Genomic insights into antimicrobial potential and optimization of fermentation conditions of pig-derived Bacillus subtilis BS21

Bacillus spp. have been widely used as probiotic supplements in animal feed as alternatives to antibiotics. In the present study, we screened a Bacillus subtilis strain named BS21 from pig feces. Antimicrobial activities, whole genome mining and UHPLC-MS/MS analysis were used to explore its antimicrobial mechanism. Strain BS21 showed Significant growth inhibition against a variety of animal pathogens, including Escherichia coli, Salmonella enterica Pullorum, Salmonella enterica Typhimurium, Citrobacter rodentium, Shigella flexneri and Staphylococcus aureus. Seven gene clusters involved in antimicrobial biosynthesis of secondary metabolites were encoded by strain BS21 genome, including four non-ribosomal peptides (bacillibactin, fengycin, surfactin and zwittermicin A), one ribosomal peptide (subtilosin A), one dipeptide (bacilysin) and one polyketide (bacillaene). Among them, production of surfactin, fengycin, bacillibactin, bacilysin and bacillaene was detected in the supernatant of B. subtilis strain BS21. To develop the potential application of BS21 in animal production, medium components and fermentation parameters optimization was carried out using response surface methodology (RSM). Production of antimicrobial secondary metabolites of strain BS21 was increased by 43.4%, and the best medium formula after optimization was corn flour 2%, soybean meal 1.7% and NaCl 0.5% with optimum culture parameters of initial pH 7.0, temperature 30°C, rotating speed at 220 rpm for 26 h. Our results suggested that strain BS21 has the potential for large-scale production and application as a potential source of probiotics and alternative to antibiotics for animal production

Reconfigurable Intelligent Computational Surfaces: When Wave Propagation Control Meets Computing

The envisioned sixth-generation (6G) of wireless networks will involve an intelligent integration of communications and computing, thereby meeting the urgent demands of diverse applications. To realize the concept of the smart radio environment, reconfigurable intelligent surfaces (RISs) are a promising technology for offering programmable propagation of impinging electromagnetic signals via external control. However, the purely reflective nature of conventional RISs induces significant challenges in supporting computation-based applications, e.g., wave-based calculation and signal processing. To fulfil future communication and computing requirements, new materials are needed to complement the existing technologies of metasurfaces, enabling further diversification of electronics and their applications. In this event, we introduce the concept of reconfigurable intelligent computational surface (RICS), which is composed of two reconfigurable multifunctional layers: the `reconfigurable beamforming layer' which is responsible for tunable signal reflection, absorption, and refraction, and the `intelligence computation layer' that concentrates on metamaterials-based computing. By exploring the recent trends on computational metamaterials, RICSs have the potential to make joint communication and computation a reality. We further demonstrate two typical applications of RICSs for performing wireless spectrum sensing and secrecy signal processing. Future research challenges arising from the design and operation of RICSs are finally highlighted

Efficient and Layer-Dependent Exciton Pumping across Atomically Thin Organic–Inorganic Type-I Heterostructures

The fundamental light–matter interactions in monolayer transition metal dichalcogenides might be significantly engineered by hybridization with their organic counterparts, enabling intriguing optoelectronic applications. Here, atomically thin organic–inorganic (O–I) heterostructures, comprising monolayer MoSe2 and mono‐/few‐layer single‐crystal pentacene samples, are fabricated. These heterostructures show type‐I band alignments, allowing efficient and layer‐dependent exciton pumping across the O–I interfaces. The interfacial exciton pumping has much higher efficiency (>86 times) than the photoexcitation process in MoSe2, although the pentacene layer has much lower optical absorption than MoSe2. This highly enhanced pumping efficiency is attributed to the high quantum yield in pentacene and the ultrafast energy transfer between the O–I interface. Furthermore, those organic counterparts significantly modulate the bindings of charged excitons in monolayer MoSe2 via their precise dielectric environment engineering. The results open new avenues for exploring fundamental phenomena and novel optoelectronic applications using atomically thin O–I heterostructures.The authors also acknowledge financial support from ANU Ph.D. student scholarship, China Scholarship Council, ANU Major Equipment Committee fund (No. 14MEC34), and Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) (DE140100805). ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), ANU node; this work is also supported by NSFC 61734003, 61521001 and National Key Basic Research Program of China 2015CB921600

Multivariate Analyses and Evaluation of Heavy Metals by Chemometric BCR Sequential Extraction Method in Surface Sediments from Lingdingyang Bay, South China

Sediments in estuary areas are recognized as the ultimate reservoirs for numerous contaminants, e.g., toxic metals. Multivariate analyses by chemometric evaluation were performed to classify metal ions (Cu, Zn, As, Cr, Pb, Ni and Cd) in superficial sediments from Lingdingyang Bay and to determine whether or not there were potential contamination risks based on the BCR sequential extraction scheme. The results revealed that Cd was mainly in acid-soluble form with an average of 75.99% of its total contents and thus of high potential availability, indicating significant anthropogenic sources, while Cr, As, Ni were enriched in the residual fraction which could be considered as the safest ingredients to the environment. According to the proportion of secondary to primary phases (KRSP), Cd had the highest bioavailable fraction and represented high or very high risk, followed by Pb and Cu with medium risks in most of samples. The combined evaluation of the Pollution Load Index (PLI) and the mean Effect Range Median Quotient (mERM-Q) highlighted that the greatest potential environmental risk area was in the northwest of Lingdingyang Bay. Almost all of the sediments had a 21% probability of toxicity. Additionally, Principal Component Analysis (PCA) revealed that the survey region was significantly affected by two main sources of anthropogenic contributions: PC1 showed increased loadings of variables in acid-soluble and reducible fractions that were consistent with the input from industrial wastes (such as manufacturing, metallurgy, chemical industry) and domestic sewages; PC2 was characterized by increased loadings of variables in residual fraction that could be attributed to leaching and weathering of parent rocks. The results obtained demonstrated the need for appropriate remediation measures to alleviate soil pollution problem due to the more aggregation of potentially risky metals. Therefore, it is of crucial significance to implement the targeted strategies to tackle the contaminated sediments in Lingdingyang Bay

Multivariate Analyses and Evaluation of Heavy Metals by Chemometric BCR Sequential Extraction Method in Surface Sediments from Lingdingyang Bay, South China

Sediments in estuary areas are recognized as the ultimate reservoirs for numerous contaminants, e.g., toxic metals. Multivariate analyses by chemometric evaluation were performed to classify metal ions (Cu, Zn, As, Cr, Pb, Ni and Cd) in superficial sediments from Lingdingyang Bay and to determine whether or not there were potential contamination risks based on the BCR sequential extraction scheme. The results revealed that Cd was mainly in acid-soluble form with an average of 75.99% of its total contents and thus of high potential availability, indicating significant anthropogenic sources, while Cr, As, Ni were enriched in the residual fraction which could be considered as the safest ingredients to the environment. According to the proportion of secondary to primary phases (KRSP), Cd had the highest bioavailable fraction and represented high or very high risk, followed by Pb and Cu with medium risks in most of samples. The combined evaluation of the Pollution Load Index (PLI) and the mean Effect Range Median Quotient (mERM-Q) highlighted that the greatest potential environmental risk area was in the northwest of Lingdingyang Bay. Almost all of the sediments had a 21% probability of toxicity. Additionally, Principal Component Analysis (PCA) revealed that the survey region was significantly affected by two main sources of anthropogenic contributions: PC1 showed increased loadings of variables in acid-soluble and reducible fractions that were consistent with the input from industrial wastes (such as manufacturing, metallurgy, chemical industry) and domestic sewages; PC2 was characterized by increased loadings of variables in residual fraction that could be attributed to leaching and weathering of parent rocks. The results obtained demonstrated the need for appropriate remediation measures to alleviate soil pollution problem due to the more aggregation of potentially risky metals. Therefore, it is of crucial significance to implement the targeted strategies to tackle the contaminated sediments in Lingdingyang Bay

Speciation of Metals and Assessment of Contamination in Surface Sediments from Daya Bay, South China Sea

The contents, speciation, source factors and potential ecological risks of the selected metals (Cr, Ni, Cu, Pb, Zn, Cd and As) were analyzed in surface sediments from Daya Bay (DYB). The results show that, with the exception of Pb, metal concentrations have decreased at all sites over the past decade. The distribution features of these concentrations represent a ring shape that descends from shore to bay by varying degrees. Speciation analysis showed that Cr, Ni, Cu, Zn and As exist mainly in the residual fraction and, thus, are of low bioavailability, while Cd and Pb were found to be abundant in the non-residual fraction and, thus, have high potential mobility. The ratio of heavy metals in non-residual form in descending order is Pb (78.83%), Cd (78.65%), Cu (48.54%), Zn (48.10%), Ni (38.31%), Cr (28.43%) and As (27.76%). The ratio of Pb content is the highest, meaning the highest mobility of Pb. The metals’ potential ecological risks to the environment were also assessed using the methods of the mean effect range-median quotient and the criteria of risk assessment code. The results showed that Cd presents the highest risk, and Pb and Cu are generally considered to be medium risks in the sub-basins of Daya Bay. The principal component analysis (PCA) revealed that natural coastal weathering and erosion of rock caused the highest input, followed by mariculture and industrial wastewater and, finally, domestic sewage discharge

A ~200 ka pollen record from Okinawa Trough: Paleoenvironment reconstruction of glacial-interglacial cycles

International audiencePollen analysis was carried out on the Core MD982194 of 29.78 m retrieved from the Middle Okinawa Trough which was dated as old as ~200 ka BP. The results revealed that pollen assemblages mainly presented an alternation of coniferous and herb pollen. The coniferous saccate pollen, principally Pinus and Tsuga, predominated in most parts of the core, especially highlighted in the interstadial stages including MIS 1,3, 5 and MIS7, whereas the herb pollen significantly increased in the gla- cial periods. Thus the pollen flora and their percentages showed the sensitive changes under the influence of ice volume during the glacial and interglacial periods. Our record from this core has first documented that the percentage of Cyperaceae was ex- tremely high in the glacial stages with a notable increase in Artemisia, Gramineae, Asteraceae, Chenopodiaceae, and freshwa- ter algae, which can be used as a proxy for sea-level change at the study site because of their close negative correlation of the orbital-scale changes in sea level. The distance between the continental coastline and the Okinawa Trough has deeply short- ened due to the sea-level drop in the LGM. As a result, the sediment materials from Yangtze River were extensively deposited on the flat, exposed continental shelf owing to the rapid decline of river flow speed, leading to that pollen grains from Okinawa Trough are derived mainly from the flat coastal vegetation of exposed continental shelf at glacial stages. Changes of pollen as- semblage were consistent with the variation of temperature and humidity, which showed that the percentage of arboreal pollen was highly augmented at MIS 7, 5 and MIS 1, corresponding to the strengthening of the East Asian summer monsoon and in- creasing of rainfall. Moreover, the peak of Pinus percentage in MIS 5.3, 5.1 and MIS 3.3 may be closely linked by orbital and sub-orbital cycles of solar radiation and monsoonal variability. The present study of core MD981294 implied lower tempera- ture and precipitation during the lowest sea-level stage (LGM), and more visibly testified that the vegetation of the flat plain on the exposed continental shelf was dominated by intrazonal communities such as halophyte grasslands and freshwater wetlands instead of zonal steppe or semi-arid desert. All above evidence demonstrated that the fundamental changes of pollen assem- blage and their origins in Okinawa Trough since ~200 ka BP were affected by combine factors including the coastline position and climate fluctuation. Moreover, the substantial shortening of distance between shoreline and the Okinawa Trough driven by orbital insolation cycles was clearly indicated by the pollen spectra, whereas the source-area climate signal of the pollen record was largely weakened

Reconstructing late Holocene vegetation and fire histories in monsoonal region of southeastern China

International audienceEastern subtropical China is a key region for understanding the variability of the East Asian Summer Monsoon (EASM). Multidisciplinary studies in southeastern China have shown that the summer monsoon intensity declined in the mid-late Holocene. We present a high-resolution pollen record of the last 4000 cal yr BP in Jinggang Mts of Jiangxi Province, southeastern China. The identified pollen taxa from the core can be statistically divided into three groups corresponding to evergreen, deciduous and wetland communities. The transitions between evergreen and deciduous-coniferous pollen associations is likely caused by temperature fluctuations, indicating that climate was relatively cool at 3800–3200 cal yr BP and 2200–1300 cal yr BP and warmer at 3200–2800 cal yr BP and 1300–800 cal yr BP. The vegetation study suggests that an Alnus-dominant association represents a secondary forest that usually takes place and expand after repeated forest fires. The charcoal concentration from the core depicts at least six major forest fire events since 4000 cal yr BP, most of which were followed by the development of an Alnus forest community. This result suggests that the EASM weakened toward the late Holocene and that its related decrease in moisture led to large forest wildfires. Furthermore, the rapid formation of a swamp and the subsequent development of the Alnus wetland community at ~ 550 cal yr BP suggest a gradual drying up of the lake, which was likely related to “the Little Ice Age”. As a result of a substantial burning related to an intensification of the human cultivation practices, Alnus reached its highest values in the last 200 years along with abundant wetland herbs, pioneer ferns (mainly Dicranopteris) and high charcoal concentrations. The present evidence of several sharp floristic and climate changes coincides with either the collapse or the beginning of some Chinese dynasties, which will need further research on the relationship between natural and human cultural changes