P < 0.05), improved the immunity and antioxidant capacity of chickens (P < 0.05), and protected them against infection with E. coli strains. To summarize, Lut from H. scandens can inhibit E. coli growth by damaging the cell membrane structureand affecting the expression level of some metabolic proteins. In vivo experiments also showed that Lut can significantly reduce the damage caused by E. coli isolates on SPF chickens, improve their antioxidant capacity and immunity, and reduce inflammatory responses following E. coli infection.

Interferon regulatory factor-1 together with reactive oxygen species promotes the acceleration of cell cycle progression by up-regulating the cyclin E and CDK2 genes during high glucose-induced proliferation of vascular smooth muscle cells.

BACKGROUND: The high glucose-induced proliferation of vascular smooth muscle cells (VSMCs) plays an important role in the development of diabetic vascular diseases. In a previous study, we confirmed that Interferon regulatory factor-1 (Irf-1) is a positive regulator of the high glucose-induced proliferation of VSMCs. However, the mechanisms remain to be determined. METHODS: The levels of cyclin/CDK expression in two cell models involving Irf-1 knockdown and overexpression were quantified to explore the relationship between Irf-1 and its downstream effectors under normal or high glucose conditions. Subsequently, cells were treated with high glucose/NAC, normal glucose/H2O2, high glucose/U0126 or normal glucose/H2O2/U0126 during an incubation period. Then proliferation, cyclin/CDK expression and cell cycle distribution assays were performed to determine whether ROS/Erk1/2 signaling pathway was involved in the Irf-1-induced regulation of VSMC growth under high glucose conditions. RESULTS: We found that Irf-1 overexpression led to down-regulation of cyclin D1/CDK4 and inhibited cell cycle progression in VSMCs under normal glucose conditions. In high glucose conditions, Irf-1 overexpression led to an up-regulation of cyclin E/CDK2 and an acceleration of cell cycle progression, whereas silencing of Irf-1 suppressed the expression of both proteins and inhibited the cell cycle during the high glucose-induced proliferation of VSMCs. Treatment of VSMCs with antioxidants prevented the Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression in high glucose conditions. In contrast, under normal glucose conditions, H2O2 stimulation and Irf-1 overexpression induced cell proliferation, up-regulated cyclin E/CDK2 expression and promoted cell cycle acceleration. In addition, overexpression of Irf-1 promoted the activation of Erk1/2 and when VSMCs overexpressing Irf-1 were treated with U0126, the specific Erk1/2 inhibitor abolished the proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression under high glucose or normal glucose/H2O2 conditions. CONCLUSIONS: These results demonstrate that the downstream effectors of Irf-1 are cyclin E/CDK2 during the high glucose-induced proliferation of VSMCs, whereas they are cyclin D1/CDK4 in normal glucose conditions. The Irf-1 overexpression-induced proliferation of VSMCs, the up-regulation of cyclin E/CDK2 and the acceleration of cell cycle progression are associated with ROS/Erk1/2 signaling pathway under high glucose conditions.

The interplays among meteorology, source, and chemistry in high particulate matter pollution episodes in urban Shanghai, China.

High particulate matter (PM) pollution episodes still occur occasionally in urban China, despite of improvements in recent years. Investigating the influencing factors of high-PM episodes is beneficial in the formulation of effective control measures. We herein present the effects of weather condition, emission source, and chemical conversion on the occurrence of high-PM episodes in urban Shanghai using multiple online measurements. Three high-PM episodes, i.e., locally-accumulated, regionally-transported, and dust-affected ones, as well as a clean period were selected. Stagnant air with temperature inversion was found in both locally-accumulated and regionally-transported high-PM episodes, but differences in PM evolution were observed. In the more complicated dust-affected episode, the weather condition interacted with the emission/transport sources and chemical conversion, resulting in consecutive stages with different PM characteristics. Specifically, there were (1) stronger local accumulation in the pre-dust period, (2) dust-laden air with aged organic aerosol (OA) upon dust arrival, (3) pollutants being swept into the ocean, and (4) back to the city with aged OA. Our results suggest that (a) local emissions could be rapidly oxidized in some episodes but not all, (b) aged OA from long-range transport (aged in space) had a similar degree of oxygenation compared to the prolonged local oxidation (aged in time), and (c) OA aged over land and over the ocean were similar in chemical characteristics. The findings help better understand the causes and evolution of high-PM episodes, which are manifested by the interplays among meteorology, source, and chemistry, providing a scientific basis for control measures.

Metagenomic Analysis of Fecal Archaea, Bacteria, Eukaryota, and Virus in Przewalski's Horses Following Anthelmintic Treatment.

Intestinal microbiota is involved in immune response and metabolism of the host. The frequent use of anthelmintic compounds for parasite expulsion causes disturbance to the equine intestinal microbiota. However, most studies were on the effects of such treatment on the intestinal bacterial microbes; none is on the entire microbial community including archaea and eukaryotic and viral community in equine animals. This study is the first to explore the differences of the microbial community composition and structure in Przewalski's horses prior to and following anthelmintic treatment, and to determine the corresponding changes of their functional attributes based on metagenomic sequencing. Results showed that in archaea, the methanogen of Euryarchaeota was the dominant phylum. Under this phylum, anthelmintic treatment increased the Methanobrevibacter genus and decreased the Methanocorpusculum genus and two other dominant archaea species, Methanocorpusculum labreanum and Methanocorpusculum bavaricum. In bacteria, Firmicutes and Bacteroidetes were the dominant phyla. Anthelmintic treatment increased the genera of Clostridium and Eubacterium and decreased those of Bacteroides and Prevotella and dominant bacteria species. These altered genera were associated with immunity and digestion. In eukaryota, anthelmintic treatment also changed the genera related to digestion and substantially decreased the relative abundances of identified species. In virus, anthelmintic treatment increased the genus of unclassified_d__Viruses and decreased those of unclassified_f__Siphoviridae and unclassified_f__Myoviridae. Most of the identified viral species were classified into phage, which were more sensitive to anthelmintic treatment than other viruses. Furthermore, anthelmintic treatment was found to increase the number of pathogens related to some clinical diseases in horses. The COG and KEGG function analysis showed that the intestinal microbiota of Przewalski's horse mainly participated in the carbohydrate and amino acid metabolism. The anthelmintic treatment did not change their overall function; however, it displaced the population of the functional microbes involved in each function or pathway. These results provide a complete view on the changes caused by anthelmintic treatment in the intestinal microbiota of the Przewalski's horses.

Emission Inventories and Particulate Matter Air Quality Modeling over the Pearl River Delta Region.

The Pearl River Delta (PRD) region is located on the southeast coast of mainland China and it is an important economic hub. The high levels of particulate matter (PM) in the atmosphere, however, and poor visibility have become a complex environmental problem for the region. Air quality modeling systems are useful to understand the temporal and spatial distribution of air pollution, making use of atmospheric emission data as inputs. Over the years, several atmospheric emission inventories have been developed for the Asia region. The main purpose of this work is to evaluate the performance of the air quality modeling system for simulating PM concentrations over the PRD using three atmospheric emission inventories (i.e., EDGAR, REAS and MIX) during a winter and a summer period. In general, there is a tendency to underestimate PM levels, but results based on the EDGAR emission inventory show slightly better accuracy. However, improvements in the spatial and temporal disaggregation of emissions are still needed to properly represent PRD air quality. This study's comparison of the three emission inventories' data, as well as their PM simulating outcomes, generates recommendations for future improvements to atmospheric emission inventories and our understanding of air pollution problems in the PRD region.

Effects of Gasterophilus pecorum infestation on the intestinal microbiota of the rewilded Przewalski's horses in China.

Horse botflies have been a threat to the Przewalski's horses in the Kalamaili Nature Reserve in Xinjiang of China since their reintroduction to the original range. As larvae of these parasites could infest the intestine of a horse for months, they could interact with and alter the structure and composition of its intestinal microbiota, affecting adversely its health. Nonetheless, there are no such studies on the rewilded Przewalski's horses yet. For the first time, this study characterizes the composition of the intestinal microbiota of 7 rewilded Przewalski's horses infected severely by Gasterophilus pecorum following and prior to their anthelmintic treatment. Bioinformatics analyses of the sequence data obtained by amplicon high throughput sequencing of bacterial 16S rRNA genes showed that G. pecorum infestation significantly increased the richness of the intestinal microbial community but not its diversity. Firmicutes and Bacteroidetes were found the dominant phyla as in other animals, and the parasitic infestation decreased the F/B ratio largely by over 50%. Large reduction in relative abundances of the two genera Streptococcus and Lactobacillus observed with G. pecorum infestation suggested possible changes in colic and digestion related conditions of the infected horses. Variations on the relative abundance of the genus groups known to be pathogenic or symbiotic showed that adverse impact of the G. pecorum infestation could be associated with reduction of the symbiotic genera Lactobacillus and Bifidobacterium that are probiotics and able to promote immunity against parasitic infection.

Temporal Patterns of Bacterial and Viral Communities during Algae Blooms of a Reservoir in Macau.

Compositions of microbial communities associated with blooms of algae in a storage reservoir in Macau, China were investigated between 2013 and 2016. Algae were enumerated by visible light microscopy. Profiles of organisms in water were examined by 16S rRNA sequences and viral metagenomics, based on next generation sequencing. Results of 16S rRNA sequencing indicated that majority of the identified organisms were bacteria closely related to Proteobacteria, Cyanobacteria, Verrucomicrobia, Bacteroidetes, and Actinobacteria. Metagenomics sequences demonstrated that the dominant virus was Phycodnavirus, accounting for 70% of the total population. Patterns of relative numbers of bacteria in the microbial community and their temporal changes were determined through alpha diversity indices, principal coordinates analysis (PCoA), relative abundance, and visualized by Venn diagrams. Ways in which the bacterial and viral communities are influenced by various water-related variables were elucidated based on redundancy analysis (RDA). Relationships of the relative numbers of bacteria with trophic status in a reservoir used for drinking water in Macau, provided insight into associations of Phycodnavirus and Proteobacteria with changes in blooms of algae.

Power Management IC for a Dual-Input-Triple-Output Energy Harvester.

We present the design of a power management integrated circuit that processes harvested energy from radio frequency waves and piezoelectric vibrations. The rectification of piezoelectric and RF sources has a power conversion efficiency (PCE) of 87.73% and 74.70%, respectively. The asynchronous and microcontroller-less integrated circuit (IC) is designed to be low power, so the bulk of the harvested energy goes to three loads. The output peak powers of 111 µW, 156 µW, and 128 µW will be sufficient to run small devices for RF communication systems.

Exploring the Potential of Antibiotic Production From Rare Actinobacteria by Whole-Genome Sequencing and Guided MS/MS Analysis.

Actinobacteria are well recognized for their production of structurally diverse bioactive secondary metabolites, but the rare actinobacterial genera have been underexploited for such potential. To search for new sources of active compounds, an experiment combining genomic analysis and tandem mass spectrometry (MS/MS) screening was designed to isolate and characterize actinobacterial strains from a mangrove environment in Macau. Fourteen actinobacterial strains were isolated from the collected samples. Partial 16S sequences indicated that they were from six genera, including Brevibacterium, Curtobacterium, Kineococcus, Micromonospora, Mycobacterium, and Streptomyces. The isolate sp.01 showing 99.28% sequence similarity with a reference rare actinobacterial species Micromonospora aurantiaca ATCC 27029T was selected for whole genome sequencing. Organization of its gene clusters for secondary metabolite biosynthesis revealed 21 clusters encoded to antibiotic production, which is higher than other Micromonospora species. Of the genome-predicted antibiotics, kanamycin was found through guided MS/MS analysis producible by the M. aurantiaca strain for the first time. The present study highlighted that genomic analysis combined with MS/MS screening is a promising method to discover potential of antibiotic production from rare actinobacteria.

High-capacity reversible data hiding in encrypted images based on two-phase histogram shifting.

With the extensive use of cloud services in different applications, it's a problem for the cloud service provider to manage or process the privacy data that are encrypted by the content owner. Therefore, signal processing technology in the encrypted domain has attracted the attention of researchers. In this paper, we propose a new reversible data hiding method for encrypted images based on two-phase histogram shifting. In the proposed method, the original image is encrypted by using special image division and additive homomorphic encryption. After image encryption, the encrypted image can partially maintain spatial correlation for data embedding while the content security of the encrypted image is ensured. Due to the spatial correlation, the data hider can generate two difference histograms from the encrypted image, which provide high embedding capacity. A two-phase histogram shift scheme is used to embed the secret data into the two difference histograms. At the receiver side, the secret data can be extracted from the encrypted image or the decrypted image, and the image can be recovered to its original version without any error. The experimental results demonstrated that the proposed method can efficiently improve the capacity of data embedding and outperform other related methods, while the visual quality of the marked image can be maintained.

Genome-guided and mass spectrometry investigation of natural products produced by a potential new actinobacterial strain isolated from a mangrove ecosystem in Futian, Shenzhen, China.

Actinobacteria, a group of gram-positive bacteria, can produce plenty of valuable bioactive secondary metabolites, especially antibiotics. Hence, in order to search for new actinobacteria, actinobacterial isolates were obtained from rhizosphere soil collected from the Futian mangrove ecosystem in Shenzhen, China. According to 16S rRNA sequences, 14 actinobacterial strains of the genus Streptomyces, Rhodococcus, Microbacterium, Micromonospora, Actinoplanes and Mycobacterium were isolated and identified. Among these, strain Mycobacterium sp.13 was described as a potential new species belonging to the genus Mycobacterium within the class of actinobacteria according to the genomic analysis. The genome-based 16S rRNA sequences had 98.48% sequence similarity with Mycobacterium moriokaense DSM 44221T. Meanwhile, the genome sequences of Mycobacterium sp.13 showed an average nucleotide identity (ANI) with the Mycobacterium mageritense DSM 44476, Mycobacterium smegmatis MKD8 and Mycobacterium goodii strain X7B of only 74.79%, 76.12% and 76.42%, respectively. Furthermore, genome-mining results showed that Mycobacterium sp.13 contained 105 gene clusters encoding to the secondary metabolite biosynthesis, where many kinds of terpene, bacteriocin, T1pks, Nrps, saccharide, fatty acid, butyrolactone, ectoine and resorcinol were included. Finally, through LC-MS and HR-MS, analyzing the small molecules from ethyl acetate extract of this strain, asukamycin C and apramycin were for the first time found present to be in Mycobacterium moriokaense strain. Our study provides evidence in support of the potential new Mycobacterium sp.13 isolated from the mangrove environment as a possible novel source of natural products.

Photonic band gap in thin wire metamaterials.

We investigate the band structure of a class of photonic crystals made from only thin wires. Using a different method, we demonstrate that a complete photonic band gap is possible for such materials. Band gap materials normally consist of space filling dielectric or metal, whereas thin wires occupy a very small fraction of the volume. We show that this is related to the large increase in scattering at the Brillouin zone boundary. The method we developed brings together the calculation techniques in three different fields. The first is the calculation of scattering from periodic, tilted antennas, which we improve upon. The second is the standard technique for frequency selective surface design. The third is obtained directly from low energy electron diffraction theory. Good agreements with experiments for left handed materials, negative materials, and frequency selective surfaces are demonstrated.

Genome guided investigation of antibiotics producing actinomycetales strain isolated from a Macau mangrove ecosystem.

Actinomycetes are a heterogeneous group of gram positive filamentous bacteria that have been found to produce a wide range of valuable bioactive secondary metabolites, particularly antibiotics. Moreover, actinomycetes isolated from unexplored environments show an unprecedented potential to generate novel active compounds. Hence, in order to search for novel antibiotics, we isolated and characterized actinomycetes strains from plant samples collected from a mangrove in Macau. Within the class of actinobacteria, fourteen actinomycetes isolates have been isolated and identified belonging to the genus of Streptomyces, Micromonospora, Mycobacterium, Brevibacterium, Curtobacterium and Kineococcus based on their 16S rRNA sequences. Further whole genome sequencing analysis of one of the isolated Streptomyces sp., which presented 99.13% sequence similarity with Streptomyces parvulus strain 2297, showed that it consisted of 118 scaffolds, 8,348,559 base pairs and had a 72.28% G + C content. In addition, genome-mining revealed that the isolated Streptomyces sp. contains 109 gene clusters responsible for the biosynthesis of known and/or novel secondary metabolites, including different types of terpene, T1pks, T2pks, T3pks, Nrps, indole, siderophore, bacteriocin, thiopeptide, phosphonate, lanthipeptide, ectoine, butyrolactone, T3pks-Nrps, and T1pks-Nrps. Meanwhile, the small molecules present in ethyl acetate extract of the fermentation broth of this strain were analyzed by LC-MS. Predicted secondary metabolites of melanin and desferrioxamine B were identified and both of them were firstly found to be produced by the Streptomyces parvulus strain. Our study highlights that combining genome mining is an efficient method to detect potentially promising natural products from mangrove-derived actinomycetes.