2022Äê1ÔÂ
Vegetation and land snail-based reconstruction of the palaeocological changes in the forest steppe eco-region of the Carpathian Basin during last glacial warming
P¨¢l S¨¹megi, D¨¢vid Moln¨¢r, Katalin N¨¢fr¨¢di, L¨¢szl¨® Mak¨®, P¨¦ter Cseh, T¨¹nde T?r?csik, Mih¨¢ly Moln¨¢r, Liping Zhou
Abstract
In the present work, well radiocarbon-dated Quaternary malacological and palynological analyses were implemented on 4 cm samples deriving from one of the thickest and best developed last glacial sequences of Central Europe the Madaras brickyard and the borehole of Kolon Lake in the southern part of Hungary. Using a combination of mollusc, anthracological, palynological and climatic proxies evidence preserved within loess, we demonstrate that long-term changes (e.g. the last 39,000 (28,000) years) in paleoclimatic dynamics on the northern edge of the Bacska-Titel loess plateau, on the southern part of the Great Hungarian Plain. These proxy data are reflected in the following ecological changes: a turnover from predominantly cold-tolerant mollusc fauna in a boreal type forest-steppe context under cold conditions during the last glacial then followed by a shift to a predominantly xerotheromphilous land snail fauna in a temperate forest-steppe context under a warm temperate climate in the early Holocene. Certain warm-adapted, Central and SSE European distribution mollusc species such as Caucasotachea vindobonensis and Granaria frumentum, were found to have been associated with temperate forest-steppe in both the Holocene record and the present-day ecosystem.
Source
GLOBAL ECOLOGY AND CONSERVATION
Volume33
DOI10.1016/j.gecco.2021.e01976
2022Äê2ÔÂ
An analytical model to predict the impact of a bullet on ultra-high molecular weight polyethylene composite laminates
Li Jintao, Liu Moubi
Abstract
High-performance fiber reinforced polymers are widely used in military and aerospace applications and easily subjected to high-velocity bullet impacts. Despite the abundantly available experimental and numerical studies related to energy absorption mechanisms of laminates under impact loading, measuring levels of the absorbed energy from different failure modes of laminates is a challenging task. Acquiring this important information using simplified analytical models is vital to evaluate the bulletproof ability of laminates and effectively optimize its structures. The present work develops an analytical model to predict the ballistic limit of a laminate and the energy absorption mechanism is considered from matrix crush, laminate shear, laminate compressive, fiber stretch, fiber break and delamination. The penetration process of a bullet striking laminates is divided into four sequential stages, including crush stage, compression-shear stage, stretch-shear stage, and fiber fracture and delamination stage. The analytical model predicts the ballistic limit, energy absorbed by each failure mode, and time histories of velocity and acceleration. The results are validated with experimental data and computational results, and good correlations are found for ballistic limits and thickness of the laminate, diameters of the deformation cone and thickness, ballistic limits, and non-dimension masses as well as energy absorptions and thicknesses.
Source
Composite Structures
Volume 282, 15 February 2022, 115064
2022Äê2ÔÂ
Type IV Pilus Shapes a 'Bubble-Burst' Pattern Opposing Spatial Intermixing of Two Interacting Bacterial Populations
Miaoxiao Wang, Xiaoli Chen, Yinyin Ma, Yue-Qin Tang, David R. Johnson, Yong Nie, Xiao-Lei Wu
Abstract
Microbes are social organisms that commonly live in sessile biofilms. Spatial patterns of populations within biofilms can be important determinants of community-level properties. Spatial intermixing emerging from microbial interaction is one of the best-studied characteristics of spatial patterns. The specific levels of spatial intermixing critically contribute to how the dynamics and functioning of such communities are governed. However, the precise factors that determine spatial patterns and intermixing remain unclear. Here, we investigated the spatial patterning and intermixing of an engineered synthetic consortium composed of two mutualistic Pseudomonas stutzeri strains that degrade salicylate via metabolic cross-feeding. We found that the consortium self-organizes across space to form a previously unreported spatial pattern (here referred to as a 'bubble-burst' pattern) that exhibits a low level of intermixing. Interestingly, when the genes encoding type IV pili were deleted from both strains, a highly intermixed spatial pattern developed and increased the productivity of the entire community. The intermixed pattern was maintained in a robust manner across a wide range of initial ratios between the two strains. Our findings show that the type IV pilus plays a role in mitigating spatial intermixing of different populations in surface-attached microbial communities, with consequences for governing community-level properties. These insights provide tangible clues for the engineering of synthetic microbial systems that perform highly in spatially structured environments.
IMPORTANCE When growing on surfaces, multispecies microbial communities form biofilms that exhibit intriguing spatial patterns. These patterns can significantly affect the overall properties of the community, enabling otherwise impermissible metabolic functions to occur as well as driving the evolutionary and ecological processes acting on communities. The development of these patterns is affected by several drivers, including cell-cell interactions, nutrient levels, density of founding cells, and surface properties. The type IV pilus is commonly found to mediate surface-associated behaviors of microorganisms, but its role on pattern formation within microbial communities is unclear. Here, we report that in a cross-feeding consortium, the type IV pilus affects the spatial intermixing of interacting populations involved in pattern formation and ultimately influences overall community productivity and robustness. This novel insight assists our understanding of the ecological processes of surface-attached microbial communities and suggests a potential strategy for engineering high-performance synthetic microbial communities.
Source
MICROBIOLOGY SPECTRUM
Volume10Issue1
DOI10.1128/spectrum.01944-21
2022Äê2ÔÂ
Drafting, kissing, and tumbling of a pair of particles settling in non-Newtonian fluids
Da Hui; Zhijing Xu; Wenbin Wu; Guiyong Zhang; Qian Wu; Moubin Liu
Abstract
The drafting, kissing, and tumbling (DKT) of a pair of particles in Newtonian fluids are frequently observed in particle sedimentations and have been well studied. However, sedimentation shows distinct behaviors when the particle pair is released in non-Newtonian fluids, and dynamics of the DKT have still not been completely understood. In this paper, the immersed boundary-lattice Boltzmann method with a hybrid multiple-relaxation-time scheme is used to examine the dynamics of the DKT of a pair of particles settling in non-Newtonian fluids. The particle pair is released in a confined channel filled with non-Newtonian fluids, in which the non-Newtonian behaviors of shearthinning/shear-thickening and yield stress are considered. The results demonstrate that the horizontal migration direction at the initial stage of the separation state in a shear-thinning fluid is totally different from that happening in a Newtonian fluid. It is attributed to the asymmetrical fluid viscosity on both sides of the pair of particles. Our findings also show that yield stress plays a dominant role in the sedimentation velocity and separation distance between the particles forming this pair. Under the effect of yield stress, three sedimentation structures, which correspond to different dynamic behaviors of the pair of particles, are also identified during the sedimentation. Furthermore, some critical conditions, regarding horizontal migration toward the right or left side, DKT/non-DKT and kissing/non-kissing states are established through the Bingham number (Bn)-power-law index (n) diagrams and tables. Also, the effect of the diameter ratio between two particles on the DKT is studied. Published under an exclusive license by AIP Publishing.
Source
PHYSICS OF FLUIDS
Volume34Issue2
DOI10.1063/5.0079491
2022Äê2ÔÂ
An immersed boundary-lattice Boltzmann method with hybrid multiple relaxation times for viscoplastic fluid-structure interaction problems
Da Hui, Zekun Wang, Yunan Cai, Wenbin Wu, Guiyong Zhang, Moubin Liu
Abstract
Existing studies of fluid-structure interaction (FSI) in ocean engineering mainly focus on the interaction between Newtonian fluids and structure. The FSI problems involving non-Newtonian fluids, especially viscoplastic fluids, have rarely been studied while the inherent dynamic behavior is not clear. In this paper, an immersed boundary-lattice Boltzmann method (IB-LBM) is developed for numerical investigations on FSI problems involving visco-plastic fluids. The present IB-LBM is integrated with a hybrid multiple relaxation times (MRT) scheme where different diagonal relaxation matrices are used for modeling Newtonian and non-Newtonian fluids, and are combined in a hybrid manner using a step function to achieve smooth transition for Newtonian to non-Newtonian fluid behavior at the FSI area. Four benchmark problems are used to validate the IB-LBM with hybrid MRT scheme. It is demonstrated that the numerical model can avoid numerical instability when modeling viscoplastic fluid flow and reduce the numerical boundary slip in the IB-LBM. The numerical model is further used to study the viscoplastic fluid flow around a fixed and moving cylinder (or particle). We show that the present IB-LBM with the hybrid MRT scheme is effective in modeling FSI involving viscoplastic fluids while the obtained phenomena are quite different from those with Newtonian fluids.
Source
APPLIED OCEAN RESEARCH
Volume119
DOI10.1016/j.apor.2021.103023
2022Äê2ÔÂ
Layering and vertical transport in sheared double-diffusive convection in the diffusive regime
Yantao Yang,Roberto Verzicco,Detlef Lohse and C.P. Caulfield
Abstract
A sequence of two- and three-dimensional simulations are conducted for the double-diffusive convection (DDC) flows in the diffusive regime subjected to an imposed shear. For a wide range of control parameters, and for sufficiently strong perturbation of the conductive initial state, staircase-like structures spontaneously develop, with relatively well-mixed layers separated by sharp interfaces of enhanced scalar gradient. Such staircases appear to be robust even in the presence of strong shear over very long times, with early-time coarsening of the observed layers. For the same set of control parameters, different asymptotic layered states, with markedly different vertical scalar fluxes, can arise for different initial perturbation structures. The imposed shear significantly spatio-temporally modifies the vertical transport of the various scalars. The flux ratio gamma* (i.e. the ratio between the density fluxes due to the total salt flux and the total heat flux) is found, at steady state, to be essentially equal to the square root of the ratio of the salt diffusivity to the thermal diffusivity, consistent with the physical model proposed by Linden & Shirtcliffe (J. Fluid Mech., vol. 87, 1978, pp. 417-432) and the variational arguments presented by Stern (J. Fluid Mech., vol. 114, 1982, pp. 105-121) for unsheared double-diffusive convection.
Source
JOURNAL OF FLUID MECHANICS
Volume933
DOI10.1017/jfm.2021.1091
2022Äê2ÔÂ
Source apportionment of carbonaceous aerosols in diverse atmospheric environments of China by dual-carbon isotope method
Mengren Li, Min Hu, Jennifer Walker, Pan Gao, Xin Fang, Nan Xu, Yanhong Qin, Liping Zhou, Kexin Liu, Claudia I. Czimczik, Xiaomei Xu
Abstract
Carbonaceous aerosols are major components in PM2.5 of both polluted and clean atmosphere. Accurate source apportionment of carbonaceous aerosols may support effective PM2.5 control. Dual-carbon isotope method (14C and 13C) was adopted to identify the contribution of three main air pollution sources biogenic and biomass (fbb), liquid fossil (fliq.fossil) and coal (fcoal). The aerosol samples were collected at three types of sites with distinctly different degree of air pollution: urban, rural and regional background. The seasonal variation of source apportionment of the carbonaceous aerosols in urban Beijing was discussed. Modern biogenic and biomass made an absolute dominance of 92.9 ¡À 0.5% contribution to the carbonaceous aerosols at the background site Mt. Yulong due to long-range transport from Southeast Asia. The three main sources contributed jointly to the atmospheric carbonaceous aerosols at the rural site Wangdu and the urban site Beijing. The biogenic and biomass source was the major contribution in summer (47.0 ¡À 0.3%) and autumn (49.3 ¡À 0.3%) of Beijing, while coal source increased from summer (26.8 ¡À 13.8%) to autumn (34.7 ¡À 11.5%). Heating significantly increased the coal source to the dominant contribution (47.0 ¡À 16.9%) in winter of Beijing. Separate day and night time coal contributions were used to evaluate the two origins of coal combustion: industrial use vs. residential use. The results of source apportionment for carbonaceous aerosols provide scientific support for the prevention and control of air pollution.
Source
Science of The Total Environment
Volume 806, Part 2, 2022, 150654, ISSN 0048-9697
https://doi.org/10.1016/j.scitotenv.2021.150654.
2022Äê3ÔÂ
Preliminary evaluation of the economic potential of the technologies for gas hydrate exploitation
Xuejun Chen, Hailong Lu, Lijuan Gu, Shilong Shang, Yi Zhang, Xin Huang, Le Zhang
Abstract
Several trial productions of natural gas hydrate (NGH) on onshore and offshore reservoirs have been implemented, signaling the start of the stage of technology development for its industrial exploitation. Several methods for NGH exploitation have been proposed, but none of them has been verified applicable to the commercial exploitation of NGH. The applicability of a technology to NGH exploitation is subject to the evaluation of its economic potential, but unfortunately few relevant studies have been conducted. In this research, each exploitation technology for NGH is evaluated for its economic potential as referring to the break-even production rate with energy return on investment (EROI) analysis. Sensitivity analysis is also performed to specify the effect of each key factor, such as gas production rate, gas-water ratio, efficiency of thermal stimulation, injection-production ratio for the methods of chemical injection or CO2 replacement, on the standard EROI. The results obtained indicate that depressurization is the most promising method, because on it the lowest critical production rate would be required for commercial exploitation of NGH, ranging from 0.16 to 0.25 million m3/day/well. Comparing with other unconventional oil and gas, the commercial exploitation of NGH still relies on further technological breakthroughs, especially those for the improvement of production rate. (c) 2021 Elsevier Ltd. All rights reserved.
Source
ENERGY
Volume243
DOI10.1016/j.energy.2021.123007
2022Äê3ÔÂ
High PM2.5 Emission from Typical Old, Small Fishing Vessels in China
Lizhi Wang, Wei Du, Yilin Chen*, Wei Wang, Yuanchen Chen, Xi Zhu, Bin Peng, Xiao Yun, Xuechan Li, Huizhong Shen, Guofeng Shen, Junfeng Liu, Xuejun Wang, Shu Tao
Abstract
Old, small fishing vessels (OSFVs) account for a considerable proportion of the fishing fleet in China, the world's top fishery country. Exhaust from OSFVs is often poorly controlled, but because of a lack of measurements, the magnitudes of OSFVs' emissions in China remain unclear. In this study, we measured real-world PM2.5 emission factors (EFs) from three typical OSFVs, together with other commonly used offshore vessels, in Hainan, China. The average PM2.5 EF for OSFVs is 71.7 (37.3-92.7) g.(kg fuel)(-1), which is 4-10 times greater than the average of other types of vessels and an order of magnitude greater than commonly adopted shipping EFs in the literature. Annual PM(2.5 )emission from OSFVs was estimated to be 2.13 (1.18-2.86) kt in Hainan in 2017, comparable to the level of on-road mobile emission there. Our results show that OSFVs are possibly a group of "super-emitters" among marine vessels, which are underrepresented in the shipping emission inventories. Prioritizing regulations for OSFVs is a viable option to mitigate ambient PM2.5 pollution in Hainan as well as in other coastal regions with active small-scale fisheries in low-income communities.
Source
ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS
Volume9Issue3Page199-204
DOI10.1021/acs.estlett.1c00927
2022Äê3ÔÂ
On-site measured emission factors of polycyclic aromatic hydrocarbons for different types of marine vessels
Lizhi Wang, Wei Du, Xiao Yun, Yuanchen Chen, Xi Zhu, Huizhong Shen, Guofeng Shen, Junfeng Liu, Xuejun Wang, Shu Tao
Abstract
A portable emission sampling system was used to perform on-site measurements of the emission factors (EFs; quantities of pollutants emitted per unit of energy consumed) of 29 polycyclic aromatic hydrocarbons (PAHs) for five types of marine vessels using light diesel in Hainan Province, China. Both gaseous- and particulate-phase PAHs from vessel emissions were sampled and measured using gas chromatography coupled with mass spectrometry (GC-MS), and the PAH EFs were calculated based on the carbon mass balance method. The average EFs of gaseous- and particulate-phase PAHs were 6.2 +/- 7.8 and 17 +/- 26 mg/kg, with naphthalene (NAP) and phenanthrene (PHE) dominating the gaseous- and particulate-phase PAH emissions, respectively. Among the five types of vessels, the EFs for small fishing boats were significantly higher than those for other types of vessels, and the lowest EFs were found for tug boats. Composition profiles and typical isomer ratios of PAHs were calculated for five types of vessels. Particulate-phase PAHs accounted for 63 +/- 16% of the total emissions of 29 PAH species, and the particulate/gaseous-phase partitioning of PAHs was dominated by organic carbon (OC) absorption rather than black carbon (BC) adsorption. Emission factors of PAHs under different activity conditions were measured and calculated, and relatively higher EFs were found in the maneuvering mode for medium fishing boats and in the operating mode for engineering vessels. No significant differences were found among the PAH composition profiles under different activity conditions.
Source
ENVIRONMENTAL POLLUTION
Volume297
DOI10.1016/j.envpol.2021.118782
2022Äê4ÔÂ
Electric Sense Based Pose Estimation and Localization for Small Underwater Robots
Junzheng Zheng; Chayutpon Huntrakul; Xin Guo; Chen Wang; Guangming Xie
Abstract
Accurate pose estimation and localization technology is always a challenge for small underwater robots, since the underwater lighting conditions could limit the use of cameras while the cramped environments restrict the use of sonars. In nature, some fishes perceive other creatures by sensing the weakly changes in their environmental electric field. Inspired by such passive electric sense behavior in fish, this letter presents an electro-localization scheme based on passive electric sense for short-distance accurate pose estimation and localization of small underwater robots. Our scheme includes a hardware solution to the electric sense and a pose estimation method. Specifically, first, we design a hardware solution including an electric emitter placed in the underwater environment and an electric receiver that can be carried by a small underwater robot. Then we construct the theoretical model of the electric field generated by our designed hardware. Finally, we propose an electric sense based method to estimate the position and orientation of the free-swimming robot, where a particle filter is utilized to combine the odometer and electric sense based measurements while the dynamic model of the robot is also included. Localization experiments for the small underwater robot equipped with the electric receiver are conducted, and the experimental results demonstrate the robustness and effectiveness of our proposed electric sense based pose estimation approach, especially in position estimation.
Source
IEEE Robotics and Automation Letters ( Volume: 7, Issue: 2, April 2022)
Page(s): 2835 - 2842
DOI: 10.1109/LRA.2022.3145094
2022Äê4ÔÂ
Sclerotiamides C-H, Notoamides from a Marine Gorgonian-Derived Fungus with Cytotoxic Activities
Xiang Guo, Qinyu Meng, Jie Liu, Jingshuai Wu, Hongli Jia, Dong Liu, Yucheng Gu, Jianrong Liu, Jian Huang, Aili Fan, Wenhan Lin
Abstract
Bioassay-guided fractionation in association with LC-MS and NMR detection led to the isolation of six new alkaloids, sclerotiamides C-H (1-6), from the marine gorgonian-derived fungus Aspergillus sclerotiorum LZDX-33-4. Their structures were determined from extensive spectroscopic data, including ECD data and single-crystal X-ray diffraction analysis for configurational assignments. Sclerotiamides C (1) and D (2) are notoamide-type alkaloids with the incorporation of a unique 2,2-diaminopropane unit, and sclerotiamides E (3) and F (4) are unprecedented notoamide hybrids with a new coumarin unit. Sclerotiamide H (6) represents a new highly oxidized notoamide scaffold. Sclerotiamides C and F showed significant inhibition against a panel of tumor cell lines with IC50 values ranging from 1.6 to 7.9 mu M. Sclerotiamide C induces apoptosis in HeLa cells by arresting the cell cycle, activating ROS production, and regulating apoptosis-related proteins in the MAPK signaling pathway. The present study extends the scaffold diversity of the notoamides and provides a potential lead for the development of a cytotoxic agent.
Source
JOURNAL OF NATURAL PRODUCTS
Volume85Issue4Page1067-1078
DOI10.1021/acs.jnatprod.1c01194
2022Äê4ÔÂ
Comparative transcriptome analysis reveals different adaptation mechanisms for degradation of very long-chain and normal long-chain alkanes in Dietzia sp. DQ12-45-1b
Hong-Xiu Xu; Yue-Qin Tang; Nie, Yong; Xiao-Lei Wu
Abstract
Hydrocarbon-degrading bacteria typically metabolize a broad range of alkane substrates, but global metabolic characteristics of strains growing on alkane substrates in different chain lengths remain unclear. In this study, we analysed the transcriptional profiles of a hydrocarbon degrading bacterium, Dietzia sp. DQ12-45-1b, during growth on octacosane (C28), hexadecane (C16) and glucose as the sole carbon sources. Our results highlight that C16 and C28 induced common genes of core alkane degradation pathways in DQ12-45-1b, whereas transcriptional patterns of genes related to lipid metabolism, energy metabolism, biomass synthesis, and metal ion transportation were distinct. In addition, the transcriptional differences of genes related to glyoxylate shunt (GS) as well as growth phenotypes of mutant strain with defects in GS demonstrated that GS is essential for C16 degradation, though it is dispensable for C28 degradation in DQ12-45-1b. These results demonstrate that DQ12-45-1b cells exhibited considerable metabolic flexibility by using various mechanisms during growth on alkane substrates in different chain lengths. This study advances our knowledge of microbial hydrocarbon degradation and provides valuable information for the application of alkane-degrading bacteria in bioremediation and microbial enhanced oil recovery.
Source
ENVIRONMENTAL MICROBIOLOGY
Volume24Issue4Page1932-1945
DOI10.1111/1462-2920.15928
2022Äê4ÔÂ
Economic Critical Resources for the Industrial Exploitation of Natural Gas Hydrate
Xuejun CHEN, Hailong LU, Jiecheng ZHANG, Jianliang YE, Wenwei XIE
Abstract
Since the implementation of several pilot production tests were in natural gas hydrate (NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for industrial exploitation. Prior to the industrial exploitation of any given NGH reservoir, the economic feasibility should be examined. The first step of economic evaluation of a NGH reservoir is to know whether its resource amount meets the requirement for industrial exploitation. Unfortunately, few relevant studies have been conducted in this regard. In this study, the net present value (NPV) method is employed to estimate the economic critical resources required for the industrial exploitation of NGHs under different production scenarios. Sensitivity analysis is also performed in order to specify the effects of key factors, such as the number of production wells, gas price, technological improvement and tax incentive, on the economic critical resources. The results indicate that China requires the lowest economic critical resource for a NGH reservoir to be industrially exploited, ranging from 3.62 to 24.02 billion m(3) methane. Changes in gas price and tax incentives also play significant roles in affecting the threshold and timeline for the industrial exploitation of NGH.
Source
ACTA GEOLOGICA SINICA-ENGLISH EDITION
Volume96Issue2Page663-673
DOI10.1111/1755-6724.14927
2022Äê6ÔÂ
Glowing Sucker Octopus (Stauroteuthis syrtensis)-Inspired Soft Robotic Gripper for Underwater Self-Adaptive Grasping and Sensing
Mingxin Wu, Xingwen Zheng, Ruosi Liu, Ningzhe Hou, Waqar Hussain Afridi, Rahdar Hussain Afridi, Xin Guo, Jianing Wu, Chen Wang, Guangming Xie
Abstract
A soft gripper inspired by the glowing sucker octopus (Stauroteuthis syrtensis)¡¯ highly evolved grasping capability enabled by the umbrella-shaped dorsal and ventral membrane between each arm is presented here, comprising of a 3D-printed linkage mechanism used to actuate a modular mold silicone-casting soft suction disc to deform. The soft gripper grasp can lift objects using the suction generated by the pump in the soft disc. Moreover, the protruded funnel-shaped end of the deformed suctorial mouth can adapt to smooth and rough surfaces. Furthermore, when the gripper contacts the submerged target objects in a turbid environment, local suctorial mouth arrays on the suction disc are locked, causing the variable flow inside them, which can be detected as a tactile perception signal to the target objects instead of visual perception. Aided by the 3D-printed linkage mechanism, the soft gripper can grasp objects of different shapes and dimensions, including flat objects, objects beyond the grasping range, irregular objects, scattered objects, and a moving turtle. The results report the soft gripper's versatility and demonstrate the vast application potentials of self-adaptive grasping and sensing in various environments, including but are not limited to underwater, which is always a key challenge of grasping technology.
Source
Advanced Science
Volume9, Issue17
June 13, 2022
2104382https://doi.org/10.1002/advs.202104382
2022Äê6ÔÂ
Substrate availability and toxicity shape the structure of microbial communities engaged in metabolic division of labor
Miaoxiao Wang, Xiaoli Chen, Yue-Qin Tang, Yong Nie, Xiao-Lei Wu
Abstract
Metabolic division of labor (MDOL) represents a widespread natural phenomenon, whereby a complex metabolic pathway is shared between different strains within a community in a mutually beneficial manner. However, little is known about how the composition of such a microbial community is regulated. We hypothesized that when degradation of an organic compound is carried out via MDOL, the concentration and toxicity of the substrate modulate the benefit allocation between the two microbial populations, thus affecting the structure of this community. We tested this hypothesis by combining modeling with experiments using a synthetic consortium. Our modeling analysis suggests that the proportion of the population executing the first metabolic step can be simply estimated by Monod-like formulas governed by substrate concentration and toxicity. Our model and the proposed formula were able to quantitatively predict the structure of our synthetic consortium. Further analysis demonstrates that our rule is also applicable in estimating community structures in spatially structured environments. Together, our work clearly demonstrates that the structure of MDOL communities can be quantitatively predicted using available information on environmental factors, thus providing novel insights into how to manage artificial microbial systems for the wide application of the bioindustry.
Source
MLIFE
Volume1Issue2Page131-145
DOI10.1002/mlf2.12025
2022Äê7ÔÂ
Simple agents, smart swarms: a cooperative search algorithm for swarms of autonomous underwater vehicles
Xiong, Minglei; Xie, Guangming
Abstract
Searching within an unknown environment quickly by utilising a small number of high-capacity robots or a large number of low-cost robots poses an endless question with a non-trivial answer. If the robot's operating environment is underwater, the problem becomes even more complicated due to its three-dimensional nature and the communication restrictions. In this paper, we propose an algorithm appropriate for target searching in unknown underwater environments. The proposed method considers a homogeneous decentralised multi-robot coordination scheme applied from a single-robot configuration to a large swarm. In this model, simple agents (SA) form smart swarms (SS), despite SA do not need to have a strong ability to transmit search and location information, and the SS can efficiently perform search tasks in unknown environments. Specifically, when a swarm performs a search task, agents only search according to the simple strategy and share mapping information within their communication range, enhancing search efficiency. Simulation results demonstrate the effectiveness and that search time reduces proportionally by increasing the number of robots comprising the swarm, while the repetition search rate does not increase with the expansion of the swarm size. We believe that our SS architecture provides insights into the future application of swarm intelligence.
Source
INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE
Volume53Issue9Page1995-2009
DOI10.1080/00207721.2022.2032465
2022Äê9ÔÂ
Even allocation of benefits stabilizes microbial community engaged in metabolic division of labor
Miaoxiao Wang, Xiaoli Chen, Xiaonan Liu, Yuan Fang, Xin Zheng, Ting Huang, Yue-Qin Tang, Martin Ackermann, Yong Nie, Xiao-Lei Wu
Abstract
Microbial communities execute metabolic pathways to drive global nutrient cycles. Within a community, functionally specialized strains can perform different yet complementary steps within a linear pathway, a phe-nomenon termed metabolic division of labor (MDOL). However, little is known about how such metabolic be-haviors shape microbial communities. Here, we derive a theoretical framework to define the assembly of a community that degrades an organic compound through MDOL. The framework indicates that to ensure community stability, the strains performing the initial steps should hold a growth advantage (m) over the "pri-vate benefit"(n) of the strain performing the last step. The steady-state frequency of the last strain is then determined by the quotient of n and m. Our experiments show that the framework accurately predicts the assembly of our synthetic consortia that degrade naphthalene through MDOL. Our results provide insights for designing and managing stable microbial systems for metabolic pathway optimization.
Source
CELL REPORTS
Volume40Issue13
DOI10.1016/j.celrep.2022.111410
2022Äê9ÔÂ
The Bacterial MtrAB Two-Component System Regulates the Cell Wall Homeostasis Responding to Environmental Alkaline Stress
Xiaoyu Qin, Kaiduan Zhang, Yuzhao Fan, Hui Fang, Yong Nie, Xiao-Lei Wu
Abstract
Throughout the course of evolution, bacteria have developed signal transduction tools such as two-component systems (TCSs) to meet their demands to thrive even under the most challenging environmental conditions. One TCS called MtrAB is commonly found in Actinobacteria and is implicated in cell wall metabolism, osmoprotection, cell proliferation, antigen secretion, and biosynthesis of secondary metabolites. However, precisely how the MtrAB TCS regulates the bacterial responses to external environments remains unclear. Here, we report that the MtrAB TCS regulates the cell envelope response of alkali-tolerant bacterium Dietzia sp. strain DQ12-45-1b to extreme alkaline stimuli. We found that under alkaline conditions, an mtrAB mutant exhibited both reduced growth and abnormal morphology compared to the wild-type strain. Electrophoretic mobility shift assay analysis showed that MtrA binds the promoter of the mraZ gene critical for cell wall homeostasis, suggesting that MtrA directly controls transcription of this regulator. In conclusion, our findings demonstrate that MtrAB TCS is involved in controlling the bacterial response to alkaline stimuli by regulating the expression of the cell wall homeostasis regulator MraZ in Dietzia sp. DQ12-45-1b, providing novel details critical for a mechanistic understanding of how cell wall homeostasis is controlled. IMPORTANCE Microorganisms can be found in most extreme environments, and they have to adapt to a wide range of environmental stresses. The two-component systems (TCSs) found in bacteria detect environmental stimuli and regulate physiological pathways for survival. The MtrAB TCS conserved in Corynebacterineae is critical for maintaining the metabolism of the cell wall components that protects bacteria from diverse environmental stresses. However, how the MtrAB TCS regulates cell wall homeostasis and adaptation under stress conditions is unclear. Here, we report that the MtrAB TCS in Dietzia sp. DQ12-45-1b plays a critical role in alkaline resistance by modulating the cell wall homeostasis through the MtrAB-MraZ pathway. Thus, our work provides a novel regulatory pathway used by bacteria for adaptation and survival under extreme alkaline stresses.
Microorganisms can be found in most extreme environments, and they have to adapt to a wide range of environmental stresses. The two-component systems (TCSs) found in bacteria detect environmental stimuli and regulate physiological pathways for survival.
Source
MICROBIOLOGY SPECTRUM
Volume10Issue5
DOI10.1128/spectrum.02311-22
2022Äê10ÔÂ
The Roles of the Two-Component System, MtrAB, in Response to Diverse Cell Envelope Stresses in Dietzia sp. DQ12-45-1b
Xiaoyu Qin, Kaiduan Zhang, Yong Nie, Xiao-Lei Wu
Abstract
Two-component systems (TCSs) act as common regulatory systems allowing bacteria to detect and respond to multiple environmental stimuli, including cell envelope stress. The MtrAB TCS of Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance, and thus is found to be highly conserved across this phylum. However, how precisely the MtrAB TCS regulates cellular homeostasis in response to environmental stress remains unclear. Here, we show that the MtrAB TCS plays an important role in the tolerance to different types of cell envelope stresses, including environmental stresses (i.e., oxidative stress, lysozyme, SDS, osmotic pressure, and alkaline pH stresses) and envelope-targeting antibiotics (i.e., isoniazid, ethambutol, glycopeptide, and beta-lactam antibiotics) in Dietzia sp. DQ12-45-1b. An mtrAB mutant strain exhibited slower growth compared to the wild-type strain and was characterized by abnormal cell shapes when exposed to various environmental stresses. Moreover, deletion of mtrAB resulted in decreased resistance to isoniazid, ethambutol, and beta-lactam antibiotics. Further, Cleavage under targets and tagmentation sequencing (CUT&Tag-seq) and electrophoretic mobility shift assays (EMSAs) revealed that MtrA binds the promoters of genes involved in peptidoglycan biosynthesis (ldtB, ldtA, murJ), hydrolysis (GJR88_03483, GJR88_4713), and cell division (ftsE). Together, our findings demonstrated that the MtrAB TCS is essential for the survival of Dietzia sp. DQ12-45-1b under various cell envelope stresses, primarily by controlling multiple downstream cellular pathways. Our work suggests that TCSs act as global sensors and regulators in maintaining cellular homeostasis, such as during episodes of various environmental stresses. The present study should shed light on the understanding of mechanisms for bacterial adaptivity to extreme environments. IMPORTANCE The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions. The two-component system (TCS) is the main sensing and responding apparatus for environmental adaptation. The MtrAB TCS highly conserved in Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance. However, how MtrAB works with regard to signals impacting changes to the cell envelope is not fully understood. Here, we found that in the Actinobacterium Dietzia sp. DQ12-45-1b, a TCS named MtrAB is pivotal for ensuring normal cell growth as well as maintaining proper cell morphology in response to various cell envelope stresses, namely, by regulating the expression of cell envelope-related genes. Our findings should greatly advance our understanding of the adaptive mechanisms responsible for maintaining cell integrity in times of sustained environmental shocks.
The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions.
Source
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
Volume88Issue20
DOI10.1128/aem.01337-22
2022Äê11ÔÂ
Prenylated notoamide-type alkaloids isolated from the fungus Aspergillus sclerotiorum and their inhibition of NLRP3 inflammasome activation and antibacterial activities
Qinyu Meng, Xiang Guo, Jingshuai Wu, Dong Liu, Yucheng Gu, Jian Huang, Aili Fan, Wenhan Lin
Abstract
Notoamides are a family of prenylated indole alkaloids with unusual ring systems and possessing a range of significant pharmaceutical activities. Based on LC-MS/MS and genome orientations, ten undescribed notoamide-type alkaloids namely sclerotiamides I-R were isolated from a marine gorgonian-derived fungus Aspergillus sclerotiorum LZDX-33-4. Their structures were determined by extensive spectroscopic data, in association with ECD data and single-crystal X-ray diffraction for configurational assignments. Bioassays resulted in sclerotiamide J along with five analogs possessing inhibitory effects against LDH and IL-1 beta expression in BV-2 cells. Further investigation revealed that sclerotiamide J significantly inhibited NLRP3 inflammasome activation and blocked NLRP3 inflammasome-induced pyroptosis via amelioration of mitochondria damage. In addition, sclerotiamide L exhibited potent inhibition against pathogenic Staphylococcus aureus ATCC 29213 with MIC value of 4.0 mu M and the growth of MRSA T144 and Enterococcus faecalis ATCC 29212. This study extends the chemical diversity of notoamide-type alkaloids, and provides potential anti-inflammasome and antibacterial lead compounds for further structure optimization.
Source
PHYTOCHEMISTRY
Volume203
DOI10.1016/j.phytochem.2022.113424
2022Äê11ÔÂ
Eremophilane-Type Sesquiterpenes from a Marine-Derived Fungus Penicillium Copticola with Antitumor and Neuroprotective Activities
Zhang, Jianping; Liu, Dong; Fan, Aili; Huang, Jian; Lin, Wenhan
Abstract
Chemical examination of a marine sponge-associated Penicillium copticola fungus resulted in the isolation of ten undescribed eremophilanes, namely copteremophilanes A-J (1-10), along with two new glycosides, 5-glycopenostatin F (11) and 5-glucopenostatin I (12). Their structures were determined by extensive spectroscopic data, in association with ECD data and chemical conversions for configurational assignments. Analogs 1, 2, and 10 represent a group of uncommon skeletons of eremophilanes with an aromatic ring and a methyl migration from C-5 to C-9, and analogs 11 and 12 are characteristic of a PKS scaffold bearing a glucose unit. The incorporation of a chlorinated phenylacetic unit in 3-9 is rarely found in nature. Analog 7 showed neuroprotective effect, whereas 8 exhibited selective inhibition against human non-small cell lung cancer cells (A549). This study enriched the chemical diversity of eremophilanes and extended their bioactivities to neuroprotection.
Source
MARINE DRUGS
Volume20Issue11
DOI10.3390/md20110712
2022Äê11ÔÂ
Acorane sesquiterpenes from the deep-sea derived Penicillium bilaiae fungus with anti-neuroinflammatory effects
Wenfang Zhang, Qingyu Meng, Jingshuai Wu, Wei Cheng, Dong Liu, Jian Huang, Aili Fan, Jing Xu, Wenhan Lin
Abstract
Acorane-type sesquiterpenes comprise a unique class of natural products with a range of pharmaceutical effects. Genome sequencing and gene annotation, along with qRT-PCR detection, demonstrate that the deep-sea derived Penicillium bilaiae F-28 fungus shows potential to produce acorane sesquiterpenes. Chromatographic manipulation resulted in the isolation of 20 acorane sesquiterpenes from the large-scale fermented fungal strain. Their structures were established by the interpretation of spectroscopic data, together with X-ray diffraction, chemical conversion, and ECD data for configurational assignments. A total of 18 new sesquiterpenes, namely, bilaiaeacorenols A-R (1-18), were identified. Bilaiaeacorenols A and B represent structurally unique tricyclic acoranes. Compound 18 exhibited efficient reduction against NO production in LPS-induced BV-2 macrophages in a dose-dependent manner, and it abolished LPS-induced NF-kappa B in the nucleus of BV-2 microglial cells. In addition, marked reductions of iNOS and COX-2 in protein and mRNA levels were observed. This study extends the chemical diversity of acorane-type sesquiterpenoids and suggests that compound 18 is a promising lead for anti-neuroinflammation.
Source
FRONTIERS IN CHEMISTRY
Volume10
DOI10.3389/fchem.2022.1036212
2022Äê11ÔÂ
Single-Cell-Based High-Throughput Cultivation and Functional Characterization of Biosurfactant-Producing Bacteria from Soil and Oilfield-Produced Water
Ying Xu, Yali Jing, Yaqian Zhang, Qingjie Liu, Jianlong Xiu, Ke Zhang, Ninghong Jia, Minghui Zhou, Xinyu Zhou ¡ Xiao-Lei Wu
Abstract
Biosurfactants are a group of surface-active compounds that can be produced by diverse microorganisms. They have been widely used in various industrial fields. Reducing production costs, improving efficiency, and collecting more diverse producing strains have become major challenges in the biosurfactant industry. These challenges could be overcome by screening for more diverse and efficient biosurfactant-producing strains. The conventional methods for the isolation and functional characterization of microorganisms are laborious and biased toward fast-growing or strongly competitive microorganisms. Here, we established a high-throughput approach of single-cell-based cultivation and functional characterization of biosurfactant-producing bacteria (SCCBB). This approach combines single-cell cultivation with the detection of optical distortions. Using this approach, we isolated 431 strains with biosurfactant production potential from petroleum-contaminated soil and oilfield-produced water. The surfactant production capabilities of the strains were subsequently validated using surface tension measurements, TLC, and CMC measurements. To investigate the industrial production potential, we optimized the production conditions of a representative glycolipids-producing strain, Pseudomonas sp. L01, using response surface methodology (RSM). Optimal conditions yielded a crude biosurfactant yield of 8.43 g/L in a flask. Our work provides a high-throughput approach to the isolation and screening of biosurfactant-producing bacteria, as well as other functional bacteria in a wide range of fields.
Source
MICROORGANISMS
Volume10Issue11
DOI10.3390/microorganisms10112216
2022Äê11ÔÂ
Development of an underwater networking system using bio-inspired electrocommunication
Han Zhang, Wei Wang, Qinghao Wang, Chen Wang and Guangming Xie
Abstract
Current underwater communication typically includes acoustic, optical, radio frequency, and magneto-inductive channels. Wireless sensor networks are usually built on these four channels. However, these underwater networks are vulnerable to complex aquatic environments. In nature, weakly electric fish are able to communicate electrically (called electrocommunication), which is 'invisible' to most other animals, to convey information such as species, courtship, and environmental conditions. Inspired by the electrocommunication of weakly electric fish, an artificial electrocommunication system that uses an electric induction (EI) channel has been developed recently. This paper further develops an underwater networking system using the EI channel, which addresses the solutions to collision avoidance and routing problems during electrocommunication networking. In particular, a CSMA/CA-based electrocommunication mechanism was used to solve the collision problem. Then, a single-hop underwater electrocommunication network (UEN) was established. Furthermore, a complex multi-hop UEN was implemented on the basis of the ad hoc on-demand distance vector routing protocol. Theoretical analysis, simulations, and experiments were conducted to demonstrate the effectiveness of the developed UEN. Extensive results show that the UEN holds the potential to serve as a complement to future underwater wireless sensor networks.
Source
BIOINSPIRATION & BIOMIMETICS
Volume17Issue6
DOI10.1088/1748-3190/ac8859
2022Äê12ÔÂ
Concise Biosynthesis of Tropone-Containing Spiromaterpenes by a Sesquiterpene Cyclase and a Multifunctional P450 from a Deep-Sea-Derived Spiromastix sp. Fungus
Jie Liu, Xiang Guo, Xingchen Guo, Boyuan Zhong, Tao Wang, Dong Liu, Hongwei Jin, Jinwei Ren, Zihe Liu, Jiangtao Gao, Shu-Ming Li, Aili Fan*, Wenhan Lin*
Abstract
Spiromaterpenes are a group of rare troponecontaining sesquiterpenes with antineuroinflammatory activity. Herein, we elucidate their biosynthetic pathway in a deep-sea-derived Spiromastix sp. fungus by heterologous expression, biochemical characterization, and incubation experiments. The sesquiterpene cyclase SptA was first characterized to catalyze the production of guaia-1(5),6-diene, and a multifunctional cytochrome P450 catalyzed the tropone ring formation. These results provide important clues for the rational mining of bioactive guaiane-type sesquiterpenes and expand the repertoire of P450 activities to synthesize unique building blocks of natural products.
Source
JOURNAL OF NATURAL PRODUCTS
Volume85Issue12Page2723-2730
DOI10.1021/acs.jnatprod.2c00614
2022Äê12ÔÂ
Versicotide G suppresses osteoclastogenesis and prevents osteolysis
He Zhang, Ying Kang, Xinyi Qi, Jingshuai Wu, Dong Liu, Aili Fan, Jian Huang, Wenhan Lin
Abstract
Excessive formation and function of osteoclasts cause various osteolytic bone diseases. Natural products are a potential source for the discovery of new therapeutic candidates to treat bone destruction diseases. In this study, chemical informatics and bioassay guided examination of the marine-derived Aspergillus versicolor F77 fungus chemically resulted in the isolation of seven cyclopeptides, of which versicotides G-J (1-4) are new cyclohexapeptides. Their structures were identified by spectroscopic data in association with Marfey method and single crystal X-ray diffraction data for configurational assignments. Bioassay revealed that versicotide G (1, VG) is the most active among the analogs to suppress the receptor activator of nuclear factor-KB ligand (RANKL)-induced osteoclastogenesis in bone marrow derived monocytes (BMMs) without affecting BMMs viability. VG also suppressed RANKL-induced actin-ring formation and resorbing function of osteoclast dose-dependently. Mechanistically, VG attenuated RANKL-induced intracellular calcium elevation by inhibiting PLC gamma 1 phosphorylation and blocking the activation of downstream phosphatase calcineurin. In addition, VG abrogated the expression and translocation of nuclear factor of activated T cells cytoplasmic-1 (NFATc1), leading to the downregulation of the expression of osteoclast-specific genes and the abolishment of the osteoclast formation. In the in vivo test, VG suppressed osteoclast formation and bone loss in Ti-induced calvarial osteolytic mouse model. These findings imply that VG is a promising candidate for the remedy of bone destruction-related diseases.
Source
BIOORGANIC CHEMISTRY
Volume129
DOI10.1016/j.bioorg.2022.106114
2022Äê12ÔÂ
A Fully 3D-Printed Tortoise-Inspired Soft Robot with Terrains-Adaptive and Amphibious Landing Capabilities
Mingxin Wu, Xiaoxian Xu, Qin Zhao, Waqar Hussain Afridi, Ningzhe Hou, Rahdar Hussain Afridi, Xingwen Zheng, Chen Wang, Guangming Xie
Abstract
Terrain adaptation and amphibious landing pose the greatest challenges for soft amphibious robots. Based on the principles of tortoises, this paper presents a fully 3D-printed soft amphibious robot with four pneumatic bionic legs that are capable of bending in three dimensions. The gaits of the robot are described in six different ways and a dynamic model is developed for its control. In addition to linear motion (0.97 BL s(-1)) and turning (25.4 degrees s(-1)) on rigid terrain, the robot can also maneuver on various surface conditions (such as hills, gaps, smooth slopes, gravel, sand, muddy terrain, and water), and even make an amphibious landing. These properties, together with the soft amphibious robot's continuous obstacle avoidance capabilities, high load-carrying capacity (28 times its own weight), low cost, and high camouflage, allow for a wide variety of applications.
Source
ADVANCED MATERIALS TECHNOLOGIES
Volume7Issue12
DOI10.1002/admt.202200536
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